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Rambaldini, D. A., i R. M. Brigham. "Pallid bat (Antrozous pallidus) foraging over native and vineyard habitats in British Columbia, Canada". Canadian Journal of Zoology 89, nr 9 (wrzesień 2011): 816–22. http://dx.doi.org/10.1139/z11-053.
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Optimal foraging theory predicts organisms will forage in habitats providing the most profitable prey. Human alterations to ecosystems may affect predators’ foraging activity by changing landscape features, prey types, and prey availability. Assessing the selection of foraging habitats in a heterogeneous landscape can provide data to improve land management and conservation policies. In Canada, the pallid bat ( Antrozous pallidus (LeConte, 1856); Vespertilionidae) is listed as threatened partly because of loss or modification of shrub–steppe habitat. Our purpose was to determine if vineyards provide a suitable surrogate for foraging habitat relative to native habitat. We used pitfall traps to compare prey abundance in each habitat and analyzed faeces to assess diet composition. Over 24 nights, we surveyed both habitats for foraging bats. Bats foraged over vineyards, but we recorded significantly more foraging activity over native habitat. We collected over 2000 arthropods in pitfall traps and found significantly more in native habitat compared with vineyards. Species eaten by pallid bats were present in both habitats. Scarab beetles (Coleoptera: Scarabidae) and Jerusalem crickets (Orthopthera: Stenopelmatidae) represented the principal prey. The use of vineyards by pallid bats for foraging suggests that while they are adapting to a changing landscape, reduced prey abundance in vineyards may negatively affect them over the long term.
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Wei, Zhenhua, Meng Zheng, Lizhi Zhou i Wenbin Xu. "Flexible Foraging Response of Wintering Hooded Cranes (Grus monacha) to Food Availability in the Lakes of the Yangtze River Floodplain, China". Animals 10, nr 4 (27.03.2020): 568. http://dx.doi.org/10.3390/ani10040568.
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Wetlands are disappearing or degrading at an unprecedented rate due to the increase in human encroachment and disturbance, eventually leading to habitat loss for waterbirds, which is the primary cause of the decline in the Hooded Crane (Grus monacha) population. The Hooded Cranes have to constantly adjust their foraging strategies to survive to cope with this situation. In order to study how cranes respond to food resources in mosaic habitat, we surveyed a total of 420 food quadrats and 736 behavioral samples from three habitats during three wintering periods in Shengjin Lake and Caizi Lake. We measured temporal and between-habitat differences in foraging time budget, foraging frequency, and foraging success rate. Akaike’s information criterion was selected between the models of food abundance and availability. The results indicated that the wintering cranes spent the majority of their time (66.55%) foraging and shifted their foraging behaviors based upon food abundance and availability in different habitats. Our analyses also indicated that cranes were willing to forage more food with poor sediment penetrability in sub-optimal habitats. Foraging time budget was based on the food depth, and the foraging frequency and foraging success rate were based on food abundance. Cranes adopted flexible foraging strategies in response to the alternative food resources in mosaic wetland habitats, as it could mitigate the negative impacts of habitat loss and facilitate survival.
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Kuhn, C. E., R. R. Ream, J. T. Sterling, J. R. Thomason i R. G. Towell. "Spatial segregation and the influence of habitat on the foraging behavior of northern fur seals (Callorhinus ursinus)". Canadian Journal of Zoology 92, nr 10 (październik 2014): 861–73. http://dx.doi.org/10.1139/cjz-2014-0087.
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Central place foraging by colonial breeders can lead to depleted prey resources around breeding areas. Segregation of foraging areas both within and between large colonies may act as a mechanism to reduce competition for prey resulting in increased foraging success. We reassessed horizontal (spatial) foraging habitat segregation for northern fur seals (Callorhinus ursinus (L., 1758)) within and between colonies on the Pribilof Islands, Alaska (St. Paul and St. George islands), after the population declined by approximately 40%. Additionally, we examined vertical habitat segregation, where foraging ranges overlapped, and describe the influence of different foraging habitats on northern fur seal dive behavior. Spatial habitat segregation in northern fur seal foraging areas occurred between islands but was variable within islands, which is similar to the pattern previously described. There was no evidence for vertical habitat segregation when fur seals from different rookeries on St. George Island used the same foraging area. Additionally, fur seals from St. Paul Island rookeries that foraged in similar habitats showed fewer differences in dive behavior, indicating that foraging habitat plays a significant role in shaping dive behavior. The use of multiple foraging strategies within the Pribilof Island fur seal population could indicate that a complex management and conservation strategy may be necessary to stop the continuing decline of this population.
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Putera, Alexander Kurniawan Sariyanto, Dyah Perwitasari-Farajallah, Yeni Aryati Mulyani, Stanislav Lhota, Riki Herliansyah i Sodikin Sodikin. "Waterbird Foraging Habitat Selection in Balikpapan Bay: Water Depth and Patch Area as Important Factors". HAYATI Journal of Biosciences 28, nr 4 (29.09.2021): 312–24. http://dx.doi.org/10.4308/hjb.28.4.312-324.
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Balikpapan Bay is one of the wetlands providing potential foraging habitat for waterbirds in Indonesia. Potential habitat loss due to oil industry expansion, recent waterbird occurrence, and co-occurrence of two closely related species with similar foraging characteristics led to habitat selection. Habitat selection could be affected by food as an intrinsic factor and extrinsic factor, for example, accessibility to the physical and biological components of the habitat. This study aimed to measure the foraging habitat selection, identify significant habitat quality parameters for the habitat selection and predict the foraging habitat selection model. We used one-zero sampling for collecting foraging habitat selection data, corer sampling for prey data, and collecting the abiotic environment, and Generalized Linear Modelling (GLM) to build the model. We identified four species as the migrant Little Egret (Egretta garzetta), Great Egret (Ardea alba), Purple Heron (Ardea purpurea), and Lesser Adjutant (Leptoptilos javanicus). All species, except Purple Heron, selected foraging habitats. A simple mathematic model of foraging habitat selection was significantly affected by two factors: water depth and patch area. A large patch area may provide primary prey abundance for waterbirds, while a low water depth level may give easy access to the prey.
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Lombardini, Katia, Robert E. Bennetts i Christophe Tourenq. "Foraging Success and Foraging Habitat Use by Cattle Egrets and Little Egrets in the Camargue, France". Condor 103, nr 1 (1.02.2001): 38–44. http://dx.doi.org/10.1093/condor/103.1.38.
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Abstract We examined habitat use by Little Egrets (Egretta garzetta) and Cattle Egrets (Bubulcus ibis) that nest together in mixed-species colonies in the Camargue of southern France. We explored the relative use of seven habitat types in relation to their availability and tested the hypothesis that selection of habitat types was related to foraging success, with the prediction that increased foraging success in a given habitat corresponded with increased use of that habitat type. Ricefields and other agricultural habitats were used more than expected by Cattle Egrets, an invasive species in southern Europe; whereas Little Egrets, which are native to the Camargue, tended to select natural freshwater marshes and lagoons. Results were consistent with the hypothesis that increasing use of habitats corresponded with higher foraging success for both species. However, when this analysis was restricted to habitats with sufficient numbers of birds to enable estimates of biomass intake, the association was no longer apparent for Little Egrets.
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BUIJ, RALPH, NIKIE VAN DORST, HENRIËTTE F. SALOMONS, BARBARA M. CROES, MAURINE W. DIETZ i JAN KOMDEUR. "Response to habitat modification by foraging Dark-chanting Goshawks Melierax metabates in a West African savanna". Bird Conservation International 25, nr 3 (11.12.2014): 335–52. http://dx.doi.org/10.1017/s0959270914000112.
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SummaryAnthropogenic habitat alteration has probably contributed significantly to the decrease of raptor populations in West African savannas. To evaluate the impact of habitat degradation on foraging by sedentary Afrotropical raptors, we investigated the differences in microhabitat selection, foraging effort and energy returns between Dark-chanting Goshawks Melierax metabates inhabiting natural and transformed savannas in Cameroon. We expected that the agro-ecosystems in the transformed savannas have become unprofitable for Dark-chanting Goshawks due to scarcity of food resources. In both savanna types we radio-tracked six mated, adult males during the non-breeding season and determined foraging effort, by time spent at each perch and distance covered between perches, and energy intake through estimation of the energy value of prey items. Goshawks in natural habitats had smaller home-ranges and exploited their range more intensively than Goshawks in transformed habitats. In both natural and transformed habitats, Goshawks selected foraging patches with comparatively tall trees, underlining their importance to foraging Goshawks. The extent of shrub and herbaceous layer cover, agriculture cover, and tree density were other important predictors of foraging patch use, but their importance differed between habitats. The extent of shrub, herbaceous layer and agriculture cover were positively associated with foraging patch use in transformed habitats, suggesting that cultivated fields and ground vegetation support important prey resources for Goshawks in agro-ecosystems. The composition of broad prey categories to the diet, foraging effort and returns were comparable between habitats. However, we found indications that the proportion of heavy-bodied lizard species among reptile prey items was higher in natural than transformed habitats, whereas on average smaller lizards were more commonly caught in the latter. Mean herbaceous layer height and tree density within home ranges, both higher in natural habitat, were negatively related to prey capture rates. Tree clearance and livestock grazing thus favored greater prey capture rates in transformed habitat, offsetting a lower meal energy value compared to natural habitat. We conclude that foraging Dark-chanting Goshawks may cope with moderate land transformation, but practices focused on conservation of tall trees and ground vegetation cover would be beneficial by maintaining important prey resources and their exploitability under growing land pressure.
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Kirk, Molly K., Daniel Esler i W. Sean Boyd. "Foraging effort of Surf Scoters (Melanitta perspicillata) wintering in a spatially and temporally variable prey landscape". Canadian Journal of Zoology 85, nr 12 (grudzień 2007): 1207–15. http://dx.doi.org/10.1139/z07-105.
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We monitored foraging effort of radio-tagged Surf Scoters (Melanitta perspicillata (L., 1758)) in three different habitats: (1) shellfish farm structures with high densities of mussels and strong seasonal prey depletion, (2) soft-bottom clam beds with more stable but less available prey, and (3) rocky intertidal beds with moderate mussel densities and depletion rates. We predicted that foraging effort would vary uniquely by habitat, with effort increasing more where depletion was strongest. However, variation in both hourly and daily foraging efforts was best explained by date only. Effort per hour was lowest in early December (presumably owing to very high prey abundance), increased until mid-February as prey declined, and then decreased again in March (probably owing to increased daylight time for foraging). Foraging effort estimated over a full day increased steadily from December to March as prey were depleted. Temporal patterns of effort did not vary by habitat after accounting for seasonal effects. Instead of increasing foraging effort in habitats with strong depletion, Surf Scoters redistributed to habitats with lower degrees of prey reduction as the season progressed. We suggest that Surf Scoters respond to variation in prey by adjusting both foraging effort and habitat selection as the prey landscape changes.
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Groff, Luke A., Aram J. K. Calhoun i Cynthia S. Loftin. "Amphibian terrestrial habitat selection and movement patterns vary with annual life-history period". Canadian Journal of Zoology 95, nr 6 (czerwiec 2017): 433–42. http://dx.doi.org/10.1139/cjz-2016-0148.
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Identification of essential habitat is a fundamental component of amphibian conservation; however, species with complex life histories frequently move among habitats. To better understand dynamic habitat use, we evaluated Wood Frog (Lithobates sylvaticus (LeConte, 1825)) habitat selection and movement patterns during the spring migration and foraging periods and described the spatiotemporal variability of habitats used during all annual life-history periods. We radio-tracked 71 frogs in Maine during 2011–2013 and evaluated spring migration, foraging activity center (FAC), and within-FAC habitat selection. Telemetered frogs spent the greatest percentage of each field season in hibernacula (≥54.4%), followed by FACs (≥25.5%), migration habitat (≥16.9%), and breeding sites (≥4.5%). FACs ranged 49 – 1 335 m2 (568.0 ± 493.4 m2) and annual home ranges spanned 1 413 – 32 165 m2 (11 780.6 ± 12 506.1 m2). During spring migration, Wood Frogs exhibited different movement patterns (e.g., turn angles), selected different habitat features, and selected habitat features less consistently than while occupying FACs, indicating that the migration and foraging periods are ecologically distinct. Habitat-use studies that do not discriminate among annual life-history periods may obscure true ecological relationships and fail to identify essential habitat necessary for sustaining amphibian populations.
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Moe, T. F., J. Kindberg, I. Jansson i J. E. Swenson. "Importance of diel behaviour when studying habitat selection: examples from female Scandinavian brown bears (Ursus arctos)". Canadian Journal of Zoology 85, nr 4 (kwiecień 2007): 518–25. http://dx.doi.org/10.1139/z07-034.
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The goal of habitat selection studies is to identify important habitats for a particular species. However, most studies using radiotelemetry have focused on habitat-selection patterns using daytime positions only. We used 24 h data from six female brown bears ( Ursus arctos L., 1758) equipped with GPS–GSM collars and activity loggers to analyse variations in habitat selection related to diel variations in activity (foraging and resting). We found that the bears rested mainly during the daylight hours and foraged mainly during the crepuscular and nocturnal hours. The bears selected habitats differently when they were resting than when they were foraging. We found no selection for tall coniferous forest using all data, but this habitat was selected by resting bears and avoided by foraging bears. Thus, for studies of habitat selection, our results show the importance of obtaining data from all 24 h and dividing these data into relevant categories based on the diel activity pattern of the studied species.
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Robinson, D. "Habitat use and foraging behaviour of the scarlet robin and the flame robin at a site of breeding-season sympatry". Wildlife Research 19, nr 4 (1992): 377. http://dx.doi.org/10.1071/wr9920377.
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The habitat selection and foraging ecology of scarlet robins (Petroica multicolor) and flame robins (Petroica phoenicea) were observed for three years at a site of breeding-season sympatry in order to examine seasonal patterns of foraging behaviour, habitat and resource use, and the significance of competition for food as a cause of interspecific aggression. Both species occupied habitats with open ground layers of grass or bark, and a sparse shrub-and-sapling layer. Flame robins occupied more mesic habitats; scarlet robins occurred in drier habitats. Seven habitat variables provided 73% separation between habitats occupied by the two species of robin. Both species foraged mostly on the ground during the cooler months. In summer and autumn, scarlet robins became snatchers of arthropods from bark and foliage substrates, and flame robins hawked for flying insects close to the ground. High overlap between their use of available foraging space, especially vertical foraging space, probably caused interspecific competition for food and space, leading to interspecific aggression and territorial behaviour. Such competition, in conjunction with the flame robin's interspecific dominance and apparently greater resilience to practices such as timber harvesting, may cause long-term changes to the distribution and relative abundance of each species. Recommendations for habitat management are considered briefly.
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Belovsky, Gary E. "Insights for caribou/reindeer management using optimal foraging theory". Rangifer 11, nr 4 (1.10.1991): 7. http://dx.doi.org/10.7557/2.11.4.987.
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Optimal foraging theory is useful to wildlife managers, because it helps explain the nutritional value of different habitats for wildlife species. Based upon nutritional value, the use of different habitats can be predicted, including how factors such as insect harassment, predation and migration might modify habitat selection. If habitat value and use can be understood, then changes in habitat availability which are of concern to wildlife managers can be assessed. The theory is used to address diet choice and habitat use of caribou/reindeer. Diet choice is examined in terms of lichen composition of the diet and is demonstrated to be a function of daily feeding time, food abundance and digestive capacity. The diet choice model is then used to assess the nutritional profitability of different habitats and which habitat should be preferred based upon nutritional profitability. Caribou/reindeer use of habitats is demonstrated to be easily modified by insect harassment and predation which change the nutritional profitability of habitats differentially. The same type of approach could be used to explain migratory behaviour; however, the needed parameter values are unavailable. The results of this analysis lead one to question some common conceptions about caribou/reindeer ecology.
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Beilharz, Lisa V., i Desley A. Whisson. "Habitat selection by two sympatric rodent species in an alpine resort". Australian Journal of Zoology 64, nr 5 (2016): 327. http://dx.doi.org/10.1071/zo16078.
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Conservation of small mammal species relies on an understanding of their habitat use. We used trapping surveys and telemetry to examine habitat selection and use by the broad-toothed rat (Mastacomys fuscus mordicus) and the bush rat (Rattus fuscipes) in an alpine resort in Victoria. M. fuscus occurred at low numbers, nesting in subalpine wet heathland and foraging in that habitat as well as small patches of disturbed woodland. In contrast, R. fuscipes was more common and nested in woodlands. Although foraging primarily in woodlands, R. fuscipes also foraged in all other available habitats. Both species showed strong selection for woodland fragments within ski runs. Although highly disturbed, these habitats may provide important habitat and connectivity between less disturbed and larger habitat patches.
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Yabsley, Samantha H., Jessica Meade, John M. Martin i Justin A. Welbergen. "Human-modified landscapes provide key foraging areas for a threatened flying mammal: The grey-headed flying-fox". PLOS ONE 16, nr 11 (1.11.2021): e0259395. http://dx.doi.org/10.1371/journal.pone.0259395.
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Urban expansion is a major threat to natural ecosystems but also creates novel opportunities that adaptable species can exploit. The grey-headed flying-fox (Pteropus poliocephalus) is a threatened, highly mobile species of bat that is increasingly found in human-dominated landscapes, leading to many management and conservation challenges. Flying-fox urbanisation is thought to be a result of diminishing natural foraging habitat or increasing urban food resources, or both. However, little is known about landscape utilisation of flying-foxes in human-modified areas, and how this may differ in natural areas. Here we examine positional data from 98 satellite-tracked P. poliocephalus for up to 5 years in urban and non-urban environments, in relation to vegetation data and published indices of foraging habitat quality. Our findings indicate that human-modified foraging landscapes sustain a large proportion of the P. poliocephalus population year-round. When individuals roosted in non-urban and minor-urban areas, they relied primarily on wet and dry sclerophyll forest, forested wetlands, and rainforest for foraging, and preferentially visited foraging habitat designated as high-quality. However, our results highlight the importance of human-modified foraging habitats throughout the species’ range, and particularly for individuals that roosted in major-urban environments. The exact plant species that exist in human-modified habitats are largely undocumented; however, where this information was available, foraging by P. poliocephalus was associated with different dominant plant species depending on whether individuals roosted in ‘urban’ or ‘non-urban’ areas. Overall, our results demonstrate clear differences in urban- and non-urban landscape utilisation by foraging P. poliocephalus. However, further research is needed to understand the exact foraging resources used, particularly in human-modified habitats, and hence what attracts flying-foxes to urban areas. Such information could be used to modify the urban foraging landscape, to assist long-term habitat management programs aimed at minimising human-wildlife conflict and maximising resource availability within and outside of urban environments.
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Jha, Shalene, i John H. Vandermeer. "Contrasting foraging patterns for Africanized honeybees, native bees and native wasps in a tropical agroforestry landscape". Journal of Tropical Ecology 25, nr 1 (styczeń 2009): 13–22. http://dx.doi.org/10.1017/s026646740800566x.
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Abstract:Ecological and temporal factors can influence animal foraging patterns and may obscure our understanding of how native and exotic species interact. To understand how such factors affect foraging, the visitation of native and exotic bees and wasps was observed at nectar feeders within Mexican agroforestry systems, while documenting (1) vegetation management (low-shade vs. high-shade coffee), (2) light and floral resource levels and (3) recruiting ability, as measured by the change in visitation between two consecutive experimental days. On day one, Africanized honeybee visitation was significantly greater in low-shade habitats, and native solitary bee abundance was significantly greater in high-shade habitats, while native social bee and solitary wasp visitation were not significantly different between habitat types. After 24 h, Africanized honeybee visitation increased significantly in both habitat types, while native social bee visitation increased significantly only in high-shade coffee. In contrast, native solitary bee and native solitary wasp visitation decreased in both habitat types. Overall, this study reveals that Africanized honeybees exhibit only initial foraging preference for low-shade habitats, while native bees exhibit both initial and delayed recruitment-based foraging preferences for high-shade habitats.
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Gallant, Daniel, Lisa Léger, Éric Tremblay, Dominique Berteaux, Nicolas Lecomte i Liette Vasseur. "Linking time budgets to habitat quality suggests that beavers (Castor canadensis) are energy maximizers". Canadian Journal of Zoology 94, nr 10 (październik 2016): 671–76. http://dx.doi.org/10.1139/cjz-2016-0016.
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According to optimal foraging theory, consumers make choices that maximize their net energy intake per unit of time. We used foraging theory as a framework to understand the foraging behaviour of North American beavers (Castor canadensis Kuhl, 1820), an important herbivore that engineers new habitats. We tested the hypothesis that beavers are energy maximizers by verifying the prediction that they allocate time to foraging activities independently of habitat quality in Kouchibouguac National Park of Canada in New Brunswick, where nearly five decades of unabated colonization by beavers led to family units established in habitats of varying quality. We observed the behaviour of 27 beavers at seven ponds from May to August 2001, at dusk and dawn. Habitat quality did not influence time that beavers allocated to foraging. This finding supported our hypothesis. The only factor in the best model explaining time spent foraging was the progression of spring and summer seasons (weekly periods). Limiting factors such as infrastructure maintenance and intermittent reactions to danger remain poorly understood for this important herbivore. Future research should focus on establishing the importance that habitat quality (food availability) and environmental stress (weather, predators) have on shaping its time budget and, consequently, its survival and reproductive success.
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Prior, Bonita, David T. Booth i Colin J. Limpus. "Investigating diet and diet switching in green turtles (Chelonia mydas)". Australian Journal of Zoology 63, nr 6 (2015): 365. http://dx.doi.org/10.1071/zo15063.
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Understanding the dietary ecology of animals provides information about their habitat requirements, facilitating informed conservation. We used last-bite diet and stable isotope analysis to assess the diet of juvenile and adult green turtles (Chelonia mydas) at two different habitats located 10 km apart within Port Curtis, Queensland, Australia. Last-bite diet analysis indicated that turtles had distinctly different diets in these two habitats: in one the diet was dominated by red macroalgae and in the other the diet was dominated by seagrass. Only juveniles (n = 12) were caught in the habitat where red macroalgae dominated the diet, while both juveniles (n = 9) and adults (n = 38) were captured in the habitat where seagrass dominated the diet. In the seagrass habitat there was no difference in diet between juveniles and adults, and no difference in diet between adult males (n = 17) and females (n = 21). Because the red macroalgae and seagrass had distinctly different carbon stable isotope ratios, it was possible to detect a change in diet by comparing the carbon stable isotope ratio between serum and epidermal tissue sampled from the same turtle. In this region, a switch in diet would reflect a shift in foraging habitat. Such comparisons indicate that ~50% of turtles switched diet, and therefore changed foraging habitat between the time when blood serum and epidermis were formed. This implies that switching foraging habitat by green turtles within this region is a common occurrence, which is somewhat surprising because previously it was thought that foraging green turtles had high site fidelity with relatively small home ranges.
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Lyons, James E. "Habitat-Specific Foraging of Prothonotary Warblers: Deducing Habitat Quality". Condor 107, nr 1 (1.02.2005): 41–49. http://dx.doi.org/10.1093/condor/107.1.41.
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Abstract Foraging behavior often reflects food availability in predictable ways. For example, in habitats where food availability is high, predators should attack prey more often and move more slowly than in habitats where food availability is low. To assess relative food availability and habitat quality, I studied the foraging behavior of breeding Prothonotary Warblers (Protonotaria citrea) in two forest habitat types, cypress-gum swamp forest and coastal-plain levee forest. I quantified foraging behavior with focal animal sampling and continuous recording during foraging bouts. I measured two aspects of foraging behavior: 1) prey attack rate (attacks per minute), using four attack maneuvers (glean, sally, hover, strike), and 2) foraging speed (movements per minute), using three types of movement (hop, short flight [≤1 m], long flight [>1 m]). Warblers attacked prey more often in cypress-gum swamp forest than in coastal-plain levee forest. Foraging speed, however, was not different between habitats. I also measured foraging effort (% time spent foraging) and relative frequency of attack maneuvers employed in each habitat; neither of these variables was influenced by forest type. I conclude that Prothonotary Warblers encounter more prey when foraging in cypress-gum swamps than in coastal-plain levee forest, and that greater food availability results in higher density and greater reproductive success for birds breeding in cypress-gum swamp. Conductas de Alimentación Específicas según el Hábitat en Protonotaria citrea: Deduciendo la Calidad del Hábitat Resumen. La conducta de alimentación a menudo refleja la disponibilidad de alimento de maneras previsibles. Por ejemplo, en los hábitats donde la disponibilidad de alimento es alta, los depredadores deberían atacar presas más a menudo y moverse más lentamente que en los hábitats donde la disponibilidad de alimento es baja. Estudié la conducta de alimentación de Protonotaria citrea durante la época reproductiva en dos tipos de hábitats boscosos, el bosque pantanoso de ciprés-gomero y el bosque plano costero de albardón, para evaluar la disponibilidad relativa de alimento y la calidad de hábitat. Cuantifiqué la conducta de alimentación mediante muestreos focales y grabaciones continuas mientras las aves se alimentaban. Medí dos aspectos de dicha conducta: 1) la tasa de ataque a presas (ataques por minuto), utilizando cuatro maniobras de ataque (desplazarse sobre un sustrato recogiendo presas, vuelo desde una percha para atrapar las presas en el aire, vuelo suspendido, y otra maniobra de revoloteo), y 2) la velocidad (movimientos por minuto), utilizando tres tipos de movimiento (salto, vuelo corto [≤1 m], vuelo largo [>1 m]). Los individuos de P. citrea atacaron presas más a menudo en el bosque pantanoso de ciprés-gomero que en el bosque plano costero de albardón. La velocidad de alimentación, sin embargo, no fue diferente entre hábitats. Medí también el esfuerzo (% del tiempo utilizado en forrajear) y la frecuencia relativa de maniobras de ataque empleadas en cada hábitat; ninguna de estas variables fue influenciada por el tipo bosque. Concluyo que los individuos de P. citrea encuentran más presas cuando se alimentan en pantanos de ciprés-gomero que en el bosque plano costero de albardón, y que una mayor disponibilidad de alimento se traduce en una mayor densidad y en un éxito reproductivo más alto para las aves de los bosques pantanosos de ciprés-gomero.
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Candolin, Ulrika, i Marita Selin. "Density-Dependent Habitat Selection in a Growing Threespine Stickleback Population". International Journal of Zoology 2012 (2012): 1–6. http://dx.doi.org/10.1155/2012/378913.
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Human-induced eutrophication has increased offspring production in a population of threespine sticklebackGasterosteus aculeatusin the Baltic Sea. Here, we experimentally investigated the effects of an increased density of juveniles on behaviours that influence survival and dispersal, and, hence, population growth—habitat choice, risk taking, and foraging rate. Juveniles were allowed to choose between two habitats that differed in structural complexity, in the absence and presence of predators and conspecific juveniles. In the absence of predators or conspecifics, juveniles preferred the more complex habitat. The preference was further enhanced in the presence of a natural predator, a perchPerca fluviatilis(behind a transparent Plexiglas wall). However, an increased density of conspecifics relaxed the predator-enhanced preference for the complex habitat and increased the use of the open, more predator-exposed habitat. Foraging rate was reduced under increased perceived predation risk. These results suggest that density-dependent behaviours can cause individuals to choose suboptimal habitats where predation risk is high and foraging rate low. This could contribute to the regulation of population growth in eutrophicated areas where offspring production is high.
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Warkentin, Ian G., Allison L. Fisher, Stephen P. Flemming i Shawn E. Roberts. "Response to clear-cut logging by northern waterthrushes". Canadian Journal of Forest Research 33, nr 5 (1.05.2003): 755–62. http://dx.doi.org/10.1139/x03-002.
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We examined the distribution and foraging behaviour of northern waterthrushes (Seiurus noveboracensis) in recently harvested and intact landscapes of Newfoundland. Data were collected along six 1-km segments of stream and adjoining upland habitat resulting in four treatments (harvested or intact, upland or stream) with three replicates each. Although known as a riparian specialist, we found waterthrush territories equally distributed across intact upland and riparian habitats. However, few waterthrushes occupied harvested uplands, while large numbers packed into riparian buffer strips adjacent to these 5- to 10-year-old postharvest clearcuts. Arthropod abundance and biomass were highly variable between years and across the four treatments, generating significant year × treatment interaction effects. Riparian habitat (in both intact and harvested areas) had consistently greater numbers of arthropod prey and more biomass than either upland habitat type. Northern waterthrushes foraging in riparian habitat adjacent to harvested uplands had lower attack rates and more frequent long flights than waterthrushes foraging in the intact treatment types. Prolonged packing of individuals into riparian buffer strips, and apparent adverse affects on waterthrush foraging efficiency, raise concerns about the effectiveness of buffer strips for sustaining viable populations of terrestrial riparian habitat specialists.
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Kieffer, J. D., i P. W. Colgan. "Foraging Flexibility in Pumpkinseed (Lepomis gibbosus); Influence of Habitat Structure and Prey Type". Canadian Journal of Fisheries and Aquatic Sciences 50, nr 8 (1.08.1993): 1699–705. http://dx.doi.org/10.1139/f93-191.
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Foraging behaviour of pumpkinseed (Lepomis gibbosus) was investigated in feeding arenas containing different habitat structures and prey types in two sets of experiments, each of three successive 10-d blocks. (A) Two groups of eight foraged in open-water habitats on different prey items: group 1 was presented with prey in the order white worms, fruit flies, white worms and group 2 with fruit flies, white worms, fruit flies. Both capture rate and success increased with successive trials for both prey types, indicating that foraging efficiency increased with experience. Shifts from one prey type to another changed performance; however, overall foraging efficiency did not change dramatically when fish were shifted back to feeding on a previously encountered prey type. (B) Two groups of eight foraged on white worms: group 1 in the habitat order open water, structured, open water and group 2 in structured, open water, structured. Fish fed faster in an open-water habitat but were flexible in a structured habitat. When fish returned to feeding in a familiar habitat type, behavioural patterns were very flexible. The results of these two experiments show that the foraging behaviour of pumpkinseed is relatively sensitive to temporally and spatially separated prey and habitat types.
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Morris, Douglas W., i Sundararaj Vijayan. "Trade-offs between sight lines and escape habitat determine spatial strategies of risk management by a keystone herbivore". FACETS 3, nr 1 (1.10.2018): 338–57. http://dx.doi.org/10.1139/facets-2016-0062.
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Prey individuals possess four basic strategies to manage predation risk while foraging: time allocation, space use, apprehension, and foraging tenacity. But there are no direct tests of theory detailing how spatial strategies change and covary from fine to coarse scales of environmental variability. We address this shortcoming with experiments that estimated space use and vigilance of snowshoe hares while we measured foraging tenacity in artificial resource patches placed in risky open versus safe alder habitat. Hares employed only two of eight a priori options to manage risk. Hares increased vigilance and reduced foraging in open areas as the distance from cover increased. Hares did not differentiate between open and alder habitats, increase vigilance at the coarse-grained scale, or reduce vigilance and foraging tenacity under supplemental cover. Hares were more vigilant in the putatively safe alder than in the purportedly risky open habitat. These apparently paradoxical results appear to reflect a trade-off between the benefit of alder as escape habitat and the cost of obscured sight lines that reduce predator detection. The trade-off also appears to equalize safety between habitats at small scales and suggests that common-sense predictions detailing how prey reduce risk may make no sense at all.
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(Gentry) Richardson, Katherine E., Daniel P. Roche, Stephen G. Mugel, Nolan D. Lancaster, Kathryn E. Sieving, Todd M. Freeberg i Jeffrey R. Lucas. "Social dynamics of core members in mixed-species bird flocks change across a gradient of foraging habitat quality". PLOS ONE 17, nr 2 (2.02.2022): e0262385. http://dx.doi.org/10.1371/journal.pone.0262385.
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Social associations within mixed-species bird flocks can promote information flow about food availability and provide predator avoidance benefits. The relationship between flocking propensity, foraging habitat quality, and interspecific competition can be altered by human-induced habitat degradation. Here we take a close look at sociality within two ecologically important flock-leader (core) species, the Carolina chickadee (Poecile carolinensis) and tufted titmouse (Baeolophus bicolor), to better understand how degradation of foraging habitat quality affects mixed-species flocking dynamics. We compared interactions of free ranging wild birds across a gradient of foraging habitat quality in three managed forest remnants. Specifically, we examined aspects of the social network at each site, including network density, modularity, and species assortativity. Differences in the social networks between each end of our habitat gradient suggest that elevated levels of interspecific association are more valuable in the habitat with low quality foraging conditions. This conclusion is supported by two additional findings: First, foraging height for the subordinate Carolina chickadee relative to the tufted titmouse decreased with an increase in the number of satellite species in the most disturbed site but not in the other two sites. Second, the chickadee gargle call rate, an acoustic signal emitted during agonistic encounters between conspecifics, was relatively higher at the high-quality site. Collectively, these results suggest an increase in heterospecific associations increases the value of cross-species information flow in degraded habitats.
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Lisson, Amanda, Kathryn H. Taffs i Leslie Christidis. "Mapping foraging habitat for migratory shorebirds in their Australian non-breeding grounds and prioritising sites for conservation and management". Pacific Conservation Biology 23, nr 1 (2017): 32. http://dx.doi.org/10.1071/pc16011.
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Shorebird populations are declining worldwide as a result of the loss of the intertidal habitats upon which they depend. Conservation status is particularly dire for shorebirds on the East Asian–Australasian Flyway. While the flyway transects many international boundaries and involves numerous bilateral conservation agreements, management of remaining habitat at a local scale is imperative to conserving these species. Coastal habitat is affected by multiple anthropogenic stressors, including loss and degradation due to increasing demand for coastal land. In Australia, migration coincides with the summer holiday season when shorebirds are significantly impacted by human disturbance. Managers are frequently required to make trade-offs between wildlife conservation and anthropogenic land uses and when specific quantitative shorebird habitat data and mapping are absent, human interests will naturally take precedence. This paper demonstrates a method for mapping and prioritising management of shorebird non-breeding habitat using an Australian coastal site, the Richmond River estuary. Foraging habitat was surveyed and mapped using GIS with a range of attributes including habitat types, foraging values, disturbance levels and specific foraging distribution of each species. The results highlighted several important foraging areas that were impacted by disturbance and would require intervening management actions to reduce impacts on shorebirds. The GIS data created provide local managers with an effective tool to consider shorebird habitat in the decision-making process. This method could be replicated at other important shorebird habitat sites, leading to enhanced conservation of these declining species.
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Mahendiran, Mylswamy. "Coexistence of three sympatric cormorants ( Phalacrocorax spp.); partitioning of time as an ecological resource". Royal Society Open Science 3, nr 5 (maj 2016): 160175. http://dx.doi.org/10.1098/rsos.160175.
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Resource partitioning is well known along food and habitat for reducing competition among sympatric species, yet a study on temporal partitioning as a viable basis for reducing resource competition is not empirically investigated. Here, I attempt to identify the mechanism of temporal partitioning by intra- and interspecific diving analyses of three sympatric cormorant species at different freshwater wetlands around the Delhi region. Diving results indicated that cormorants opted for a shallow diving; consequently, they did not face any physiological stress. Moreover, diving durations were linked with seasons, foraging time and foraging habitats. Intraspecific comparison suggested that cormorants spent a longer time underwater in early hours of the day. Therefore, time spent for dive was higher in the forenoon than late afternoon, and the interspecific analysis also yielded a similar result. When Phalacrocorax niger and Phalacrocorax fuscicollis shared the same foraging habitat, they tended to differ in their foraging time (forenoon/afternoon). However, when P. niger and Phalacrocorax carbo shared the same foraging time, they tended to use different foraging habitats (lentic/lotic) leading to a mechanism of resource partitioning. Thus, sympatric cormorants effectively use time as a resource to exploit the food resources and successful coexistence.
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ENDO, CHIHIRO, i HISASHI NAGATA. "Seasonal changes of foraging habitats and prey species in the Japanese Crested Ibis Nipponia nippon reintroduced on Sado Island, Japan". Bird Conservation International 23, nr 4 (23.11.2012): 445–53. http://dx.doi.org/10.1017/s0959270912000457.
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SummarySeasonal foraging habitats, prey species and foraging frequency of Japanese Crested Ibis Nipponia nippon in farmland were studied one year after its reintroduction on Sado Island, Japan. Paddies were the main foraging habitat in spring, early summer, autumn and winter. In late summer, ibises often used levees around paddies, grasslands, uncropped paddies and abandoned paddies. Small invertebrates were important prey components in terms of frequency (70–90%) throughout the year. Ibises took Misgurnus loaches (less than 20% of prey captured) throughout the year; the capture rate of loaches in ditches was especially high in winter. Ibises depended on terrestrial invertebrates, including earthworms, particularly in late summer. No clear correlations between the rate of capture for each prey species and the proportion of habitat use in each season were detected. However, abandoned and uncropped paddies provided suitable habitats for the ibis because human disturbance was relatively low and the rate of capture for each prey type was relatively high throughout the year. Management of grass height in grasslands and on levees around the paddies will be effective in ensuring the availability of foraging habitats in late summer. Seasonal changes in the availability of foraging habitats in farmland ecosystems should be considered when designing effective management strategies for the establishment of Japanese Crested Ibis populations.
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Strong, Allan M. "Divergent Foraging Strategies of Two Neotropical Migrant Warblers: Implications for Winter Habitat Use". Auk 117, nr 2 (1.04.2000): 381–92. http://dx.doi.org/10.1093/auk/117.2.381.
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Abstract To address whether foraging strategies affect habitat-use patterns of nonbreeding warblers, I quantified foraging behavior, bill dimensions, and diet (based on regurgitation samples) of Ovenbirds (Seiurus aurocapillus) and Swainson's Warblers (Limnothlypis swainsonii) wintering in three habitats in Jamaica. Ovenbirds primarily gleaned prey from the surface of the leaf litter (95% of foraging maneuvers), resulting in a diet comprised predominantly of ants (62% of all prey items), seeds (18%), and beetles (9%). Swainson's Warblers foraged by lifting leaves (80% of foraging maneuvers), resulting in a significantly different diet dominated by beetles (39%), spiders (22%), and ants (19%). More than 60% of the regurgitation samples from Swainson's Warblers contained orthopterans and/or gecko (Sphaerodactylus goniorhynchus) bones. Averaged across all habitat types, Ovenbirds consumed ants in direct proportion to their abundance based on visual counts of arthropods. Swainson's Warblers consumed beetles more than expected based on the abundance of beetles in visual counts and Berlese funnels. The use of a diversity of habitats by Ovenbirds may be related to their ability to feed opportunistically on ants, which are a widespread, abundant, and reliable resource. In contrast, based on their foraging behavior and diet, Swainson's Warblers may be restricted to habitats with a well-developed canopy and an abundant subsurface leaf-litter fauna.
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RODRÍGUEZ, CARLOS, LUIS TAPIA, EMANUEL RIBEIRO i JAVIER BUSTAMANTE. "Crop vegetation structure is more important than crop type in determining where Lesser Kestrels forage". Bird Conservation International 24, nr 4 (8.04.2013): 438–52. http://dx.doi.org/10.1017/s0959270913000129.
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SummaryWe studied foraging habitat selection by Lesser Kestrel Falco naumanni throughout the breeding period in south-west Spain by means of transects on which foraging observations were recorded. We focused on the effects of habitat and crop type, but also on the effect of vegetation structure and the presence of agricultural activities in the field on Lesser Kestrel use. We considered both the accumulated use of the foraging area during the breeding season and the instantaneous foraging habitat selection by kestrels. Foraging habitat selection was highly dynamic following crop development and agricultural activities. Almost all major arable crop types showed positive selection during some part of the breeding cycle. Accumulated use by kestrels demonstrated positive associations with wheat and cotton fields and negative selection of permanent habitat types, such as forested areas, woody crops and built-up areas that have no prey or are not used by the species due to unfavourable structure. Vegetation structure appears to play a major role in instantaneous foraging selection. Lesser Kestrels select fields with short vegetation and intermediate cover. They also forage on field margins and where agricultural activities such as ploughing or harvesting that facilitate access to prey are being conducted. Our results help to clarify apparent controversies among previous studies on the subject, highlighting the importance of the heterogeneity of agricultural landscapes around colonies (crops at different growth stages which provide variable vegetation height and cover during the breeding cycle) and the effect that agricultural activities have on facilitating access to prey. Beyond the species-specific approach, our work encourages further studies on habitat selection by farmland birds to account not only for human-based categorisation of habitats (e.g. crop type) but also on objective measures such as vegetation height and cover that influence access to prey and better reflect the high dynamism of agricultural landscapes.
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BURNHAM, JAMES, JEB BARZEN, ANNA M. PIDGEON, BAOTENG SUN, JIANDONG WU, GUANHUA LIU i HONGXING JIANG. "Novel foraging by wintering Siberian Cranes Leucogeranus leucogeranus at China’s Poyang Lake indicates broader changes in the ecosystem and raises new challenges for a critically endangered species". Bird Conservation International 27, nr 2 (9.01.2017): 204–23. http://dx.doi.org/10.1017/s0959270916000150.
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SummaryFollowing an abnormal flood in 2010 at China’s Poyang Lake, we observed wintering Siberian Cranes Leucogeranus leucogeranus switch from foraging in the shallow-water wetlands they typically use to grassland habitats. These previously undocumented habitat selection patterns raised questions whether differences in crane behaviour such as foraging success existed between the two habitats and how those differences might affect this critically endangered species. Over two winters, we used the density of customary food items (tubers of Vallisneria spp.) obtained from long-term monitoring efforts, Siberian Cranes flock behaviours, individual foraging success and estimated total flock foraging effort across both habitats. Novel foraging patterns by Siberian Cranes were associated with low densities of Vallisneria tubers across multiple sub-lakes within Poyang Lake National Nature Reserve (PLNR). Foraging success was higher in grasslands than in wetlands in winter 2010–2011, but higher in wetlands following a recovery of Vallisneria in 2011–2012. Subsequent to upland foraging during the winter of 2010–2011, we observed lower juvenile to adult ratio of Siberian Cranes at a fall migratory stopover location in north-eastern China despite indications of average environmental conditions in the nesting areas from 2010 to 2012. While grasslands adjacent to shallow-water habitats may be important refugia for wintering Siberian Cranes when Vallisneria is absent or inaccessible, and should be included in protected areas, multi-year dependence on grasslands for foraging could negatively impact population levels. Eliminating crab farming in protected areas and extending protection to shallow water areas sheltered from flooding by dykes could also help secure high quality foraging habitat under a variety of hydrological regimes. Novel foraging patterns by wintering Siberian Cranes represent a new challenge to the conservation efforts for this species that focus on shallow-water wetlands, and may be indicative of broader changes within Poyang’s ecosystem.
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Fujisaki, I., KM Hart, D. Bucklin, AR Iverson, C. Rubio, MM Lamont, RJ Gonzales Diaz Miron, PM Burchfield, J. Peña i DJ Shaver. "Predicting multi-species foraging hotspots for marine turtles in the Gulf of Mexico". Endangered Species Research 43 (22.10.2020): 253–66. http://dx.doi.org/10.3354/esr01059.
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Quantifying the distribution of animals and identifying underlying characteristics that define suitable habitat are essential for effective conservation of free-ranging species. Prioritizing areas for conservation is important in managing a geographic extent that has a high level of disturbance and limited conservation resources. We examined the potential use of a species distribution model ensemble for multi-species conservation in marine habitats. Using satellite telemetry locations during foraging as input data, and ensemble ecological niche models, we predicted foraging areas for 2 nesting marine turtle species within the Gulf of Mexico (GoM): Kemp’s ridley Lepidochelys kempii (n = 63) and loggerhead Caretta caretta (n = 63). We considered 7 geophysical, biological, and climatic variables and compared contributing factors for each species’ foraging habitat selection. For both species, predicted suitable foraging habitats encompassed large areas along the GoM coast, but only intersected with each other in relatively small areas. Highly parameterized models resulted in overall greater fits, suggesting that multiple factors influence habitat selection by these species. Model validation results were mixed: cross-validation resulted in high prediction accuracy for both species, but an evaluation against independent data resulted in a low omission rate (5%) for Kemp’s ridleys and a high omission rate (72%) for loggerheads. The relatively small intersection of model-predicted foraging areas for these 2 species within the study area may indicate possible niche differentiations. The high omission rate for loggerheads indicates our samples likely underrepresent the population and illustrates the challenges in predicting suitable foraging extents for species that make dynamic movements and have greater individual variability.
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Fontoura, Priscila Montes, i Mário Luis Orsi. "Ecological partitioning of three Columbidae species in Northern Paraná, Southern Brazil". Biota Neotropica 13, nr 3 (wrzesień 2013): 44–49. http://dx.doi.org/10.1590/s1676-06032013000300005.
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Three species of Columbidae (Columbina talpacoti,Columbina picui and Zenaida auriculata) were studied in Londrina, Northern Paraná (Brazil), with the aim of analyzing which foraging and habitat factors contribute to their ecological partitioning. The study was conducted over one year in three different areas (urban, rural and pasture). We made monthly observations of the foraging strategies used by the species and the habitats they selected. Possible variations in availability of resources over the twelve months of the study did not influence the type of foraging used by the three species. Significant differences between the foraging strategies used by the species were observed in relation to the foraging site, specifically the foraging substrate. Soil, grass and paving were the foraging substrates that were most used by all three species, indicating that they are ground-foraging birds. Differences in the time spent in the foraging areas were significant between species; Z. auriculata remained in the foraging area for the longest time, often foraging in a group, suggesting a possible adaptation of this species in order to obtain a greater amount of resources. Adapting to anthropological environments without continuous forest cover could be one of factors that the most influential in the selection of habitat by the three species of Columbidae. Principal Components Analysis (PCA) showed differences between the proportions of herbaceous and gramineae plants, paving, plantations and shrubs in the habitats selected by each species. We also concluded that differences in the time spent in the foraging areas and between foraging substrates are factors contributing to the ecological separation of the three species and therefore allowing their coexistence in the region.
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Hussey, Nigel E., Joseph D. DiBattista, Jonathan W. Moore, Eric J. Ward, Aaron T. Fisk, Steven Kessel, Tristan L. Guttridge i in. "Risky business for a juvenile marine predator? Testing the influence of foraging strategies on size and growth rate under natural conditions". Proceedings of the Royal Society B: Biological Sciences 284, nr 1852 (5.04.2017): 20170166. http://dx.doi.org/10.1098/rspb.2017.0166.
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Mechanisms driving selection of body size and growth rate in wild marine vertebrates are poorly understood, thus limiting knowledge of their fitness costs at ecological, physiological and genetic scales. Here, we indirectly tested whether selection for size-related traits of juvenile sharks that inhabit a nursery hosting two dichotomous habitats, protected mangroves (low predation risk) and exposed seagrass beds (high predation risk), is influenced by their foraging behaviour. Juvenile sharks displayed a continuum of foraging strategies between mangrove and seagrass areas, with some individuals preferentially feeding in one habitat over another. Foraging habitat was correlated with growth rate, whereby slower growing, smaller individuals fed predominantly in sheltered mangroves, whereas larger, faster growing animals fed over exposed seagrass. Concomitantly, tracked juveniles undertook variable movement behaviours across both the low and high predation risk habitat. These data provide supporting evidence for the hypothesis that directional selection favouring smaller size and slower growth rate, both heritable traits in this shark population, may be driven by variability in foraging behaviour and predation risk. Such evolutionary pathways may be critical to adaptation within predator-driven marine ecosystems.
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Kavanagh, RP. "Forest Phenology and Its Effect on Foraging Behavior and Selection of Habitat by the Yellow-Bellied Glider, Petaurus-Australis Shaw". Wildlife Research 14, nr 4 (1987): 371. http://dx.doi.org/10.1071/wr9870371.
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The foraging behaviour of the yellow-bellied glider was observed for more than 3 years in south-eastern New South Wales. The use of different substrates by foraging gliders followed an annual cycle which was correlated with the phenological pattern in the forest. Flowering and bark shedding on eucalypts were the characters of tree phenology most useful for predicting the behaviour of foraging animals. Gliders concentrated their foraging efforts on ephemeral food resources, particularly those obtained from under loose bark; this led to a seasonal pattern in the use of tree species and habitats in the study area. The preferred habitat of P. australis is likely to be characterised by a mosaic of tree-species associations, including those which flower in winter. Smooth-barked eucalypts are important because of the diversity of foraging substrates, and hence food resources, which they provide. The patchy distribution of these gliders may be explained by differences in floristic diversity and the complexity of the habitat mosaic.
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M. Pandian. "Studies on the habitats of Grey Francolin Francolinus pondicerianus (J.F. Gmelin, 1789) (Galliformes: Phasianidae) in northern districts of Tamil Nadu, India". Journal of Threatened Taxa 13, nr 13 (26.11.2021): 19948–55. http://dx.doi.org/10.11609/jott.6237.13.13.19948-19955.
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This paper pertains to the habitats of the Grey Francolin Francolinus pondicerianus with specific reference to populations, habitat type, vegetation, foraging, impact of human dwellings, and probable threats to populations in 20 villages covering four northern districts of Tamil Nadu, India. A total of 252 individuals were enumerated. During the non-breeding season, birds move in small groups of 2–6. Of four habitats identified, the maximum number of 143 birds was observed foraging in grasslands, while 61 were seen in dry fallow agricultural lands, 37 in dry lakes/canals, and 11 in harvested fields. No significant association was observed between habitat type and bird behaviour. They feed on termites and spilled paddy grains. Males have repeated loud calls and fight with each other. Four species of tall grasses, six of stunted trees and two shrubs were identified to provide bird habitat. Birds preferred to live away from human dwellings, with 193 found 1,000 m away from settlements. The study area continues to be a suitable habitat for Grey Francolin populations, hence this habitat needs protection.
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Masero, José A., i Alejandro Pérez-Hurtado. "Importance of the Supratidal Habitats for Maintaining Overwintering Shorebird Populations: How Redshanks Use Tidal Mudflats and Adjacent Saltworks in Southern Europe". Condor 103, nr 1 (1.02.2001): 21–30. http://dx.doi.org/10.1093/condor/103.1.21.
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Abstract The prey-size selection, foraging behavior, and intake rate of overwintering Redshanks (Tringa totanus) were studied in a supratidal-intertidal system with high intertidal densities of shorebirds (100 birds ha−1). For assessing the importance of the energy obtained in the supratidal habitat (saltworks), daily consumption in this habitat was compared with the total daily energy requirement. Redshanks passively select prey within a certain size range from those accessible on the intertidal area. Despite the high prey biomass on the mudflats, Redshanks exhibited a low intake rate during winter (0.321 kJ min−1). This low intake seems to be related to the influence of the high densities of foraging shorebirds on the behavior of prey. Although intake rate was higher in the saltworks, the majority of Redshanks did not choose to feed there in winter. This foraging pattern seems to be related to density-dependent effects in habitat occupancy, as social interactions could have kept Redshanks out of the saltworks in winter according to the predictions of the ideal-despotic model. Energy intake in the supratidal habitat contributed 23% and 82% of the total daily energy requirement in winter and the pre-migration period, respectively. Redshanks were able to meet the total daily energy requirement during the pre-migration period by increasing foraging time in the saltworks. The availability of supratidal foraging habitats seems to contribute significantly to the maintenance of the population of overwintering Redshanks.
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Zharikov, Yuri, i Gregory A. Skilleter. "Sex-specific intertidal habitat use in subtropically wintering Bar-tailed Godwits". Canadian Journal of Zoology 80, nr 11 (1.11.2002): 1918–29. http://dx.doi.org/10.1139/z02-178.
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Habitat use by sexually dimorphic Bar-tailed Godwits (Limosa lapponica) was examined in an Australian estuary during the midwintering (NovemberDecember) and premigratory (March) periods of a nonbreeding season. In an area with two available habitats, Zostera seagrass beds and unvegetated sand flats, males occurred almost exclusively in seagrass, whereas the females occurred at equal densities in both habitats. Estimates of intake rates seemed greater for individuals foraging in seagrass (0.1140.128 g dry mass (DM)·min1) than on sand (0.0640.087 g DM·min1). Males appeared less well adapted for foraging on sand than in seagrass, and the presence of females could interfere with males' foraging on sand. The reason for the equal distribution of the females between the habitats probably lies in the inability of one particular habitat to support the entire population of females. Little interhabitat movement by individuals was detected. Within a habitat, sexes moved synchronously at the 1-ha scale but showed a degree of segregation at the individual scale, suggesting that some avoidance existed. Three diet types were observed in the godwits in the area: (1) dominated by soldier crabs (Mictyris longicarpus) on sand, (2) dominated by sentinel crabs (Macrophthalmus spp.) in seagrass, and (3) dominated by soft-bodied prey in seagrass.
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Kassa, Mulugeta, M. Balakrishnan i Bezawork Afework. "Diurnal activity patterns, habitat use and foraging habits of Egyptian goose (Alopochena egyptiacus Linnaeus, 1766) in the Boyo wetland, southern Ethiopia". SINET: Ethiopian Journal of Science 44, nr 2 (30.12.2021): 182–92. http://dx.doi.org/10.4314/sinet.v44i2.5.
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Egyptian goose (Alopochena egyptiacus) is a resident bird species in Africa South of the Sahara occurring throughout the entire Nile Valley. Despite the wide distribution, the available information on its behavioral ecology is limited in Ethiopia. A study on the activity patterns, habitat use and foraging habits of Egyptian goose was carried out in and around Boyo wetland, Ethiopia, during the dry and wet seasons. Scan sampling method was used to study the activity patterns and habitat use of Egyptian goose in grassland, mudflat and shallow water habitats of the wetland. The feeding behavior of Egyptian goose was also observed in the surrounding farmland habitats using scan sampling method. Generally, Egyptian geese spent most of their time resting (39.81%) followed by foraging (32.64%). They spent 10.43% of their time in comfort movement preening or stretching. The rest of their time was allocated for locomotion (6.63%), vigilance (5.75%), and social behavior (1.59%), and other activities (2.86%). Most of the birds were engaged in foraging activity in the morning (07:00-9:00 h) and afternoon (16:00 - 18:00 h) hours both during the wet and dry seasons. About 39% of Egyptian geese were scanned in mudflat, 31.5% in grassland, and 30.05% in shallow water habitats engaged in different activities. Most individuals used the grassland habitat for foraging during the dry (59.5%) and wet (74%) seasons, while they used shallow water and mudflat habitats for resting both during the wet and dry seasons seasons. The birds were observed foraging mainly grass during the dry (93.62%) and wet (59.52%) seasons. The Egyptian geese show diurnal activity pattern with feeding peaks in early morning and late afternoon hours as is observed in many other avian taxa. The Boyo wetland is also as an important foraging ground for this species and other birds in the area. Further ecological studies on the species and impact of human activities on the Boyo wetland should be conducted for the conservation of the avifauna.
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Mestre, Julie, Matthieu Authier, Yves Cherel, Rob Harcourt, Clive R. McMahon, Mark A. Hindell, Jean-Benoît Charrassin i Christophe Guinet. "Decadal changes in blood δ 13 C values, at-sea distribution, and weaning mass of southern elephant seals from Kerguelen Islands". Proceedings of the Royal Society B: Biological Sciences 287, nr 1933 (19.08.2020): 20201544. http://dx.doi.org/10.1098/rspb.2020.1544.
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Changes in the foraging environment and at-sea distribution of southern elephant seals from Kerguelen Islands were investigated over a decade (2004–2018) using tracking, weaning mass, and blood δ 13 C values. Females showed either a sub-Antarctic or an Antarctic foraging strategy, and no significant shift in their at-sea distribution was detected between 2004 and 2017. The proportion of females foraging in sub-Antarctic versus Antarctic habitats did not change over the 2006–2018 period. Pup weaning mass varied according to the foraging habitat of their mothers. The weaning mass of sub-Antarctic foraging mothers' pups decreased by 11.7 kg over the study period, but they were on average 5.8 kg heavier than pups from Antarctic foraging mothers. Pup blood δ 13 C values decreased by 1.1‰ over the study period regardless of their sex and the presumed foraging habitat of their mothers. Together, these results suggest an ecological change is occurring within the Indian sector of the Southern Ocean with possible consequences on the foraging performance of southern elephant seals. We hypothesize that this shift in δ 13 C is related to a change in primary production and/or in the composition of phytoplankton communities, but this requires further multidisciplinary investigations.
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Reisinger, Ryan R., Tegan Carpenter-Kling, Maëlle Connan, Yves Cherel i Pierre A. Pistorius. "Foraging behaviour and habitat-use drives niche segregation in sibling seabird species". Royal Society Open Science 7, nr 9 (wrzesień 2020): 200649. http://dx.doi.org/10.1098/rsos.200649.
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To mediate competition, similar sympatric species are assumed to use different resources, or the same but geographically separated resources. The two giant petrels ( Macronectes spp.) are intriguing in that they are morphologically similar seabirds with overlapping diets and distributions. To better understand the mechanisms allowing their coexistence, we investigated intra- and interspecific niche segregation at Marion Island (Southern Indian Ocean), one of the few localities where they breed in sympatry. We used GPS tracks from 94 individuals and remote-sensed environmental data to quantify habitat use, combined with blood carbon and nitrogen stable isotope ratios from 90 individuals to characterize their foraging habitat and trophic ecology. Females of both species made distant at-sea foraging trips and fed at a similar trophic level. However, they used distinct pelagic habitats. By contrast, males of both species mainly foraged on or near land, resulting in significant sexual segregation, but high interspecific habitat and diet overlap. However, some males showed flexible behavioural strategies, also making distant, pelagic foraging trips. Using contemporaneous tracking, environmental and stable isotope data we provide a clear example of how sympatric sibling species can be segregated along different foraging behaviour dimensions.
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Leppi, Jason C., Daniel J. Rinella, Mark S. Wipfli i Matthew S. Whitman. "Broad Whitefish (Coregonus nasus) isotopic niches: Stable isotopes reveal diverse foraging strategies and habitat use in Arctic Alaska". PLOS ONE 17, nr 7 (26.07.2022): e0270474. http://dx.doi.org/10.1371/journal.pone.0270474.
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Understanding the ecological niche of some fishes is complicated by their frequent use of a broad range of food resources and habitats across space and time. Little is known about Broad Whitefish (Coregonus nasus) ecological niches in Arctic landscapes even though they are an important subsistence species for Alaska’s Indigenous communities. We investigated the foraging ecology and habitat use of Broad Whitefish via stable isotope analyses of muscle and liver tissue and otoliths from mature fish migrating in the Colville River within Arctic Alaska. The range of δ13C (-31.8– -21.9‰) and δ15N (6.6–13.1‰) across tissue types and among individuals overlapped with isotope values previously observed in Arctic lakes and rivers, estuaries, and nearshore marine habitat. The large range of δ18O (4.5–10.9‰) and δD (-237.6– -158.9‰) suggests fish utilized a broad spectrum of habitats across elevational and latitudinal gradients. Cluster analysis of muscle δ13Cˈ, δ15N, δ18O, and δD indicated that Broad Whitefish occupied four different foraging niches that relied on marine and land-based (i.e., freshwater and terrestrial) food sources to varying degrees. Most individuals had isotopic signatures representative of coastal freshwater habitat (Group 3; 25%) or coastal lagoon and delta habitat (Group 1; 57%), while individuals that mainly utilized inland freshwater (Group 4; 4%) and nearshore marine habitats (Group 2; 14%) represented smaller proportions. Otolith microchemistry confirmed that individuals with more enriched muscle tissue δ13Cˈ, δD, and δ18O tended to use marine habitats, while individuals that mainly used freshwater habitats had values that were less enriched. The isotopic niches identified here represent important foraging habitats utilized by Broad Whitefish. To preserve access to these diverse habitats it will be important to limit barriers along nearshore areas and reduce impacts like roads and climate change on natural flow regimes. Maintaining these diverse connected habitats will facilitate long-term population stability, buffering populations from future environmental and anthropogenic perturbations.
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Dobbs, Kirstin, Leanne Fernandes, Suzanne Slegers, Belinda Jago, Leanne Thompson, James Hall, Jon Day i in. "Incorporating marine turtle habitats into the marine protected area design for the Great Barrier Reef Marine Park, Queensland, Australia". Pacific Conservation Biology 13, nr 4 (2007): 293. http://dx.doi.org/10.1071/pc070293.
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Marine turtle habitats were considered in the design of the new zoning network for the Great Barrier Reef Marine Park as part of the Representative Areas Programme. One of the specific design guidelines developed was the incorporation of marine turtle inter-nesting and foraging habitats into the overall network of no-take areas. The guideline was refined further for individual nesting and foraging sites to incorporate all very high priority nesting sites and to incorporate 20% of each identified foraging site, respectively. Marine turtle inter-nesting habitat increased in no-take area protection from 781 km2 to 1 886 km2 (23.4% to 56.5% of all identified sites); marine turtle foraging habitat increased in no-take area protection from 3 063 km2 to 12 490 km2 (7.1% to 29.1% of all identified sites). Although the nesting and foraging principles were not achieved in total for all identified marine turtle sites, overall the level of protection afforded by the Great Barrier Reef Marine Park Zoning Plan 2003 increased for nearly all marine turtle sites identified. Additionally, other activities (e.g. water quality, fisheries, traditional use of marine resources) occurring in the Great Barrier Reef Marine Park that may impact upon marine turtles are being addressed via other mechanisms.
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Blancher, Peter J., i Raleigh J. Robertson. "A comparison of eastern kingbird breeding biology in lakeshore and upland habitats". Canadian Journal of Zoology 63, nr 10 (1.10.1985): 2305–12. http://dx.doi.org/10.1139/z85-342.
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We compared aspects of eastern kingbird (Tyrannus tyrannus) breeding biology between lakeshore and upland habitats in eastern Ontario. Nests were more closely spaced and eggs were laid earlier at the lakeshore than in the uplands. Within the lakeshore habitat, nests were more likely to be placed on small islands (< 0.2 ha) and eggs were laid earlier there than on large islands or the mainland shore. Kingbirds nesting in lakeshore habitat had some advantages: (i) moderated temperatures for nests placed low over water, (ii) more efficient foraging when feeding nestlings, and (iii) faster growing nestlings, relative to upland nestlings. However, upland nests fledged more young than lakeshore nests. Within lakeshore habitat, small island sites had the highest breeding success. With the exception of nest site location, which differed markedly between habitats, differences in breeding biology and behaviour between the two habitats were small. A lack of substrate specificity in foraging, together with an ability to use a range of nest sites, apparently allow kingbirds to nest successfully in a wide variety of habitats.
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Arditi, Roger, i Bernard Dacorogna. "Optimal Foraging in Nonpatchy Habitats. 2: Unbounded One-Dimensional Habitat". SIAM Journal on Applied Mathematics 47, nr 4 (sierpień 1987): 800–821. http://dx.doi.org/10.1137/0147054.
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Lyons, James E. "HABITAT-SPECIFIC FORAGING OF PROTHONOTARY WARBLERS: DEDUCING HABITAT QUALITY". Condor 107, nr 1 (2005): 41. http://dx.doi.org/10.1650/7462.
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Tadesse, Solomon A., i Burt P. Kotler. "Habitat Choices of Nubian Ibex (Capra Nubiana) Evaluated with A habitat Suitability Modeling and Isodar Analysis". Israel Journal of Ecology and Evolution 56, nr 1 (6.05.2010): 55–74. http://dx.doi.org/10.1560/ijee.56.1.55.
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The value of a habitat for a forager may be affected by habitat characteristics related to food availability, energetic costs of foraging, predation costs, and the foraging opportunities available in other habitats. Nubian ibex (Capra nubiana) are stout, sure-footed social wild goats that inhabit arid landscapes with steep terrain. We investigated their habitat selection behavior using indicators to (1) develop a habitat suitability index (HSI) model that would account for the variation in the activity densities of Nubian ibex across habitat types and seasons, (2) apply the isodar technique to look for density-dependent habitat selection behavior in Nubian ibex, and (3) investigate the proximate environmental factors that correlate to relative activity densities of Nubian ibex. We determined relative densities of the ibex by recording sightings of animals along standard walking transects. We incorporated the habitat variables that had greatest influence on the densities of Nubian ibex into habitat suitability index models for both spring and summer seasons.The HSI models revealed that Nubian ibex most preferred open cliff face habitat offering safety during the spring season, but their habitat preference shifted towards an area with watered gardens ("grave area habitat") during the summer season. Significant isodars were only obtained for the summer season comparisons between grave area versus cliff face, and between grave area versus plateau habitats. The slopes of the isodars suggest that the grave area habitat is 10.5 and 7.6 times more productive than the plateau and the cliff face habitats, respectively. Our results suggest that the relative abundances and habitat preferences of Nubian ibex varied with the seasonal availability of habitat resources, extent of predation risks, and human nuisance disturbances across the landscape. We recommend that wildlife managers dealing with the conservation and protection of the endangered Nubian ibex should focus on the various ecological and anthropogenic factors governing the habitat selection and preferences.
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Braun McNeill, J., L. Avens, A. Goodman Hall, I. Fujisaki i AR Iverson. "Foraging and overwintering behavior of loggerhead sea turtles Caretta caretta in the western North Atlantic". Marine Ecology Progress Series 641 (7.05.2020): 209–25. http://dx.doi.org/10.3354/meps13296.
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Discerning the foraging habitat requirements of wildlife is key to providing for their conservation and management, especially with rare species. Sea turtles are slow-growing, late-maturing species that undertake wide-ranging migrations, making them especially susceptible to changes and disruptions in their environment. To protect and successfully manage these imperiled populations, an understanding of their spatial ecology is required; thus, characterizing critical habitats, identifying high-density areas, and identifying foraging regions is essential. We captured 30 loggerhead sea turtles Caretta caretta (male and female; juvenile and adult) in the estuarine waters of North Carolina (USA) and tracked them in western North Atlantic neritic (nearshore and offshore) waters. Using a combination of satellite telemetry and spatial modeling techniques, we characterized their movements and identified foraging and overwintering sites. Average core-use areas in the north had greater net primary production (NPP) and were smaller than those in the south, indicating more abundant marine resources in northern foraging regions. In summer, loggerheads migrated to both northern and southern foraging grounds, but most (53%) resided within North Carolina neritic waters. Likewise, the majority of loggerheads (67%) we tracked in winter remained in North Carolina neritic waters, underscoring the importance of this area as year-round foraging habitat, and lending to its consideration as potential critical habitat for both juvenile and adult loggerheads. The change to foraging behavior mode was significantly influenced by day of the year, geographic location, and NPP; however, individual-specific factors influenced switching probabilities relative to other covariates. Data highlighting ‘hotspots’ or densely used areas by foraging sea turtles can thus be used by conservation managers to make informed decisions concerning sea turtle conservation measures.
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Höjesjö, Johan, Rasmus Kaspersson i John D. Armstrong. "Size-related habitat use in juvenile Atlantic salmon: the importance of intercohort competition". Canadian Journal of Fisheries and Aquatic Sciences 73, nr 8 (sierpień 2016): 1182–89. http://dx.doi.org/10.1139/cjfas-2015-0446.
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In stream-living salmonids, an underlying mechanism for the critical period after emergence has generally been assumed to be size-dependent swimming capacity constraining fry (age-0) to low-velocity habitats with reduced food availability and intense competition. A further plausible mechanism is that intercohort habitat exclusion confines fry to marginal habitats. This possibility was tested using a seminatural stream with 16 test arenas, each comprising one high-velocity, deep habitat and one low-velocity, shallow habitat. We observed groups of newly emerged Atlantic salmon (Salmo salar) fry, either alone or in sympatry with one or two age-1 salmon. Salmon fry used high-velocity areas (42.2 ± 0.4 cm·s−1) most extensively in the absence of intercohort competition, where they obtained more food than in low-velocity areas (3.3 ± 0.3 cm·s−1), even though foraging efficiency was lower (though not significantly so). In sympatry with older cohorts, fry increased their use of the low-velocity habitat, with a reduced foraging activity, suggesting that strong older cohorts in natural populations may have the potential to influence the strength of the recruiting cohort by negative density dependence due to interference competition for habitat.
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Robinson, Beren. "TRADE OFFS IN HABITAT-SPECIFIC FORAGING EFFICIENCY AND THE NASCENT ADAPTIVE DIVERGENCE OF STICKLEBACKS IN LAKES". Behaviour 137, nr 7-8 (2000): 865–88. http://dx.doi.org/10.1163/156853900502501.
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AbstractI assessed habitat-specific foraging efficiency of shallow-water and open-water forms from a morphologically variable population of threespine sticklebacks. Individuals sampled from open-water or shallow-water habitats tend to be morphologically divergent, although the morphology of the modal form is intermediate between the better-known benthic and limnetic pairs of stickleback species that coexist in other local lakes. I tested two hypotheses about this intraspecific variation. First, that heritable genetic variation in body form exists between forms. Morphological differences occurred between progeny reared under common laboratory conditions indicating that heritable genetic variation contributes to morphological variation. Second, that open-water and shallow-water forms face trade offs involving foraging on habitat-specific prey. The foraging efficiency of both forms was measured in two types of habitat (benthos and open-water) simulated in lab aquaria. Foraging efficiency was related to morphological differences between morphs. Relative morph efficiencies were reversed between habitats in a predictable fashion. More streamlined open-water forms consumed Artemia nauplii at a higher rate and with fewer bites than more robust shallow-water morphs. Conversely, shallow-water morphs required fewer bites to capture and consume more and larger amphipods than open-water forms. An asymmetry in the trade offs indicates that shallow-water types may be the more specialized form. These results are consistent with a hypothesis that trade offs in habitat use efficiency can be involved early in the adaptive divergence of sticklebacks into different lake environments. Similar trade offs exist for the coexisting pairs of stickleback species, suggesting that trade offs are more likely a cause, rather than a consequence, of speciation in sticklebacks that colonize lakes.
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Waggitt, James J., Pierre W. Cazenave, Leigh M. Howarth, Peter G. H. Evans, Jeroen van der Kooij i Jan G. Hiddink. "Combined measurements of prey availability explain habitat selection in foraging seabirds". Biology Letters 14, nr 8 (sierpień 2018): 20180348. http://dx.doi.org/10.1098/rsbl.2018.0348.
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Understanding links between habitat characteristics and foraging efficiency helps predict how environmental changes influence populations of top predators. This study examines whether measurements of prey (clupeids) availability varied over stratification gradients, and determined if any of those measurements coincided with aggregations of foraging seabirds (common guillemot Uria aalge and Manx shearwater Puffinus puffinus ) in the Celtic Sea, UK. The probability of encountering foraging seabirds was highest around fronts between mixed and stratified water. Prey were denser and shallower in mixed water, whilst encounters with prey were most frequent in stratified water. Therefore, no single measurement of increased prey availability coincided with the location of fronts. However, when considered in combination, overall prey availability was highest in these areas. These results show that top predators may select foraging habitats by trading-off several measurements of prey availability. By showing that top predators select areas where prey switch between behaviours, these results also identify a mechanism that could explain the wider importance of edge habitats for these taxa. As offshore developments (e.g. marine renewable energy installations) change patterns of stratification, their construction may have consequences on the foraging efficiency of seabirds.
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Schemnitz, Sanford, i Kevin Coates. "Habitat Utilization, Interspefic Interactions and Status of a Recolonized Population of Bighorn Sheep at a Wild Horse Range". UW National Parks Service Research Station Annual Reports 11 (1.01.1987): 11–16. http://dx.doi.org/10.13001/uwnpsrc.1987.2611.
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Data have been collected from 05-86 to 11-87 to aid in the development of a management program for Rocky Mountain bighorn sheep (Ovis canadensis canadensis) at Bighorn Canyon National Recreation Area (BICA). The purpose of this report is to summarize progress toward completing the following Objectives: 1. Determine the size, and age/sex composition of the sheep herd at BICA; determine the general health of the herd. 2. Analyze the seasonal food habits of sheep and wild horses; analyze the dietary overlap of these species; analyze the foraging behavior of sheep in habitats occupied exclusively by sheep and compare with the foraging behavior of sheep in habitats used in common with horses and/or humans. 3. Analyze seasonal habitat use throughout the annual cycle; analyze activity patterns during all daylight hours and relate to habitat use; identify and describe sensitive use areas for consideration in future sheep management programs. 4. Determine the total habitat potential of BICA.
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Smith, Robert J., Frank R. Moore i Christopher A. May. "Stopover Habitat Along the Shoreline of Northern Lake Huron, Michigan: Emergent Aquatic Insects as a Food Resource for Spring Migrating Landbirds". Auk 124, nr 1 (1.01.2007): 107–21. http://dx.doi.org/10.1093/auk/124.1.107.
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Abstract Recent work in Michigan's eastern Upper Peninsula suggests that terrestrial areas bordering northern Lake Huron provide important stopover habitat for spring migrating landbirds, principally because of the presence of emergent aquatic midges (Diptera: Chironomidae). Migrants were concentrated in lakeshore habitats abundant with midges during spring migration. American Redstarts (Setophaga ruticilla) and Black-throated Green Warblers (Dendroica virens) foraged and used habitat differently, depending on their distance from the lakeshore. Here, we describe results of an integrative study in which we sampled resources, quantified American Redstart foraging behavior, and estimated mass change in American Redstarts and five other common migrant landbird species to evaluate the importance of adult midges as an early season resource for spring migrants. Resource sampling and American Redstart foraging behavior suggested that more food was available in shoreline habitats than inland during spring migration. Furthermore, migrants gained mass in shoreline habitat during stopover, which supports the argument that nearshore areas provide important stopover habitat for spring migrants. Finally, resource sampling, mass change estimates, and American Redstart foraging behavior suggested that midges and spiders (Araneae: Arachnidae) provided an important early season resource for migrating landbirds. Evidence suggests that midges were responsible for elevated spider abundance at the shoreline and that birds foraged on both midges and spiders. Midges appear to play an important role in providing high-quality stopover habitat for landbirds migrating through Michigan's eastern Upper Peninsula. Hábitat de las Paradas Migratorias a lo Largo de la Costa Norte del Lago Huron, Michigan: Insectos Acuáticos Emergentes como Recurso Alimenticio para las Aves Terrestres Migratorias Durante la Primavera