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1
Iffiong, S. A., I. J. Fulani, and J. M. Olomu. "THE EFFECTS OF STOCKING DENSITY ON THE PERFORMANCE OF BROILER CHICKENS." Nigerian Journal of Animal Production 6 (January 19, 2021): 21–25. http://dx.doi.org/10.51791/njap.v6i.2652.
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THREE trials were conducted to determine the optimum stocking density for broiler chickens raised in a tropical environment In Trial 1, 100,67, 50,40, 34 and 29 birds were placed in duplicates in each pen with an area of 3.72 M2 to give stocking densities of 0.037, 0.056, 0.074, 0.093, 0.10 and 0 128 M2 per bird respectively. In Trial 2, stocking densities of 0.046, 0056, 0.064, 0.074, 0.083 and 0.093 M2 per bird were compared. Trial 3 involved studying the effects of providing equal feeder space (5cm/bird) or equal number of similar sized feeders (2 feeders per pen) when birds were stocked at floor spaces of 0.056, 0.064, 0.74, 0.083 and 0.093 sq meter per bird. Results showed that weight gain and feed consumption decreased, while total meat yield and net income per unit area increased, with increase in stocking rates. Feed efficiency, mortality and carcass dressing percentages were not significantly affected by the stocking rates. The effects of stocking densities on the performance of the birds were not altered by equalizing the feeder space per bird or by providing equal number of feeders per unit space. Management problems in terms of wetness of litter, feeding and watering were encountered with stocking densities of 0.037, 0.046 and 0.056 M2/ bird. Stocking rates of 0.083, 0.093, 0.10 and 0.128 M2 were uneconomic and did not produce superior performances to stocking densities of 0.064 or 0.074 M2/bird. On the basis of the results, floor spaces of 0.064 or 0.074 M2 per bird may be recommended as the optimum for broiler chickens raised in the tropics. The feeder space at these optimum stocking rates need not be more than 5cm per bird.
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Loe, Leif Egil, Atle Mysterud, Audun Stien, Harald Steen, Darren M. Evans, and Gunnar Austrheim. "Positive short-term effects of sheep grazing on the alpine avifauna." Biology Letters 3, no. 1 (November 21, 2006): 110–12. http://dx.doi.org/10.1098/rsbl.2006.0571.
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Abstract Grazing by large herbivores may negatively affect bird populations. This is of great conservation concern in areas with intensive sheep grazing. Sheep management varies substantially between regions, but no study has been performed in less intensively grazed systems. In a fully replicated, landscape scale experiment with three levels of sheep grazing, we tested whether the abundance and diversity of an assemblage of mountain birds were negatively affected by grazing or if grazing facilitated the bird assemblage. Density of birds was higher at high sheep density compared with low sheep density or no sheep by the fourth grazing season, while there was no clear effect on bird diversity. Thus, agricultural traditions and land use politics determining sheep density may change the density of avifauna in either positive or negative directions.
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Perkins, Genevieve C., Amanda E. Martin, Adam C. Smith, and Lenore Fahrig. "Weak Effects of Owned Outdoor Cat Density on Urban Bird Richness and Abundance." Land 10, no. 5 (May 10, 2021): 507. http://dx.doi.org/10.3390/land10050507.
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Domestic cats (Felis catus) are ubiquitous predators of birds in urban areas. In addition to the lethal effect of predation, there can also be sublethal, negative effects of domestic cats on individual birds. These effects have led to the inference that reducing outdoor cat densities would benefit urban bird communities. Here we estimate the likely result of policies/programs designed to reduce densities of owned outdoor cats in urban areas, estimating relationships between bird richness/abundance and cat densities across 58 landscapes in Ottawa, Ontario, Canada. We estimate that we would most likely observe one additional bird species, and 0.003 additional individuals per species, if policies/programs reduced owned outdoor cat densities to zero in an average landscape in Ottawa (with 130.2 cats/km2). However, these effects of cat density on birds were uncertain, with 95% confidence intervals crossing zero. Our findings—in combination with those of previous studies—suggest a need for research to resolve the apparent disconnect between the strong, negative effects of cats on individual urban birds and the weak, uncertain effects of cats on bird populations. Although measures that reduce owned outdoor cat densities are justified based on the precautionary principle, evidence to date does not support prioritizing these measures over those addressing threats that have consistently strong effects on bird populations.
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Shao, Quan, Yan Zhou, Pei Zhu, Yan Ma, and Mengxue Shao. "Key Factors Assessment on Bird Strike Density Distribution in Airport Habitats: Spatial Heterogeneity and Geographically Weighted Regression Model." Sustainability 12, no. 18 (September 4, 2020): 7235. http://dx.doi.org/10.3390/su12187235.
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Although the factors influencing bird strikes have been studied extensively, few works focused on the spatial variations in bird strikes affected by factors due to the difference in the geographical environment around the airport. In this paper, the bird strike density distribution of different seasons affected by factors in a rectangular region of 800 square kilometers centered on the Xi’an Airport runway was investigated based on collected bird strike data. The ordinary least square (OLS) model was used to analyze the global effects of different factors, and the Geographically Weighted Regression (GWR) model was used to analyze the spatial variations in the factors of bird strike density. The results showed that key factors on the kernel density of bird strikes showed evident spatial heterogeneity and the seasonal difference in the different habitats. Based on the results of the study, airport managers are provided with some specific defense measures to reduce the number of bird strikes from the two aspects of expelling birds on the airfield area and reducing the attractiveness of habitats outside the airport to birds, so that achieve the sustainable and safe development of civil aviation and the ecological environment.
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Lovász, Lilla, Fränzi Korner-Nievergelt, and Valentin Amrhein. "Grazer density and songbird counts in a restored conservation area." PeerJ 9 (January 5, 2021): e10657. http://dx.doi.org/10.7717/peerj.10657.
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Grazing by large herbivores is increasingly used as a management tool in European nature reserves. The aim is usually to support an open but heterogeneous habitat and its corresponding plant and animal communities. Previous studies showed that birds may profit from grazing but that the effect varies among bird species. Such studies often compared bird counts among grazed areas with different stocking rates of herbivores. Here, we investigated how space use of Konik horses and Highland cattle is related to bird counts in a recently restored conservation area with a year-round natural grazing management. We equipped five horses and five cattle with GPS collars and correlated the density of their GPS positions on the grazed area with the density of bird observations from winter through the breeding season. We found that in the songbirds of our study site, both the overall density of bird individuals and the number of species increased with increasing density of GPS positions of grazers. Correlations of bird density with horse density were similar to correlations with cattle density. Of the eight most common songbird species observed in our study area, the Eurasian Skylark and the Common Starling had the clearest positive correlations with grazer density, while the Blackbird showed a negative correlation. Skylarks and Starlings in our study area thus seem to profit from year-round natural grazing by a mixed group of horses and cattle.
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Hager, Stephen B., Heidi Trudell, Kelly J. McKay, Stephanie M. Crandall, and Lance Mayer. "Bird density and mortality at windows." Wilson Journal of Ornithology 120, no. 3 (September 2008): 550–64. http://dx.doi.org/10.1676/07-075.1.
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Omotoriogun, Taiwo Crossby, Joseph Daniel Onoja, Talatu Tende, Shiiwua Manu, and Ulf Ottosson. "Density and diversity of birds in the wetlands of Yankari Game Reserve Bauchi Nigeria." Journal of Wetlands Ecology 5 (December 28, 2011): 48–58. http://dx.doi.org/10.3126/jowe.v5i0.4778.
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The biological, chemical, and physical operations and attributes of wetlands are vital in facilitating food resources, water, and shelter, which many terrestrial bird and waterbird species rely on for their daily requirments. Wetlands in Yankari Game Reserve, Nigeria are key stone ecosystem that provides a stopover, breeding and/or foraging platform for migratory and resident birds. This study determined the density and diversity of birds in the wetlands of Yankari Game Reserve. Ten wetlands within the reserve were identified and surveyed. The sizes (kilometer square) and isolation distances (kilometer) of the wetlands were measured (using GPS and Map Source) to determine their effects on bird density and diversity. Point count survey method was used to count birds. One hundred and twenty three species of birds belonging to 51 families were recorded in the wetlands. Significant patterns in the densities of birds were observed across the wetlands (Kruskal-Wallis H, X2=167.116, P=0.001) and also sizes of wetlands (Wilcoxon test: Z= -2.803, P=0.005). There was differences in mean number of birds in survey time (Kruskal-Wallis, X2=15.784, P=0.045). Evenings were probably most preferred in bird-wetland utilization. Key words: Density; Diversity; Yankari ecosystem; Wetland utilization DOI: http://dx.doi.org/10.3126/jowe.v5i0.4778 J Wet Eco 2011 (5): 48-58
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Asaniyan, E. K., and V. O. Akinduro. "Impact of stocking density on the rearing environment and growth performance of broiler chicken." Nigerian Journal of Animal Production 47, no. 6 (February 28, 2021): 65–81. http://dx.doi.org/10.51791/njap.v47i6.2875.
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The consequence of high stocking density in commercial production of broiler chickens under the changing climate could predispose the chickens to adverse conditions. Therefore, this study was conducted to investigate the influence of stocking density on the rearing environment and performance of broiler chicken. Ninety (90) one day-old chicks of Arbor acre breed were used as experimental units in the trial that lasted eight (8) weeks. The bird were randomly assigned to three treatments of stocking densities 5, 10 and 15 birds/m2 with three replicates per treatment. The birds were raised in deep litter system bedded with woodshaving at 1 m2 per replicate. They were fed ad libitum with commercial broiler diets with drinking water supplied without restrictions. The meteorological data (Temperature and Relative Humidity) within the pen were obtained using the Maxims thermocron i-button Temperature and Humidity sensors and a stand-alone automated weather station was deployed outside the pen house which measured Temperature and Relative humidity parameters within the premises (Figure 1c), which were programmed to measure at 10 minutes sampling interval. Data collected were on daily ambient temperature and relative humidity, feed intake, water intake, weight gain and computed feed conversion ratio. The temperature of the broiler pens was found inversely related to its relative humidity across the treatments with relative fluctuations as the birds grow. Temperature within the pens (ambient temperature) increased with the stocking densities; stocking density 15 birds/m2 (25.94±0.125oC -31.79±0.360oC) being the hottest while 5 birds/m2 (25.47±0.136oC - 31.43±0.353oC ) was the least. Birds at stocking density of 5 birds/m2 (90.00g/bird/week – 2197.78g/bird/week) performed better in terms of growth and followed by those of 10 birds/m2 (95.00g/bird/week – 2018.52g/bird/week). Stocking densities of 15 birds/m2 (84.19g/bird/week – 1907.44g/bird/week) recorded the lowest weight gain. The combine influence of weather parameters (temperature and relative humidity) in bringing about growth of the birds diminishes as the stocking density increases. There was virtually no significant influence of the stocking densities on weekly mean temperature and relative humidity in the broiler chicken pens throughout the period of the study. Therefore, for eight weeks rearing period under any of the stocking density levels, fatality of weather modification could be prevented within the rearing environment through provision of adequate ventilation. La conséquence de la forte densité d'élevage dans la production commerciale de poulets de chair dans le climat changeant pourrait prédisposer les poulets à des conditions défavorables. Par conséquent, cette étude a été menée pour étudier l'influence de la densité d'élevage sur l'environnement d'élevage et les performances des poulets de chair. Quatrevingt-dix (90) poussins d'un jour de race 'Arbor acre' ont été utilisés comme unités expérimentales dans l'essai qui a duré huit (8) semaines. Les oiseaux ont été assignés auhasard à trois traitements de densités de peuplement de 5, 10 et 15 oiseaux / m2 avec trois répétitions par traitement. Les oiseaux ont été élevés dans un système de litière profonde recouvert d'un rasage de bois à 1 m2 par répétition. Ils ont été nourris ad libitum avec des régimes commerciaux pour poulets de chair avec de l'eau potable fournie sans restrictions. Les données météorologiques (température et humidité relative) à l'intérieur du stylo ont été obtenues à l'aide des capteurs de température et d'humidité 'Maximsthermocron i-button' et une station météorologique automatisée autonome a été déployée à l'extérieur de l'enclos qui mesurait les paramètres de température et d'humidité relative dans les locaux (Figure 1c), et ils ont été programmés pour mesurer à 10 minutes d'intervalle d'échantillonnage. Les données recueillies concernaient la température ambiante quotidienne et l'humidité relative, la consommation alimentaire, la consommation d'eau, le gain de poids et le taux de conversion alimentaire calculé. La température des enclos a été trouvée inversement proportionnelle à son humidité relative pendant les traitements avec des fluctuations relatives à mesure que les oiseaux grandissent. La température à l'intérieur des enclos (température ambiante) augmentait avec les densités de stockage ; densité de peuplement 15 oiseaux / m2 (25,94 ± 0,125 ° C -31,79 ± 0,360 ° C) étant le plus chaud tandis que 5 oiseaux / m2 (25,47 ± 0,136 ° C -31,43 ± 0,353 ° C) était le moins. Les oiseaux ayant une densité de peuplement de 5 oiseaux / m2 (90,00 g / oiseau / semaine - 2197,78 g / oiseau / semaine) ont obtenu de meilleurs résultats en termes de croissance et suivis par ceux de 10 oiseaux / m2 (95,00 g / oiseau / semaine - 2018,52 g / oiseau / semaine). Des densités de peuplement de 15 oiseaux / m2 (84,19 g / oiseau / semaine - 1907,44 g / oiseau / semaine) ont enregistré le gain de poids le plus faible. L'influence combinée des paramètres météorologiques (température et humidité relative) dans la croissance des oiseaux diminue au fur et à mesure que la densité d'élevage augmente. Il n'y avait pratiquement aucune influence significative des densités de peuplement sur la température moyenne hebdomadaire et l'humidité relative dans les enclos de poulets de chair pendant toute la période de l'étude. Par conséquent, pendant une période d'élevage de huit semaines, quel que soit le niveau de densité de peuplement, la mortalité due aux modifications climatiques pourrait être évitée dans l'environnement d'élevage grâce à une ventilation adéquate.
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Manhães, MA, and MM Dias. "Spatial dynamics of understorey insectivorous birds and arthropods in a southeastern Brazilian Atlantic woodlot." Brazilian Journal of Biology 71, no. 1 (February 2011): 1–7. http://dx.doi.org/10.1590/s1519-69842011000100003.
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Spatial distribution and spatial relationships in capture rates of understorey insectivorous birds and density of arthropods were investigated in a patch of upper montane rain forest in Minas Gerais state, southeastern Brazil, from January to December 2004. The composition of the arthropod fauna collected was similar to that reported for other tropical forests, with predominance of Araneae, Coleoptera, Hymenoptera and Hemiptera non-Heteroptera. A total of 26 bird species were captured, among which the more common were Dysithamnus mentalis, Conopophaga lineata, Platyrinchus mystaceus, Basileuterus culicivorus and Sclerurus scansor. Variation in the bird capture rates among sampling net lines were not correlated with arthropod density. Rather, individual analyses of some bird species suggest that spatial distribution of understorey insectivorous birds is better explained by habitat type.
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Aronson, Myla F. J., Frank A. La Sorte, Charles H. Nilon, Madhusudan Katti, Mark A. Goddard, Christopher A. Lepczyk, Paige S. Warren, et al. "A global analysis of the impacts of urbanization on bird and plant diversity reveals key anthropogenic drivers." Proceedings of the Royal Society B: Biological Sciences 281, no. 1780 (April 7, 2014): 20133330. http://dx.doi.org/10.1098/rspb.2013.3330.
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Urbanization contributes to the loss of the world's biodiversity and the homogenization of its biota. However, comparative studies of urban biodiversity leading to robust generalities of the status and drivers of biodiversity in cities at the global scale are lacking. Here, we compiled the largest global dataset to date of two diverse taxa in cities: birds (54 cities) and plants (110 cities). We found that the majority of urban bird and plant species are native in the world's cities. Few plants and birds are cosmopolitan, the most common being Columba livia and Poa annua . The density of bird and plant species (the number of species per km 2 ) has declined substantially: only 8% of native bird and 25% of native plant species are currently present compared with estimates of non-urban density of species. The current density of species in cities and the loss in density of species was best explained by anthropogenic features (landcover, city age) rather than by non-anthropogenic factors (geography, climate, topography). As urbanization continues to expand, efforts directed towards the conservation of intact vegetation within urban landscapes could support higher concentrations of both bird and plant species. Despite declines in the density of species, cities still retain endemic native species, thus providing opportunities for regional and global biodiversity conservation, restoration and education.
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Sacchi, Roberto, Augusto Gentilli, Edoardo Razzetti, and Francesco Barbieri. "Effects of building features on density and flock distribution of feral pigeons Columba livia var. domestica in an urban environment." Canadian Journal of Zoology 80, no. 1 (January 1, 2002): 48–54. http://dx.doi.org/10.1139/z01-202.
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We censused feral pigeons (Columba livia) living in Milan, Italy (a 181-km2 area), between July 1999 and February 2000 by means of linear transects to examine population densities in different urban habitats and the relationships between population density and structural features of buildings. The pigeon population of Milan was 103 650 birds, with an average density of 570/km2. Population density increased significantly from farmland (434 birds/km2) to the suburbs (604 birds/km2) and from the suburbs to the centre of the city (2083 birds/km2). There was a positive relationship between both bird number and flock number and the abundance of buildings constructed before 1936. There were no significant associations between either bird number or flock number and the abundance of buildings when we did not consider date of construction. This indicated active selection of old buildings by feral pigeons.
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Benoy, Glenn A. "Variation in tiger salamander density within prairie potholes affects aquatic bird foraging behaviour." Canadian Journal of Zoology 83, no. 7 (July 1, 2005): 926–34. http://dx.doi.org/10.1139/z05-081.
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Through competitive asymmetry, coexisting fish populations can alter aquatic bird distributions and reduce the reproductive success of their offspring. Gray tiger salamanders (Ambystoma mavortium diaboli Dunn, 1940) may function similarly in fishless prairie potholes. To test the hypothesis that tiger salamanders compete with aquatic birds (including ducks, grebes, and American Coot (Fulica americana J.F. Gmelin, 1789)) for prey resources during the breeding season, 16 potholes were divided into halves by an impermeable plastic barrier and tiger salamander densities were increased or decreased on opposite sides of the barrier. From late May until early July, aquatic invertebrates were sampled from both sides of the divider and the foraging activities of birds were observed. Invertebrate samples revealed that densities of most macroinvertebrate taxa were lower in the halves of potholes with relatively higher densities of tiger salamanders. On average, bird occupancy was evenly distributed on either side of the divider. In contrast, birds spent 65% more time foraging where tiger salamander densities were low (71.2% of total time observed) than where they were high (46.2% of total time observed). The birds most responsive to differences in tiger salamander density and food availability were dabbling ducks, followed by American Coot and diving ducks. This ranking corresponds to the degree of dietary overlap documented between tiger salamanders and aquatic bird assemblages in the study area.
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Moyers, Sahnzi C., James S. Adelman, Damien R. Farine, Courtney A. Thomason, and Dana M. Hawley. "Feeder density enhances house finch disease transmission in experimental epidemics." Philosophical Transactions of the Royal Society B: Biological Sciences 373, no. 1745 (March 12, 2018): 20170090. http://dx.doi.org/10.1098/rstb.2017.0090.
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Anthropogenic food provisioning of wildlife can alter the frequency of contacts among hosts and between hosts and environmental sources of pathogens. Despite the popularity of garden bird feeding, few studies have addressed how feeders influence host contact rates and disease dynamics. We experimentally manipulated feeder density in replicate aviaries containing captive, pathogen-naive, groups of house finches ( Haemorhous mexicanus ) and continuously tracked behaviours at feeders using radio-frequency identification devices. We then inoculated one bird per group with Mycoplasma gallisepticum (Mg), a common bacterial pathogen for which feeders are fomites of transmission, and assessed effects of feeder density on house finch behaviour and pathogen transmission. We found that pathogen transmission was significantly higher in groups with the highest density of bird feeders, despite a significantly lower rate of intraspecific aggressive interactions relative to the low feeder density groups. Conversely, among naive group members that never showed signs of disease, we saw significantly higher concentrations of Mg-specific antibodies in low feeder density groups, suggesting that birds in low feeder density treatments had exposure to subclinical doses of Mg. We discuss ways in which the density of garden bird feeders could play an important role in mediating the intensity of Mg epidemics. This article is part of the theme issue ‘Anthropogenic resource subsidies and host–parasite dynamics in wildlife'.
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Woinarski, JCZ, SC Tidemann, and S. Kerin. "Birds in a Tropical Mosaic - the Distribution of Bird Species in Relation to Vegetation Patterns." Wildlife Research 15, no. 2 (1988): 171. http://dx.doi.org/10.1071/wr9880171.
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Wilson and Bowman (1986) classified and mapped vegetation in a complex mosaic at Howard's Peninsula, Northern Territory. The relationship of bird distribution to this vegetation classification was considered through 10 repeat censuses of 5 replicate quadrats in each of 20 vegetation units. Censusing period was April-May. 118 bird species were recorded. Closed forests (3 units), mangroves (2 units) and swamplands (3 units) all had distinctive bird species compositions, but bird species showed a relatively poor relationship with the classification of woodland and grassland units. Eucalyptus woodlands regrowing after devastation by a cyclone in 1974 had similar bird species diversity and density to undamaged woodlands, though somewhat different bird species composition. Eucalyptus woodlands with a dense shrubby understorey had significantly greater bird density and species diversity than those with open or grassy understories and their bird species composition showed appreciable association with that of closed forests. Closed forest and, less so, mangrove units had highest diversity and density (despite their relatively small proportion in the study area and in the region generally), probably because they offered a wider range of foraging possibilities.
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Pyke, GH, and HF Recher. "Estimated Forest Bird Densities by Variable Distance Point Counts." Wildlife Research 12, no. 2 (1985): 307. http://dx.doi.org/10.1071/wr9850307.
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During variable distance point counts a stationary observer records the species and distance for all birds detected during a fixed time interval. Such counts, repeated throughout the area of interest, can be used to estimate bird density so long as the following assumptions are made: (1) the distribution of birds is unaffected by the observer; (2) observers are certain of detecting near birds; (3) there is no error in measurement or estimation of distances; and (4) birds are stationary. Data collected during the present study indicated that at least two of these assumptions are not satisfied: estimates of distance based on sound are inaccurate and observers do not always detect near birds. No effect of observer presence on bird distribution was detected nor did there appear to be any significant movement of birds during counts. We recommend that bird counts be based only on sight detections and that, when bird movement is significant, instantaneous counts be used.
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Kim, Jin-Yong, Sanghun Lee, Man-Seok Shin, Chang-Hoon Lee, Changwan Seo, and Soo Hyung Eo. "Altitudinal patterns in breeding bird species richness and density in relation to climate, habitat heterogeneity, and migration influence in a temperate montane forest (South Korea)." PeerJ 6 (May 23, 2018): e4857. http://dx.doi.org/10.7717/peerj.4857.
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Altitudinal patterns in the population ecology of mountain bird species are useful for predicting species occurrence and behavior. Numerous hypotheses about the complex interactions among environmental factors have been proposed; however, these still remain controversial. This study aimed to identify the altitudinal patterns in breeding bird species richness or density and to test the hypotheses that climate, habitat heterogeneity (horizontal and vertical), and heterospecific attraction in a temperate forest, South Korea. We conducted a field survey of 142 plots at altitudes between 200 and 1,400 m a.s.l in the breeding season. A total of 2,771 individuals from 53 breeding bird species were recorded. Altitudinal patterns of species richness and density showed a hump-shaped pattern, indicating that the highest richness and density could be observed at moderate altitudes. Models constructed with 13 combinations of six variables demonstrated that species richness was positively correlated with vertical and horizontal habitat heterogeneity. Density was positively correlated with vertical, but not horizontal habitat heterogeneity, and negatively correlated with migratory bird ratio. No significant relationships were found between spring temperature and species richness or density. Therefore, the observed patterns in species richness support the hypothesis that habitat heterogeneity, rather than climate, is the main driver of species richness. Also, neither habitat heterogeneity nor climate hypotheses fully explains the observed patterns in density. However, vertical habitat heterogeneity does likely help explain observed patterns in density. The heterospecific attraction hypothesis did not apply to the distribution of birds along the altitudinal gradient. Appropriate management of vertical habitat heterogeneity, such as vegetation cover, should be maintained for the conservation of bird diversity in this area.
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Cody, Martin. "Breeding Bird Popluations in Grand Teton National Park: Density and Distribution." UW National Parks Service Research Station Annual Reports 19 (January 1, 1995): 19–23. http://dx.doi.org/10.13001/uwnpsrc.1995.3233.
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GTNP (Grand Teton National Park) recently initiated a breeding bird monitoring program, with a view toward assessing population densities of breeding birds and their potential changes, both of residents and neotropical migrants; the 1995 season was the first in which the monitoring protocols of the program were fully instigated. The program goals are the monitoring of both species and densities over a broad range of habitats within the park, with a view to detecting changes over time in these variables, in year-to-year "background" variation and in possible long-term trends. Site selection, mapping and marking, and deployment of various bird census techniques, will be completed and refined over three introductory years, 1995-1997. Thence, it is anticipated that the monitoring program will become permanently established, contributing yearly to an expanding data base on the park's breeding bird populations. This data base, it is believed, will become a useful backup and basis for management decisions, and an increasingly sensitive index from which changes in the park's avifauna, natural or anthropogenic, can be calibrated.
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Lima, L. R. De, J. A. D. Barbosa Filho, E. R. Freitas, D. H. Souza, V. S. S. Viana, N. A. F. Machado, and R. C. Nepomuceno. "Effect of Different Breeding Densities and Inclusion of Soybean Oil on Performance, Carcass Trait and Heat Loss in Meat Quails." Journal of Agricultural Science 11, no. 7 (May 31, 2019): 130. http://dx.doi.org/10.5539/jas.v11n7p130.
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Quails are homeothermic animals, in countries with a tropical climate, such as Brazil, birds face great difficulties in controlling body temperature inside the sheds. Several practices are being studied in order to keep these animals within the thermal comfort zone, and thus, to minimize the effects of thermal stress, partial substitution of carbohydrates by oils and changes in density are some of them. The objective of this study was to evaluate the different breeding densities and inclusion levels of soybean oil in performance, carcass characteristics and heat loss in quail. 450 quails, seven days old, distributed in a completely randomized design in a 3 × 2 factorial scheme, two densities (215.6 cm2 bird-1 and 188.6 cm2 bird-1) and three inclusion levels of soybean oil (0, 2, 4%) were used, totaling six treatments with five replicates each. The heat loss by radiation was estimated with the aid of infrared thermography. The results showed that there was an effect of the density on feed consumption, which was lower for birds raised in the density of 188.6 cm2 bird-1 (783.78 g of feed), but without its effect on weight gain and food conversion. No effect of inclusion levels of soybean oil was observed on any performance variables. There was no statistical difference (P > 0.05) between treatments for any variables of carcass yield and parts, and heat loss by radiation analyzed. Therefore, it is concluded that soybean oil inclusion levels do not affect the performance and yield of quails, nor do they influence the loss of heat throughout the life cycle of these animals. The birds raised in the density of 188.6 cm2 bird-1 obtained the lowest average dietary intake, with no impact on weight gain and feed conversion, allowing the creation of a greater number of birds per box.
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Carrascal, L. M., and J. L. Telleria. "Bird Size and Density: A Regional Approach." American Naturalist 138, no. 3 (September 1991): 777–84. http://dx.doi.org/10.1086/285250.
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Dawson, Deanna K., and Murray G. Efford. "Bird population density estimated from acoustic signals." Journal of Applied Ecology 46, no. 6 (November 26, 2009): 1201–9. http://dx.doi.org/10.1111/j.1365-2664.2009.01731.x.
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Grundel, Ralph, and Noel B. Pavlovic. "Response of Bird Species Densities to Habitat Structure and Fire History Along a Midwestern Open–Forest Gradient." Condor 109, no. 4 (November 1, 2007): 734–49. http://dx.doi.org/10.1093/condor/109.4.734.
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Abstract Oak savannas were historically common but are currently rare in the Midwestern United States. We assessed possible associations of bird species with savannas and other threatened habitats in the region by relating fire frequency and vegetation characteristics to seasonal densities of 72 bird species distributed across an open–forest gradient in northwestern Indiana. About one-third of the species did not exhibit statistically significant relationships with any combination of seven vegetation characteristics that included vegetation cover in five vertical strata, dead tree density, and tree height. For 40% of the remaining species, models best predicting species density incorporated tree density. Therefore, management based solely on manipulating tree density may not be an adequate strategy for managing bird populations along this open–forest gradient. Few species exhibited sharp peaks in predicted density under habitat conditions expected in restored savannas, suggesting that few savanna specialists occur among Midwestern bird species. When fire frequency, measured over fifteen years, was added to vegetation characteristics as a predictor of species density, it was incorporated into models for about one-quarter of species, suggesting that fire may modify habitat characteristics in ways that are important for birds but not captured by the structural habitat variables measured. Among those species, similar numbers had peaks in predicted density at low, intermediate, or high fire frequency. For species suggested by previous studies to have a preference for oak savannas along the open–forest gradient, estimated density was maximized at an average fire return interval of about one fire every three years.
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Srivastava, U. C., Durgesh Singh, Prashant Kumar, and Sippy Singh. "Neuronal diversity and their spine density in the hippocampal complex of the House Crow (Corvus splendens), a food-storing bird." Canadian Journal of Zoology 94, no. 8 (August 2016): 541–53. http://dx.doi.org/10.1139/cjz-2015-0260.
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Hippocampus, one of the parts included in the limbic system, is involved in various functions such as learning, memory, food-storing behavior, and sexual discrimination. Neuronal classes of the hippocampal complex in food-storing birds have been also reported, but the study lacks details pertaining to neuronal characteristics and the spine density of the neurons in different subfields of the hippocampus. Hence, the present study was undertaken with the aim to explore the morphology of neurons and the spines present on their dendrites within the hippocampal complex of the House Crow (Corvus splendens Vieillot, 1817), a food-storing Indian bird, and to compare it with previously reported nonfood-storing bird species. It was observed that the hippocampus of C. splendens harbors diverse neuronal classes with substantial percentages of pyramidal neurons, well-developed local circuit neurons, and high spine density. All these neuronal specializations in C. splendens can be related with the food-storing behavior of the bird, which itself is an advantage over nonfood-storing birds.
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Schieck, Jim, Marie Nietfeid, and J. Brad Stelfox. "Differences in bird species richness and abundance among three successional stages of aspen-dominated boreal forests." Canadian Journal of Zoology 73, no. 8 (August 1, 1995): 1417–31. http://dx.doi.org/10.1139/z95-167.
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Birds and vegetation were surveyed in young, mature, and old aspen-dominated boreal forests in Alberta. Height and size of live trees, density of large dead trees, and volume of downed woody material increased during succession, whereas density of live trees decreased. Canopy heterogeneity had a bimodal relationship with succession: old forests had the highest, mature forests the lowest, and young forests an intermediate canopy heterogeneity. Old forests had greater bird species richness than young forests, which in turn had greater richness than mature forests. Twenty-seven, 3, and 10 bird species had their highest abundances in old, mature, and young forests, respectively. Seven bird species that nest and forage in canopy gaps and three bird species that nest and forage in large trees and snags were more abundant in young and old forests than in mature forests. Contrary to our predictions, patterns of richness and abundance for bird species that nest and forage in the canopy or in tree cavities were similar to those for bird species that nest or forage in the lower strata. Bird species preferring coniferous forests tended to be more abundant in old than in young or mature aspen-dominated forests, possibly because old aspen forests had more conifers than younger aspen forests.
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Adams, Heidi L., L. Wes Burger, and Sam Riffell. "Edge Effects on Avian Diversity and Density of Native Grass Conservation Buffers." Open Ornithology Journal 8, no. 1 (February 2, 2015): 1–9. http://dx.doi.org/10.2174/1874453201508010001.
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Conservation Reserve Program Conservation Practice 33 (CP33: Conservation Buffers for Upland Birds) provides habitat for grassland birds in agriculture-dominated landscapes. However, landscape context and adjacency of other land covers may influence colonization, occupancy, and reproductive performance of breeding grassland birds in buffers. Our objective was to determine how edge effects influence diversity and density of breeding grassland birds in CP33 buffers. Data collected during transect surveys in CP33 buffers at a privately-owned farm in Clay County, Mississippi, USA during the 20072009 breeding seasons indicated that buffers with a woody edge had the least diversity and density of grassland and facultative grassland birds. Dickcissels (Spiza americana), the most abundant grassland bird species detected in buffers, had a lower density in woodland-bordered buffers than in grassland-bordered buffers. Red-winged Blackbirds (Agelaius phoeniceus) had a lower density in buffers adjacent to woodlands than buffers adjacent to developed areas and those bordered on both sides by crop fields. Conversely, Indigo Buntings, (Passerina cyanea) a woodland edge species, had the greatest density in woodland-bordered buffers when compared to buffers adjacent to grassland and developed areas. These results demonstrate that adjacency influences colonization processes and conservation design should explicitly incorporate local landscape context in field and farm-scale conservation plans. Where conservation of obligate grassland birds is a primary objective of native grass conservation buffers, avoidance of buffer establishment adjacent to woodlands may maximize environmental services as measured by grassland bird diversity and density.
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Persulessy, Yan Eliazer, and J. D. Putuhena. "A Keragaman dan Populasi Burung Endemik pada Hotspot Kesatuan Pengelolaan Hutan Produksi Wae Sapalewa Seram Utara." MAKILA 14, no. 2 (December 30, 2020): 99–113. http://dx.doi.org/10.30598/makila.v14i2.2930.
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Endemic bird species have a high conservation value concentrated in a critical location for conservation with an exciting value in endemic bird species groups. The site of concentration of endemic bird species can be referred to as Endemic Bird Diversity Hotspot. There are seven bird diversity hotspot locations identified in the KPHP Wae Sapalewa region in North Seram, with a good bird species diversity, including endemic bird species. The study aimed to examine the variety and population of endemic bird species at seven hotspot locations within kphp Wae Sapalewa. The research method uses Point Count, which is placed in the transek. The results showed 121 species of birds, consisting of 9 species, namely: Basilornis corythaix, Cacatua moluccensis, Gymnophaps mada, Eos semilarvata, Lorius domicella, Halcyon lazuli, Rhipidura dedemi, Philemon subcorniculatus, and Myzomela blasii. Most endemic bird species have a low population density. This condition shows the need for conservation action for endemic bird species groups in these hotspot locations. KPHP Wae Sapalewa organization has the opportunity to take appropriate conservation actions to accelerate the existence of these endemic bird species.
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Glatz, P. C., and Z. H. Miao. "Husbandry of ratites and potential welfare issues: a review." Australian Journal of Experimental Agriculture 48, no. 10 (2008): 1257. http://dx.doi.org/10.1071/ea08136.
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Since the mid-1980s, there has been worldwide farming of ratites, particularly with ostriches, emus and rheas for feathers, meat, skin and oil. Most of these ratites are produced commercially outside their native habitat. This has raised concerns about welfare, particularly whether birds are provided the five freedoms: food and water; shelter; health care; alleviation of pain and suffering; and the freedom of movement. This paper reviews the factors that influence bird welfare before hatch with breeder, egg and hatchery management and after hatch with brooding and rearing systems, stocking density, handling, transport, disease and slaughter. Assessment of bird welfare in each of the production sectors in the industry is based on how well the five freedoms are being met. The review identifies egg handling practices and hatchery hygiene that can have a major impact on the subsequent health of hatched chicks. In addition, feeding of appropriate diets, reducing stocking density and improving housing can improve bird health and freedom of movement. When the husbandry practice of toe trimming is not practiced according to the best practice method, chronic pain may result and impair walking ability of birds. Stress and injuries to birds can be reduced when birds are handled correctly on farm and in the lairage and are transported using appropriate vehicles. Farmers, transporters and abattoir staff can have a major impact on maintaining bird welfare if best practice farming systems and husbandry practices are implemented.
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Ali, A. A., N. H. Idris, and M. H. I. Ishak. "THE INFLUENCE OF LAND-USE LAND-COVER CHANGES ON URBAN BIRD COMMUNITIES." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-4/W16 (October 1, 2019): 93–100. http://dx.doi.org/10.5194/isprs-archives-xlii-4-w16-93-2019.
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Abstract. City development changes the landscape and has been claimed to pose threat to the survival of birds that heavily relies on healthy forest ecosystem. As such, this study assessed the effect of land-use land-cover (LULC) changes due to sub-urbanisation on birds’ community using geostatistical method. In this study, geostatistical analyses, namely Kernel Density and Ordinary Least Square (OLS), were executed to identify the dominant factors that affected the birds’ community in the Johor Bahru region. The birding data were obtained from eBird, an online crowd source database of bird distribution. The distribution of bird community was analysed by using Kernel density for years 2016 and 2018. This study found that the hotspot locations of the birds were in Danga Bay and Kempas Denai for year 2016, whereas Kampung Pok, Bukit Chagar, Taman Sentosa and Kampung Dato Sulaiman Menteri for year 2018. Certain urban bird species increased from year 2016 to 2018. The OLS regression was applied to analyse the relationship between birds’ occurrence and LULC features within the study area. The global regression model indicated that distance to forest and distance to recreational and open space were positively associated with the number of bird occurrence. On the contrary, distance to road was negatively associated with the number of bird occurrence. The OLS model for year 2016 between birds’ occurrence and distance to road, distance to forest, as well as distance to recreational and open space, demonstrated an adjusted R2 value of 0.32. In year 2018, the correlation between birds’ occurrence and distance to road, as well as distance to recreational and open space, demonstrated an adjusted R2 value of 0.11. As a conclusion, urbanisation seems to affect the birds’ communities as it increases the number of urban birds spotted in Johor Bahru, which is attributed to the increasing recreational and open space areas in Johor Bahru. The study outcomes can be applied to comprehend the relationship between birds’ community and LULC changes, as a result of urbanisation.
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Herbers, Jim R., Robert Serrouya, and Katherine A. Maxcy. "Effects of elevation and forest cover on winter birds in mature forest ecosystems of southern British Columbia." Canadian Journal of Zoology 82, no. 11 (November 1, 2004): 1720–30. http://dx.doi.org/10.1139/z04-151.
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Winter diversity, distribution, and density of nonmigratory birds were examined in six mature forest ecosystems from two study areas in southern British Columbia. Forest age ranged from 91 to 150 years and the ecosystems ranged from 500 to 2100 m above sea level. Sampled forest stands had no previous history of logging and were a minimum 30 ha in size. The main objectives of this study were to measure nonmigratory birds in relation to elevation and to percentage of stand-level lodgepole pine composition. Twenty-one nonmigratory bird species totaling 2747 observations were detected at 775 point-count stations in 107 stands using 10-min unlimited-distance point counts. Pine siskins (Carduelis pinus (Wilson, 1810)), red-breasted nuthatches (Sitta canadensis L., 1766), and red crossbills (Loxia curvirostra L., 1758) were the three most commonly detected species. Mature forests at low elevation had between 1.7 and 3.5 times more species and between 2.0 and 4.7 times more birds than forests at high elevation. In addition, species richness and bird density declined with increasing stand-level composition of lodgepole pine. We suggest that low-elevation ecosystems be given high priority in coarse-filter management of winter bird habitat.
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Marques, Tiago A., Len Thomas, Steven G. Fancy, and Stephen T. Buckland. "Improving Estimates of Bird Density Using Multiple- Covariate Distance Sampling." Auk 124, no. 4 (October 1, 2007): 1229–43. http://dx.doi.org/10.1093/auk/124.4.1229.
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Abstract Inferences based on counts adjusted for detectability represent a marked improvement over unadjusted counts, which provide no information about true population density and rely on untestable and unrealistic assumptions about constant detectability for inferring differences in density over time or space. Distance sampling is a widely used method to estimate detectability and therefore density. In the standard method, we model the probability of detecting a bird as a function of distance alone. Here, we describe methods that allow us to model probability of detection as a function of additional covariates—an approach available in DISTANCE, version 5.0 (Thomas et al. 2005) but still not widely applied. The main use of these methods is to increase the reliability of density estimates made on subsets of the whole data (e.g., estimates for different habitats, treatments, periods, or species), to increase precision of density estimates or to allow inferences about the covariates themselves. We present a case study of the use of multiple covariates in an analysis of a point-transect survey of Hawaii Amakihi (Hemignathus virens). Amélioration des estimations de densité d’oiseaux par l’utilisation de l’échantillonnage par la distance avec covariables multiples
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Leavesley, Adam J., and Geofferey J. Cary. "The effect of patch area on birds in central Australian mulga (Acacia aneura) woodland of different times-since-fire." Pacific Conservation Biology 19, no. 1 (2013): 28. http://dx.doi.org/10.1071/pc130028.
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It is often assumed that a fine-scaled mosaic of different times-since-fire supports greater biodiversity than a coarsescaled mosaic — the fire mosaic hypothesis. A potential mechanism of the fire mosaic hypothesis is the effect of area on species diversity. We investigated the effect of patch area on bird communities in mulga (Acacia aneura) woodland in central Australia. The study was conducted at Uluru Kata-Tjuta National Park using 55 fixed-area sites classified to the time since last fire: burnt 2002; burnt 1976 and long unburnt. Birds were surveyed in the winter and spring of 2005 and 2006. Of 20 key species, two showed a positive density-area effect (i.e. higher density in larger patches). Patch area did not affect total bird density or species richness. However, species turnover (ß-diversity) was greater in large patches in the burnt 2002 treatment than it was in small patches. There was no effect of patch area on the composition of the bird communities in any of the time-since-fire classes. We concluded that patch area did affect the distribution of some birds in mulga woodland. However, patch area was not a mechanism of the fire mosaic hypothesis because the effects of patch size tended to increase avian diversity in larger patches rather than small.
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Blumstein, Daniel T., Douglas R. Mcclain, Carrie De Jesus, and Gustavo Alarcón-Nieto. "Breeding bird density does not drive vocal individuality." Current Zoology 58, no. 5 (October 1, 2012): 765–72. http://dx.doi.org/10.1093/czoolo/58.5.765.
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Abstract Many species produce individually specific vocalizations and sociality is a hypothesized driver of such individuality. Previous studies of how social variation influenced individuality focused on colonial or non-colonial avian species, and how social group size influenced individuality in sciurid rodents. Since sociality is an important driver of individuality, we expected that bird species that defend nesting territories in higher density neighborhoods should have more individually-distinctive calls than those that defend nesting territories in lower-density neighborhoods. We used Beecher’s information statistic to quantify individuality, and we examined the relationship between bird density (calculated with point-counts) and vocal individuality on seven species of passerines. We found non-significant relationships between breeding bird density and vocal individuality whether regressions were fitted on species values, or on phylogenetically-independent contrast values. From these results, we infer that while individuality may be explained by social factors, breeding bird density is unlikely to be generally important in driving the evolution of individually-specific vocalizations.
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Aberle, M. A., K. E. Langwig, J. S. Adelman, and D. M. Hawley. "Effects of bird feeder density on the foraging behaviors of a backyard songbird (the House Finch, Haemorhous mexicanus) subject to seasonal disease outbreaks." Canadian Journal of Zoology 98, no. 9 (September 2020): 611–21. http://dx.doi.org/10.1139/cjz-2019-0282.
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Provisioning of wildlife, such as backyard bird feeding, can alter animal behavior and ecology in diverse ways. For species that are highly dependent on supplemental resources, it is critical to understand how variation in the degree of provisioning, as occurs naturally across backyards, alters wildlife behavior and ecology in ways potentially relevant to disease spread. We experimentally manipulated feeder density at suburban sites and tracked local abundance, foraging behaviors, body mass, and movement in House Finches (Haemorhous mexicanus (P.L. Statius Müller, 1776)), the primary host of a pathogen commonly spread at feeders. Sites with high feeder density harbored higher local House Finch abundance, and birds at these sites had longer feeding bouts and total time on feeders relative to sites with low feeder density. House Finches at high-density feeder sites had lower residual body mass despite greater apparent feeder access. Finally, birds first recorded at low-density feeder sites were more likely to move to neighboring high-density feeder sites than vice versa. Because local abundance and time spent on feeders have both been linked with disease risk in this species, the effects of heterogeneity in bird feeder density on these traits may have important consequences for disease dynamics in this system and more broadly.
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Schuler, Carol A., William H. Rickard, and Glen A. Sargeant. "Conservation of Habitats for Shrubsteppe Birds." Environmental Conservation 20, no. 1 (1993): 57–64. http://dx.doi.org/10.1017/s037689290003722x.
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Extending over a year, all the birds that could be detected were counted on two transects which together sampled an area of 1.39 km2. Only 37 species were recorded during 82 surveys. Total bird density during the spring (March–June) was 43.0 birds/km2, and the density for the entire year was 26.7 birds/km2. The characteristic nesting birds were Western Meadowlark, Sage Sparrow, Burrowing Owl, Mourning Dove, Horned Lark, Long-billed Curlew, Lark Sparrow, and Loggerhead Shrike. Western Meadow-larks and Sage Sparrows were the most abundant nesting birds, having an average density of 11.2 and 7.8 birds/km2, respectively. Seasonal distribution of birds varied with species, but most species were present only from March to September.Sixty-three per cent of the habitat surveyed was dominated by Big Sagebrush, 26% was dominated by Cheatgrass, and the remaining 11% was dominated by Spiny Hopsage. Big Sagebrush habitat supported a greater total bird density than the Cheatgrass or Hopsage habitats. Sage Sparrows were closely associated with Sagebrush habitats, while Western Meadowlarks showed no strong habitat affinities.Extensive habitat modifications induced by more than a century of agriculture and livestock grazing have greatly depleted native Shrubsteppe habitat in the Columbia Basin. Over the past 40 years, the Hanford Site has served as a refugium for Shrubsteppe habitat that supports populations of native Shrubsteppe birds. The concept of the Hanford Site as a refugium for native Shrubsteppe habitat and Shrubsteppe nesting birds is favourably discussed.
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Das, Delip K., Mohammad Mostafa Feeroz, and Sajeda Begum. "Diversity and population density of birds at the Jahangirnagar University campus, Bangladesh." Bangladesh Journal of Zoology 48, no. 2 (April 11, 2021): 289–300. http://dx.doi.org/10.3329/bjz.v48i2.52369.
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Rapid urbanization is changing the habitats of many wildlife species. Even so, certain species appear to adapt and now have thriving populations within cities. To look at the capacity for these spaces to provide “habitat” we examined population density of bird species using Jahangirnagar University campus close to the Dhaka mega city, Bangladesh. Four strip transects were surveyed from March 2008 to February 2009 (12 times/transect). A total of 101 species were found along the transect areas. The density of Lesser Whistling Duck (Dendrocygna javanica) was the highest 107.02indiv. /ha while Large-tailed Nightjar (Caprimulgus macrurus) was the lowest 0.01indiv. /ha among resident birds of Jahangirnagar University campus. Among the migratory birds, the density of Pintail Snipe (Gallinago stenura) and Common Stonechat (Saxicola torquata) were the highest (1.99indiv. /ha.) and the lowest (0.02indiv. /ha.), of the different available habitats, water bodies contained the highest density (318.59indiv. /ha) and grassland contained the lowest (2.48indiv./ha) of bird population. The percentage of average density of non-passerine and passerine birds was 65% and 35%, respectively. Future studies of avian composition and density is recommended at a regular interval to understand changes in the carrying capacity and avian community of the campus as a function of altering habitat due urbanization.
Bangladesh J. Zool. 48(2): 289-300, 2020
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Dokter, Adriaan M., Felix Liechti, Herbert Stark, Laurent Delobbe, Pierre Tabary, and Iwan Holleman. "Bird migration flight altitudes studied by a network of operational weather radars." Journal of The Royal Society Interface 8, no. 54 (June 2, 2010): 30–43. http://dx.doi.org/10.1098/rsif.2010.0116.
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A fully automated method for the detection and quantification of bird migration was developed for operational C-band weather radar, measuring bird density, speed and direction as a function of altitude. These weather radar bird observations have been validated with data from a high-accuracy dedicated bird radar, which was stationed in the measurement volume of weather radar sites in The Netherlands, Belgium and France for a full migration season during autumn 2007 and spring 2008. We show that weather radar can extract near real-time bird density altitude profiles that closely correspond to the density profiles measured by dedicated bird radar. Doppler weather radar can thus be used as a reliable sensor for quantifying bird densities aloft in an operational setting, which—when extended to multiple radars—enables the mapping and continuous monitoring of bird migration flyways. By applying the automated method to a network of weather radars, we observed how mesoscale variability in weather conditions structured the timing and altitude profile of bird migration within single nights. Bird density altitude profiles were observed that consisted of multiple layers, which could be explained from the distinct wind conditions at different take-off sites. Consistently lower bird densities are recorded in The Netherlands compared with sites in France and eastern Belgium, which reveals some of the spatial extent of the dominant Scandinavian flyway over continental Europe.
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Putri, Indra A. S. L. P., Bayu Wisnu Broto, and Fajri Ansari. "Bird responses to habitat change in the karst area of Bantimurung Bulusaraung National Park." Jurnal Penelitian Kehutanan Wallacea 6, no. 2 (August 31, 2017): 101. http://dx.doi.org/10.18330/jwallacea.2017.vol6iss2pp101-112.
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Birds are useful bioindicators to habitat changes. This study aims to determine the responses of birds to habitat change at Maros-Pangkep karst area, Bantimurung-Bulusaraung National Park. The research was carried out in three disturbance degrees (core-zone, wilderness-zone, and the community-gardens), which represents minimal, middle, and high interference level. A modified square-line method was used to observe vegetation of bird habitat. Point count method was used to observe bird population. Data of the bird habitat vegetation was analyzed using vegetation density. The difference of vegetation composition was analyzed using Sorensen-similarity index. Data of the bird was analyzed using abundance, and indexes of Shannon-Weinner diversity, Simpson dominance, Pielou evenness, and Margalef species richness. Significant differences between the number of the individual bird were tested using one-way ANOVA, Tukey-Bonferroni test. The results showed that birds living in karst were sensitive to habitat changes. Birds responded through reducing the number of individuals and species, shifting the species of bird that has high importance value index from low tolerance species to high tolerance species. Birds also responded by shifting the feeding guild that has high important value index from frugivore to frugivore-insectivore and then to granivore, decreasing the number of bird species with large body size, reducing the number of bird species that need a special location to build nest. Considering that Maros-Pangkep Karst has vital roles, scientific values, and biodiversity richness, it is necessary to involve all stakeholders to maintain its sustainability, including the establishment of entire Maros-Pangkep Karst area as the karst-landscape area.
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Sasvári, L., J. Török, and L. Tóth. "Density dependent effects between three competitive bird species." Oecologia 72, no. 1 (April 1987): 127–30. http://dx.doi.org/10.1007/bf00385056.
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Solomou, Alexandra, and Athanassios Sfougaris. "Comparing conventional and organic olive groves in central Greece: plant and bird diversity and abundance." Renewable Agriculture and Food Systems 26, no. 4 (April 1, 2011): 297–316. http://dx.doi.org/10.1017/s1742170511000111.
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AbstractThe present study was conducted in Magnesia Prefecture, central Greece, during the period May–June 2007. It aimed at the comparison between conventional and certified organic olive groves with regard to olive and olive oil production, diversity of plants (herbaceous and woody) and diversity and abundance of avifauna. Correlations between variables within herbaceous plants (linear regression) and woody plants (Principal Component Analysis), and the role of integration time of olive groves to the organic system were investigated. Also, finding easily measurable parameters indicating high bird diversity levels within organic and conventional management systems was a main target of the study. According to our findings, neither edible olive yield nor olive oil yield showed significant differences between conventional and certified organic olive groves. There is an increasing trend for alpha and beta diversity of herbaceous plant species, woody plant beta diversity, density and cover of woody plants, and density of breeding birds in certified organic olive groves (10 years) in comparison with conventional ones. The effect of time since the adoption of organic procedures is very important and produces benefits for the biodiversity. In the total olive groves 15 insectivorous, six granivorous and three insectivorous/granivorous birds species were recorded. Nine bird species distinguished by Ward's hierarchical clustering were identified as typical (indicator value, IndVal>50%) of specific farming systems. Among them, the Eurasian jay, associated with the 10-year certified organic olive groves, and the common cuckoo, Orphean warbler and Red-backed shrike, associated with the 6-year certified organic olive groves, should be regarded as characteristic species (IndVal>70%). Conclusively, organic farming favors some aspects of diversity of herbaceous and woody plants of olive grove ecosystems. On the contrary, similar effects on breeding bird diversity and density were not clearly recorded. However, breeding bird density proved a good indicator of their richness.
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Monroe, Adrian P., David R. Edmunds, Cameron L. Aldridge, Matthew J. Holloran, Timothy J. Assal, and Alison G. Holloran. "Prioritizing landscapes for grassland bird conservation with hierarchical community models." Landscape Ecology 36, no. 4 (March 6, 2021): 1023–38. http://dx.doi.org/10.1007/s10980-021-01211-z.
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Abstract Context Given widespread population declines of birds breeding in North American grasslands, management that sustains wildlife while supporting rancher livelihoods is needed. However, management effects vary across landscapes, and identifying areas with the greatest potential bird response to conservation is a pressing research need. Objectives We developed a hierarchical modeling approach to study grassland bird response to habitat factors at multiple scales and levels. We then identified areas to prioritize for implementing a bird-friendly ranching program. Methods Using bird survey data from grassland passerine species and 175 sites (2009–2018) across northeast Wyoming, USA, we fit hierarchical community distance sampling models and evaluated drivers of site-level density and regional-level distribution. We then created spatially-explicit predictions of bird density and distribution for the study area and predicted outcomes from pasture-scale management scenarios. Results Cumulative overlap of species distributions revealed areas with greater potential community response to management. Within each species’ potential regional-level distribution, the grassland bird community generally responded negatively to cropland cover and vegetation productivity at local scales (up to 10 km of survey sites). Multiple species declined with increasing bare ground and litter cover, shrub cover, and grass height measured within sites. Conclusions We demonstrated a novel approach to multi-scale and multi-level prioritization for grassland bird conservation based on hierarchical community models and extensive population monitoring. Pasture-scale management scenarios also suggested the examined community may benefit from less bare ground cover and shorter grass height. Our approach could be extended to other bird guilds in this region and beyond.
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Michel, Nicole L., Thomas W. Sherry, and Walter P. Carson. "The omnivorous collared peccary negates an insectivore-generated trophic cascade in Costa Rican wet tropical forest understorey." Journal of Tropical Ecology 30, no. 1 (November 11, 2013): 1–11. http://dx.doi.org/10.1017/s0266467413000709.
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Abstract:Insectivorous birds and bats often protect plants through density- and trait-mediated cascades, but the degree to which insectivores reduce herbivorous arthropods and leaf damage varies among systems. Top-down interaction strength may be influenced by the biotic and abiotic context, including the presence of vegetation-disturbing animals. We tested two hypotheses: (1) insectivorous birds and bats initiate trophic cascades in tropical rain-forest understorey; and (2) the native, omnivorous collared peccary (Pecari tajacu) negates these cascades via non-trophic effects. We studied the top-down effects of birds and bats on understorey plants in north-eastern Costa Rica using 60 netted exclosures within and outside existing peccary exclosures. Excluding birds and bats increased total arthropod densities by half, both with and without peccaries. Bird/bat exclosures increased Diptera density by 28% and leaf damage by 24% without peccaries, consistent with a trophic cascade. However, bird/bat exclosures decreased Diptera density by 32% and leaf damage by 34% with peccaries, a negation of the trophic cascade. Excluding peccaries increased leaf damage by 43% on plants without birds and bats. This is the first study, to our knowledge, to demonstrate that the non-trophic activity of an omnivorous ungulate can reverse a trophic cascade.
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Yackel Adams, Amy A., Melia G. Nafus, Page E. Klug, Björn Lardner, M. J. Mazurek, Julie A. Savidge, and Robert N. Reed. "Contact rates with nesting birds before and after invasive snake removal: estimating the effects of trap-based control." NeoBiota 49 (July 22, 2019): 1–17. http://dx.doi.org/10.3897/neobiota.49.35592.
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Invasive predators are responsible for almost 60% of all vertebrate extinctions worldwide with the most vulnerable faunas occurring on islands. The brown treesnake (Boigairregularis) is a notorious invasive predator that caused the extirpation or extinction of most native forest birds on Guam. The success of avian reintroduction efforts on Guam will depend on whether snake-control techniques sufficiently reduce contact rates between brown treesnakes and reintroduced birds. Mouse-lure traps can successfully reduce brown treesnake populations at local scales. Over a 22-week period both with and without active snake removal, we evaluated snake-trap contact rates for mouse- and bird-lure traps. Bird-lure traps served as a proxy for reintroduced nesting birds. Overall, mouse-lure traps caught more snakes per trap night than did bird-lure traps. However, cameras revealed that bird-lure traps had a snake contact rate almost 15 times greater than the number of successfully captured snakes. Snakes that entered bird-lure traps tended to be larger and in better body condition and were mostly captured in bird-lure traps, despite numerous adjacent mouse-lure traps. Traps placed along grid edges caught more snakes than interior traps, suggesting continuous immigration into the trapping grid within which bird-lure traps were located. Contact between snakes and bird-lure traps was equivalent before and after snake removal, suggesting mouse-lure traps did not adequately reduce the density of snakes that posed a risk to birds, at least at the timescale of this project. This study provides evidence that some snakes exhibit prey selectivity for live birds over live mouse lures. Reliance on a single control tool and lure may be inadequate for support of avian reintroductions and could lead to unintended harvest-driven trait changes of this invasive predator.
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Régnière, Jacques, Lisa Venier, and Dan Welsh. "Avian Predation in a Declining Outbreak Population of the Spruce Budworm, Choristoneura fumiferana (Lepidoptera: Tortricidae)." Insects 12, no. 8 (August 11, 2021): 720. http://dx.doi.org/10.3390/insects12080720.
Full textAbstract:
The impact of avian predation on a declining population of the spruce budworm, Choristoneura fumifereana (Clem.), was measured using single-tree exclosure cages in a mature stand of balsam fir, Abies balsamea (L.), and white spruce, Picea glauca (Moench.) Voss. Bird population censuses and observations of foraging and nest-feeding activity were also made to determine the response of budworm-linked warblers to decreasing food availability. Seasonal patterns of foraging. as well as foraging success in the declining prey population was compared to similar information from birds observed in another stand where the spruce budworm population was rising. Avian predation was an important source of mortality between the 4th instar and moth emergence in the declining outbreak population. Mortality by predation increased from negligible to over 98% as budworm density dropped from 100 to <1 larva/kg of host foliage, over 3 years. Calculations based on nest-feeding activity and basic metabolic demands support these observed rates. Seasonal and yearly differences in predation rates observed between the two host-tree species correspond to equivalent shifts in bird foraging behavior in response to dropping insect density. In particular, a preference for searching on white spruce disappeared, although budworm-linked birds remained more efficient at finding food on this plant. The ability to change foraging behavior as prey density dropped differed between bird species.
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Simon, N. PP, F. E. Schwab, and R. D. Otto. "Songbird abundance in clear-cut and burned stands: a comparison of natural disturbance and forest management." Canadian Journal of Forest Research 32, no. 8 (August 1, 2002): 1343–50. http://dx.doi.org/10.1139/x02-057.
Full textAbstract:
To evaluate the efficacy of forest management to emulate natural disturbance, we compared bird abundances among burned and clear-cut, former black spruce (Picea mariana (Mill.) BSP) sites, after 5, 14, and 27 years of succession. Total bird density was lower in clear-cut sites resulting from fewer hermit thrushes, yellow warblers, Swainson's thrushes, and fox sparrows. Hermit thrushes were positively correlated with snag density while yellow warblers and Swainson's thrushes were positively associated with deciduous tree cover and negatively correlated with conifer cover. Only yellow-rumped warblers had higher densities on clear-cut sites, likely due to greater conifer cover. Bird densities and species richness peaked in the 14-year-old burns and exceeded that of mature forests reported for Labrador. This demonstrates the importance of natural early successional forests for birds. Although logged areas support several species found in natural young burns, logging does not precisely mimic fire. This suggests that forest managers should allow some forests to burn naturally.
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Hoefer, Christopher J. "Marine Bird Attraction to Thermal Fronts in the California Current System." Condor 102, no. 2 (May 1, 2000): 423–27. http://dx.doi.org/10.1093/condor/102.2.423.
Full textAbstract:
AbstractI relate marine bird density to the 55 strongest thermal fronts encountered during a survey of much of the eastern portion of the California Current and the adjacent coastal upwelling region. Elevated densities were recorded for all marine bird taxa except the Leach's Storm-Petrel (Oceanodroma leucorhoa). The variance explained by the regression models ranged from 3% for the Leach's Storm-Petrel to 85% for all marine birds. The response observed is notably stronger than previous analyses with similar data.
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L. Oliver, Damon, Andrew J. Ley, Hugh A. Ford, and Beth Williams. "Habitat of the Regent Honeyeater Xanthomyza phrygia and the value of the Bundarra-Barraba region for the conservation of avifauna." Pacific Conservation Biology 5, no. 3 (1999): 224. http://dx.doi.org/10.1071/pc990224.
Full textAbstract:
Five types of woodland and forest in the Bundarra-Barraba region of northern New South Wales were surveyed for Regent Honeyeaters Xanthomyza phrygia and other birds over two years. Regent Honeyeaters were found in 24 of the 93 transects, at a density of 0.09 birds/ha. Most were found in box-ironbark woodland (34% of 62 sites), with single records from box-gum woodland, box-stringybark woodland and dry plateau complex woodland. No Regent Honeyeaters were found in riparian gallery forest during censuses, but they were found breeding there at other times. All habitats contained a high density of birds, compared to other wooded regions in southern Australia, with riparian gallery forest and box-ironbark woodland being particularly rich in species and numbers. These habitats had greater flowering indices, larger trees and more mistletoes than other habitats. Sites used by Regent Honeyeaters supported significantly more birds and bird species than unoccupied sites. The region supports a total of 193 species, four of which are nationally threatened and seven which are threatened in New South Wales. The richness of the bird community in the region is partly because it retains a higher proportion of native vegetation cover (43%) than many other parts of rural Australia. Protection and rehabilitation of box-ironbark woodland and riparian gallery forest is of high priority in a regional conservation plan. However, all habitats in the Bundarra-Barraba region should be protected from clearing and degradation, because they are also used at times by Regent Honeyeaters and support a wide range of bird species. Wise management should retain many sensitive bird species that have disappeared from or declined in other regions of southeastern Australia.
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Wang, F. S., Z. F. Yue, and W. Z. Yan. "Factors Study Influencing on Numerical Simulation of Aircraft Windshield against Bird Strike." Shock and Vibration 18, no. 3 (2011): 407–24. http://dx.doi.org/10.1155/2011/304541.
Full textAbstract:
The combined model of UniGraphics(UG) and ANSYS-LS-DYNA software and finite element (FE) model of aircraft windshield and windshield structure for bird strike were built. The windshield structure is composed of windshield, framework, arc-frame and gasket. The factors influencing on dynamic response for bird strike were analyzed such as bird velocity, mesh density of windshield, mesh density of bird, boundary condition, material model of windshield, analytic methods and components of windshield structure. The results showed that these factors must be taken into account when FE analysis method is applied to aircraft anti-bird design.
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Tassicker, A. L., A. S. Kutt, E. Vanderduys, and S. Mangru. "The effects of vegetation structure on the birds in a tropical savanna woodland in north-eastern Australia." Rangeland Journal 28, no. 2 (2006): 139. http://dx.doi.org/10.1071/rj05029.
Full textAbstract:
Management of the dynamics of woody vegetation in Australia’s tropical savannas is a vexing issue for both pastoralists and conservation biologists. In savanna regions around the world, increasing density of woody vegetation contributes to declines in pastoral productivity, but its effects on native fauna are largely unknown. In this paper we examine the avifauna in savanna woodlands of varying structure in the Desert Uplands bioregion, Queensland. Vegetation cover maps derived from aerial photographs were used to choose 60 sites, across 4 cattle stations. We sampled sites mapped at 30–45% and 45–60% foliage cover, and areas which previously had these levels of cover but had been mechanically modified, both by broad scale clearing and selective thinning. Between May and June 2004, we measured a range of habitat variables and sampled the birds at each site. Bird species composition varied significantly between treatments. Bird richness and frequency was greatest in intact vegetation. Thirteen species of birds were most frequently encountered in sites with 30–45% canopy cover, compared with 10 species in the 45–60% cover sites, 4 species in the thinned sites and 7 in the cleared sites. Our results suggest that increasing density of woody vegetation in savanna woodland may be to the advantage of some savanna bird species. Mechanical modification to reduce woody vegetation appears to also benefit some common, widespread species, but has a generally negative overall effect on bird species richness.
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Rajpar, Muhammad Nawaz, and Mohamed Zakaria. "Bird Species Abundance and Their Correlationship with Microclimate and Habitat Variables at Natural Wetland Reserve, Peninsular Malaysia." International Journal of Zoology 2011 (2011): 1–17. http://dx.doi.org/10.1155/2011/758573.
Full textAbstract:
Birds are the most conspicuous and significant component of freshwater wetland ecosystem. Presence or absence of birds may indicate the ecological conditions of the wetland area. The objectives of this study were to determine bird species abundance and their relationship with microclimate and habitat variables. Distance sampling point count method was applied for determining species abundance and multiple regressions was used for finding relationship between bird species abundance, microclimate and habitat variables. Bird species were monitored during November, 2007 to January, 2009. A total of 8728 individual birds comprising 89 species and 38 families were detected. Marsh Swamp was swarmed by 84 species (69.8%) followed open water body by 55 species (17.7%) and lotus swamp by 57 species (12.6%). Purple swamphenPorphyrio porphyrio(9.1% of all detections) was the most abundant bird species of marsh swamp, lesser whistling duck—Dendrocygna javanica(2.3%) was dominant species of open water body and pink-necked green pigeon—Treron vernans(1.7%) was most common species of lotus swamp. Results revealed that the habitat characteristics such as vegetation composition (i.e. emergent and submerged vegetations, grasses, shrubs, and trees), vegetation structures (tree diameter and height) and microclimate variables (temperature, relative humidity and light intensity) were the key factors that influenced the distribution, diversity and density of the wetland bird species. This study also revealed that the wetland bird species have adapted a fairly unique set of microhabitat and microclimate conditions.
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Phillips, Hannah N., and Bradley J. Heins. "Effects of Outdoor Stocking Density on Growth, Feather Damage and Behavior of Slow-Growing Free-Range Broilers." Animals 11, no. 3 (March 4, 2021): 688. http://dx.doi.org/10.3390/ani11030688.
Full textAbstract:
Access to pasture is a main benefit of free-range broiler housing systems, yet the level of outdoor stocking density on broiler animal welfare remains unsettled. The growth, feather damage, pasture ranging and behaviors were assessed for 150 mixed-sex, slow-growing Freedom Rangers from 5 to 11 weeks of age of with free access to either a high outdoor stocking density pasture (0.5 m2 per bird) or a low outdoor stocking density pasture (2.5 m2 per bird). The probability (mean, 95% CI) of tail feather damage was greater for the high-density (23.1%, 16.3 to 31.7%) compared to the low-density group (11.9%, 7.1 to 19.3%). The percent of observations resulting in sunbathing and aggressive attacks (i.e., pecking and fighting behaviors) were greater for the high-density (1.0%, 0.6 to 1.8% and 0.5%, 0.2 to 1.3%, respectively) compared to the low-density group (0.3%, 0.1 to 0.7% and 0.1%, 0.0 to 0.4%, respectively). Furthermore, an interaction between treatment and age indicated that birds in the high-density group displayed greater stretching (during weeks 7 to 10) and panting (during weeks 6 and 9). Results of this study suggest that additional outdoor pasture space may be positively associated with broiler welfare.
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Nussbaumer, Raphaël, Baptiste Schmid, Silke Bauer, and Felix Liechti. "A Gaussian Mixture Model to Separate Birds and Insects in Single-Polarization Weather Radar Data." Remote Sensing 13, no. 10 (May 19, 2021): 1989. http://dx.doi.org/10.3390/rs13101989.
Full textAbstract:
Recent and archived data from weather radar networks are extensively used for the quantification of continent-wide bird migration patterns. While the process of discriminating birds from weather signals is well established, insect contamination is still a problem. We present a simple method combining two Doppler radar products within a Gaussian mixture model to estimate the proportions of birds and insects within a single measurement volume, as well as the density and speed of birds and insects. This method can be applied to any existing archives of vertical bird profiles, such as the European Network for the Radar surveillance of Animal Movement repository, with no need to recalculate the huge amount of original polar volume data, which often are not available.