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McIntosh, Sydney Moore, Christian Kerut, Payton P. Hollenshead, Dorothy H. Askins, Kasra Mansourian, Zachary R. Palowsky, Varsha Allampalli, Shahab Ahmadzadeh, Sahar Shekoohi und Alan D. Kaye. „Golimumab for Polyarticular Juvenile Idiopathic Arthritis and Psoriatic Arthritis: Pharmacologic and Clinical Considerations“. Life 13, Nr. 7 (21.07.2023): 1601. http://dx.doi.org/10.3390/life13071601.
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Psoriatic arthritis is a chronic debilitating autoimmune condition, and when diagnosed in patients before the age of eighteen, it is considered pediatric polyarticular juvenile idiopathic arthritis. Monoarticular or polyarticular psoriatic arthritis can be distinguished from other arthropathies by its unique cutaneous manifestations. With numerous treatments already in clinical practice, there are numerous options for treatment. The current literature indicates an elevated level of tumor necrosis factor is present in the epidermis of patients with psoriatic arthritis when compared with the general population. For this reason, anti-tumor necrosis factor therapies have become a hallmark option for psoriatic arthritis patients. Golimumab, a human monoclonal antibody tumor necrosis factor-alpha (TNF-a) receptor antagonist, was chosen as the focus therapy for this investigation. The mechanism of action behind anti-tumor necrosis factor-alpha blockers involves the binding of human TNF-a soluble and transmembrane proteins to competitively inhibit TNF-a from binding to its cellular receptors. The present investigation evaluated current treatment options available for both juvenile- and adult-onset psoriatic arthritis and compared them with the efficacy seen with golimumab use. Pediatric patients included children ages 2–17, while adult populations included adults 18–83 years old. The Food and Drug Administration has approved golimumab for the treatment of rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, ulcerative colitis, and polyarticular juvenile idiopathic arthritis. The results of four different studies reporting on the therapeutic effects and adverse events of golimumab use in psoriatic arthritis, juvenile psoriatic arthritis, juvenile idiopathic arthritis, and juvenile polyarticular arthritis were used for comparison. The meta-analysis referenced studies including children ages 2–17 with no reference mentioning children less than age 2. Based on the results of each study, it can be concluded that golimumab, a human monoclonal antibody that prevents the activation of cellular inflammatory reactions when it binds to the TNF-a receptor, is an effective option for patients with active psoriatic arthritis and psoriatic juvenile idiopathic arthritis and for patients who are no longer responding to their current treatment with adalimumab. Each study also reported minimal adverse events associated with golimumab use, and the drug can be safely used in the pediatric population.
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Gentry, Dale J., und Kerri T. Vierling. „Old Burns as Source Habitats for Lewis's Woodpeckers Breeding in the Black Hills of South Dakota“. Condor 109, Nr. 1 (01.02.2007): 122–31. http://dx.doi.org/10.1093/condor/109.1.122.
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Abstract Abstract Crown-burned pine forests are an important breeding habitat for many cavity-nesting birds, and can serve as a source habitat for some woodpecker species. However, it is unclear if this function continues with postburn succession as predators recolonize burned habitats and snag density declines. Lewis's Woodpeckers (Melanerpes lewis) are considered “burn specialists” and are a species of conservation concern. We monitored Lewis's Woodpeckers nesting in ponderosa pine (Pinus ponderosa) forests to determine the source or sink function of old-burn habitats in the Black Hills of South Dakota (study units burned in 1988 and 1991); concurrently, we examined avian and mammalian predator communities within burned and unburned areas. Between 2002 and 2005 we found 55 Lewis's Woodpecker nests, 51 of which were successful. Using adult and juvenile mortality rates for other melanerpine species taken from the literature, we determined that the old-burn habitats we sampled were acting as sources for Lewis's Woodpeckers. Point counts and tracking tube surveys suggested that both avian and mammalian predators had successfully recolonized these old-burn habitats, as both groups were common in old burns and in unburned forests. The unusually high nesting success of Lewis's Woodpeckers in the Black Hills is likely due to the absence of some common nest predators. While the high success rates might continue, we suggest that the overall contribution of young to the region from these burned sites will decline as suitable habitat components (such as snags) decline with the continuation of postfire succession.
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Goldberg, Jesse H., und Michale S. Fee. „Singing-Related Neural Activity Distinguishes Four Classes of Putative Striatal Neurons in the Songbird Basal Ganglia“. Journal of Neurophysiology 103, Nr. 4 (April 2010): 2002–14. http://dx.doi.org/10.1152/jn.01038.2009.
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The striatum—the primary input nucleus of the basal ganglia—plays a major role in motor control and learning. Four main classes of striatal neuron are thought to be essential for normal striatal function: medium spiny neurons, fast-spiking interneurons, cholinergic tonically active neurons, and low-threshold spiking interneurons. However, the nature of the interaction of these neurons during behavior is poorly understood. The songbird area X is a specialized striato-pallidal basal ganglia nucleus that contains two pallidal cell types as well as the same four cell types found in the mammalian striatum. We recorded 185 single units in Area X of singing juvenile birds and, based on singing-related firing patterns and spike waveforms, find six distinct cell classes—two classes of putative pallidal neuron that exhibited a high spontaneous firing rate (>60 Hz), and four cell classes that exhibited low spontaneous firing rates characteristic of striatal neurons. In this study, we examine in detail the four putative striatal cell classes. Type-1 neurons were the most frequently encountered and exhibited sparse temporally precise singing-related activity. Type-2 neurons were distinguished by their narrow spike waveforms and exhibited brief, high-frequency bursts during singing. Type-3 neurons were tonically active and did not burst, whereas type-4 neurons were inactive outside of singing and during singing generated long high-frequency bursts that could reach firing rates over 1 kHz. Based on comparison to the mammalian literature, we suggest that these four putative striatal cell classes correspond, respectively, to the medium spiny neurons, fast-spiking interneurons, tonically active neurons, and low-threshold spiking interneurons that are known to reside in area X.
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Lougheed, Cecilia, Brett A. Vanderkist, Lynn W. Lougheed und Fred Cooke. „Techniques for Investigating Breeding Chronology in Marbled Murrelets, Desolation Sound, British Columbia“. Condor 104, Nr. 2 (01.05.2002): 319–30. http://dx.doi.org/10.1093/condor/104.2.319.
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AbstractWe used several methods to study the chronology and synchrony of breeding events of the Marbled Murrelet (Brachyramphus marmoratus) population at Desolation Sound, British Columbia, from 1996 to 1998. The timing of breeding events varied among years; on average the breeding season lasted from 21 April to 5 September. We assessed the biases of each method used by comparing the results to the estimate of the integrated breeding chronology. Counts of hatch-year birds at sea were biased toward earlier breeders, missing an estimated 24% of the fledglings. Two other methods, physiological analysis of the yolk precursor vitellogenin from blood samples and monitoring by radio-telemetry could produce a complete distribution of breeding events if sampling were done throughout laying. Observations in the forest, date of first observation of a fledgling at sea during the breeding season, and fish-holding behavior produced insufficient data to be used as sole indicators of breeding chronology of this species. In general, breeding synchrony in alcids, assessed using data from a literature review, was unrelated to feeding habits but increased with latitude (41% of the variation was explained by latitude). Marbled Murrelets, however, bred less synchronously than predicted for an alcid at this latitude (50°N).Técnicas para Investigar la Cronología Reproductiva de Brachyramphus marmoratus en Caleta Desolación, Columbia BritánicaResumen. Utilizamos varios métodos para investigar la cronología reproductiva de la población de Brachyramphus marmoratus en la Caleta Desolación de la Columbia Británica desde 1996 a 1998. Encontramos variaciones temporales en la época reproductiva entre años. En promedio, la estación reproductiva se extendió del 21 de abril al 5 de septiembre. Evaluamos el sesgo de los métodos utilizados comparando los resultados individuales con los resultados de la cronología obtenida al integrar todos los métodos. Los conteos de juveniles en el mar estuvieron sesgados hacia aquellas aves que anidan temprano, no detectando aproximadamente 24% de los juveniles producidos en la estación reproductiva. Los otros dos métodos, análisis fisiológico de muestras de sangre para detectar el precursor de vitelogenina en la yema y monitoreo por telemetría, podrían producir una distribución completa de las etapas reproductivas siempre que el muestreo se lleve a cabo a lo largo de todo el período de puesta. Las observaciones directas en los sitios de anidación, la fecha de la primera observación de juveniles en el mar y las observaciones de aves con pescado en el pico produjeron datos insuficientes para ser considerados indicadores únicos de la cronología reproductiva para esta especie. Con base en una revisión bibliográfica se investigó la sincronía reproductiva en álcidos, encontrándose que ésta no está relacionada con hábitos alimenticios pero que aumenta con la latitud (41% de la variación fue explicada por cambios latitudinales). Sin embargo, B. marmoratus se reprodujo menos sincrónico que lo predicho para un álcido a esta latitud (50°N).
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Maness, Terri J., und David J. Anderson. „Predictors of Juvenile Survival in Birds“. Ornithological Monographs 78, Nr. 1 (Oktober 2013): 1–55. http://dx.doi.org/10.1525/om.2013.78.1.1.
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Gwiazda, Robert, Adam Flis, Piotr Skórka und Wioleta Oleś. „Effect of Age on the Foraging Behaviour of Grey Heron Ardea Cinerea L., 1758 at a Submontane Dam Reservoir in the Post-Breeding Season“. Avian Biology Research 10, Nr. 2 (Mai 2017): 76–83. http://dx.doi.org/10.3184/175815617x14878495436442.
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The components of foraging behaviour and success of adult and juvenile Grey Heron Ardea cinerea were studied at the Dobczyce Reservoir (southern Poland) in July and September 2015. Juvenile and adult birds moved at similar rates during both months. Fish capture attempt rate was significantly higher for juvenile birds than for adults in July but not in September. Capture rate and foraging success probability (number of captures over all attempts) was significantly lower in juveniles in July but not in September. The foraging success probability of juveniles increased from July to September. Adult and juvenile birds caught mostly small fish, with no differences in size. However, handling time in juvenile birds was much longer than in adults in July but not in September, after controlling for differences in prey size. Thus, juvenile Grey Heron increased their efficiency of catching fish from July to September by reducing the number of mistakes, probably as a result of experience.
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Zvereva, Elena L., und Mikhail V. Kozlov. „Seasonal variations in bird selection pressure on prey colouration“. Oecologia 196, Nr. 4 (28.07.2021): 1017–26. http://dx.doi.org/10.1007/s00442-021-04994-9.
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AbstractThe direction and strength of selection for prey colouration by predators vary in space and time and depend on the composition of the predator community. We tested the hypothesis that bird selection pressure on prey colouration changes through the season due to changes in the proportion of naïve juvenile individuals in the bird community, because naïve and educated birds differ in their responses to prey colours. Bird predation on caterpillar-shaped plasticine models in two boreal forest sites increased sevenfold from early summer to mid-summer, and the time of this increase coincides with the fledging of juvenile birds. In early summer, cryptic (black and green) models were attacked at fivefold higher rates compared with conspicuous (red and yellow) models. By contrast, starting from fledging time, cryptic and conspicuous models were attacked at similar rates, hinting at a lower selectivity by naïve juvenile birds compared with educated adult birds. Cryptic models exposed in a group together with conspicuous models were attacked by birds at a threefold lower rate than cryptic models exposed singly, thus supporting the aposematic commensalism hypothesis. However, this effect was not observed in mid- and late summer, presumably due to the lack of avoidance of conspicuous prey by the juvenile birds. We conclude that selection pressure on prey colouration weakens considerably when naïve birds dominate in the community, because the survival advantages of aposematic colouration are temporarily lost for both the conspicuous and their neighbouring cryptic prey.
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Suedkamp Wells, Kimberly M., Mark R. Ryan, Joshua J. Millspaugh, Frank R. Thompson und Michael W. Hubbard. „Survival of Postfledging Grassland Birds in Missouri“. Condor 109, Nr. 4 (01.11.2007): 781–94. http://dx.doi.org/10.1093/condor/109.4.781.
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Abstract We describe survival patterns during the postfledging period for two species of grassland birds in Missouri. We monitored 155 radio-marked juvenile Dickcissels (Spiza americana) and 107 juvenile Eastern Meadowlarks (Sturnella magna; hereafter meadowlark) in southwestern Missouri, from 2002 to 2004. We used an information theoretic approach to evaluate support for biological, temporal, and spatial covariates on survival estimates using Cox proportional hazards models, and also identified cause-specific mortality. For Dickcissels, the model with biological covariates containing body mass had the lowest score using Akaike's information criterion, corrected for small sample sizes (AICc) and almost twice the support of the second-best model. For meadowlarks, the null model had the lowest AICc score, but the second-best model containing body mass was also competitive (within 2 AICc units), so we used the latter model for inference. Hazard ratios indicated that a 1 g increase in body mass was associated with a 3% (Dickcissels) and 2% (meadowlarks) reduction in the risk of death. The cumulative probability of surviving the study period (Dickcissels, 58 days, meadowlarks, 72 days) was 0.56 (95% CI: 0.49–0.65) for Dickcissels and 0.63 (95% CI: 0.54–0.74) for meadowlarks. Predation was the largest source of cause-specific mortality for both species and responsible for 56% (Dickcissels) and 70% (meadowlarks) of deaths. Snakes were the numerically dominant predator of juvenile Dickcissels, but there was not a numerically dominant predator of juvenile meadowlarks. Our results emphasize the importance of body condition on postfledging survival. Future studies should consider estimating postfledging survival rates within species across systems to understand the potential impacts of different predator communities on juvenile survival.
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Ruaux, Geoffrey, Sophie Lumineau und Emmanuel de Margerie. „The development of flight behaviours in birds“. Proceedings of the Royal Society B: Biological Sciences 287, Nr. 1929 (24.06.2020): 20200668. http://dx.doi.org/10.1098/rspb.2020.0668.
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Flight is a unique adaptation at the core of many behaviours in most bird species, whether it be foraging, migration or breeding. Birds have developed a wide diversity of flight modes (e.g. flapping, gliding, soaring, hovering) which involves very specialized behaviours. A key issue when studying flight behaviours is to understand how they develop through all the ontogenetic stages of birds, from the embryo to the flying adult. This question typically involves classical debates on animal behaviour about the importance of maturation and experience. Here, we review the literature available on the development of flight behaviours in birds. First, we focus on the early period when young birds are not yet capable of flight. We discuss examples and show how endogenous processes (e.g. wing flapping in the nest, flight development timing) and environmental factors (e.g. maternal stress, nutritional stress) can influence the development of flight behaviours. Then, we review several examples showing the different processes involved in the development of flight in flight-capable juveniles (e.g. practice, trial and error learning, social learning). Despite the lack of experimental studies investigating this specific question at different developmental stages, we show that several patterns can be identified, and we anticipate that the development of new tracking techniques will allow us to study this question more thoroughly in more bird species.
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Wong, P. L., und R. C. Anderson. „Transmission of Skrjabinoclava morrisoni Wong and Anderson, 1988 (Nematoda: Acuarioidea) to semipalmated sandpipers (Calidris pusilla (L.)) (Charadriiformes: Scolopacidae)“. Canadian Journal of Zoology 66, Nr. 10 (01.10.1988): 2265–69. http://dx.doi.org/10.1139/z88-336.
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Skrjabinoclava morrisoni Wong and Anderson, 1988 of the proventriculus of semipalmated sandpipers (Calidris pusilla (L.)) developed to the infective stage in the marine amphipod Corophium volutator (Pallas). The first moult occurred 8 d and the second, 11 d postinfection at 20 °C. In the final host, fourth-stage larvae were recovered from one experimental bird examined 8 d postinfection. Juvenile birds collected at Long Point, Ontario, were not infected with S. morrisoni suggesting that transmission may not occur on the breeding ground. Transmission occurs, however, in the Canadian Maritimes and the Gulf of Mexico, as evidenced by the presence of juvenile S. morrisoni in birds collected on Grand Manan Island, New Brunswick, and birds recently arrived at Delta Marsh, Manitoba, from the Gulf Coast.
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Spiezio, Caterina, Valentina Valsecchi, Camillo Sandri und Barbara Regaiolli. „Investigating individual and social behaviour of the Northern bald ibis (Geronticus eremita): behavioural variety and welfare“. PeerJ 6 (04.09.2018): e5436. http://dx.doi.org/10.7717/peerj.5436.
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The Northern bald ibis (Geronticus eremita) (NBI) is one of the most threatened birds in the world. Intense conservation efforts have been undertaken and several research projects on the species are being done in Morocco and in Europe. Observing animal behaviour has been proved to be an efficient and non-invasive technique to assess the animal welfare, with the performance of a wide array of natural behaviours being one of the mostly used indicators of good mental and physical well-being. The aim of this study was to investigate the behaviour of a flock of 14 zoo-living NBI of different ages. The study focused on the variety of species-specific individual and social behaviours, in the light of reintroduction of the study juveniles in the wild. Per subject, 20 10-min. sessions were done. A continuous focal animal sampling method was used to collect individual and social behaviours. Behavioural data have been compared between adults and juveniles. Moreover, a Behavioural Variety Index (BVI) has been proposed and calculated based on previous literature describing natural ibis behaviours. The BVI might help in the evaluation of the variety of behaviours performed by each individual and the monitoring of the diversity of the behavioural repertoire of zoo animals. Our results showed that the birds performed species-specific behaviours and no abnormal behaviour was reported. Moreover, the BVI highlighted a good behavioural variety as each bird performed approximately 78% of the natural behaviours described in the Northern bald ibis and in close relative species. Our findings seem to suggest the presence of qualitative and quantitative similarities between the behavioural repertoires of the study ibises and those described in wild conspecifics, suggesting a good welfare of the colony. Finally, the BVI proposed in the current study seems to be a useful and practical tool to test behavioural diversity in zoo animals.
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Yorinks, Nancy, und Carter T. Atkinson. „Effects of Malaria on Activity Budgets of Experimentally Infected Juvenile Apapane (Himatione Sanguinea)“. Auk 117, Nr. 3 (01.07.2000): 731–38. http://dx.doi.org/10.1093/auk/117.3.731.
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Abstract We used behavioral, physiological, and parasitological measures to document effects of acute malarial infections on activity budgets of experimentally infected juvenile Apapane (Himatione sanguinea). Five of eight birds died within 20 to 32 days after exposure to a single infective mosquito bite. Infected Apapane devoted less time to locomotory activities involving flight, walking or hopping, and stationary activities such as singing, preening, feeding, and probing. The amount of time spent sitting was positively correlated with parasitemia and increased dramatically after infection and between treatment and control groups. Birds that succumbed to infection experienced a significant loss of body mass and subcutaneous fat, whereas surviving Apapane were better able to maintain body condition and fat levels. When rechallenged with the parasite five months after initial infection, surviving birds experienced no increase in parasitemia, indicating that they had become immune to reinfection. Regardless of the outcome, infected birds experienced acute illness that would have left them unable to forage or to escape from predators in the wild.
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Bottjer, Sarah W., Tanya L. Alderete und Daniel Chang. „Conjunction of Vocal Production and Perception Regulates Expression of the Immediate Early Gene ZENK in a Novel Cortical Region of Songbirds“. Journal of Neurophysiology 103, Nr. 4 (April 2010): 1833–42. http://dx.doi.org/10.1152/jn.00869.2009.
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The cortical nucleus LMAN (lateral magnocellular nucleus of the anterior nidopallium) provides the output of a basal ganglia pathway that is necessary for acquisition of learned vocal behavior during development in songbirds. LMAN is composed of two subregions, a core and a surrounding shell, that give rise to independent pathways that traverse the forebrain in parallel. The LMANshell pathway forms a recurrent loop that includes a cortical region, the dorsal region of the caudolateral nidopallium (dNCL), hitherto unknown to be involved with learned vocal behavior. Here we show that vocal production strongly induces the IEG product ZENK in dNCL of zebra finches. Hearing tutor song while singing is more effective at inducing expression in dNCL of juvenile birds during the auditory–motor integration stage of vocal learning than is hearing conspecific song. In contrast, hearing conspecific song is relatively more effective at inducing expression in adult birds, regardless of whether they are producing song. Furthermore, ZENK+ neurons in dNCL include projection neurons that are part of the LMANshell recurrent loop and a high proportion of dNCL projection neurons express ZENK in singing juvenile birds that hear tutor song. Thus juvenile birds that are actively refining their vocal pattern to imitate a tutor song show high levels of ZENK induction in dNCL neurons when they are singing while hearing the song of their tutor and low levels when they hear a novel conspecific. This pattern indicates that dNCL is a novel brain region involved with vocal learning and that its function is developmentally regulated.
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Tietz, James R., und Matthew D. Johnson. „Stopover Ecology and Habitat Selection of Juvenile Swainson's Thrushes During Fall Migration Along the Northern California Coast“. Condor 109, Nr. 4 (01.11.2007): 795–807. http://dx.doi.org/10.1093/condor/109.4.795.
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Abstract We investigated selection of stopover habitat by juvenile Swainson's Thrushes (Catharus ustulatus) during fall migration at a site along the northern California coast. The study site vegetation consisted mainly of coniferous forest (pine [Pinus] and spruce [Picea]), with interspersed patches of broadleaf forest (willow [Salix] and alder [Alnus]) in poorly drained swales. For 26 birds captured and radio-tracked in 2002 and 2003, the average minimum stopover duration was 8.9 ± 1.0 days. For 20 of these birds with a sufficient number of locations, the average home range size was 1.9 ± 0.3 ha. Thrushes showed no overall pattern of selection for forest type within the study area or for forest type used inside their home range. Fat and lean birds selected forest types similarly within the study area and their home ranges. However, locations occupied by lean birds had twice as much huckleberry (Vaccinium ovatum) shrub cover and were 1.3 times more concealed by vegetation than locations occupied by fat birds. There were 2.5 times more huckleberries at occupied than random locations, and locations occupied by lean birds had 2.1 times more berries overall than those frequented by fat birds. Fecal analyses confirmed that huckleberries were a commonly consumed food (70% of sampled thrushes), but also revealed that thrushes ate arthropods (87%) and wax myrtle (Myrica californica) bracteoles (43%). The overall lack of forest type selection coupled with differences between fat and lean birds in selection for cover and fruit abundance suggests that fat level may influence microsite selection.
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Fedynich, Alan M., William C. Colson, David G. Hewitt, Shelly R. Kremer und Corey D. Mason. „Pilot Study for Aging Classification Criteria of Fledged Juvenile Eastern White-winged Doves“. Journal of Fish and Wildlife Management 4, Nr. 2 (01.08.2013): 290–97. http://dx.doi.org/10.3996/062012-jfwm-050.
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Abstract Nineteen eastern white-winged doves Zenaida asiatica asiatica were hatched and raised in captivity and used to develop an aging key that 1) quickly identifies juveniles based on a series of morphological features, and 2) provides estimates of juvenile age based on primary feather replacement. Birds were photographed every three days from 17 to 170 d posthatch to determine sequence of primary flight feather replacement; persistence of juvenile secondary coverts; and development of blue eye ring, black neck bars, and leg color. Eleven birds exhibited adult features such as absence of buffy-tipped primary coverts, blue eye-ring color, complete black neck bar, and red leg color at day 170 posthatch; two birds had these features as early as day 122. Replacement of primary feathers was variable among individuals beyond day 35 beginning with the third primary. Primary feather (primary notation P1–P10) replacement occurred gradually. By day 170, 2 of 17 birds had replaced all primary feathers, 3 birds had fully molted P9 but not P10, 8 birds had begun molting P9 but not P10, and 4 birds did not molt either P9 or P10. Increased variability in primary feather replacement occurred as juveniles progressed toward adulthood; this precluded accurate age estimates of older juveniles based exclusively on primary replacement. The present study provides a better understanding of the molting process that wildlife managers, biologists, and researchers can use at hunter check stations or during trapping and banding operations to separate age classes, which is necessary to establish hunting frameworks and to assess the population effects of harvest and other mortality factors. This pilot study provides the foundation needed for further investigations into developmental patterns of fledged juvenile white-winged doves and provides an aging key that represents an improvement over previous white-winged dove aging keys or reliance on aging keys of closely related species.
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Lougheed, Cecilia, Lynn W. Lougheed, Fred Cooke und Sean Boyd. „Local Survival of Adult and Juvenile Marbled Murrelets and Their Importance for Estimating Reproductive Success“. Condor 104, Nr. 2 (01.05.2002): 309–18. http://dx.doi.org/10.1093/condor/104.2.309.
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Abstract Juvenile ratios estimated using numbers of hatch year (HY) and after-hatch-year (AHY) Marbled Murrelets (Brachyramphus marmoratus) counted concurrently during at-sea surveys have been used to estimate fecundity in this species. These “concurrent” juvenile ratios assume that HY birds remain in an area, and are likely biased because they do not account for potential differences in emigration rate of HY and AHY birds. We studied the emigration rates of adult and juvenile Marbled Murrelets marked with radio-transmitters. Juveniles had a high emigration rate compared to adults. The weekly local survival rate (ϕ) of newly radio-tagged HY birds was 27%. AHY local survival was 95% during incubation and early chick rearing, suggesting a resident population during the breeding season. We calculated juvenile ratios from 1996–1998 using (1) HY counts corrected for emigration and mean AHY counts around the breeding season peak, and (2) HY and AHY counts from concurrent at-sea surveys. The average “corrected” juvenile ratio (0.13 ± 0.05 SE) was higher than the “concurrent” juvenile ratio (0.04 ± 0.02 SE) but lower than estimates of fecundity from nest monitoring (0.18–0.22). Low juvenile ratios from at-sea surveys could result either from an unknown proportion of nonbreeding birds in the population, or, more likely, from differences in the at-sea distribution of AHY and HY birds. Fluctuation in the timing of the peak number of AHY birds across years might result in an uncorrectable bias in the counts. Because of biases and potential problems, caution is needed when interpreting juvenile ratios from at-sea surveys. Supervivencia Local de Brachyramphus marmoratus Adultos y Juveniles y su Importancia para Estimar Éxito Reproductivo Resumen. Utilizamos los cocientes entre individuos juveniles (nacidos en un año) y adultos (nacidos en años anteriores) de Brachyramphus marmoratus, censados simultáneamente durante conteos en el mar, para estimar la fecundidad de esta especie. Estos cocientes “simultáneos” de individuos asumen que los juveniles permanecen en una misma área, y podrían estar sesgados ya que no toman en cuenta diferencias en las tasas de migración de juveniles y adultos. Estudiamos las tasas de emigración de individuos juveniles y adultos de B. marmoratus marcados con radio-transmisores. Los juveniles tuvieron una tasa alta de emigración comparada con los adultos. La tasa de supervivencia local semanal (ϕ) para juveniles fue del 27%. La tasa de supervivencia local para adultos durante la incubación e inicio de la cría de polluelos fue del 95%, sugiriendo que se trata de una población residente durante la estación reproductiva. Calculamos el cociente entre juveniles y adultos para 1996–1998 utilizando (1) conteos de juveniles corregidos por emigración y promedio de adultos contados durante el pico de la estación reproductiva, y (2) juveniles y adultos contados simultáneamente durante los censos. El cociente “corregido” promedio entre juveniles a adultos (0.13 ± 0.05 EE) fue mayor que el cociente “simultáneo” (0.04 ± 0.02 EE) pero menor que las estimaciones de fecundidad obtenidas por medio del monitoreo de nidos (0.18–0.22). Los bajos cocientes obtenidos de conteos en el mar podrían explicarse por la presencia de una proporción desconocida de aves no-reproductivas en la población, o, más probablemente, por diferencias existentes en la distribución de juveniles y adultos en el mar. Fluctuaciones anuales en la sincronización del período pico de la estación reproductiva podrían introducir error a los conteos de adultos. Debido a estos sesgos y problemas potenciales, es importante interpretar con cautela los cocientes entre juveniles y adultos obtenidos de conteos en el mar.
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Miller-Sims, Vanessa C., und Sarah W. Bottjer. „Auditory experience refines cortico-basal ganglia inputs to motor cortex via remapping of single axons during vocal learning in zebra finches“. Journal of Neurophysiology 107, Nr. 4 (15.02.2012): 1142–56. http://dx.doi.org/10.1152/jn.00614.2011.
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Experience-dependent changes in neural connectivity underlie developmental learning and result in life-long changes in behavior. In songbirds axons from the cortical region LMANcore (core region of lateral magnocellular nucleus of anterior nidopallium) convey the output of a basal ganglia circuit necessary for song learning to vocal motor cortex [robust nucleus of the arcopallium (RA)]. This axonal projection undergoes remodeling during the sensitive period for learning to achieve topographic organization. To examine how auditory experience instructs the development of connectivity in this pathway, we compared the morphology of individual LMANcore→RA axon arbors in normal juvenile songbirds to those raised in white noise. The spatial extent of axon arbors decreased during the first week of vocal learning, even in the absence of normal auditory experience. During the second week of vocal learning axon arbors of normal birds showed a loss of branches and varicosities; in contrast, experience-deprived birds showed no reduction in branches or varicosities and maintained some arbors in the wrong topographic location. Thus both experience-independent and experience-dependent processes are necessary to establish topographic organization in juvenile birds, which may allow birds to modify their vocal output in a directed manner and match their vocalizations to a tutor song. Many LMANcore axons of juvenile birds, but not adults, extended branches into dorsal arcopallium (Ad), a region adjacent to RA that is part of a parallel basal ganglia pathway also necessary for vocal learning. This transient projection provides a point of integration between the two basal ganglia pathways, suggesting that these branches convey corollary discharge signals as birds are actively engaged in learning.
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Rymkevich, T. A., Eu N. Smirnov, D. A. Starikov, A. A. Ufimtseva, V. A. Ryzhenkova, A. Yu Kretova, D. I. Malyscheva und Yu M. Bannikova. „The using of data on the moult progress in the study of migration periods of the annual cycle of passerines“. Proceedings of the Zoological Institute RAS 327, Nr. 1 (25.03.2023): 109–22. http://dx.doi.org/10.31610/trudyzin/2023.327.1.109.
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Using trapping and ringing of birds for studying the ecology and the demographic parameters of populations is necessary to determine as accurately as possible in which period of the annual cycle each individual was caught. The first-year passerine birds undergo juvenile migration (usually in form of postfledging dispersal) and postmoulting (autumn) migration in summer-autumn period. These stages of annual cycle are difficult to identify in trapping birds by calendar dates because the timing of migration seasons can significantly overlap in the same location. The study of moult at the Ladoga Ornithological Station made it possible to determine the states of plumage that mark juvenile and postmoulting migrations in first-year birds. The article presents two examples of the use of moult progress in the study of bird migrations. The first one is an analysis of the ratio of the terms of departure and passage in three long-distant and three short-distant migrants of passerines. It has been shown that the timing of the departure of local birds is earlier than the timing of the passage of other populations in all studied species, while the last local individuals in long-distance migrants are recorded long before the end of the passage of the species, and in short-distance migrants they can be found until its end. As another example, an analysis of long-term trends in the timing of summer-autumn movements in the Garden Warbler was performed. It is shown that for almost a fifty-year observation period, neither the timing of juvenile migration nor the timing of postmoulting migration of first-year birds has changed. At the same time, the timing of the spring passage of the species shifted to earlier. As a result, the duration of stay of the Garden Warbler in the Ladoga region has increased.
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Cadena-Ortiz, Héctor, Martín Quiroga und Elisa Bonaccorso. „First report of the Philornis torquans complex in adult birds in continental Ecuador: Is parasitism by Philornis being underestimated?“ Revista Mexicana de Biodiversidad 93 (07.12.2022): e934080. http://dx.doi.org/10.22201/ib.20078706e.2022.93.4080.
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Myiasis by Philornis is a usual phenomenon in Neotropical birds. Philornis larvae are hematophagous and are known to affect both nestlings and adults. Still, parasitism in adults seems opportunistic and has been poorly studied compared to parasitism in nestlings. Here, we inspected 1,429 adult and juvenile birds of 41 species from an Andean dry forest in northern Ecuador, searching for infestations by Philornis larvae. For the first time, we report parasitism by Philornis in adult birds of 6 species of passerine birds (Troglodytes aedon, Conirostrum cinereum, Geospizopsis plebejus, Zonotrichia capensis, Pheucticus chrysogaster, and Spinus magellanicus). We also report the first cases of infestation by the Philornis torquans complex in Ecuador and provide data on the prevalence of Philornis myiasis in this Andean dry forest. We extend both the host range and the geographic distribution of the P. torquans complex.
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Pidoux, Morgane, Tejapratap Bollu, Tori Riccelli und Jesse H. Goldberg. „Origins of basal ganglia output signals in singing juvenile birds“. Journal of Neurophysiology 113, Nr. 3 (01.02.2015): 843–55. http://dx.doi.org/10.1152/jn.00635.2014.
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Across species, complex circuits inside the basal ganglia (BG) converge on pallidal output neurons that exhibit movement-locked firing patterns. Yet the origins of these firing patterns remain poorly understood. In songbirds during vocal babbling, BG output neurons homologous to those found in the primate internal pallidal segment are uniformly activated in the tens of milliseconds prior to syllable onsets. To test the origins of this remarkably homogenous BG output signal, we recorded from diverse upstream BG cell types during babbling. Prior to syllable onsets, at the same time that internal pallidal segment-like neurons were activated, putative medium spiny neurons, fast spiking and tonically active interneurons also exhibited transient rate increases. In contrast, pallidal neurons homologous to those found in primate external pallidal segment exhibited transient rate decreases. To test origins of these signals, we performed recordings following lesion of corticostriatal inputs from premotor nucleus HVC. HVC lesions largely abolished these syllable-locked signals. Altogether, these findings indicate a striking homogeneity of syllable timing signals in the songbird BG during babbling and are consistent with a role for the indirect and hyperdirect pathways in transforming cortical inputs into BG outputs during an exploratory behavior.
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Bende, Attila. „Az erdei szalonka (Scolopax rusticola L.) tollváltása, a tollazat alapján történő kormeghatározás lehetőségei“. Magyar Vízivad Közlemények, Nr. 37 (01.12.2023): 45–58. http://dx.doi.org/10.17242/mvvk_37.04.
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Moult of the Woodcock (Scolopax rusticola L.), possibilities of age determination based on the feather. This study summarises the most important data in the literature on the feather changing of woodcock. This is supported by a set of recommendations for an easy-to-use field practice, summarising the typical age stamps by age group. This is an important topic, because there is no detailed literature available in Hungarian on feather changing and age determination for domestic practice. For ringing work in Hungary and for the analysis of data sets evaluated by sex and age in wildlife studies, the age of birds is an indispensable knowledge, but in this respect, it is sufficient to distinguish between adult and juvenile specimens, and a finer-scale grouping is not common practice in Hungarian woodcock research, although the criteria for this classification are also presented in this paper for the sake of completeness. The distinction between juvenile and adult age classes is based on the degree of moulting, and the examination of this for each group of feathers in the wing, for which the following stamps should be considered: In juvenile specimens, the large upper wing coverts are short and narrow, with a typically dull reddish-brown to brownish tint, the black parts also dull, and the down at the base of the feathers less developed. In juvenile secondaries, the rusty, cinnamon-brown striping near the shaft of the feather is distally pointed and reduced to a triangular dark patch. The characteristic light spot on the underside of the tail-feathers is a dull shade of greyish white, with a more diffuse light brown pattern than on the adult plumage. (Figure 5). First-year birds can be distinguished from older birds by the wear and shape of the tips of the 8th to 10th primaries, which are not shed during juvenile moulting. In addition to their weariness, it should be noted that they are distinctly pointed, not concave, and their edges are usually not bone-coloured. Primaries have a wide edge (1,5-2,5 mm), which is usually the same brownish colour as the ridge pattern. The contrast can be stark for the greater coverts, because birds that hatch early in the breeding season have time to shed all the greater coverts before the autumn migration, so these feathers already reflect adult characteristics. During the first wintering, the tips of the 5th and 6th primaries are slightly convex, and the wing covers have a sugar-loaf tip. The light patch at the base of the tail-feathers is white at this stage, the brown pattern is well defined and not diffuse. Adults moult between July and September (primaries, secondaries, tertials and tail-feathers), so their plumage is free from wear in autumn and winter, compared to the worn, poorer condition of the first-year birds with unmoulted feathers. The tip of the 5th and 6th primaries in adult birds is broadly flattened and slightly concave. The tips of primaries have narrow edges (<1,5 mm), usually white with a bone colour. All greater upper-wing coverts are reddish brown. and light brown with a light pattern. Fairly long and broad, with well-developed down at the base. The greater under-wing coverts (typically the primary coverts of primaries and secondaries) are greyish with broad, “angular” tips. Occasionally adults do not fully shed juvenile wing feathers, so these can also be seen in second-year birds (Figure 6).
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Anderson, Kurt E., Stephen I. Rothstein, Robert C. Fleischer und Adrian L. O’Loghlen. „Large-Scale Movement Patterns Between Song Dialects in Brown-Headed Cowbirds (Molothrus Ater)“. Auk 122, Nr. 3 (01.07.2005): 803–18. http://dx.doi.org/10.1093/auk/122.3.803.
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AbstractExtensive past research has attempted to determine whether song dialects represent reproductively isolated social systems, with individuals tending to spend their entire lives in a single dialect. We addressed that issue by analyzing banding data for Brown-headed Cowbirds (Molothrus ater) on the eastern slope of the Sierra Nevada of California. For 14 years, 1,393 juveniles and 2,568 mature individuals were banded along a 40-km span encompassing three dialects. Of those juvenile and mature birds, 7.9% and 12.1%, respectively, were recaptured in a later year. All classes of mature birds (second-year males, older males, and females) had significantly higher recapture rates than birds banded as juveniles, but there were no differences among the mature classes. Overall, 22.7% of 110 juveniles recaptured in a subsequent year were trapped in a dialect region other than the one in which they were banded, as compared with 8.1% of 310 mature birds. Neither juvenile nor mature birds showed sex-related differences in proportions recaptured in subsequent years in different dialect regions. Birds in all sex-age classes were more likely to have moved to a new dialect region when recaptured in a subsequent year than when recaptured within the year, which suggests that apparent movements between years were cases of dispersal, rather than short-term foraging trips. Although our banding data cannot confirm gene flow, the high levels of movement they show agree with genetic and morphometric studies indicating high levels of gene flow among these cowbird dialects.Patrones de Movimiento de Gran Escala entre Dialectos del Canto de Molothrus ater
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Mukhin, Andrey. „Night Movements of Young Reed Warblers (Acrocephalus Scirpaceus) in Summer: Is it Postfledging Dispersal?“ Auk 121, Nr. 1 (01.01.2004): 203–9. http://dx.doi.org/10.1093/auk/121.1.203.
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Abstract I studied summer movements of juvenile Reed Warblers (Acrocephalus scirpaceus) marked as nestlings during four field seasons (1999–2002). To control for birds' movements, nocturnal playback of songs and daytime mist-netting were done. Captures by song playback suggest the existence of nocturnal postfledging movements in Reed Warblers. Birds' age (days) during such movements was found to be 39–52 days. I analyze the temporal schedule and physiological condition of the birds during this period and discuss the mechanism of nocturnal postfledging dispersal and its background and relationships with other events of the annual cycle during the premigratory period.
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Sazima, Ivan. „Playful birds: cormorants and herons play with objects and practice their skills“. Biota Neotropica 8, Nr. 2 (Juni 2008): 259–64. http://dx.doi.org/10.1590/s1676-06032008000200025.
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Play is a behaviour known mostly for mammals, although birds are recorded to play as well. Here I describe the play behaviour for two bird species, the Neotropic Cormorant (Phalacrocorax brasilianus) and the Green Heron (Butorides striata) in southeastern Brazil. Juvenile and adult cormorants were recorded to manipulate sticks, leaves, rootlets, and plant debris while on the ground. They also played with sticks, leaves, pods, and plant debris, as well as live or dead fish while in the water, repeatedly grabbing the object and submerging it. When the object was a fish, they tossed it in the air as well. Juvenile herons played with small pieces of wood, fruits, and other floating objects, which they picked up and tossed repeatedly in the water. The behaviours recorded for the cormorants and herons qualify as object play, i.e., frolicsome interactions with an inanimate object including exploratory manipulation. This behaviour is regarded as having an important role in general motor development and for practice of particular skills, mostly foraging and breeding.
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Breen, Alexis J., Keren E. Lovie, Chloé Guerard, Sophie C. Edwards, Jasmine Cooper, Susan D. Healy und Lauren M. Guillette. „Juvenile socio-ecological environment shapes material technology in nest-building birds“. Behavioral Ecology 31, Nr. 4 (30.04.2020): 892–901. http://dx.doi.org/10.1093/beheco/araa027.
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Abstract Variation in animal material technology, such as tool use and nest construction, is thought to be caused, in part, by differences in the early-life socio-ecological environment—that is, who and what is around—but this developmental hypothesis remains unconfirmed. We used a tightly controlled developmental paradigm to determine whether adult and/or raw-material access in early life shape first-time nest construction in laboratory-bred zebra finches Taeniopygia guttata at sexual maturity. We found that juvenile access to both an unrelated adult and raw material of one color led to a majority preference (75%) by novice builders for this color of material over that for either natal-nest or novel-colored material, whereas a lack of juvenile access to both an unrelated adult and raw material led to a 4- and nearly 3-fold reduction in the speed at which novice builders initiated and completed nest construction, respectively. Contrary to expectation, neither the amount of time juveniles nor their adult groupmate spent handling the raw material appear to drive these early-life effects on zebra finches’ first-time nest construction, suggesting that adult presence might be sufficient to drive the development of animal material technology. Together these data show that the juvenile socio-ecological environment can trigger variation in at least two critical aspects of animal material technology (material preference and construction speed), revealing a potentially powerful developmental window for technological advancement. Thus, to understand selection on animal material technology, the early-life environment must be considered.
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Carlos, C., und J. Voisin. „title“. Seabird Journal, Nr. 21 (2008): 1–15. http://dx.doi.org/10.61350/sbj.21.1.
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The two similar-looking species of giant petrels, the Northern Giant Petrel Macronectes halli and the Southern Giant Petrel M. giganteus, are renowned for being difficult to identify. In this paper we review and offer new guidelines on identification of these birds at sea, on land, and as dead specimens. Criteria for identifying giant petrels are available in the scientific literature, especially regarding bill-tip coloration which readily differ from one species to another. Plumage characters, although useful to discriminate species, are not adequately covered at present. Thus, for each species we describe in detail and illustrate distinctive age-related plumage stages, or types, from juveniles through to adult breeders. We also comment on giant petrel biometrics, body weight, and some aspects of their behaviour, in order to help ornithologists and birdwatchers separate males and females, and eventually specimens from South America–Gough Island, Antarctic and sub-Antarctic regions.
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Bartlett, Cheryl M., und R. C. Anderson. „Eulimdana florencae n.sp. (Nematoda: Filarioidea) from Micropalama himantopus (Aves: Charadriiformes): evidence for neonatal transmission, ephemeral adults, and long-lived microfilariae among filarioids of shorebirds“. Canadian Journal of Zoology 68, Nr. 5 (01.05.1990): 986–92. http://dx.doi.org/10.1139/z90-142.
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Eulimdana florencae n.sp. from Stilt Sandpipers (Micropalama himantopus (Bonaparte)) (Charadriiformes: Scolopacidae) at Little Quill Lake, Saskatchewan, and Gem, Alberta, Canada, differs from its closest congener (Eulimdana pseudolari) by the lack of a cleft at the posterior extremity of the female. In addition, the microfilaria of E. florencae has a long, attenuated tail unlike that of any previously described species. Adult worms occurred in neck tissues and microfilariae in skin. Seven of 17 juvenile (less than 2 months old) Stilt Sandpipers were infected; four contained mixed sex infections and in two of these birds microfilariae were present in both the female worms and the host's skin. The remaining three infected juvenile birds contained only adult male or only adult female worms. Eight of 12 adult birds were infected; six contained only skin-inhabiting microfilariae, one contained microfilariae plus a single adult female (probably senescent), and one contained a single male. Support is provided, therefore, for a recent hypothesis predicting that Eulimdana spp. are often acquired early in life by scolopacid shorebirds, that postreproductive adult worms are ephemeral, and that the skin-inhabiting microfilariae are long-lived.
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Loskot, V. M. „On the type specimens of Locustella ochotensis (Middendorff, 1853) in the collection of the Zoological Institute, St. Petersburg (Aves: Sylviidae)“. Zoosystematica Rossica 11, Nr. 1 (25.12.2002): 239–42. http://dx.doi.org/10.31610/zsr/2002.11.1.239.
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Individual variation of the size and plumage colour in three type specimens of Middendorff’s Grasshopper Warbler, Locustella ochotensis is examined, the dates and localities of collecting are defined more exactly and the lectotype is designated. Examination of allpreserved specimens, collected by Middendorff, and of the original description show that he misidentified adult birds of L. ochotensis as L. certhiola. This is imorotant for understanding of the diagnosis of L. ochotensis based on characters of young birds in juvenile plumage.
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García, Natalia C. „What have we recently learned about song learning and social interactions?“ Behavioral Ecology 30, Nr. 5 (19.06.2019): 1193–95. http://dx.doi.org/10.1093/beheco/arz098.
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Abstract Vocal learning in birds is a complex animal behavior with several parallels to vocal learning in humans. Early experiments in the 70s showing that juvenile birds could learn their species’ normal song presented only through loudspeakers led to the general notion that social interactions are unnecessary for song learning. These views were soon challenged, and after decades of research we know that different social factors influence song learning. Here, I discuss recent research that is getting us closer to understanding how. Juvenile birds in the wild are exposed to both direct and indirect interactions with singing adults, which can be relevant to different aspects of the learning process. The exposure to a potential living tutor may trigger or enhance the learning process, but direct interaction with a tutor producing the song type that is finally learned or incorporated to the repertoire is not required. Social interactions that the learner witnesses may be more important in determining which songs are included in the final repertoire of an adult bird. Further research is also required to better understand the role of interactions with females, not by providing a model song to imitate but by exhibiting responses contingent to juveniles practicing their songs.
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Cooke, Belinda, und Ursula Munro. „Orientation studies on the regent honeyeater, Xanthomyza phrygia (Meliphagidae), an endangered bird of south-eastern Australia“. Australian Journal of Zoology 48, Nr. 4 (2000): 379. http://dx.doi.org/10.1071/zo00005.
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Six juvenile regent honeyeaters, Xanthomyza phrygia, from a captive population held at Taronga Zoo, Sydney, were tested for their orientation in the early morning between April and July 1998. Testing was performed outdoors in Emlen orientation cages, which were covered with opaque lids. All study birds oriented in a north-easterly direction between April and late May (Stage 1). During June and July (Stage 2) no uniform directional preferences were shown. The results obtained for regent honeyeaters during the April/May period suggest that there is some genetic control of seasonal movements and that the birds use a non-visual compass mechanism, as in some migratory Australian birds. The interpretation of our results remains tentative due to the lack of knowledge of regent honeyeater movements in the wild.
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Lane, JV, CJ Pollock, R. Jeavons, M. Sheddan, RW Furness und KC Hamer. „Post-fledging movements, mortality and migration of juvenile northern gannets“. Marine Ecology Progress Series 671 (05.08.2021): 207–18. http://dx.doi.org/10.3354/meps13804.
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Studying the at-sea movements and behaviour of juvenile seabirds is logistically challenging, but new technologies now allow tracking birds on their first migration, giving a more complete picture of population-level spatial ecology. We investigated the post-fledging migration of juvenile northern gannets Morus bassanus from the world’s largest colony, at Bass Rock, Scotland. We first examined the movements and survival of 38 juveniles over their initial days at sea with GPS precision for up to 53 d post-fledging. We then compared their migration journeys with those of 35 adults tracked with geolocators. Almost one-third of juveniles died within 2 mo of leaving the colony, and this mortality was often associated with apparent uncertainties in their direction of migration, including marked, abrupt and often repeated changes in bearing within the North Sea. Both juveniles and adults then migrated as far as the Canary Current Large Marine Ecosystem (CCLME) off the Atlantic coast of West Africa, initially taking both clockwise and counter-clockwise routes around the UK. Juveniles covered a distance each day similar to that of adults, but they reached the CCLME much more quickly, mainly because they travelled more directly, staying close to the coast throughout most of their migration, whereas adults additionally spent long periods over relatively restricted areas of ocean further offshore. The CCLME is a hotspot of unregulated fishing activity, and our findings highlight the importance of this region across different age-classes of birds, echoing previous calls that the regional strengthening of marine conservation should be a high priority.
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Bonier, Frances, Paul R. Martin, Jay P. Jensen, Luke K. Butler, Marilyn Ramenofsky und John C. Wingfield. „PRE-MIGRATORY LIFE HISTORY STAGES OF JUVENILE ARCTIC BIRDS: COSTS, CONSTRAINTS, AND TRADE-OFFS“. Ecology 88, Nr. 11 (November 2007): 2729–35. http://dx.doi.org/10.1890/07-0696.1.
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Ward, David H., Joel A. Schmutz, James S. Sedinger, Karen S. Bollinger, Philip D. Martin und Betty A. Anderson. „Temporal and Geographic Variation in Survival of Juvenile Black Brant“. Condor 106, Nr. 2 (01.05.2004): 263–74. http://dx.doi.org/10.1093/condor/106.2.263.
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Abstract First-year survival has important implications for the structure and growth of populations. We examined variation in seasonal survival of first-year Pacific Black Brant (Branta bernicla nigricans) marked late in summer in Alaska at two brood-rearing areas on the Yukon-Kuskokwim Delta (Tutakoke and Kokechik) and one area on the Arctic Coastal Plain to provide insight into the magnitude and timing of mortality during fall migration. First-year survival was lower in early fall (15 July–1 October), when birds fledged from brood-rearing areas and migrated to their primary fall staging area at Izembek Lagoon, Alaska, than during late fall and early winter (1 October–15 February), when birds made a long-distance transoceanic flight (>5000 km) to wintering areas in Baja California, Mexico. When compared to other years, monthly survival during early fall was 20–24% lower in 1992, the year of latest hatch dates and slowest growth of goslings. There was strong evidence to indicate that survival varied geographically within the early fall period. Monthly survival estimates during early fall were lowest for birds from Tutakoke, highest for birds from the Arctic Coastal Plain, and intermediate at Kokechik. Our findings revealed that most juvenile mortality occurred during the first 2 months following banding, and variation in juvenile survival during this period was likely influenced significantly by environmental parameters and habitat conditions on the breeding grounds. Monthly survival estimates during the subsequent 4 months were similar across geographic areas, and long-distance migration was likely the most important contributor to juvenile mortality during this period. Variación Temporal y Geográfica en la Supervivencia de Juveniles de Branta bernicla nigricans Resumen. La supervivencia durante el primer año de vida tiene implicancias importantes para la estructura y el crecimiento de las poblaciones. Examinamos la variación en la supervivencia estacional en individuos añales de Branta bernicla nigricans marcados al final del verano en Alaska en dos áreas de cría del Delta Yukon-Kuskokwim (Tutakoke y Kokechik) y un área en la planicie costera ártica para brindar información sobre la magnitud y el esquema temporal de mortalidad durante la migración de otoño. La supervivencia durante el primer año fue menor a principios del otoño (15 July–1 October), cuando las aves abandonaron las áreas de cría y migraron hacia el área principal de permanencia otoñal en Izembek Lagoon, Alaska, que durante fines de otoño y comienzos del invierno (1 October–15 February), cuando las aves realizaron un vuelo transoceánico de larga distancia (>5000 km) hacia las áreas de invernada en Baja California, México. Comparando con otros años, la supervivencia mensual durante principios del otoño fue un 20–24% menor en 1992, el año con fechas más tardías de eclosión y con crecimiento más lento de los polluelos. Hubo fuerte evidencia para indicar que la supervivencia varió geográficamente a principios del otoño. Las estimaciones mensuales de supervivencia durante principios del otoño fueron menores para las aves de Tutakoke, mayores para las aves de la planicie costera ártica, e intermedias para Kokechik. Nuestros resultados revelaron que la mayoría de la mortalidad juvenil ocurrió durante los dos primeros meses luego del anillado, y la variación en la supervivencia de los juveniles durante este período fue probablemente influenciada de forma significativa por parámetros ambientales y condiciones del hábitat en las áreas de cría. Las estimaciones mensuales de supervivencia durante los cuatro meses siguientes fueron similares para las distintas áreas geográficas, y la migración de larga distancia fue probablemente la causa más importante de mortalidad juvenil durante este período.
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Rintamäki, Pekka T., Mikko Ojanen, Heikki Pakkala und Matti Tynjälä. „Blood parasites of migrating Willow Warblers (Phylloscopus trochilus) at a stopover site“. Canadian Journal of Zoology 76, Nr. 5 (01.05.1998): 984–88. http://dx.doi.org/10.1139/z98-027.
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Populations are often difficult to separate on the basis of morphometric data. However, since blood parasites have shown significantly different prevalences and parasitaemias in natural host populations, such discrepancies may provide an opportunity of studying population differences in migrating birds. We obtained blood samples from 312 Willow Warblers (Phylloscopus trochilus) at the Tauvo Bird Observatory, Gulf of Bothnia, Finland. Approximately one-fifth of the birds were parasitized by at least one out of four different haematozoans. Most of these birds (88%) were infected with either Haemoproteus belopolskyi (Hb) or Leucocytozoon phylloscopus (Lp). These parasite species were predominant in the samples at different times, Hb earlier and Lp later. Based on tail and wing lengths, body mass, and wing length - tail length ratio, Hb-infected juvenile males were significantly larger than Lp-infected birds. Different dipteran vectors transmit these haematozoa, and in conjunction with morphological evidence, the observed difference in time of main occurrence of these two parasites may indicate that the birds had become infected in different areas. Thus, our samples may include different (sub)populations of Willow Warblers. In general, blood parasites may provide a means of differentiating among individuals originating from different areas.
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Song, Fangbin, Ruihua Li, Wei Wang und Shenyu Zhang. „Psychological Characteristics and Health Behavior for Juvenile Delinquency Groups“. Occupational Therapy International 2022 (02.08.2022): 1–11. http://dx.doi.org/10.1155/2022/3684691.
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The related literature is studied to explore the psychological characteristics of juvenile delinquency groups and implement their psychological characteristics model for the intervention of health behavior. Drawing on the results of current literature research, the Youth Psychological Characteristics Crime Prevention Questionnaire (YPPQ) was compiled, which can be simply referred to as the Crime Prevention Questionnaire. The whole psychological characteristics of juvenile delinquency are analyzed by means of a questionnaire. Firstly, the YPPQ scores of different groups were compared, and a structured interview was conducted on the reasons for the crime of the problem youth group. Secondly, data analysis was carried out on the results of questionnaires and interviews, and the psychological characteristics of juvenile delinquency were summarized. A “mixed hierarchical intervention model” was proposed to intervene in the mental health behavior of juvenile delinquency groups, and corresponding intervention strategies were also proposed. The results reveal that through the questionnaire survey, the educational background of juvenile subjects was generally distributed in middle school, the number of juveniles with primary school education was less than 30% of the juvenile delinquency groups, the middle school education accounted for more than 60% of the juvenile delinquency groups, and the approximate age was about 18 years old. The largest number in each group were adolescents with secondary school education, indicating the importance of psychological education on crime prevention for adolescents in secondary school. By comparing the YPPQ test scores of different groups, the adolescent group has higher test scores than the juvenile delinquency groups in five of the dimensions. Through the comparative analysis of the YPPQ test results of the juvenile delinquency groups, the problem youth group, and the normal youth group, it is found that the YPPQ has high reliability and validity, so its detection and evaluation are highly feasible. By comparing the odds ratio (OR) of each question in the YPPQ test between the experimental group and the control group, it is found that the psychological characteristics of the experimental group are significantly affected by family, school, and even society. Finally, it proposes a “mixed hierarchical intervention model” for juvenile delinquency to intervene in health behaviors. The purpose is to provide some research ideas for the study of the psychological characteristics of juvenile delinquency groups and to put forward some suggestions for the prevention of juvenile delinquency and the intervention of health behavior.
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Bottjer, Sarah W. „Silent Synapses in a Thalamo-Cortical Circuit Necessary for Song Learning in Zebra Finches“. Journal of Neurophysiology 94, Nr. 6 (Dezember 2005): 3698–707. http://dx.doi.org/10.1152/jn.00282.2005.
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Developmental changes in synaptic properties may act to limit neural and behavioral plasticity associated with sensitive periods. This study characterized synaptic maturation in a glutamatergic thalamo-cortical pathway that is necessary for vocal learning in songbirds. Lesions of the projection from medial dorsolateral nucleus of the thalamus (DLM) to the cortical nucleus lateral magnocellular nucleus of the anterior nidopallium (LMAN) greatly disrupt song behavior in juvenile birds during early stages of vocal learning. However, such lesions lose the ability to disrupt vocal behavior in normal birds at 60–70 days of age, around the time that selective auditory tuning for each bird’s own song (BOS) emerges in LMAN neurons. This pattern has suggested that LMAN is involved in processing song-related information and evaluating the degree to which vocal motor output matches the tutor song to be learned. Analysis of reversed excitatory postsynaptic currents at DLM→LMAN synapses in in vitro slice preparations revealed a pronounced N-methyl-d-aspartate receptor (NMDAR)-mediated component in both juvenile and adult cells with no developmental decrease in the relative contribution of NMDARs to synaptic transmission. However, the synaptic failure rate at DLM→LMAN synapses in juvenile males during the sensitive period for song learning was significantly lower at depolarized potentials than at hyperpolarized potentials. In contrast, the failure rate at DLM→LMAN synapses did not differ at hyper- versus depolarized holding potentials in adult males that had completed the acquisition of a stereotyped song. This pattern indicates that juvenile cells have a higher incidence of silent (NMDAR-only) synapses, which are postsynaptically silent at hyperpolarized potentials due to the voltage-dependent gating of NMDARs. Thus the decreased involvement of the LMAN pathway in vocal behavior is mirrored by a decline in the incidence of silent synapses but not by changes in the relative number of NMDA and AMPA receptors at DLM→LMAN synapses. These findings suggest that a developmental decrease in silent synapses within LMAN may represent a neural correlate of behavioral plasticity during song learning.
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Chinsamy, Anusuya, Delphine Angst, Aurore Canoville und Ursula B. Göhlich. „Bone histology yields insights into the biology of the extinct elephant birds (Aepyornithidae) from Madagascar“. Biological Journal of the Linnean Society 130, Nr. 2 (04.04.2020): 268–95. http://dx.doi.org/10.1093/biolinnean/blaa013.
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Abstract Given that the biology of the recently extinct aepyornithids is poorly understood, we undertook a histological study of 29 skeletal elements of adult and juvenile specimens of Aepyornithidae, i.e. Aepyornis maximus, Aepyornis hildebrandti and Vorombe titan, in addition to a group of taxonomically unidentifiable juvenile Aepyornithiformes. Comparative analysis of the histology of the different skeletal elements showed that although the femur retained a good record of growth during early ontogeny, the tibiotarsus provided the best record of growth. Our data showed that, like other insular birds and their extant relative, the kiwi, Aepyornithidae experienced protracted growth. We also found that intracortical remodelling began early in ontogeny and continued throughout their lives, becoming more extensive throughout the compacta with age, albeit more restricted to the perimedullary region in the femora. We also deduced that the different skeletal elements experienced variable amounts of intracortical remodelling, which was most likely to be related to biomechanical constraints, size of the element and ontogenetic age. Additionally, we documented the occurrence of an unusual endosteal tissue within the large perimedullary erosional spaces of a femur of A. maximus. Overall, our study provided a lot of new information about the life history of these giant, recently extinct ratites.
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Delhey, Kaspar, Santiago Guallar, Rafael Rueda‐Hernández, Mihai Valcu, Daiping Wang und Bart Kempenaers. „Partial or complete? The evolution of post‐juvenile moult strategies in passerine birds“. Journal of Animal Ecology 89, Nr. 12 (15.10.2020): 2896–908. http://dx.doi.org/10.1111/1365-2656.13354.
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Whitehead, PJ, WJ Freeland und K. Tschirner. „Early Growth of Magpie Geese, Anseranas-Semipalmata - Sex-Differences and Influence of Egg Size“. Australian Journal of Zoology 38, Nr. 3 (1990): 249. http://dx.doi.org/10.1071/zo9900249.
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The magpie goose, Anseranas semipalmata, is the most conspicuous and among the most numerous of waterfowl inhabiting the seasonal wetlands of tropical northern Australia. Modelling of juvenile growth rates of captive birds with the logistic equation showed that magpie geese grow at rates similar to the fast-growing anserine geese. High juvenile growth rates permit exploitation of seasonally favourable environments that, although highly productive, may deteriorate rapidly and unpredictably. Sex differences in juvenile growth patterns are consistent with pronounced sexual dimorphism in adult body size (larger males), which is associated with an unusual polygynous mating system. Although smaller, females grow relatively faster than males, so that at a given age they have completed a greater proportion of the pre-fledging growth phase; wing growth is particularly advanced and females fly earlier. Slower development may increase mortality among juvenile males when family groups are forced to abandon drying swamps, and contribute to skewing of the sex ratio towards females. Larger hatchlings from large eggs tend to maintain a size advantage, at least until fledging.
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Kerry, KR, DJ Agnew, JR Clarke und GD Else. „USe of morphometric parameters for the determination of sex of Adelie penguins.“ Wildlife Research 19, Nr. 6 (1992): 657. http://dx.doi.org/10.1071/wr9920657.
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The sex of Addie penguins, Pygoscelis adeliae, may be determined by cloacal examination during the early part of the breeding season. Later in the season it becomes increasingly difficult to determine the sex of penguins by this method as the structures used for identification regress. Discriminant analysis of morphometric characters has been suggested as an alternative. This technique was examined for breeding birds of known sex near Mawson Station, Antarctica. The sex of 89% of breeding birds could be correctly determined by comparing the discriminant score D = 0.582 Bl + 1.118 Bd + 0.219Fw, where Bl is bill length, Bd is bill depth and Fw is flipper width, with a mean discriminant score (MDS) of 55.39. In all, the sexes of 87% were correctly determined by means of length and depth only (D=0.601Bl+ 1.154Bd, MDS=44.96). The sex of juvenile birds could not be determined. Determination of sex by discriminant analysis is shown to give acceptable estimates of morphometric characters divided by sex where only the mean and variance of these variables but not the sexual identity of individual birds is required. Where absolute accuracy in sex determination is required, 80% of the birds in our samples would have to be discarded to be 90% confident of the sex of the remainder.
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Goater, C. P., J. D. Goss-Custard und C. R. Kennedy. „Population dynamics of two species of intestinal helminth in oystercatchers (Haematopus ostralegus)“. Canadian Journal of Zoology 73, Nr. 2 (01.02.1995): 296–308. http://dx.doi.org/10.1139/z95-034.
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The cestode Micrasomacanthus rectacantha and the trematode Psilostomum brevicolle are the two most common intestinal helminths of oystercatchers, Haematopus ostralegus, on the Exe estuary, England. Each was present in 57 of 60 birds, in numbers ranging from 1 to 9833 and from 1 to 182, respectively. Cockles (Cerastoderma edule) were used as paratenic host by M. rectacantha and as second intermediate host by P. brevicolle. Over 90% of the transmission of M. rectacantha from intermediate hosts occurred in winter, between cockles and juvenile birds. Exposure to M. rectacantha was highest in cockles from muddy sites, where up to 80% of older cockles were infected with 1–14 larvae. Exposure to P. brevicolle was similarly high at one sandy site. Juveniles also made up > 90% of the birds present on the estuary in summer, when significantly more worms were gravid. Estimates based on the numbers of uterine eggs per individual P. brevicolle showed that 8 % of the total Exe population of oystercatchers (ca. 200) contributed 51% of the eggs to the estuary. The results implicate host age, host feeding preference, and host population structure as important factors determining variation in helminth abundance in birds.
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Dreitz, Victoria J., Wiley M. Kitchens und Donald L. DeAngelis. „Effects of Natal Departure and Water Level on Survival of Juvenile Snail Kites (Rostrhamus Sociabilis) in Florida“. Auk 121, Nr. 3 (01.07.2004): 894–903. http://dx.doi.org/10.1093/auk/121.3.894.
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Abstract Survival rate from fledging to breeding, or juvenile survival, is an important source of variation in lifetime reproductive success in birds. Therefore, determining the relation-ship between juvenile survival and environmental factors is essential to understanding fitness consequences of reproduction in many populations. With increases in density of individuals and depletion of food resources, quality of most habitats deteriorates during the breeding season. Individuals respond by dispersing in search of food resources. Therefore, to understand the influence of environmental factors on juvenile survival, it is also necessary to know how natal dispersal influences survival of juveniles. We examined effects of various environmental factors and natal dispersal behavior on juvenile survival of endangered Snail Kites (Rostrhamus sociabilis) in central and southern Florida, using a generalized estimating equations (GEEs) approach and model selection criteria. Our results suggested yearly effects and an influence of age and monthly minimum hydrologic levels on juvenile Snail Kite survival. Yearly variation in juvenile survival has been reported by other studies, and other reproductive components of Snail Kites also exhibit such variation. Age differences in juvenile survival have also been seen in other species during the juvenile period. Our results demonstrate a positive relationship between water levels and juvenile survival. We suggest that this is not a direct linear relationship, such that higher water means higher juvenile survival. The juvenile period is concurrent with onset of the wet season in the ecosystem we studied, and rainfall increases as juveniles age. For management purposes, we believe that inferences suggesting increasing water levels during the fledging period will increase juvenile survival may have short-term benefits but lead to long-term declines in prey abundance and possibly wetland vegetation structure.
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Burger, Alan E., und David W. Powell. „Diving depths and diet of Cassin's Auklet at Reef Island, British Columbia“. Canadian Journal of Zoology 68, Nr. 7 (01.07.1990): 1572–77. http://dx.doi.org/10.1139/z90-232.
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Diving depths of Cassin's Auklets (Ptychoramphus aleuticus) breeding at Reef Island, Queen Charlotte Islands, British Columbia, were measured with miniature gauges attached to the birds. Maximum diving depths of 22 birds averaged 28 m, with a mode of 40 m. A time-at-depth recorder showed that one auklet dived to 29 m, but spent 80% of its time underwater at 3–13 m. Food delivered in gular pouches to chicks contained mainly euphausiids (predominantly Thysanoessa spinifera) and juvenile fish (Ammodytes hexapterus), with lesser amounts of copepods, amphipods, small pandalid shrimps, Brachyura larvae, and ctenophores. Euphausiid meals were most common during spring tides. Auklets that delivered significant amounts of euphausiids appeared to have dived deeper than those that delivered fish.
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Sarwanto, Agus. „The Phenomenon of Juvenile Delinquency that Occurs in the Era of Globalization“. Easta Journal Law and Human Rights 1, Nr. 02 (28.02.2023): 45–50. http://dx.doi.org/10.58812/eslhr.v1i02.53.
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Youth is the future asset of a nation. But nowadays, a lot is happening to teenagers, such as drugs and motorcycle gangs. This is a familiar problem. Juvenile delinquency includes all behavior that deviates from criminal law norms committed by juveniles. This study aims to determine the causes, impacts, and solutions to juvenile delinquency. The research method used is a literature review or literature review with qualitative data analysis. The variable in this study is juvenile delinquency in the era of globalization. From the results of this study, many internal and external factors cause juvenile delinquency that needs attention. In addition, juvenile delinquency can impact oneself, family, and society.
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Horner, John R. „Dinosaur behavior and growth“. Paleontological Society Special Publications 6 (1992): 135. http://dx.doi.org/10.1017/s247526220000695x.
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Geological and paleontological data derived from the Upper Cretaceous Two Medicine Formation of Montana indicates that at least some dinosaur species exhibited complex social behaviors comparable to many living birds. Two species of duck-billed dinosaurs, a hypsilophodontid and a troodontid, nested in colonies and attended their respective young. Duckbilled dinosaurs had altricial young, whereas the hypsilophodontid and troodontid had precocial young. Morphological evidence indicates that several of the cranial elements of the nestling duckbills experienced retarded development, and a retention of juvenile features. Following their respective nesting periods duck-billed and horned dinosaurs aggregated into large herds, and apparently migrated seasonally. Cranial ornamentations possessed by duck-billed and horned dinosaurs were most likely used for sexual display and mate recognition.Osteohistological data indicates that the duck-billed dinosaurs hatched from their eggs at .50 to .75 meters in length, and exited their nests at 1.5 to 2 meters in length, at an age of about one month. These dinosaurs reached 3 to 4 meters in length their first year, and 7 to 8 meters in length after about 5 years. Growth and metabolic rates decreased substantially upon reaching adult size.
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Magoon, Maggie E., Rina Gupta und Jeffrey Derevensky. „Juvenile Delinquency and Adolescent Gambling“. Criminal Justice and Behavior 32, Nr. 6 (Dezember 2005): 690–713. http://dx.doi.org/10.1177/0093854805279948.
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Despite the increasing body of literature that supports the connection between adolescent gambling and risk-taking behavior, participation in criminal or delinquent acts has not been thoroughly addressed. With the established relationship between substance abuse and juvenile delinquency, past research and prevention, intervention, and treatment programs can be used to help guide issues concerning adolescent gambling for youthful offenders. How problem gambling may create a pattern of behavior that includes illegal acts and delinquent behaviors is examined. The role of the juvenile justice system and educational strategies for intervention, treatment, and follow-up efforts are provided. Suggestions for data collection and research using populations in detention centers to garner further information on problem gambling and deviant behaviors are addressed.
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Maryuti, Ira ayu. „STUDI LITERATUR: PENGARUH POLA ASUH PERMISIF TERHADAP KENAKALAN REMAJA DI SURABAYA“. JPK : Jurnal Penelitian Kesehatan 13, Nr. 2 (14.12.2023): 60–65. http://dx.doi.org/10.54040/jpk.v13i2.245.
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Juvenile delinquency is criminal behavior committed by young people which is a symptom of social illness in children and adolescents caused by a form of social neglect, so that they develop into a form of behavior that deviates from the norms that apply in public. This literature study was conducted to review articles with the aim of identifying the effect of permissive parenting on juvenile delinquency in Surabaya. Data collection in the form of articles was carried out through the Google Scholar database with a focus on juvenile delinquency in Sutrabaya and parenting parents on adolescents in Surabaya and found 15,000 articles, but only 4 articles were relevant to the inclusion criteria. Four (4) articles were found after analyzing the data according to the inclusion criteria with the 2017-2023 publication period. The literature study conducted shows that there is an influence of permissive parenting on juvenile delinquency in Surabaya. Permissive parenting can significantly influence juvenile delinquency in Surabaya.
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Mo, Matthew, und Elouise Mo. „A juvenile Eastern Spinebill Acanthorhynchus tenuirostris escapes from entrapment after colliding with an Australian Golden Orb-weaving Spider Trichonephila edulis web“. Australian Field Ornithology 41 (2024): 92–95. http://dx.doi.org/10.20938/afo41092095.
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This note describes an observation of a juvenile Eastern Spinebill Acanthorhynchus tenuirostris escaping from spider silk twice in rapid succession. First, the bird collided with the web of an Australian Golden Orb-weaving Spider Trichonephila edulis, from which it was able to free itself. Then, it became temporarily affixed to a tree branch by a portion of silk still attached to its tail-feathers. Although this individual escaped both events, the mean body mass of the Eastern Spinebill (11 g) places the species within the size range of birds documented in the scientific literature to have succumbed to web entrapment.
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MacDougall-Shackleton, Scott A., Elizabeth A. MacDougall-Shackleton und Thomas P. Hahn. „Physiological and behavioural responses of female mountain white-crowned sparrows to natal- and foreign-dialect songs“. Canadian Journal of Zoology 79, Nr. 2 (01.02.2001): 325–33. http://dx.doi.org/10.1139/z00-207.
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The objective of this study was to determine the effect of early song learning on physiological and behavioural responses to song in adulthood in female mountain white-crowned sparrows (Zonotrichia leucophrys oriantha). Juvenile females were captured before they had dispersed from their natal region. In experiment 1, natal-dialect song, foreign-dialect song, and heterospecific song were played back to the birds during photostimulation when they were 1 year old and physiological responses were measured. The physiological responses (luteinizing hormone and ovarian growth) did not indicate that natal-dialect song was more stimulating than foreign-dialect song. In experiment 2, behavioural responses (solicitation displays) to the same songs were measured when the birds were 2 years old. The birds showed a clear preference for natal-dialect song, exhibiting more displays to natal-dialect song than to foreign-dialect or heterospecific song. This effect was attenuated in birds that had heard heterospecific or foreign-dialect song when they were 1 year old. These results indicate a dissociation between behavioural preferences and longer-term physiological responses to song. Although there was a behavioural preference for natal-dialect song, this did not translate into enhanced physiological response as measured here. Moreover, natal dialect song preferences may be attenuated by adult experience.
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Naie, Katja, und Richard H. R. Hahnloser. „Regulation of learned vocal behavior by an auditory motor cortical nucleus in juvenile zebra finches“. Journal of Neurophysiology 106, Nr. 1 (Juli 2011): 291–300. http://dx.doi.org/10.1152/jn.01035.2010.
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In the process of song learning, songbirds such as the zebra finch shape their initial soft and poorly formed vocalizations (subsong) first into variable plastic songs with a discernable recurring motif and then into highly stereotyped adult songs. A premotor brain area critically involved in plastic and adult song production is the cortical nucleus HVC. One of HVC's primary afferents, the nucleus interface of the nidopallium (NIf), provides a significant source of auditory input to HVC. However, the premotor involvement of NIf has not been extensively studied yet. Here we report that brief and reversible pharmacological inactivation of NIf in juvenile birds leads to transient degradation of plastic song toward subsong, as revealed by spectral and temporal song features. No such song degradation is seen following NIf inactivation in adults. However, in both juveniles and adults NIf inactivation leads to a transient decrease in song stereotypy. Our findings reveal a contribution of NIf to song production in juveniles that agrees with its known role in adults in mediating thalamic drive to downstream vocal motor areas during sleep.