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Identifying factors that drive variation in vital rates among populations is a prerequisite to understanding a species' population biology and, ultimately, to developing effective conservation strategies. This is especially true for imperiled species like the golden‐winged warbler (Vermivora chrysoptera) that exhibit strong spatial heterogeneity in demography and responds variably to conservation interventions. Habitat management actions recommended for breeding grounds conservation include timber harvest, shrub shearing, and prescribed fire that maintain or create early successional woody communities. Herein, we assessed variation in the survival of nests [n = 145] and fledglings [n = 134] at 17 regenerating timber harvest sites within two isolated populations in Pennsylvania that differed in productivity and response to habitat management. Although the overall survival of nests and fledglings was higher in the eastern population than the central population, this was only true when the nest phases and fledgling phases were considered wholly. Indeed, survival rates of nestlings and recently fledged young (1–5 days post‐fledging) were lower in the central population, whereas eggs and older fledglings (6–30 days post‐fledging) survived at comparable rates in both populations. Fledglings in the central population were smaller (10% lower weight) and begged twice as much as those in the eastern population, suggesting food limitation may contribute to lower survival rates. Fledgling survival in the central population, but not the eastern, also was a function of habitat features (understory vegetation density [positive] and distance to mature forest [negative]) and individual factors (begging effort [negative]). Our findings illustrate how identifying how survival varies across specific life stages can elucidate potential underlying demographic drivers, such as food resources in this case. In this way, our work underscores the importance of studying and decomposing stage‐specific demography in species of conservation concern. Appalachian golden‐winged warbler declines have been linked to breeding productivity, however, the factors that drive disparities in breeding output remain unknown. In two regions of Pennsylvania, the survival of eggs and older fledglings was similar, but nestlings and young fledglings were different. These differences may be related to prey availability.

Breeding output of geese, measured as the proportion of juveniles in autumn or winter flocks, is lower in years with a late onset of spring in some species, but higher in at least one other species. Here we argue that this is because the timing of spring affects different stages of the reproductive cycle differently in different species. Because the effects on 2 different stages are opposite, the combined effects can result in either a positive or a negative overall effect. These stages are the pre-laying, laying, and nesting phase on the one hand; and the hatchling, fledgling, and juvenile phase on the other hand. The first phase is predominantly positively affected by an early snowmelt, with higher breeding propensity, clutch size, and nest success. The second phase in contrast is negatively affected by early snowmelt because of a mismatch with a nutrient food peak, leading to slow gosling growth and reduced survival. We argue that recognition of this chain of events is crucial when one wants to predict goose productivity and eventually goose population dynamics. In a rapidly warming Arctic, the negative effects of a mismatch might become increasingly important.

Invasive predators have caused widespread loss of biodiversity in island ecosystems, yet certain species are able to tolerate the presence of generalist invaders. For example, the invasive brown treesnake (BTS; Boigairregularis) caused the extirpation of 10 of 12 native forest bird species on the island of Guam, but a remnant population of the Micronesian Starling (Aplonis opaca), or Såli, has managed to persist on a military installation in northern Guam. Understanding how Micronesian Starlings are coping with the presence of BTS can inform conservation efforts for island bird populations facing invasive predators and provide insight into strategies for expanding the starling population. We monitored the survival, movements, and habitat use of 43 radio-tagged starling fledglings during this vulnerable life-history stage. Invasive predators accounted for 75% of fledgling mortality (56% from BTS; 19% from feral cats) and contributed to one of the lowest post-fledging survival rates (38% through day 21 post-fledging) recorded for passerine birds. Predation by BTS persisted at elevated rates following natal dispersal, further reducing cumulative survival to 26% through 53 days post-fledging. Nest location was an important predictor of survival: fledglings from nest boxes closer to the forest edge were more likely to use forest habitat at younger ages and more likely to be depredated by BTS. Overall, our findings indicate that BTS continue to severely impact Guam's starling population, even more so than invasive predators affect native birds in other island systems. We recommend deploying nest boxes farther from the forest to improve fledgling survival and implementing urban predator control to promote growth of the Micronesian Starling population on Guam and facilitate future reintroductions of other species.

Suburban forest patches can have important conservation value for birds. This is a hopeful trend because the extent of urbanization is increasing, many avian populations are declining, and urban areas are where most people interact with wildlife. There is evidence that, despite an increased density of potential predators, the breeding success of birds in urban or suburban forest patches is comparable to that in rural areas. However, extremely limited data exists on the fledgling life stage of birds in urban or suburban areas, even though it is known that the fledgling stage strongly influences population growth rates. We used radio telemetry to look at the survival, movement, and habitat use of fledgling Wood Thrushes (Hylocichla mustelina) originating from nests in suburban forest patches and in larger swaths of rural, undeveloped forests in western Massachusetts. We tracked 168 fledglings over four field seasons and found that survival was similar for rural and suburban fledglings. Fledglings had lower mortality as they aged. Force-fledging and being left outside the nest after radio-tagging had a negative effect on survival, and we developed techniques to minimize its occurrence. We also found that rural fledglings moved farther from their natal nests, at any given age, than suburban fledglings. Fledglings in both suburban and rural sites selected denser understory growth, and the use of non-forested land cover increased as they aged.

Fledgling ecology remains understudied for many passerine species, yet information about the fledgling life stage is critical for understanding full-annual life cycles and population recruitment. We examined the survival, habitat selection, and movements of fledgling Bachman’s Sparrows (Peucaea aestivalis) in a longleaf pine-wiregrass (Pinus palustris-Aristida stricta) community managed with frequent prescribed fire. We captured and marked 36 fledglings on the day of fledging and used radio-telemetry to relocate them daily until independence during three breeding seasons (2014–2016). We visually confirmed the status of fledglings as live or dead during daily relocations and determined causes of mortality. We measured vegetation characteristics at fledgling locations and compared them to the characteristics of vegetation at the locations of adult males. We used a Known Fates analysis in Program MARK to estimate fledgling survival, and generalized linear mixed effect models to determine habitat selection. Estimated fledgling survival until independence was 0.31 (SE = 0.08), with most mortality during the first 4 d post-fledging. Fledglings with longer wing chords had higher rates of survival than those with shorter wing chords, possibly due to an increased ability to evade predators. Fledgling movements were restricted primarily to natal territories. Fledgling Bachman’s Sparrows were located in areas with greater woody plant, forb, and grass cover and less bare ground than available in natal territories. Similar to fledglings of other songbirds, understory woody and herbaceous plants appear to provide critical cover for fledgling Bachman’s Sparrows, and maintenance of such cover should receive consideration in management plans for longleaf pine communities. La ecología de los volantones permanece poco estudiada para muchas especies de paseriformes, sin embargo, la información sobre la etapa volantona de la vida es fundamental para comprender los ciclos de vida anuales completos y el reclutamiento de la población. Examinamos la supervivencia, la selección del hábitat y los movimientos del Chingolo de Bachman (Peucaea aestivalis) en una comunidad de pino hoja larga-pasto alambre (Pinus palustris - Aristida stricta) manejada con frecuentes incendios controlados. Capturamos y marcamos 36 volantones el día del abandono del nido y utilizamos radiotelemetría para reubicarlos diariamente hasta la independencia durante tres temporadas de cría (2014–2016). Confirmamos visualmente el estado de los volantones como vivos o muertos durante las reubicaciones diarias y determinamos las causas de mortalidad. Medimos las características de la vegetación en las ubicaciones de los volantones y las comparamos con las características de la vegetación en las ubicaciones de los machos adultos. Usamos un an aláisis de Destinos Conocidos en el Programa MARK para estimar la supervivencia de los volantones, y modelos lineales generalizados de efectos mixtos para determinar la selección del hábitat. La supervivencia estimada de los volantones hasta la independencia fue de 0.31 (EE = 0.08), con la mayor mortalidad durante los primeros cuatro días después del abandono del nido. Los polluelos con cuerdas alares más larga tenían tasas más altas de supervivencia que aquellos con cuerdas alarer alas más cortas, posiblemente debido a una mayor capacidad para evadir a los depredadores. Los movimientos de volantones se restringieron principalmente a los territorios natales. Los volantones de Chingolo de Bachman se ubicaron en áreas con mayor cobertura de plantas leñosas, hierbas y pastos y menos terreno desnudo que el disponible en los territorios natales. Al igual que los polluelos de otras aves cantoras, las plantas leñosas y herbáceas del sotobosque parecen proporcionar una cobertura crítica para los volantones de Chingolo de Bachman, y el mantenimiento de dicha cobertura debería ser considerado en los planes de gesti on para las de pinos de hoja larga.

Despite recent increases in the number of demographic studies of birds in urban environments, the postfledging period remains poorly understood. Because novel ecological factors, including changes in predator abundance and invasive exotic shrubs, are associated with urbanization, we asked (1) how does postfledging survivorship vary across a rural-to-urban landscape gradient and (2) to what extent does Amur Honeysuckle (Lonicera maackii), an invasive exotic shrub, influence patterns of survivorship and habitat selection? During the 2008 and 2009 breeding seasons, we placed radiotransmitters on fledgling Northern Cardinals (Cardinalis cardinalis; n = 45) and Acadian Flycatchers (Empidonax virescens; n = 31) that occupied riparian forest stands embedded within a rural-to-urban landscape gradient in central Ohio, USA. Predation was the primary cause of fledgling mortality for both species, but cumulative survivorship (± SE) for Acadian Flycatchers (0.720 ± 0.097; 22 days) was 1.6 × that of Northern Cardinals (0.440 ± 0.077; 71 days). Survivorship across the entire postfledging period was not associated with urbanization, but during the initial 3 days after fledging, when mortality rates were highest, Northern Cardinal survivorship was positively related to urbanization. Northern Cardinals strongly selected for complex understory vegetation that was positively associated with survivorship, but survival was not related specifically to cover by Amur Honeysuckle. Contrary to assumptions that postfledging survival declines as landscapes urbanize, our results suggest that urban forests may provide suitable habitat for juvenile birds living within metropolitan areas.

Survival estimates for juvenile birds are rarely empirically derived and have been typically estimated as some percentage of adult survival. In particular, little information is available on survival when juveniles are independent of parental care or whether juvenile survival is sex biased. Additionally, little information is available about behaviors of juvenile birds that might be relevant to their survival. From 2010 to 2013, we radio tracked 71 independent juvenile Black-capped Vireos (Vireo atricapilla) in central Texas to estimate their survival and to quantify their behaviors. Using a known-fate model in program MARK, we calculated overall survival during the independent period to be 57% (86% for females and 28% for males). Males moved farther between consecutive locations than females and movement patterns varied substantially among individuals. Both sexes were frequently seen in association with conspecifics and heterospecifics. Half the males we tracked were observed singing, both sexes made many types of vocalizations, and the frequency of vocalizations did not differ between sexes. Whether behavioral differences contributed to survival differences between males and females will require further research. Our results indicate juvenile mortality is likely important for the population dynamics of this species and emphasize the need for studies of juvenile survival across a range of species and regions.

Identifying vegetation types that result in the highest quality habitat will help direct management and conservation activities designed to recover endangered species. Shrubland is considered to result in high quality habitat for black-capped vireos (Vireo atricapilla), whereas deciduous and oak-juniper woodlands are considered to result in marginal habitat (i.e., lower quality). We investigated differences in nest and fledgling survival among shrubland and woodland vegetation types. We monitored 302 black-capped vireo nests in 259 territories from 2008 to 2010 in Kerr County, Texas' and collected vegetation data at each nest. We also resighted 350 fledglings to estimate individual survival. Nest survival and fecundity did not differ statistically among vegetation types. Although nest-site characteristics differed among vegetation types, none affected nest survival. Nests that were parasitized were less likely to survive and parasitism was the only variable to affect survival of those measured. Parasitism frequency was nearly twice as great in shrubland (22%) than in either woodland type (12% in each) and varied by year (31% in 2008 to 0% in 2010). Vegetation type and proximity of the nest to oak-juniper woodland did not affect fledgling survival. Our results suggest woodlands may result in good quality habitat in areas with large populations of black-capped vireos. Recognizing woodlands as non-typical, yet good quality, habitat will allow managers to incorporate these vegetation types into management plans and make recommendations for conservation incentive programs directed at private landowners.

Relative nestling condition, typically measured as nestling mass or as an index including nestling mass, is commonly purported to correlate with fledgling songbird survival. However, most studies directly investigating fledgling survival have found no such relationship. We weighed feces and stomach contents of nestling golden-winged warblers (Vermivora chrysoptera) to investigate the potential contribution of variation in digestive contents to differences in nestling mass. We estimated that the mass of a seventh-day (near fledging) nestling golden-winged warbler varies by 0.65 g (approx. 9% of mean nestling mass) depending on the contents of the nestling's digestive system at the time of weighing, and that digestive contents are dissimilar among nestlings at any moment the brood is removed from the nest for weighing. Our conservative estimate of within-individual variation in digestive contents equals 72% and 24% of the mean within-brood and population-wide range in nestling mass, respectively. Based on our results, a substantive but typically unknown amount of the variation in body mass among nestlings is confounded by differences in digestive contents. We conclude that short-term variation in digestive contents likely precludes the use of body mass, and therefore any mass-dependent index, as a measure of relative nestling condition or as a predictor of survival in golden-winged warblers and likely in many other songbirds of similar size.

We studied the effects of chronic avian malaria (Plasmodium relictum) infections on the reproductive success of a native Hawaiian honeycreeper, Hawaii Amakihi (Hemignathus virens). Chronic malaria infections in male and female parents did not significantly reduce reproductive success as measured by clutch size, hatching success, fledging mass, number of nestlings fledged, nesting success (daily survival rate), and minimum fledgling survival. In fact, nesting success of pairs with chronically infected males was significantly higher than those with uninfected males (76% vs. 38%), and offspring that had at least one parent that had survived the acute phase of malaria infection had a significantly greater chance of being resighted the following year (25% vs. 10%). The reproduction and survival of infected birds were sufficient for a per-capita population growth rate >1, which suggests that chronically infected Hawaii Amakihi could support a growing population. Efectos de las Infecciones Crónicas de Malaria Aviaria (Plasmodium relictum) en el Éxito Reproductivo de Hemignathus virens