Vermivora Chrysoptera Research Articles

Mapping wetlands in the Hudson Highlands ecoregion with ALOS PALSAR: an effort to identify potential swamp forest habitat for golden-winged warblers

In New York State, the golden-winged warbler (GWW), a state species of special concern, has recently been found to nest in swamp forest habitat in Sterling Forest State Park in the Hudson Highlands ecoregion. These swamp forest breeding territories are often embedded in a mosaic of wetland cover types. An accurate map of wetlands in the Hudson Highlands would be a useful input to a GWW habitat suitability model and could help conservation managers better allocate limited resources towards GWW monitoring and habitat management. This study tests the effectiveness of single and dual-season dual-polarization L-band ALOS PALSAR data and National Wetlands Inventory ground reference data for classifying wetlands at high resolution in a mountainous landscape using a maximum likelihood decision rule. PALSAR imagery was chosen over Landsat for its ability to detect surface conditions beneath a vegetation canopy and for its higher spatial resolution, necessary for capturing land cover characteristics at a scale that would be meaningful for characterizing GWW territories. Dual-season dual-polarization imagery produced the highest overall accuracy (72 %, kappa = 0.5669) and the highest producer’s accuracy for forested wetlands (~58 %). Errors in classifying forested wetlands were dominated by misclassification to the Urban class, most likely due to the similarity of SAR double bounce trunk-ground and building-ground interactions. Emergent and scrub-shrub wetlands proved difficult to segregate and were classified with maximum accuracies of 49 and 14 %, respectively. These results are comparable to those of similar studies and could be improved with more current ground reference data. In addition, the classification captured the mosaic of wetland cover types present in GWW study sites and territories in Sterling Forest State Park indicating PALSAR imagery could be used for GWW habitat analyses.

Using audio lures to improve golden‐winged warbler (Vermivora chrysoptera) detection during point‐count surveys

ABSTRACTThe golden‐winged warbler (Vermivora chrysoptera) is a Neotropical migratory songbird listed as a “Bird of Conservation Concern” by the U.S. Fish and Wildlife Service. To manage golden‐winged warblers, it is important to develop effective survey techniques for conservation research and monitoring. We conducted point counts in 1–8‐year‐old aspen (Populus sp.) stands in the northern Lower Peninsula of Michigan (USA), during 2011, to estimate detection probability of golden‐winged warblers, with and without an electronic broadcast of a golden‐winged warbler song (i.e., audio lure). We compared audio lure effectiveness for detecting golden‐winged warblers during fixed‐ (50‐m radius) and variable‐radius point counts. Golden‐winged warbler detection estimates were = 0.84 (95% CI = 0.39–0.98) and = 0.22 (0.11–0.40) for fixed‐radius point counts, with and without audio lure, respectively. For variable‐radius point counts, golden‐winged warbler detection estimates were = 0.79 (CI = 0.51–0.93) and = 0.57 (0.42–0.71), with and without audio lure, respectively. We also estimated the number of 3‐minute sub‐counts required to achieve detection probability ≥95% for both radii, with and without audio lures. We found that 2 sub‐counts with audio lure resulted in >95% detection probability for golden‐winged warblers at both radii. Without audio lure, 12 and 4 sub‐counts were required for fixed and variable radii, respectively. Regardless of survey technique, golden‐winged warbler detection probability was always <1.0, which highlights the importance of accounting for imperfect detection of golden‐winged warblers. Our results indicate that the use of an audio lure is an effective design technique for improving detectability of golden‐winged warblers. © 2014 The Wildlife Society.

Retirement investment theory explains patterns in songbird nest-site choice

When opposing evolutionary selection pressures act on a behavioural trait, the result is often stabilizing selection for an intermediate optimal phenotype, with deviations from the predicted optimum attributed to tracking a moving target, development of behavioural syndromes or shifts in riskiness over an individual's lifetime. We investigated nest-site choice by female golden-winged warblers, and the selection pressures acting on that choice by two fitness components, nest success and fledgling survival. We observed strong and consistent opposing selection pressures on nest-site choice for maximizing these two fitness components, and an abrupt, within-season switch in the fitness component birds prioritize via nest-site choice, dependent on the time remaining for additional nesting attempts. We found that females consistently deviated from the predicted optimal behaviour when choosing nest sites because they can make multiple attempts at one fitness component, nest success, but only one attempt at the subsequent component, fledgling survival. Our results demonstrate a unique natural strategy for balancing opposing selection pressures to maximize total fitness. This time-dependent switch from high to low risk tolerance in nest-site choice maximizes songbird fitness in the same way a well-timed switch in human investor risk tolerance can maximize one's nest egg at retirement. Our results also provide strong evidence for the adaptive nature of songbird nest-site choice, which we suggest has been elusive primarily due to a lack of consideration for fledgling survival.

Do digestive contents confound body mass as a measure of relative condition in nestling songbirds?

ABSTRACTRelative 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. © 2014 The Wildlife Society.

Bird–building collisions in the United States: Estimates of annual mortality and species vulnerability

Abstract Building collisions, and particularly collisions with windows, are a major anthropogenic threat to birds, with rough estimates of between 100 million and 1 billion birds killed annually in the United States. However, no current U.S. estimates are based on systematic analysis of multiple data sources. We reviewed the published literature and acquired unpublished datasets to systematically quantify bird–building collision mortality and species-specific vulnerability. Based on 23 studies, we estimate that between 365 and 988 million birds (median = 599 million) are killed annually by building collisions in the U.S., with roughly 56% of mortality at low-rises, 44% at residences, and <1% at high-rises. Based on >92,000 fatality records, and after controlling for population abundance and range overlap with study sites, we identified several species that are disproportionately vulnerable to collisions at all building types. In addition, several species listed as national Birds of Conservation Concern due to their declining populations were identified to be highly vulnerable to building collisions, including Golden-winged Warbler (Vermivora chrysoptera), Painted Bunting (Passerina ciris), Canada Warbler (Cardellina canadensis), Wood Thrush (Hylocichla mustelina), Kentucky Warbler (Geothlypis formosa), and Worm-eating Warbler (Helmitheros vermivorum). The identification of these five migratory species with geographic ranges limited to eastern and central North America reflects seasonal and regional biases in the currently available building-collision data. Most sampling has occurred during migration and in the eastern U.S. Further research across seasons and in underrepresented regions is needed to reduce this bias. Nonetheless, we provide quantitative evidence to support the conclusion that building collisions are second only to feral and free-ranging pet cats, which are estimated to kill roughly four times as many birds each year, as the largest source of direct human-caused mortality for U.S. birds.

Reproductive success and habitat characteristics of Golden-winged Warblers in high-elevation pasturelands

The Golden-winged Warbler (Vermivora chrysoptera) is one of the most rapidly declining vertebrate species in the Appalachian Mountains. It is the subject of extensive range-wide research and conservation action. However, little is known about this species' breeding ecology in high-elevation pasturelands, a breeding habitat with conservation potential considering the U.S. Natural Resource Conservation Service's Working Lands for Wildlife program targeting private lands in the Appalachian Mountains. We located 100 nests of Golden-winged Warblers in pastures in and around the Monongahela National Forest in West Virginia during 2008–2012. Daily nest survival rate (mean ± SE = 0.962 ± 0.006), clutch size (4.5 ± 0.1), and number of young fledged per nest attempt (2.0 ± 0.2) and successful nest (4.0 ± 0.1) fell within the range of values reported in other parts of the species' range and were not significantly affected by year or the presence/absence of cattle grazing. Classification tree analysis revealed that nests were in denser vegetation (≥52%) and closer to forest edges (<36.0 m) and shrubs (<7.0 cm) than random locations within the male's territory. Successful nests had significantly more woody cover (≥9%) within 1 m than failed nests. Our results suggest that cattle grazing at 1.2–2.4 ha of forage/animal unit with periodic mowing can create and maintain these characteristics without interfering with the nesting of Golden-winged Warblers. High-elevation pasturelands may provide a refuge for remaining populations of Golden-winged Warblers in this region.

Demographic comparison of Golden-Winged Warbler (Vermivora chrysoptera) populations in northern and southern extremes of their breeding range

Abstract Conservation strategies for declining species often are based on limited knowledge about how fecundity and survival may change across a species' range, and what factors may be limiting for a given population. Incomplete understanding of how a species' demography varies across a range of conditions may lead to inappropriate management decisions. Our objective was to compare demographic data from northern and southern extremes of the breeding range of Golden-winged Warblers (Vermivora chrysoptera). Specifically, we compared minimum estimates of annual adult survival, daily nest survival, fecundity, and population growth (lambda) for Tennessee and Ontario breeding populations. Tennessee nest survival decreased throughout the nesting season and as daily minimum temperature increased, but the constant survival model was equally supported (model averaged daily survival rate, DSR = 0.972 [0.01 SE]). Ontario nest survival also decreased throughout the nesting season, but not as a function of temperatur...

Radio-transmitters do not affect seasonal productivity of female Golden-winged Warblers

Investigating the potential effects of handling and marking techniques on study animals is important for correct interpretation of research results and to effect progress in data-collection methods. Few investigators have compared the reproductive output of radio-tagged and non-radio-tagged songbirds, and no one to date has examined the possible effect of radio-tagging adult songbirds on the survival of their fledglings. In 2011 and 2012, we compared several parameters of reproductive output of two groups of female Golden-winged Warblers (Vermivora chrysoptera) breeding in Minnesota, including 45 females with radio-transmitters and 73 females we did not capture, handle, or mark. We found no difference between groups in clutch sizes, hatching success, brood sizes, length of incubation and nestling stages, fledging success, number of fledglings, or survival of fledglings to independence. Thus, radio-tags had no measurable impact on the productivity of female Golden-winged Warblers. Our results build upon previous studies where investigators have reported no effects of radio-tagging on the breeding parameters of songbirds by also demonstrating no effect of radio-tagging through the post-fledging period and, therefore, the entire breeding season. RESUMEN Radio trasmisores no afectan la productividad estacional en las hembras de Vermivora chrysoptera Investigar los efectos potenciales de las tecnicas de manipulacion y marcaje en estudios de animales es importante para interpretar correctamente los resultados de las investigaciones y para llevar a cabo los avances en los metodos de colecta de datos. Pocos investigadores han comparado el rendimiento reproductivo de las aves paserinas con o sin radios trasmisores, y nadie hasta la fecha ha examinado el posible efecto en la supervivencia de los juveniles de aves marcadas con radios trasmisores. En el 2011 y 2012 comparamos varios parametros reproductivos en dos grupos de hembras de Vermivora chrysoptera reproduciendose en Minnesota, los cuales incluian 45 hembras con radio trasmisores y 72 hembras que no capturamos, manipulamos o marcamos. No encontramos diferencias entre los grupos en el tamano de la nidada, exito de eclosion, numero de polluelos, duracion del periodo de incubacion o polluelos, exito de salida de los polluelos del nido o supervivencia de los juveniles hasta su independencia. En consecuencia, radio trasmisores no tienen un impacto apreciable en la productividad de hembras de V. chrysoptera. Nuestros resultados aportan ha estudios anteriores en donde investigadores no han encontrados efecto de los radio trasmisores sobre parametros reproductivos de aves paserinas y tambien demuestra que no hay un efecto de los radio trasmisores sobre la supervivencia de los juveniles a lo largo del periodo despues del abandono del nido, y por ende durante toda la temporada reproductiva.

Legacy tree retention in young aspen forest improves nesting habitat quality for Golden-winged Warbler (Vermivora chrysoptera)

Residual canopy trees as biological legacies in harvested aspen stands may mimic characteristics of naturally disturbed forests. We investigated the effects of legacy tree retention in young aspen (Populus spp.) forest stands on the quality of nesting habitat for the Golden-winged Warbler (Vermivora chrysoptera), a species of conservation concern that is dependent upon recently disturbed forest and shrub habitats. Habitat quality was assessed by evaluating male density, male pairing success, percent of successful nests, daily nest survival, and productivity in young aspen stands (4–7years post-harvest) with retained conifer legacy trees (n=3), with retained hardwood legacy trees (n=3), and without legacy trees (also referred to as clearcuts; n=3). Male pairing success was higher in stands with legacy trees (68% in stands with conifer legacy trees, 71% in stands with hardwood legacy trees) than in clearcuts (10%). Only one nest was found in clearcuts. The percent of successful nests, daily nest survival rate, and productivity did not vary between stands with conifer legacy trees and stands with hardwood legacy trees. Based on high pairing success (resulting in high levels of nesting activity), retention of legacy trees in young aspen stands provided higher quality nesting habitat than clearcuts. Male density was an excellent indicator of pairing success (pseudo R2=0.976). Aspen stands harvested for nesting habitat should support a minimum density of 0.2males/ha to have approximately 75% of males successfully paired. High male densities (>0.2males/ha) were achieved by retaining at least 13 legacy trees/ha with at least nine of these comprising hardwood species with a mean diameter at breast height ≥ 16cm.

The effects of force-fledging and premature fledging on the survival of nestling songbirds

Despite the broad consensus that force-fledging of nestling songbirds lowers their probability of survival and therefore should be generally avoided by researchers, that presumption has not been tested. We used radiotelemetry to monitor the survival of fledglings of Ovenbirds Seiurus aurocapilla and Golden-winged Warblers Vermivora chrysoptera that we unintentionally force-fledged (i.e. nestlings left the nest in response to our research activities at typical fledging age), that fledged prematurely (i.e. nestlings left the nest earlier than typical fledging age), and that fledged independently of our activities. Force-fledged Ovenbirds experienced significantly higher survival than those that fledged independent of our activities, and prematurely fledged Ovenbirds had a similarly high survival to those that force-fledged at typical fledging age. We observed a similar, though not statistically significant, pattern in Golden-winged Warbler fledgling survival. Our results suggest that investigator-induced force-fledging of nestlings, even when deemed premature, does not necessarily result in reduced fledgling survival in these species. Instead, our results suggest that a propensity or ability to fledge in response to disturbance may be a predictor of a higher probability of fledgling survival.

Testing common assumptions in studies of songbird nest success

We studied Ovenbird Seiurus aurocapilla and Golden-winged Warbler Vermivorachrysoptera populations in northern Minnesota, USA, to test two common assumptions instudies of songbird nest success: (1) that the condition of an empty nest on or near itsexpected fledge date is an indicator of nest fate; and (2) that the presence of a fledgling orfamily group within a territory confirms a successful nest in that territory. We monitoredthe condition of nests and used radiotelemetry to monitor juveniles through the expectedfledging date and early post-fledging period. Of nests that contained nestlings 1–2 daysbefore the expected fledge date, fates were misidentified using nest condition alone for9.5% of Ovenbird nests, but those misidentifications were made in both directions (suc-ceeded or failed), yielding only a small bias in estimated nest success. However, 20% ofGolden-winged Warbler nests were misidentified as successful using nest condition duringthe final visit interval, biasing the nest success estimate upward by 21–28% depending onthe treatment of uncertain nest fates. Fledgling Ovenbirds from 58% of nests travelledbeyond their natal territory within 24 h, rising to 98% after 5 days, and those fledglingstravelled up to 390 m from nests within 10 days of fledging. Fledgling Golden-wingedWarblers from 13% of nests travelled beyond their natal territory within 24 h, rising to85% after 5 days, and those fledglings travelled up to 510 m from nests within 10 days offledging. We conclude that nest condition and fledgling presence can be misleading indica-tors of nest fate, probably commonly biasing nest success estimates upward, and we rec-ommend that these assumptions should be tested in additional species.Keywords: fledgling, Golden-winged Warbler, Ovenbird, Seiurus aurocapilla, telemetry,Vermivora chrysoptera.Estimates of songbird reproductive success, typi-cally limited to nest data, are used to assess habitatquality (e.g. Weinberg & Roth 1998), model pop-ulation dynamics (e.g. Podolski et al. 2007), iden-tify source and sink populations (e.g. Donovan etal. 1995), and inform conservation and manage-ment plans (e.g. Woodworth 1999). Althoughsongbird population growth may be generally moresensitive to adult annual survival and fledgling sur-vival (Donovan & Thompson 2001, Streby &Andersen 2011), population growth is also sensi-tive to variation in nest success (Donovan et al.1995), and nest success is the only directly esti-mated parameter in most studies of songbirdreproductive success (Anders et al. 1997). Manypopulation models account for re-nesting (birdsnesting again after initial failure) and estimates ofnest productivity (number of young produced persuccessful nest). All such studies require accuratefield identification of whether each monitored nestsucceeded or failed in producing young. However,observational studies of songbird nests often

Avian mortality at communication towers in the United States and Canada: which species, how many, and where?

Birds migrating to and from breeding grounds in the United States and Canada are killed by the millions in collisions with lighted towers and their guy wires. Avian mortality at towers is highly variable across species, and the importance to each population depends on its size and trajectory. Building on our previous estimate of avian mortality at communication towers, we calculated mortality by species and by regions. To do this, we constructed a database of mortality by species at towers from available records and calculated the mean proportion of each species killed at towers within aggregated Bird Conservation Regions. These proportions were combined with mortality estimates that we previously calculated for those regions. We then compared our estimated bird mortality rates to the estimated populations of these species in the United States and Canada. Neotropical migrants suffer the greatest mortality; 97.4% of birds killed are passerines, mostly warblers (Parulidae, 58.4%), vireos (Vireonidae, 13.4%), thrushes (Turdidae, 7.7%), and sparrows (Emberizidae, 5.8%). Thirteen birds of conservation concern in the United States or Canada suffer annual mortality of 1–9% of their estimated total population. Of these, estimated annual mortality is >2% for Yellow Rail (Coturnicops noveboracensis), Swainson’s Warbler (Limnothlypis swainsonii), Pied-billed Grebe (Podilymbus podiceps), Bay-breasted Warbler (Setophaga castanea), Golden-winged Warbler (Vermivora chrysoptera), Worm-eating Warbler (Helmitheros vermivorum), Prairie Warbler (Setophaga discolor), and Ovenbird (Seiurus aurocapilla). Avian mortality from anthropogenic sources is almost always reported in the aggregate (“number of birds killed”), which cannot detect the species-level effects necessary to make conservation assessments. Our approach to per species estimates could be undertaken for other sources of chronic anthropogenic mortality.

Working Lands for Wildlife: Will Voluntary Habitat Conservation Save Two Threatened Pennsylvania Species?

On March 8, 2012, the U.S. Department of Agriculture’s Natural Resources Conservation Service and the Department of the Interior’s Fish and Wildlife Services revealed a new conservation program called Working Lands for Wildlife. This federally funded partnership devotes 33 million dollars to voluntary landowner habitat conservation for seven target species, including two rare Pennsylvanian species, the bog turtle and the golden-winged warbler. In exchange for an agreement to improve habitats for one of these species, landowners receive a promise from regulating agencies that any incidental harm to the species caused by their habitat conservation practices will be exempt from penalties under the Endangered Species Act (hereinafter “ESA”). Landowners also receive some technical and financial assistance to support their conservation efforts. Although Working Lands for Wildlife provides these admirable new incentives for habitat conservation, the program could also be used to avoid ESA listings for currently unlisted species, like the golden-winged warbler. This article argues the program’s potential costs and benefits to unlisted species should be carefully weighed, and the program cannot serve as a politically convenient procedure to abandon listing efforts.

Blood parasite infection and heterozygosity in pure and genetic-hybrid Golden-winged Warblers (Vermivora chrysoptera) across Canada

ABSTRACT. We examined heterozygosity at hypervariable microsatellite loci and blood parasite presence—absence in five populations of Golden-winged Warblers (Vermivora chrysoptera) that span the species' Canadian range. All populations were predominantly composed of genetically pure individuals, with small proportions of phenotypic and genetic hybrids. By comparing heterozygosity and infection status in concert, we tested whether more-heterozygous individuals have lower parasite prevalence, perhaps because they possess a more robust immune system. By considering the genetic status (pure vs. hybrid) of individuals in relation to infection by parasites and heterozygosity, we build on existing research that examines the effect of Blue-winged Warbler (V. cyanoptera) hybridization on Golden-winged Warbler populations. Finally, by looking at populations across the east—west range of the species, we could hypothesize what role geographic variation in vectors might play in population-level infection rates. We foun...

Spot‐mapping underestimates song‐territory size and use of mature forest by breeding golden‐winged warblers in Minnesota, USA

AbstractStudies of songbird breeding habitat often compare habitat characteristics of used and unused areas. Although there is usually meticulous effort to precisely and consistently measure habitat characteristics, accuracy of methods for estimating which areas are used versus which are unused by birds remains generally untested. To examine accuracy of spot‐mapping to identify singing territories of golden‐winged warblers (Vermivora chrysoptera), which are considered an early successional forest specialists, we used spot‐mapping and radiotelemetry to record song perches and delineate song territories for breeding male golden‐winged warblers in northwestern Minnesota, USA. We also used radiotelemetry to record locations (song and nonsong perches) of a subsample (n = 12) of males throughout the day to delineate home ranges. We found that telemetry‐based estimates of song territories were 3 times larger and included more mature forest than those estimated from spot‐mapping. In addition, home ranges estimated using radiotelemetry included more mature forest than spot‐mapping‐ and telemetry‐based song territories, with 75% of afternoon perches located in mature forest. Our results suggest that mature forest comprises a larger component of golden‐winged warbler song territories and home ranges than is indicated based on spot‐mapping in Minnesota. Because it appears that standard observational methods can underestimate territory size and misidentify cover‐type associations for golden‐winged warblers, we caution that management and conservation plans may be misinformed, and that similar studies are needed for golden‐winged warblers across their range and for other songbird species. © 2012 The Wildlife Society.

Genetic Introgression: An Integral but neglected component of speciation in birds

The Auk, Vol. 128, Number 4, pages 620−632. ISSN 0004-8038, electronic ISSN 1938-4254.  2011 by The American Ornithologists’ Union. All rights reserved. Please direct all requests for permission to photocopy or reproduce article content through the University of California Press’s Rights and Permissions website, http://www.ucpressjournals. com/reprintInfo.asp. DOI: 10.1525/auk.2011.128.4.620 3E-mail: frankrheindt@yahoo.com.au Hybridization, or the act of reproduction between different species, is common in birds (Grant and Grant 1992) and can be an agent of adaptive evolution (Veen et al. 2001). When hybridization occurs, a species’ genetic material may enter the gene pool of another and thereby introduce genetic novelty. This process is called “genetic introgression” (hereafter “introgression”; Anderson 1949). Although known for decades, the incidence of introgression in nature has long been underappreciated (e.g., Currat et al. 2008). Only recently have evolutionists come to regard it as an important and pervasive mechanism in speciation, in the maintenance of genetic diversity and in the introduction of advantageous novelty into the gene pool (Arnold et al. 1999, Noor et al. 2000, Seehausen 2004). In fact, genetic data now suggest that our own species may have undergone a complicated history of introgression with at least two extinct hominine lineages (Green et al. 2010, Reich et al. 2010). Another reason why introgression is an important topic is the impact of human-induced climate change, which is rapidly shifting vegetation boundaries and creating new hybrid zones, with little-known consequences for the genetic integrity of species (Mank et al. 2004, Brumfield 2010). There has been a tremendous increase in introgressionrelated avian research since a comprehensive overview of the introgression complex between the Blue-winged Warbler (Vermivora cyanoptera) and the Golden-winged Warbler (V. chrysoptera) appeared in The Auk five years ago (Confer 2006). Here, we seek to fill a gap by summarizing the most important recent advances in avian introgression research and our current understanding of locus-specific differences in introgression dynamics, the detection of introgression, its directionality, and its relevance to conservation, phylogenetics, and speciation research.

Taxonomic recommendations for British birds: seventh report

Taxonomic recommendations for British birds: seventh report

Habitat quality and habitat selection of golden-winged warblers in Costa Rica: an application of hierarchical models for open populations

Summary 1. Identifying high-quality habitat is integral to effective species conservation efforts and requires information about habitat-specific abundance and demographics. This information is lacking for many species of conservation concern because of the inherent difficulties associated with implementing mark–recapture studies at large spatial scales. 2. The golden-winged warbler Vermivora chrysoptera is a Neotropical–Nearctic migratory bird experiencing a long-term population decline; yet no information about non-breeding season habitat quality or habitat selection exists to inform conservation efforts. We used a novel hierarchical model that requires only spatially and temporally replicated count data to estimate habitat-specific abundance, apparent survival, recruitment and detection probability of golden-winged warblers wintering in Costa Rica. We quantified habitat selection at the home-range level using radiotelemetry. 3. Golden-winged warblers were absent from tropical dry forest and were most abundant in premontane evergreen forest. Within their home ranges, golden-winged warblers selected microhabitat features associated with intermediate disturbance that reflected their preference for foraging in hanging dead leaves. 4. Consistent with other evidence of a declining population, local population size decreased over the duration of the study. The rate of decrease was higher during the non-breeding season than among seasons. We found no differences in apparent survival or recruitment among habitat types; however, our estimates of these parameters were imprecise. 5. Synthesis and applications. Golden-winged warblers are forest-dependent species during the non-breeding season and have specialized microhabitat requirements that make them vulnerable to ongoing tropical deforestation. However, advanced secondary forests can provide the requisite microhabitat features, and because we found no evidence of reduced survival in this habitat type, regenerating forest on degraded lands may be an effective component of a conservation strategy for this species. Our study also demonstrates that information on population dynamics and habitat quality can be obtained using repeated counts instead of mark–recapture methods.

Golden-winged Warbler (Vermivora chrysoptera)

Golden-winged Warbler (Vermivora chrysoptera)

Golden- and Blue-winged Warblers: Distribution, Nesting Success, and Genetic Differences in Two Habitats

Abstract We analyzed phenotypic distribution, nesting success, and genetic purity of Golden-winged Warblers (Vermivora chrysoptera) and Blue-winged Warblers (V. pinus) in two ecologically distinct nesting habitats: early-succession uplands, and swamp forests. The proportion of phenotypically pure Golden-winged Warblers in swamp forests (94%) differed significantly from uplands (53%) as did the proportion of Golden-winged Warbler pairs (93%) in swamp forests compared to uplands (48%). Only 1% of the phenotypically pure Golden-winged Warblers in swamp forests paired with either a hybrid or a Blue-winged Warbler, but 7% of the phenotypically pure Golden-winged Warblers in uplands formed a hybrid pair. The probability of nesting success for Golden-winged Warbler pairs in swamp forests (65%) was significantly higher than in uplands (37%). Mitochondrial DNA analyses indicate that all 10 phenotypically pure Golden-winged Warblers sampled from swamp forests had the ancestral Golden-winged Warbler haplotype, while...