We obtained the first DNA sequences from the extinct Carolina Parakeet (Conuropsis carolinensis) and used these data to infer the phylogenetic relationships of this iconic North American parrot. We compared our sequences of the mitochondrial COI and ND2 genes obtained from multiple Carolina Parakeet museum specimens to homologous sequences from individuals representing 43 species in 28 genera of Neotropical parrots (Tribe Arini), and four species from more distantly related Old World species of the Order Psittaciformes. Bayesian and maximum likelihood analyses place C. carolinensis on a long branch within a well-supported clade of parakeets that also includes Aratinga solstitialis, A. auricapillus, and Nandayus nenday. These species of Aratinga (but not N. nenday) closely resemble C. carolinensis in the presence of yellow and orange head plumage and blue feathers in the wings. Our data do not support a close relationship with the Monk Parakeet (Myiopsitta monachus), with which the Carolina Parakeet shares fully feathered ceres, a putative adaptation for cold tolerance that appears to have evolved independently in both species. Given the high level of sequence divergence from all sampled species, we recommend continued recognition of the monotypic genus Conuropsis. Taxonomic revision of the highly polyphyletic genus Aratinga is needed.

We assessed carry-over effects from winter location on timing of nest initiation and clutch size of Black Brant (Branta bernicla nigricans) using observations of individually marked brant breeding at the Tutakoke River colony in Alaska, and wintering along a latitudinal gradient at three areas on the Pacific coast of Baja California: northernmost Bahia San Quintin (BSQ), Laguna Ojo de Liebre (LOL), and southernmost Laguna San Ignacio (LSI). Black Brant initiated nests according to a north—south trend in winter location, although year was a stronger predictor of initiation date than was wintering site. Female Black Brant that wintered at BSQ initiated nests 2.2 days earlier than females from LSI. Conversely, Black Brant showed only a weak south—north trend in clutch size; individuals from LSI laid slightly larger clutches than individuals from BSQ, probably because a smaller proportion of only high-quality females from the southernmost wintering area in Baja California were able to attain the nutritional condition necessary to breed. These results indicate that winter location can influence individual reproductive performance and, potentially, limit population growth of southern segments of the wintering Black Brant population.

Avian coloration has played a central role in the study of sexual selection and other aspects of animal behavior. However, only recently have analyses of avian coloration been able to incorporate avian visual abilities. Although several studies have broadly sampled species for evidence of plumage coloration visible to birds but invisible to humans, few studies have quantified these data for all species in a single taxonomic group. We quantify ultraviolet (UV) plumage reflectance and document cryptic sexual dichromatism in the largest radiation of Neotropical songbirds, the cardinals and tanagers. Ultraviolet reflectance was common in the patches measured, with almost half of the species reflecting >20% of light in the UV range in at least one patch. High UV-reflecting patches, including 73 of the 91 patches that were found to be primarily UV colored, belonged to species in either Passerina or 2 of 13 major clades of tanagers. This indicates that high UV reflectance is not randomly distributed across the phytogeny. Sexual dichromatism was much more widespread in the group than previously thought. From a human visual perspective, about half the species in the group are sexually dichromatic; but from an avian visual perspective, 97% of species are dichromatic. We compared the implications of using human-perceived versus avian-perceived sexual dichromatism by mapping these traits onto tanager phytogenies. Quantifying dichromatism using an avian visual model provided a more accurate and detailed history of plumage coloration change across evolutionary history.

Bird species vary greatly in the duration of their annual complete feather molt. However, such variation is not well documented in birds from many biogeographic areas, which restricts our understanding of the diversification of molt strategies. Recent research has revealed that molt duration can be estimated in passerines from ptilochronology-based measurements of the growth rate of their tail feathers. We used this approach to explore how molt duration varied in 98 Nearctic species that have different migratory strategies and molt patterns. As previously documented for Palearctic species, migration was associated with a shortening of molt duration among species that molted during summer on their breeding range. However, molts of winter-molting migratory species were as long as those of summer-molting sedentary species, which suggests that winter molt also allows Nearctic migrants to avoid the temporal constraints experienced during summer. Our results also suggest that migratory species that undergo a stopover molt within the Mexican monsoon region have the shortest molt duration among all Nearctic passerines. Interestingly, and contrary to expectations from a potential tradeoff between molt duration and feather quality, observed variation in feather growth rate was positively correlated with differences in tail feather mass, which may be caused by differences among groups in the availability of resources for molting. We encourage the use of similar approaches to study the variation in molt duration in other geographic areas where knowledge of the evolution of molt is limited.

We tested one of the foundational hypotheses of the field of ecological immunology: that it is difficult for animals to simultaneously carry out two or more especially demanding physiological processes at optimal levels because of energy needs or other factors that cause tradeoffs among competing components of life history. We investigated possible effects of molt (a costly life-history stage that all birds share) on three physiological parameters in 32 male and female Brown-headed Cowbirds (Molothrus ater). We measured hematocrit, corticosterone levels (CORT), and the bactericidal competence (BC) of blood plasma by drawing blood from the birds before, twice during, and twice after their molt from late July to early September 2009. In accordance with our predictions, BC dropped during molt for both males and females. Interestingly, BC recovered faster after molt ended in males, and female BC remained depressed for the rest of our sampling period. Hematocrit also dropped during the molt but returned to initial levels after molt in both males and females. CORT dropped during molt, but the change was significant only for males. Our results highlight possible physiological consequences of molt in Brown-headed Cowbirds even when the birds are maintained in optimal conditions (i.e., shelter, ad libitum food and water, relatively low-stress environment). Furthermore, we suggest that the slower recovery of female immune function following molt may be related to higher female mortality resulting in the ubiquitous phenomenon of male-biased sex ratios in Brown-headed Cowbird populations.

Timing of molt is a critical life-history trait because molt is a nutritionally demanding process that must be completed before fall migration. We used data from 1992–2008 to assess hypotheses that initiation of the prebasic molt by Black Brant (Branta bernicla nigricans) was ultimately controlled by (1) the need to complete the molt before fall migration and (2) advantages of restoring depleted nutrient reserves before growing feathers. Specifically, we expected molt to occur sooner after hatching in years when nesting was delayed (prediction 1), but we expected individuals to delay molt in relation to hatch date when nesting was earlier (prediction 2). Our rationale for prediction 1 was that the need to complete molt before fall migration is exacerbated when nesting is delayed. Prediction 2 is suggested by the advantage of restoring nutrients depleted during nesting before initiating molt. We tested predictions by assessing patterns of ninth-primary length in relation to number of days posthatch, modal hatch date, and relative hatch date within years. We calculated molt initiation dates using parameter estimates from the best-supported model, using lengths and growth rates of ninth primaries. We estimated that Black Brant initiated molt an average of 14.5–19.5 days posthatch, depending on year. For modal hatch dates before 22 June (summer solstice), date of mean initiation of molt was negatively correlated with modal hatch date (β = -0.56), whereas for modal hatch dates after 22 June, mean initiation of molt began an average of 16.1 days after hatch. In years when modal hatch date was before 22 June, Black Brant waited longer after their clutches hatched before beginning molt, which suggests an advantage of greater stored nutrient levels before initiating molt. By contrast, in late-nesting years, Black Brant began molt 16 days after they hatched their clutches, which suggests that (1) a minimum average period posthatch was required before molt commenced and (2) there was a cost of further delay in molt in late-nesting years. Declining photoperiod following the summer solstice is a reasonable candidate for the signal that Black Brant use to initiate molt in late-nesting years.

Understanding the spatial scale of gene flow can yield valuable insight into the ecology of an organism and guide conservation strategies. Fine-scale genetic structure is uncommon in migratory passerines because of their high vagility and presumed high dispersal abilities. Aspects of the behavior and ecology of some migratory species, however, may promote structure on a finer scale in comparison to their mobility. We investigated population genetic structure in the Saltmarsh Sparrow (Ammodramus caudacutus), a migratory passerine that breeds along the northeastern coast of the United States, where it is restricted exclusively to a narrow strip of patchily distributed tidal marsh habitat. Using genotyping with 10 microsatellite loci, we detected weak but significant population structure among Saltmarsh Sparrows from nine marshes on the breeding grounds between Scarborough, Maine, and Oceanside, New York. Genetic variation among marshes was largely consistent with a pattern of isolation by distance, with some exceptions. One inland marsh was genetically divergent despite its proximity to other sampled marshes, which suggests that mechanisms besides geographic distance influence population genetic structure. Bayesian clustering, multivariate analyses, and assignment tests supported a population structure consisting of five groups. Estimates of migration rates indicated variation in gene flow among marshes, which suggests asymmetrical dispersal and possible source-sink population dynamics. The genetic structure that we found in Saltmarsh Sparrows may result from natal philopatry and breeding-site fidelity, combined with restricted dispersal due to obligate dependence on a patchy habitat. Our findings suggest that fine-scale population structure may be important in some migratory passerines.

The North American Breeding Bird Survey (BBS) is an annual transect point-count survey of >500 species and >3,500 survey routes (transects). Observers drive and record birds seen and heard within a radius of 400 m of 50 survey points (“stops”) evenly spaced along a 39.4-km survey route. Thus, the land area along both sides of a route composes a linear or curvilinear landscape. Although BBS data have been used in many studies and conservation plans, there have been few attempts to determine how well the landscapes along BBS routes represent landscapes at larger spatial extents, particularly with regard to land-cover composition. Using data from the 2001 National Land Cover Database, we conducted a study of representativeness of 3,230 routes by comparing the differences in percent cover of 15 land-cover types in BBS landscapes (buffer width of 0.4 km surrounding a route) to larger local landscapes (10 km buffer width) and regions. At the local level, BBS landscapes were representative for most of the cover types except open water, which was underrepresented, and lightly developed open space, which was overrepresented. At the regional level, the collective composition of BBS landscapes was very similar to the composition within entire Bird Conservation Regions. Overall, these results should encourage the continued use of BBS data in ornithological and ecological research and in conservation planning.

We used binomial distance-sampling models to estimate the effective detection radius (EDR) of point-count surveys across boreal Canada. We evaluated binomial models based on 0–50 m and >50 m distance categories for goodness-of-fit and sensitivities to variation in survey effort and habitats sampled. We also compared binomial EDRs to Partners in Flight's maximum detection distances (MDD) to determine differences in landbird population sizes derived from each. Binomial EDRs had a small positive bias (4%) averaged across 86 species and a large positive bias (30–82%) for two species when compared with EDRs estimated using multinomial distance sampling. Patterns in binomial EDRs were consistent with how bird songs attenuate in relation to their frequencies and transmission through different habitats. EDR varied 12% among habitats and increased 17% when birds were counted to an unlimited distance, compared with a limited distance of 100 m. The EDR did not vary with the duration of surveys, and densities did not differ when using unlimited-distance versus truncated data. Estimated densities, however, increased 19% from 3- to 5-min counts and 25% from 5- to 10-min counts, possibly from increases in the availability, movement, or double counting of birds with longer counts. Thus, investigators should be cautious when comparing distance-sampling results among studies if methods vary. Population sizes estimated using EDR averaged 5 times (0.8–15 times) those estimated with MDD. Survey data from which to estimate binomial EDRs are widely available across North America and could be used as an alternative to MDD when estimating landbird population sizes.

Breeding dispersal is often affected by previous reproductive success, age, and sex. Birds with multiple broods within a season can disperse not only between, but also within, years. Little is known about factors that govern dispersal within a season or how strong it is compared with dispersal between years. We studied breeding dispersal of Eurasian Hoopoes (Upupa epops) in Valais, Switzerland, using capture-recapture data collected over 8 years (n = 712 individuals). We analyzed breeding dispersal probability and distance, both between and within years, in relation to age, sex, and reproductive output, using multistate capture-recapture models and generalized linear models. Between years, females dispersed more often and over longer distances than males (mean distance, females = 1.98 km; males = 0.83 km), but dispersal was only weakly affected by age and previous reproductive success. Dispersal within a year also differed between sexes (mean distance, females = 1.45 km; males = 0.46 km) and varied little with age or previous reproductive success. Dispersal probability within years was lower and occurred over shorter distances than dispersal between years. Thus, dispersal decisions did not seem to depend on different cues, although dispersal within the breeding season might be constrained by habitat saturation. Breeding dispersal was common in Hoopoes, compared with other bird species. Together with the fact that immigration is an important component of this species' population dynamics, such dispersal patterns suggest that successful conservation of Eurasian Hoopoes requires extended breeding grounds to maintain sustainable populations.

Flooding can cause widespread nest failure and chick mortality in sandbar-and beach-nesting waterbirds, particularly when human activity has either altered natural hydrology or limited available nesting habitat. Such widespread reproductive failure could increase breeding-season dispersal, leading to the abandonment of established nesting sites. We examined how annual movement ψ; varied by sex, reproductive success, and flooding in three Piping Plover (Charadrius melodus) breeding areas in Saskatchewan during 2002–2009, using a multistate capture-mark-recapture model in Program MARK (n = 782). On average, female Piping Plovers were twice as likely as males to disperse and both sexes were more likely to disperse following years of poor versus moderate reproductive success (minimum to maximum values: ψ;_{no-fledglings}, 0.0054–0.0998 vs. ψ;_{two-fledglings}, 0.0017–0.0607). In addition, breeding Piping Plovers exhibited higher dispersal following flood years, even in years of moderate reproductive success (minimum to maximum values: ψ;_males-flood, 0.0025–0.0653 vs. ψ;_{males-noflood}, 0.0019–0.0399; and ψ;_{females-flood}, 0.0092–0.1089 vs. ψ;_{females-no flood}, 0.0070–0.0666). Consecutive floods could force Piping Plovers to nest at artificially high densities in new habitats that may be ill-suited to reproductive success. Given the benefits of site familiarity to reproductive success and survival, we recommend that conservation planning consider dispersal of breeding adults, in addition to nests and chicks, when water levels are managed at nesting locations used by Piping Plovers.

Despite recent progress in avian demography, much still needs to be learned about patterns of survival and dispersal across different ages and sexes of birds. This is expressly true for Brown-headed Cowbirds (Molothrus ater) in light of their vagility and importance in the life history of many other bird species. We used multistate mark—recapture models to estimate annual survival and dispersal rates of Brown-headed Cowbirds across dialect subpopulations in the Sierra Nevada of California across the 1982–1988 breeding seasons. We estimated rates for male and female hatch-year (HY) and after-hatch-year (AHY) birds and found no evidence of differences in capture probabilities across sex and age states. To account for high apparent nonresidency, adult survival was estimated separately for the year following initial capture and for subsequent years. The latter estimates are near the midpoint of those from other studies (AHY females: 56.1%; after-second-year [ASY] males: 63.4%; second-year [SY] males: 32.9%). Survival estimates for HY birds are high for passerines (females: 24.6%; males: 25.3%), although they are largely consistent with estimates from long-term mark—recapture studies in other species. We found no evidence of sex-biased dispersal, although rates for HY birds (about 14–15%) were about 3× higher than those for adults (about 4–5%). Our study provides a more detailed understanding of the demography and dispersal of cowbirds, offering a platform for future research on the social behavior and ecology of this species and on possible strategies for its management.

In many bird species, survival can vary with the age of the nest, with the date a nest was initiated, or among years within the same nesting area. A literature review showed that patterns of survival vary in relation to nest age and date and are often contradictory. Inconsistencies could be a result of temporal variation in the environment or life-history differences among species. We examined patterns of nest survival in relation to nest age, date, and year for several duck and passerine species nesting at a single location in North Dakota during 1998–2003. We predicted that if environment shaped nest survival patterns, then temporal patterns in survival might be similar among three species of upland nesting ducks, and also among three species of grassland passerines nesting at the same site. We expected that survival patterns would differ between ducks and passerines because of relatively disparate life histories and differences in predators that prey on their nests. Nest survival was rarely constant among years, seasonally, or with age of the nest for species that we studied. As predicted, the pattern of survival was similar among duck species, driven mainly by differences in nest survival associated with nest initiation date. The pattern of survival also was similar among passerine species, but nest survival was more influenced by nest age than by date. Our findings suggest that some but not all variation in temporal patterns of nest survival in grassland birds reported in the literature can be explained on the basis of temporal environmental variation. Because patterns of survival were dissimilar among ducks and passerines, it is likely that mechanisms such as predation or brood parasitism have variable influences on productivity of ducks and passerines nesting in the same area. Our results indicate that biologists and managers should not assume that temporal environmental variations, especially factors that affect nest survival, act similarly on all grassland birds.

Reproductive success commonly improves with age in birds. However, it is difficult to determine whether this phenomenon is due to breeding experience or other age-related factors because most potential explanatory factors are positively correlated. Using a 17-year database, we investigated how age, breeding experience, location experience, and pair-bond experience influenced Piping Plover (Charadrius melodus) reproductive success in the Great Lakes region. Reproductive success was measured as number of offspring fledged per pair for 415 successful nests during 1993–2009. We controlled for individual and site variation with random effects and tested for increased reproductive success associated with age, prior breeding experience, prior location experience, and prior pair-bond experience using generalized linear mixed models. Reproductive success increased with location-specific breeding experience of females and declined when females moved to a new location. After statistically controlling for these effects, we found no additional effect of male age, male experience, or pair experience. Additionally, fledging success declined with later hatching dates, so we examined the relative influence of age and experience on hatch date and determined that older females and males bred earlier. Our results indicate that improvement in reproductive success with age in Piping Plovers has two components: a direct effect of female location experience on fledging success, and an indirect effect of timing of breeding, which leads to greater reproductive success through earlier nesting by older males and females. Actions by resource managers to promote breeding philopatry and successful early nesting attempts may enhance reproductive success of this federally endangered population.

We present a systematic revision of the polytypic Spotted Antpitta (Grallariidae: Hylopezus macularius) based on morphometric, plumage, vocal, and molecular characters. Morphological and vocal analyses were based, respectively, on 97 specimens and 106 recordings. Molecular phytogenies were inferred on the basis of 1,352 base pairs of the mitochondrial DNA genes 16S, ND2, and cytochrome b from 30 specimens, including several outgroups. Our results revealed the existence of an undescribed taxon endemic to the Madeira—Xingu interfluvium, similar in morphology to paraensis, but vocally and genetically readily distinguished from the latter and any other taxon grouped under H. macularius. We also found that populations from the Negro River basin (currently treated in paraensis) and those from northern Peru and southern Venezuela (placed in diversus) should be treated as a single taxon, for which the name dilutus is available. Reconstructed phytogenies recovered, with overall strong support, the reciprocal monophyly among four main lineages of the Spotted Antpitta, three corresponding to already named taxa (dilutus, macularius, and paraensis), and one to the unnamed taxon, which we describe. We show that those four taxa are also mutually diagnosed by a combination of both vocal and morphological features, and we recommend treating them as separate species under alternative species concepts.