We describe a new species of spinetail, Synallaxis beverlyae (Río Orinoco Spinetail), from river island scrub in the lower and middle sections of the main river channel of the Río Orinoco in Venezuela and adjacent Colombia. This taxon has been overlooked previously because river islands were not examined by earlier collecting expeditions. In plumage the species is closest to the widespread Pale-breasted Spinetail (S. albescens), but in vocalizations it is most similar to Dark-breasted Spinetail (S. albigularis), Cinereous-breasted Spinetail (S. hypospodia), and Spix's Spinetail (S. spixi). The new species is, as far as we know, restricted to scrubby river island vegetation and adjacent river edges that are subject to seasonal inundation. It is presently known only from two well-separated areas but is likely to occur on appropriate intervening islands. The restricted range and narrow ecological requirements of S. beverlyae are a conservation concern.

Because of continental-scale declines of grassland birds over the past century, conservation agendas are focused on increasing understanding of grassland bird ecology and habitat associations. Shortgrass prairie is a unique grassland ecosystem maintained, in part, by Black-tailed Prairie Dogs (Cynomys ludovicianus). The Mountain Plover (Charadrius montanus) and western Burrowing Owl (Athene cunicularia hypugaea) are species of conservation concern known to be associated with prairie dog colonies. We estimated abundance of Mountain Plovers and Burrowing Owls in three habitats within the Colorado shortgrass prairie ecosystem—prairie dog colonies, grassland not occupied by prairie dogs, and dryland agriculture. Further, we investigated habitat associations of Mountain Plovers and Burrowing Owls at multiple landscape scales. We estimated 8,577 Mountain Plovers (95% CI: 7,511–35,130) and 3,554 Burrowing Owls (95% CI: 3,298–8,445) in eastern Colorado. Mountain Plover density on prairie dog colony plots ( = 2.26 birds per 100 ha, 95% CI: 2.15–5.13) was significantly higher than densities on either grassland ( = 0.23,95% CI: 0.17–1.76) or dryland-agriculture plots ( = 0.45,95% CI: 0.44–0.53). Burrowing Owl density on prairie dog colony plots ( = 3.04 birds per 100 ha, 95% CI: 2.82–6.92) was significantly higher than densities on either grassland ( = 0.044, 95% CI: 0.041–0.12) or dryland-agriculture plots (no Burrowing Owls detected). Our results suggest that increased prairie dog colonies would positively influence the abundance of Mountain Plover and Burrowing Owl.

Maternal preference for nest sites is predicted to be an adaptive consequence of selective pressures acting on parents and young at the nest site. Nest predation risk has been linked to nest-site placement in birds, but microclimatic extremes can impose fitness costs on both adults and young, and these two factors may conflict. I used the temporal and spatial variation in microclimatic conditions and nest predation risk generated by variation in wildfire severity to examine the relationship between nest-site preference, nest microclimate, and fitness costs to parents and young in the Dark-eyed Junco (Junco hyemalis), a facultative cavity-nester. Adults preferred to select exposed nest sites oriented toward the north—sites that consistently had the most moderate thermal regimes. Nestlings reared in burrow-type nests gained mass more slowly and experienced retarded skeletal growth compared with exposed nests, but slower growth was not explained by suboptimal nest temperatures, nestling provisioning rates, or nest attentiveness. Although young raised in the warmest nest sites (exposed and south-facing) did not experience reduced growth rates as predicted, incubating females reduced their nest attentiveness and parents increased their nestling provisioning rate at these nest sites. The results suggest that nest microclimate can affect thermoregulatory costs to parents and offspring that can influence parental care decisions. Variation in nest predation was unrelated to microclimatic characteristics of nest sites, which suggests that parents do not make tradeoffs between microclimate and risk of nest predation when locating nests.

Flight calls are commonly produced by nocturnal migrant birds. Uncertain or unknown identities and lack of information about inter- and intraspecific variation in call notes limit the usefulness of flight calls in monitoring bird populations. We developed a novel method for recording flight calls of temporarily captive birds that allows us to study inter- and intraspecific variation in call notes of birds of known identity, age, and sex. We recorded calls and analyzed data from 13,271 flight calls recorded from 469 individuals of 28 warbler species (Parulidae) over a two-year period. Principal coordinate ordination of spectral cross-correlation data on 7 of the 28 species indicated that flight calls recorded in captivity are similar to those recorded from wild birds. Visual and aural comparisons of species' flight calls from these two different types of recordings support these results. Additionally, we verified flight calls previously identified primarily on inferential evidence and report on previously undocumented flight calls. This method quickly provides many high-quality recordings of the flight calls of individuals of known age and sex, and the results of our analyses greatly facilitate the development of automated sound-analysis algorithms critical for implementing and strengthening future acoustic monitoring applications.

Several bird species in the endemic New Guinean genus Pitohui contain potent defensive toxins of the batrachotoxin family of steroidal alkaloid neurotoxins. We surveyed toxin concentrations in various tissues of Hooded Pitohui (Pitohui dichrous) using radioligand binding assays. The highest concentrations were found in the skin and feathers, on the outside of the birds, where predators or parasites are likely to encounter toxins. Significant levels of toxins also were found in skeletal muscle, heart, and liver. Muscle and liver would normally be poisoned by batrachotoxins; thus, Hooded Pitohuis must be insensitive to the toxins. The presence of toxins in internal organs further argues against the hypothesis that Hooded Pitohuis merely apply toxins topically to skin and feathers. Finally, we used scanning and transmission electron microscopy to examine skin and feathers for unusual morphological or histological adaptations for storing and secreting toxins. The skin of Hooded Pitohuis appears to have typical dermal and epidermal morphology, and we speculate on possible ways in which this species may sequester and secrete toxins using typical avian skin structural features, unique among vertebrates.

The Southern Swamp Sparrow (Melospiza georgiana georgiana) breeds in northeastern North America in montane, freshwater marshes and fens. Its close relative, the Coastal Plain Swamp Sparrow (M. g. nigrescens), breeds in northeastern North America, but in coastal salt marshes. Coastal Plain Swamp Sparrows are darker than Southern Swamp Sparrows. Darkly colored feathers are more resistant to bacterial degradation by bacilli, which are unusually salt-tolerant. We tested whether the difference in feather color of the pale montane Southern Swamp Sparrow and the dark Coastal Plain Swamp Sparrow could be an adaptive response to differences in the occurrence and activity of bacilli in habitats that differ in salinity. Southern Swamp Sparrows were caught and sampled in cranberry fens in western Maryland, whereas Coastal Plain Swamp Sparrows were sampled in salt marshes on the western shore of the Delaware River, just where it broadens into Delaware Bay. The number of birds with feather-degrading bacteria in their plumage was significantly greater among Swamp Sparrows in salt marshes than among those in freshwater fens. The number of colonies of feather-degrading bacilli per bird was also higher for salt-marsh Swamp Sparrows than for those from freshwater fens. We conclude that the dark plumage of Coastal Plain Swamp Sparrows evolved to resist feather-degradation by salt-tolerant bacilli that occur more frequently and abundantly in their plumage than in the pale plumage of the Southern Swamp Sparrow.

Females may engage in extrapair copulations to receive indirect benefits in the form of more immunocompetent young. Nestling quality is often assessed by examining immune function using the phytohemagglutinin (PHA) skin test, which can be a predictor of nestling recruitment. However, the PHA test can also be influenced by factors such as nest temperature. We tested the prediction that extrapair young mount greater immune responses to a PHA challenge and recruit at a greater rate than within-pair young in a wild population of Savannah Sparrows (Passerculus sandwichensis). We also investigated ambient temperature and its relationship with immune response. Extra-and within-pair young did not significantly differ with respect to PHA-induced immune response or with respect to recruitment. In contrast to other studies, we found that PHA-induced immune response was not associated with nestling recruitment rates. However, it was positively correlated with minimum ambient temperature for males hatched in 2002 and 2003, and for females in 2003 (with a similar, but marginally nonsignificant, trend in 2002). Immune response to PHA also was positively correlated with nestling mass for males hatched in 2002 and for females hatched in 2002 and 2003. We concluded that given the lack of relationship among immune responses, paternity, and recruitment rates in this population of Savannah Sparrows, nestling immune response to PHA injection should not be considered predictive of recruitment in populations where this relationship has not been explicitly explored, and environmental variables such as nest temperature may be an important covariate in immunoresponsiveness.

Invasive insects pose a significant threat to biodiversity, often affecting entire communities through the destruction of foundation species. Eastern Hemlock (Tsuga canadensis [L.] Carr.) forests, which are unique habitats in eastern North America, are threatened by an introduced insect, the Hemlock Woolly Adelgid (Adelges tsugae Annand). Previous studies have found declines in the abundance of some forest bird species, including the Acadian Flycatcher (Empidonax virescens), with increasing infestation by Hemlock Woolly Adelgids. To identify potential mechanisms behind these declines, we studied abundance, breeding biology, and habitat selection of Acadian Flycatchers in 11 Eastern Hemlock-dominated riparian sites in Pennsylvania and New Jersey, representing a continuum of infestation levels, in 2001–2002 and 2006–2007. Eastern Hemlock supported 90% of all nests and was used more as a nesting substrate than expected at most sites. We found ∼70% fewer breeding pairs at heavily infested sites, though nest survival rates were not affected. The results suggest that Acadian Flycatcher populations in Eastern Hemlock forests may decrease with continued decline of Eastern Hemlocks. Populations in the Appalachian Highlands, where the species' association with Eastern Hemlock is most pronounced, may be at greatest risk.

Seeking more precise knowledge of avian endemism on the east slope of the Andes in Peru and Bolivia, one of the most diverse faunal regions on Earth, we used distribution models based on locality records and 10–12 uncorrelated environmental variables to map the distributions of 115 species. Both maximum-entropy and deductive models reveal three areas of endemism, broadly supporting previous assessments of endemism in the region but showing much more detail. Regions such as the southwestern Cordillera de Vilcabamba and the Río Mapacho-Yavero valley in Cusco, Peru, and the Cordillera de Apolobamba in western Bolivia support a greater richness of endemic species than has been recognized, a result likely attributable to the ability of predictive models to partially control for biases in survey effort. National-level protected areas cover ≥1,000 km² of the ranges, or four-fifths of the ranges of species with distributions <1,000 km², of 77% of the endemic species. However, an analysis of summed irreplaceability, which emphasizes the locations of the most narrowly distributed endemics, showed that only 18% of these critical areas are currently protected. The fine-scale maps of endemic areas are suitable for regional and local-scale conservation planning, activities that can fill current gaps in protection of many species.

Kleptoparasitism, in which an individual steals food from other individuals of the same or a different species, is frequent in birds and represents a form of direct competition that can potentially influence the structure of communities. We addressed this idea by analyzing the foraging behavior and the spatiotemporal patterns of use of a refuse dump by four species of corvids: the Rook (Corvus frugilegus), Carrion Crow (C. corone), Eurasian Jackdaw (C. monedula), and European Magpie (Pica pica). Carrion Crows showed a unique degree of specialization in kleptoparasitism, allocating most of their time to scanning from the periphery of the dump and attacking other individuals rather than searching directly for food on the refuse. During winter, when the presence of corvids was highest, the species segregated through different timing of visits to the dump: Rooks and Eurasian Jackdaws were most abundant in the early hours, Carrion Crows in the middle of the morning, and European Magpies in the early afternoon. We suggest that kleptoparasitism played a role in shaping the temporal assemblage of species in the dump. On one hand, Carrion Crows matched the daily pattern of abundance of their main hosts, the starlings (Sturnus spp.), thus increasing their opportunities for kleptoparasitism. On the other hand, European Magpies' delayed arrival prevented overlapping with Carrion Crows, which reduced their risk of being robbed and, therefore, enhanced the efficiency of foraging. Temporal segregation of species has rarely been reported among vertebrates, but our results suggest that it may be an important mechanism of coexistence on spatially clumped food resources.

Limited stopover habitat along migration routes is a possible contributor to population declines in migratory landbirds. In highly fragmented agricultural landscapes, potential stopover sites are often limited to riparian corridor forests and small forest patches, but there are little quantitative data on stopover habitat selection in these areas, especially with regard to how migrants use isolated versus connected, and riparian versus upland, habitat patches. We examined the use of upland forest woodlots in the forest—agricultural landscape of northwest Indiana as stopover habitat, to determine whether migrants selected stopover sites on the basis of proximity to riparian corridor forest. In two spring and two fall seasons, we conducted 384 surveys in 12 small woodlots at three levels of isolation from a riparian forest corridor, detecting 3,695 en-route migrants of 76 species. We detected no difference in migrant abundance or species richness among distance classes in either season, and a principal-component variable comprising several woodlot isolation metrics was not a significant contributor to migrant abundance in linear regression models. Fall migrant abundance was positively associated with early-successional forests containing fruiting trees and shrubs, whereas spring abundance was not associated with any vegetation characteristics. The lack of patterns of habitat occupancy at the landscape level suggests that migrants select stopover sites on the basis of local habitat characteristics such as food resources, regardless of the landscape context. Small, isolated woodlots composed largely of forest edge with high fruit and insect abundance may, therefore, be important conservation targets in highly fragmented landscapes where forest cover is limited.

Adult male Marvelous Spatuletails (Loddigesia mirabilis) have greatly specialized tail feathers (rackets) that are used in dramatic displays. We compared adult males' tail structure with that of immature males and females, and with that of related species, to determine the nature of adaptations in the tail. We provide the first detailed description and inference of the function of the rectricial bulb of the tail in hummingbirds. Metamorphic enlargement of the outer rectrices (pair 5) of male Marvelous Spatuletails first occurs before the body plumage is fully adult. The first two rackets apparently are grown sequentially; in subsequent, definitive molts they may be grown simultaneously. Vanes of the other postjuvenal rectrices (pairs 1–4) are small or rudimentary, and pairs 2–4 serve no aerodynamic function. However, the calami of these feathers contribute to the general structural complex of the rectricial bulb. Intrinsic muscles of the bulb govern spreading of the rackets, whereas extrinsic muscles mainly govern elevation, depression, and tilting of the entire bulb and its imbedded rectrices. Together, these muscles effect the spectacular movements of the racket head. The shape and structure of the rackets contribute to unique features of the display. The tails of females and immature males are well suited to maximize lift:drag ratios during normal flight, whereas the elaborate tail of the adult male probably reduces this ratio. An elongate pair of central, ventral major tail coverts may replace some of the aerodynamic function lost in the rudimentary rectrices of the adult male.

Phaethornis longuemareus aethopyga was described by John T. Zimmer in 1950 and treated as a valid subspecies until it was proposed that the three known specimens were hybrids between P. ruber and P. rupurumii amazonicus. On the basis of some recently collected specimens, we reevaluated the validity of P. l. aethopyga. Despite showing some differences related to age and sex, all specimens agree in the general plumage pattern and are fully diagnosable when compared with any other taxon of the genus. The hypothesis of a hybrid origin becomes unsustainable when one notes that (1) P. l. aethopyga has characters that are unique and absent in the purported parental species, such as the white outer margins at the base of the rectrices; and (2) P. l. aethopyga occurs far from the distribution of one of the alleged parental species. Furthermore, field data show that P. l. aethopyga has attributes typical of a valid and independent taxon, such as lekking behavior. Therefore, given its overall diagnosis, P. aethopyga could at least be treated as a phylogenetic species. Yet its morphological and vocal distinctiveness with respect to other Phaethornis spp. in the “Pygmornis group” is greater than that observed between some species pairs traditionally regarded as separate biological species within the group, which supports its recognition as a species under the biological species concept.

Breeding seabirds are extreme central-place foragers, commuting long distances between colonies and feeding areas. Central-place foraging theory predicts that prey items close to the colony will be preferred over prey items distant from the colony, which can lead to prey depletion near the colony (“Storer-Ashmole's halo”). To investigate the relevance of these ideas to a single-prey loader, we equipped chick-rearing Thick-billed Murres (Uria lomvia) with time—depth recorders (1999–2007) and monitored prey deliveries (1993–2008). Because feeding rates were constant for chicks 3–15 days old, we restricted analyses to that age group. Between-date relationships were examined within individuals to avoid confounding effects of specialization and parental quality. The mass of prey items increased with foraging distance0,5, which suggests that large prey items were depleted by foraging pressure. Foraging distance for pelagic species increased through the season in years without spawning. After accounting for bathymetry, foraging effort decreased with distance from the colony for benthic fish and, in years without spawning, for pelagic fish. Within each season, Thick-billed Murres “fished down the food web”; they began by feeding on large fish, progressed to medium-sized prey (small fish), and finished feeding on small prey (invertebrates). We concluded that pelagic species responded to seabird foraging pressure by moving away from the colony, creating a three-dimensional halo. Benthic species, meanwhile, were depleted from a nearby shelf but remained abundant at a more distant offshore bench. We suggest that populations of central-place foragers are partially regulated by prey depletion.

Documenting space-use patterns of animals is important for understanding their ecology and providing for their conservation. The concept of territory refers to a defended area, whereas the concept of home range refers to any area used by an animal during its normal activities. Few studies have explored quantitatively how these areas differ, and the use of these terms in the literature has, at times, been inconsistent. Many studies attempt to estimate territory size of a bird by territory mapping, which involves using locations obtained by following a singing bird. This is often assumed to be an effective measure of territory size, but few studies have examined the efficacy of this technique. Here, we used radiotelemetry to estimate breeding home-range and territory sizes of Swainson's Warbler (Limnothlypis swainsonii), a Neotropical migrant songbird. We found that territories were much larger than had been estimated by territory-mapping methods and suggest that researchers use caution when assuming that territory mapping accounts for all areas used by a bird. We also found that home ranges were significantly larger than territories, and these relatively large home ranges necessitate protection of large areas of habitat for Swainson's Warblers. We emphasize the importance of precise terminology when referring to areas of space use and suggest that radiotracking may uncover previously unknown use patterns and important ecological information in species that have not been radiotracked.

The importance of the formation of the Panamanian land bridge for mammalian diversification in the New World is well documented; however, studies investigating the role of this land bridge in avian diversification have only recently been reported. We used mitochondrial DNA data to reconstruct the phylogeny of a group of lowland tanagers (Thraupidae) that contains species distributed in both Central America and South America. Phylogenetic analyses identified a clade that includes all 26 species in the genera Tachyphonus, Ramphocelus, Eucometis, Lanio, Trichothraupis, Coryphospingus, and Rhodospingus. Three of these species (Rhodospingus cruentus, Coryphospingus cucullatus, and C. pileatus) have traditionally been classified with the finches (Emberizidae); here, we show that they are tanagers. The genus Tachyphonus is polyphyletic, with some species more closely related to species in the genus Ramphocelus than they are to other Tachyphonus. The ancestor of the entire clade was distributed in South America or was widespread there and in Central America. Reconstructing the biogeographic history of this group showed a dispersal bias from South America to Central America. Nine dispersal events were inferred, and eight of these involve dispersals from South America to Central America. Temporally, most dispersal events coincide with or postdate the final formation of the Panamanian isthmus. We also used our phylogeny to investigate plumage evolution. Two species are sexually monochromatic, and this condition was derived from sexual dichromatism through the evolution of more colorful female plumage. Although 11 species in the clade have crests, this feature evolved no more than twice within the group.

We describe a new genus and species of pigeon (Columbiformes) from a single coracoid from the St Bathans Fauna of New Zealand (16–19 mya). It is the first columbid species described from pre-Pliocene deposits in Australasia. Two apomorphies identify the fossil as belonging to the ptilinopine group of fruit pigeons, among which it is most similar to Hemiphaga, the large fruit pigeon currently endemic to the New Zealand biogeographic area. This reveals that the Hemiphaga lineage has been in New Zealand since the Early Miocene, which supports recent divergence-date estimates for Hemiphaga and its modern sister taxon (Lopholaimus) based on molecular data.

The Great Bustard (Otis tarda) is one of the heaviest flying birds and the most sexually dimorphic living bird. Adult males weighed 2.48x more than females, and their linear measurements were 18–30% larger. Weight increased between the prebreeding and breeding seasons by 16% in females and 20% in males. Sexual size dimorphism emerges very early in development and explains why growth in males is so costly. Weight and central toe length were hyperallometric when related to wing length in males but isometric in females and varied more in males, as compared with females and with other male traits. Although hyperallometry and high variability have frequently been used to invoke sexual selection as a driving force, our results support different functional hypotheses for the evolution of each trait. Male—male competition is intense in this lekking species, and high rank among males and access to females are weight-dependent. Thus, sexual selection has likely pushed male weight close to the limit imposed by powered flight. Because Great Bustards are mostly cursorial, the hyperallometry of the central toes of males in relation to wing length most likely evolved for support and balance.

Hemoglobins play a key role in oxygen transport. High-oxygen-affinity hemoglobins are adaptive in hypoxic environments. To better understand adaptation to high-altitude hypoxia, we extracted RNA from the bone marrow of six Crested Ducks (Lophonetta specularioides) inhabiting the central high Andes of Peru (4,218–4,605 m elevation) and sequenced >2,000 expressed sequence tags (EST) from a non-normalized complementary-DNA (cDNA) library. Overall, we identified 1,692 ESTs in the expression profile representing 462 different genes. Among those, the ESTs that occurred at the highest frequency were the αA (major) hemoglobin subunit (HBA2; 22.7%), leukocyte cell-derived chemotaxin 2 (LECT2; 10%), αD (minor) hemoglobin subunit (HBA1; 9.6%), beta defensins (DEFB; 6.3%), and the βA hemoglobin subunit (HBB; 3.7%). These results provide the first quantitative identification of gene expression in bone marrow of individuals inhabiting high-altitude regions and are in agreement with the known hemopoietic and immune function of this tissue. The EST sequences identified here will be useful for a variety of studies focusing on other nontraditional model organisms. Further studies of Crested Ducks and other highland taxa will be required to determine whether the αA and αD hemoglobin subunits, which contribute to distinct isoforms with potentially different oxygen-binding properties, are differentially expressed in lowland and highland populations.

The influence of landscape structure on abundance or spacing patterns of generalist bird species may be nonlinear and vary annually depending on the severity of environmental conditions. The Eastern Wild Turkey (Meleagris gallopavo sylvestris) is a generalist forest species that experiences high mortality when snow reduces food availability. Although increasing amounts of cornfield habitat may benefit Wild Turkeys by providing an alternate food source, reduced forest cover or elevated levels of forest fragmentation associated with increased corn (Zea mays) production could be detrimental. We evaluated the hypothesis that spring density of male Wild Turkeys increases with the amount of corn habitat as long as forest cover remains a dominant landscape component and that this increase is more prominent following a winter with thick snow accumulations. We performed point counts and corrected for imperfect detection in 2003 and 2004 at 130 randomly distributed sites in southern Québec. After a mild winter, male density peaked in landscapes characterized by 25–50% forest cover and a large amount of edge between forest and open habitats. After a harsh winter, male density decreased with annual crop cover when forests represented <20% of the landscape and increased when they represented >40%. Male aggregation was higher and increased with male density at a slower rate than if individuals had been randomly distributed, yet landscape structure had only a marginal effect on aggregation. Our results suggest that Wild Turkeys' response to landscape structure depends on environmental conditions and that this generalist forest species benefits from cornfields where forest cover is fragmented but abundant.