A new highland species of chestnut-capped Arremon brush-finch is described from the Sierra Madre del Sur of central Guerrero. This form, although indistinguishable in external phenotype from adjacent populations to the east in Oaxaca, is dramatically differentiated in mitochondrial DNA sequence characters, and quite unexpectedly is the sister lineage to the very distinct (phenotype and genotype), central-Mexican-endemic A. virenticeps. Nuclear sequence differentiation in the new lineage is more subtle than in mitochondrial DNA, but is on par with that in the well-marked A. virenticeps. The new species is thus distinct from its sister lineage in genotype and phenotype, and clearly distinct from all other forms in genotype; however, it has retained an ancestral external phenotype similar to other members of the broader A. brunneinucha complex.

Geographic variation in morphology that develops among closely related populations can help drive genetic divergence, and eventually speciation, when those morphological traits are the basis for social interactions that influence reproduction. The North American Dark-eyed Junco (Junco hyemalis) complex is an interesting case in speciation. The numerous subspecies have distinct breeding ranges and unique plumage coloration, but based on the presence of hybrid populations and recent genetic data, can be considered to belong to a single species. Research within various populations of juncos has shown first, that wing length and the amount of white on the tail feathers (“tail white”) influence an individual's dominance status and mating success, and second, that these traits can undergo rapid evolution when social and environmental conditions change. Here, I used museum specimens to examine tail white and body size, as measured by wing and tail length, of males and females within and among 13 geographically distinct Dark-eyed Junco subspecies. I documented geographic variation of mean values for each of these morphological traits, as well as patterns of trait co-variation and the degree of sexual dimorphism. I discuss these results in relation to what they may indicate about the generation and maintenance of divergence among the subspecies.

The natural history of many tropical bird species is poorly described, preventing more detailed studies of ecology, behavior, and evolution. For most sexually monochromatic tropical bird species, we lack field methodologies to categorize the sex of adults. In this study, we describe sex-based morphological differences of three monochromatic species in the genus Melozone: White-eared Ground-Sparrow, M. leucotis; Prevost's Ground-Sparrow, M. biarcuata; and Rusty-crowned Ground-Sparrow, M. kieneri. We collected six standard morphological measurements (tarsus length, tail length, wing chord length, culmen length, beak width, and beak depth) from live birds and museum specimens. We collected data from all recognized subspecies of the three Mesoamerican Melozone species. Morphological measurements capably distinguished males from females in all three species. In all cases, three or fewer morphological measurements were required to identify sex with accuracy levels that ranged from 75–100%, well beyond the 50% expected by chance. Comparisons involving all six measurements yielded accuracies that ranged from 58–93%. Our results provide the first field-based method for estimating the sex of individuals in this poorly studied genus of tropical birds. We recommend our findings be used to distinguish males from females in banding stations where Melozone ground-sparrow species occur.

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 temperature (model averaged DSR  =  0.956 [0.02 SE]). Despite larger clutch sizes and number of young fledged per successful nest in Ontario, fecundity estimates were greater for the Tennessee population. Males had greater annual survival than females in both Tennessee and Ontario populations (Tennessee male  =  0.616 [0.11 SE], Tennessee female  =  0.427 [0.12 SE], Ontario male  =  0.618 [0.08 SE], and Ontario female  =  0.477 [0.14 SE]). Minimum lambda estimates suggest that both populations were declining (λ  =  0.7468 and 0.7935 for Tennessee and Ontario, respectively). However, as with many mark-recapture studies of birds, we are unable to separate mortality from dispersal which likely biases these survival estimates. Further, annual survival is affected by events in the wintering and migratory periods and until these are known, we will be limited in our ability to effectively manage this and other declining Neotropical migratory songbirds.

Very little is known about the home range and movement patterns of tinamous. The Ornate Tinamou (Nothoprocta ornata), a species of the central Andes that is important for cynegetic and biomonitoring purposes, was previously reported to have a very small territory (2.43 ha). This was based solely on field observations. In order to gain a better understanding of the movement patterns, home range size, and home range overlap of this species, we radio tracked 12 adult individuals in an Andean agro-ecosystem for a full year. The birds remained within their home ranges all year; 100% MCP (minimum convex polygon) home ranges were 43.8 ± 21.6 ha (22–85 ha), 95% kernel home ranges were 58.8 ± 31.9 ha (25–118 ha) and 50% kernel core areas were 15.3 ± 8.9 ha (6–33 ha). Only two birds, probably sub-adults, showed extensive movement patterns before their death. Individuals overlapped their home ranges extensively (from 30–98% with 2–3 tagged individuals), but these values were probably higher because a small proportion of the population was tagged. No sexual differences were detected in home range size or overlap. Our results support the usefulness of Ornate Tinamou as a sentinel species in biomonitoring studies and highlight the need for further research into the philopatric and dispersion behavior of juveniles before planning cynegetic strategies.

North American grassland birds show long-term population declines that generally exceed the declines of other bird groups. Efforts to conserve grassland birds require knowledge of ecological and habitat requirements during both the breeding and nonbreeding periods of annual life cycles. Nonbreeding habitat associations may affect survival and the acquisition of resources needed for migration and breeding. We focused on the winter habitat associations of a suite of co-occurring grassland sparrows in the dry prairie of south-central Florida, an understudied region within the wintering range of Grasshopper Sparrows (Ammodramus savannarum pratensis) and Henslow's Sparrows (A. henslowii). During the nonbreeding winter months, these two migratory sparrows commingle with resident Bachman's Sparrows (Peucaea aestivalis) and federally endangered Florida Grasshopper Sparrows (Ammodramus savannarum floridanus). We investigated sparrow habitat associations within two defined plant communities of the dry prairie ecosystem, the dry-mesic and wet-mesic prairie, for four prescribed fire treatments over two consecutive winters. Grasshopper and Henslow's sparrows showed higher relative abundance in wet-mesic prairie and Bachman's Sparrows were more abundant in dry-mesic prairie across all fire treatments. Florida Grasshopper Sparrows were detected only in the first and second years post-burn; samples were too small to yield information on potential preferences between the two prairie communities evaluated. We used an information-theoretic approach to select models that best predicted abundances for each species (except Florida Grasshopper Sparrows) based on time since fire and plant community. Abundances of Grasshopper and Bachman's sparrows were best predicted by plant community association and secondly by time since fire; whereas for Henslow's Sparrows, habitat and time since fire were equally important. This is the first concurrent study of these four sparrow taxa in peninsular Florida and indicates that time since fire influences the habitat preferences exhibited by wintering sparrows, but that this role differs across co-occurring species and dry prairie plant communities.

All vertebrates must contend with an increase in oxidative stress during intense exercise. Birds, in particular, may be exposed to increased oxidative stress during long-distance migration, and dietary antioxidants are likely important in alleviating the deleterious effects associated with such a stressor. We evaluated whether fruit selection by birds at a migratory stopover site in southern New England was related to the antioxidant and macronutrient content of fruits from seven commonly consumed fall-fruiting shrub species. Our objectives were to: (1) quantify, for the first time, total hydrophilic and lipophilic antioxidants, as well as two types of lipophilic antioxidants (i.e., carotenoids, and tocopherols) in wild fruits consumed by migrating birds, (2) test the hypothesis that antioxidant content of wild fruits is related to macronutrient composition, and (3) relate patterns of avian frugivory to antioxidant availability and macronutrient content of wild fruits during autumn migration. We found significant differences between fruits in total lipophilic antioxidants, carotenoids, and tocopherols, but not total hydrophilic antioxidants. Viburnum spp. and Myrica pennsylvanica had the most lipophilic antioxidants and tocopherols, whereas Celastrus orbiculatus and Rosa multiflora contained the most carotenoids. Carotenoid content was positively correlated with protein content but no significant relationships were evident between the other antioxidants and macronutrients. Fruit consumption was negatively correlated with carotenoid content and was not related to any other antioxidant measure. Interestingly, the most consumed fruit species, arrowwood, was among the highest in fat, total lipophilic antioxidants, and tocopherols. These data indicate that antioxidant content differs significantly between fruit species and suggest that (1) birds can acquire different types of antioxidants depending on the fruits they select and (2) lipophilic antioxidants, especially tocopherols, may be important antioxidants for birds during autumn migration.

We investigated the influence of Old World bluestem (Bothriochloa ischaemum; OWB) monocultures on grassland bird abundance through analysis of vegetation structure and food availability. We compared breeding bird density, vegetation structure and composition, and arthropod biomass between six native grass and six OWB fields in the southern Great Plains. The OWB fields supported 1.70 ± 0.27 (mean ± SE) Grasshopper Sparrows (Ammodramus savannarum) per ha compared to 0.95 ± 0.25 in native grass fields, but total species richness was greater in native grass fields (40 versus 28 species). Density of some bird species was correlated with vegetation structure regardless of field type, suggesting that management practices may be more influential than plant species composition. Mean arthropod biomass was 3.39× greater in native grass fields than in OWB monocultures. Native grass fields provided habitat for a larger complement of birds than did OWB monocultures, and reduced food availability in OWB fields suggests a mechanism for that difference.

Parental roles in nestling provisioning and composition of prey brought to nestlings are not well-studied for North American woodpeckers (Picidae). We studied nestling diets and the role of adult Hairy (Picoides villosus) and White-headed woodpeckers (Picoides albolarvatus) in provisioning nestlings and nest sanitation during 2009–2011 in managed ponderosa pine (Pinus ponderosa) forests, Cascade Range, Washington, USA. Male White-headed Woodpeckers removed fecal material from cavities more frequently than females; a difference we did not observe between sexes in Hairy Woodpeckers. Male and female White-headed Woodpeckers, and female Hairy Woodpeckers, fed significantly more small (beak closed when holding prey) than large prey (beak unable to close when holding prey) to nestlings. We did not find differences in provisioning rates by sex of the parent, by nestling age, or by date of provisioning trip for either species. Morisita's Index (C) of diet overlap showed a large similarity in the nestling diets of Hairy and White-headed woodpeckers (C  =  0.81), and dietary niche breadth was low for both species. Of the prey we identified, larvae of wood-boring beetles (Coleoptera: Cerambycidae and Buprestidae) were most frequently fed to nestlings by both species. White-headed Woodpeckers fed caterpillars (Lepidoptera) and winged prey to nestlings more often than Hairy Woodpeckers. The diet of Hairy Woodpecker nestlings did not change appreciably over the nesting season, with wood-boring beetle larvae having the highest relative frequency for most of the breeding period. In contrast, relative frequency of wood-boring beetle larvae in the diet of White-headed Woodpecker nestlings declined toward the end of the breeding period as the relative frequency of caterpillars increased. Our results suggest that both sexes of these woodpeckers contribute equally to nestling provisioning.

Manakins are prominent fruit-eaters and seed dispersers in the Neotropics. Most manakin species establish lek areas where males devote long periods of time displaying to attract mates, interspersed with brief absences to feed on fruits located near lek areas. We compared the frequency of visits to plants, fruit handling behavior, and number of fruits ingested by the lek-forming Manacus manacus (White-bearded Manakin) and species of non-lekking birds in two species of fruiting trees (Miconia rigidiuscula and Ocotea pulchella) in lek and non-lek areas during the lek and non-lek periods of M. manacus in a threatened Atlantic forest ecosystem. During the non-lek season, M. manacus and non-lekking birds did not differ in the frequency of visits to Miconia trees near lek and non-lek areas. However, M. manacus swallowed a higher number of fruits near leks than non-lekking birds, while the opposite was true in non-lek areas. During the lek season, M. manacus visited Ocotea trees more frequently and swallowed more fruits than non-lekking birds in lek areas. No birds were recorded on Ocotea trees in non-lek areas. This study provides an example of context dependence in the quantity component of seed dispersal effectiveness in which the lek breeding system of a frugivorous species influences the identity of seed removers and the quantity of seeds removed in and around lek areas.

North American wood-warblers (Parulidae) are well known for exhibiting two distinct singing modes: first category song, in which a single song type is sung repeatedly, usually before dawn, and second category song, in which several song types are sung in irregular sequence. Studies suggest that first category song types have higher performance characteristics and that second category song types are shared preferentially among territorial neighbors. Here we present the first formal description of two-category singing in the Pine Warbler (Setophaga pinus). Similar to other species in the genus Setophaga, Pine Warblers produce second category song before dawn and first category song primarily during daylight hours. First category songs also had significantly higher trill rates, suggesting that they are more challenging to perform. Unlike many congeners, however, Pine Warblers regularly alternate between first and second category singing throughout the day, and first category song types often appear intermixed in second category singing, including singing before dawn. Furthermore, comparisons among territorial males showed that individuals do not share song types more with neighbors than with non-neighbors. Our results suggest that Pine Warblers have two song categories similar to other Setophaga warblers, but singing patterns in this species differ from congeners in interesting ways that warrant further investigation.

Wood Thrushes (Hylocichla mustelina) are experiencing widespread population declines. Knowing the relative contribution of predator species to overall rates of nest predation of Wood Thrushes, and understanding how the thrushes are affected by temporal and landscape factors, may be important elements in choosing and devising effective management strategies. We used miniature video cameras to identify nest predators of Wood Thrushes in a highly fragmented landscape in Ontario. Eleven species of birds and mammals were recorded as nest predators. Birds accounted for almost twice as many predation events as mammals, and three species – Brown-headed Cowbird (Molothrus ater), Cooper's Hawk (Accipiter cooperii), and raccoon (Procyon lotor) – accounted for the majority. Species such as American Crow (Corvus brachyrynchos), Blue Jay (Cyanocitta cristata), eastern gray squirrel (Sciurus carolinensis), and Common Grackle (Quiscalus quiscula) that are often speculated to be important nest predators in agricultural and suburban landscapes contributed little or nothing to overall predation rates. We tested hypotheses concerning effects of nest stage, time of nesting season, forest size, forest cover, urban housing pressure, and prior predation events at a nest on the probability of nest predation. Our models showed only two of these factors to be significant: prior predation at a nest increased the chance of a subsequent predation event and increasing the measure of urban pressure reduced the chance of a predation event. The many alternate and easy food sources associated with humans might divert the attention of potential predators from nesting birds in urban forests.

Spruce Grouse (Falcipennis canadensis) are listed as threatened in Wisconsin, and the boreal habitats in which they occur are likely to be threatened by changing climatic conditions. However, the limited information available on Spruce Grouse in the Upper Great Lakes region makes it unclear which habitat features are important for Spruce Grouse nesting in Wisconsin. We radiotracked 30 female Spruce Grouse in northern Wisconsin from 2007–2012 and located 25 nests. Eighteen of 25 nests were beneath black spruce (Picea mariana) trees. Only three nests were in upland, and only one in a stand of jack pines (Pinus banksiana), in contrast to studies from Michigan and Ontario. Overall concealment was a good predictor of nest sites for Spruce Grouse, but not a good predictor of nest survival. Nest survival was associated with moderately dense and uniform 0–0.5 m lateral vegetation cover. Seventeen of 25 nests were successful, with a daily survival rate of 0.985, overall productivity of 1.0 young/female, and 1.9 young/successful nest. Annual survival of adult males was estimated at 54%, adult females at 40%, and juvenile survival at 14% and 24% by two different methods. Estimates of λ of 0.65 and 0.67 suggest a declining population, but the upper confidence limit exceeds 1, not ruling out a stable or slightly increasing population. Protecting black spruce swamps will protect important nesting habitat for Spruce Grouse in Wisconsin.

We describe the nest-site characteristics and breeding habitat use of Kelp Geese (Chloephaga hybrida) and Flightless Steamer-Ducks (Tachyeres pteneres) along 137 km of coastline on the northern shore of the Beagle Channel, Argentina, and 87 km of island coastline. We examined the importance of vegetation cover, predation, and tourism on the distribution of nests among islands. We found all nests only on islands and islets. Nesting sites for both species were strongly associated with higher proportions of high vegetation cover (shrubs). Kelp Geese were also associated with the absence of terrestrial predators. Tourist presence on islands was not associated with the occurrence of nests for either species. The northern coasts of the Beagle Channel and the islands and islets along the channel have similar habitat types. However, the islands and islets are relatively inaccessible to mammalian terrestrial predators compared to the coast of the channel where terrestrial predators are frequently recorded. Therefore, islands and islets seem to provide a relatively safe nesting habitat for Kelp Geese and Flightless Steamer-Ducks by offering refuge mainly from ground predators. Additionally, habitat changes caused by increased human disturbance along the northern shore of the Beagle Channel may also explain the presence of nests only on islands and islets, though further studies are needed to assess these effects. This study contributes new information on the breeding habitat and nesting sites of Flightless Steamer-Ducks and Kelp Geese in the Beagle Channel, to assist in the identification of priority breeding sites and habitats to protect. Also, it highlights the importance of islands and islets of the Beagle Channel as safe breeding refuge for these two ground nesting seabirds.

The Coal-crested Finch (Charitospiza eucosma) is a rare, globally near threatened and poorly known species, endemic to the savannas of central Brazil and Bolivia. We investigated this species' breeding biology in the Brazilian savannas between 2008–2010. We found 44 nests of Coal-crested Finches during one and a half breeding seasons. Coal-crested Finches reproduced in two discrete peaks within the rainy season (i.e., bimodal breeding). Nests were cup-shaped and built on trees with a mean height of 2.18 ± 1.34 m (n  =  42). Modal clutch size was 2 (range  =  1–3). Eggs averaged 16.32 ± 1.16 mm (length; n  =  46), 11.30 ± 1.06 mm (width; n  =  46) and 1.40 ± 0.14 g (mass; n  =  44). Incubation and nestling periods lasted on average 13.4 ± 0.42 days (n  =  5) and 12.0 ± 2.63 days (n  =  7), respectively. Young (0–4 days old), middle-aged (5–9 days old) and late nestlings (10–13 days old) weighed from 1.25–6.35 g (n  =  10), from 5.30–12.65 g (n  =  12) and from 9–11.90 g (n  =  9), respectively. Estimated nesting success was 20.08% (n  =  38). The Coal-crested Finch has similarities (e.g., nest material, clutch size, eggs, nestling period, nestlings and nesting success) and differences (e.g., nest structure, nest sites, incubation period, breeding season) with other Neotropical finches. We suggest that their bimodal breeding season may have evolved in response to two annual peaks of food resource abundance: arthropods followed by grass seeds.

The O‘ahu ‘Elepaio (Chasiempis ibidis) is an endangered monarch flycatcher endemic to the Hawaiian Island of O‘ahu. Current information on abundance, distribution, and population trend is needed to help assess the species status and identify areas where conservation efforts can be focused. We used spot-mapping methods with song playbacks to conduct surveys in the Ko‘olau Mountains from 2011–2012, and we used occupancy sampling with repeated visits to estimate detection probability. We detected 545 male and 317 female O‘ahu ‘Elepaio. The detection probability of males was 0.92 ± 0.03 and that of females was 0.86 ± 0.05, yielding corrected estimates of 592 males (95% CI  =  554–630) and 369 females (95% CI  =  327–411). Combined with results of a previous census in the Wai‘anae Mountains that found 192 males and 84 females, the total estimated population of the species is 1,261 birds (95% CI  =  1,205–1,317), consisting of about 477 breeding pairs and 307 single males. The O‘ahu ‘Elepaio has declined in abundance by about 50% since the 1990s, when the population was estimated to be about 1,974 birds. The current geographic range of the O‘ahu ‘Elepaio encompassed about 5,187 ha and has declined by 75% since 1975, becoming fragmented into four larger subpopulations with 100 or more birds each and 12 smaller subpopulations. Rat control to reduce nest predation remains the cornerstone of the conservation strategy for the O‘ahu ‘Elepaio, but variation in forest structure, forest dynamics, and continuing evolution of ‘elepaio nesting behavior are likely to play important roles in determining whether this species can persist.

We present the first breeding records of Nonggang Babbler (Stachyris nonggangensis), a newly described bird species found in the limestone area of southwestern Guangxi, in southern China in 2008. The records presented here include information on behavior, nest, egg, incubation, and reproductive success rate. We discovered six nests (including three active nests) through systematic checking and radio tracking. Most Nonggang Babblers were found to begin foraging in pairs (male and female) from mid to late March. They build their nests in April. The nests were placed in cavities in a limestone cliff or on a massive rock located on the mountainside at altitudes ranging from 206–323 m. The nests were made of aerial roots, leaves, twigs, and soft grasses. Nonggang Babblers would lay 4–5 pure white eggs with an average fresh weight of 4.80 ± 0.11 g. Female Nonggang Babblers would spend 74.5 ± 5.0% of the day incubating their eggs, and the incubation period would last >18 days. We propose that Nonggang Babblers could prolong the incubation period and reduce foraging time to enhance the survival rate of fledglings. The high nest predation rate is an important limiting factor for the population growth of Nonggang Babblers.

I describe the feeding habits of Ramphastos toco (Toco Toucan) in relation to fruit abundance and diversity in a variety of habitat types in central Brazil. I traversed transects to sample fruit production and toucans that were feeding in four habitat types: two wet (streams and river) and two dry (cerrado and deciduous forest). Fruit abundance exhibited substantial temporal and spatial variability in which dry habitats provided fruits to toucans mainly in the dry season; the same occurred in the wet habitats during the rainy season. As a result, toucans experienced similar fruit diversity between seasons, while feeding niche breadth exhibited high values all year. The variable spatial and temporal fruiting patterns reflected differences among the vegetation of the four habitat types, and floristic variations between related sites as well. The data emphasize the importance of the peculiarities of a given site within a habitat mosaic and which should be included in conservation plans for declining species.

Recent experiments support the long-standing hypothesis that Common Cuckoos (Cuculus canorus) are mimics of Eurasian Sparrowhawks (Accipiter nisus). Additional experiments further suggest that mimicry benefits the cuckoos by reducing the intensity of mobbing they suffer near host nests, at least in some host populations, potentially increasing their access to the hosts' nests. We observed two species of birds—one very rarely parasitized and the other never parasitized by cuckoos—responding to a cuckoo as they would a bird of prey. On the island of Öland, Sweden, we observed two instances of a gray phase cuckoo being mobbed by a group of Barn Swallows (Hirundo rustica) during the non-breeding season. These mobbing observations cannot be explained as a consequence of selection in the context of brood parasitism, because swallows are extremely rare cuckoo hosts and should not show co-evolutionary responses to parasitism. Instead, the swallows appear to have mistaken the cuckoos for Eurasian Sparrowhawks and responded as they would to true hawks. Similar observations were made in California, where a vagrant Common Cuckoo repeatedly elicited alarm calls from Bushtits (Psaltriparus minimus), a species completely allopatric with cuckoos and thus with no evolutionary history of brood parasitism. Because Eurasian Sparrowhawks visually resemble related North American bird-eating Accipiter hawks in plumage and flight characteristics, the cuckoo likely triggered a general Accipiter response in the Bushtits. Together, these observations provide additional evidence that cuckoos successfully mimic Eurasian Sparrowhawks and that such mimicry comes not only with benefits to the cuckoos, but costs as well.

Nestling growth may be used to estimate age of nestling raptors, which is valuable for investigating hatch order dynamics and nestling behavior, as well as assessing reproductive rate and back-calculating hatching date. To estimate nestling age, the most valuable parameter to measure growth is one that does not vary greatly with environmental factors, and ideally is applicable over a wide range of populations. We measured growth of nestling Red-shouldered Hawks (Buteo lineatus) in Quebec, Canada, from ages 3 days to near fledging (38 days old), and compared growth of several parameters in different size broods. As a validation study, we measured similar parameters one time in known-age nestling Red-shouldered Hawks in southwestern Ohio. Growth rates for tarsus length, bill length, and tail length differed between nestlings in broods of one and three young, respectively, in Quebec. However, mass gain and growth of secondary feathers (mean length of first and second secondaries) did not differ between brood sizes, although mass gain was more variable than secondary growth. These results suggested that secondary feather length was the most valuable parameter for estimating nestling age in Red-shouldered Hawks. Comparing Ohio nestlings to Quebec nestlings, we found that growth of secondary feathers differed significantly, with Ohio nestlings having smaller secondary length, relative to age estimate. Application of the equation generated with the Quebec data to estimate the age of the Ohio nestlings based on secondary length resulted in estimates that were 2.3 ± 0.3 days (range 0.25–4.5 days; n  =  22) younger than the Ohio nestlings' actual ages. Based on this validation study, we suggest that the use of the Quebec age-secondary length equation to estimate age for nestling Red-shouldered Hawks in other parts of eastern North America is acceptable, though with the caveat that such estimates are associated with potential small errors.

Here we present recent accounts of Kirtland's Warblers (Setophaga kirtlandii) captured and observed on San Salvador Island, The Bahamas, in 2012 and 2013. We conducted mist-netting and passive surveys in a variety of habitats on the island from January–March 2012 and December 2012–March 2013. We captured four warblers and sighted at least six other individuals, including two color-banded birds originally banded near Mack Lake, Michigan, USA. Warblers were primarily captured or observed in coastal scrub and inland low coppice habitats where vegetation height is <4 m, has a scrub/shrub appearance, and openings because of disturbance. These habitats are similar to habitats preferred by Kirtland's Warblers on other Bahamian islands, and also have fruiting plants the warblers prefer such as Erithalis fruticosa, and Lantana involucrata. To our knowledge, these are the first confirmed cases of observed Kirtland's Warblers on the island in over 46 years.

Red-bellied Woodpeckers (Melanerpes carolinus) feed primarily on arthropods and plant matter, but a growing body of evidence suggests that Red-bellied Woodpeckers may also be a common passerine nest predator. Cerulean Warblers are the fastest declining Neotropical migratory wood warbler in North America. We report our observations of a Red-bellied Woodpecker depredating a nestling Cerulean Warbler (Setophaga cerulea) in Indiana. Further suggesting their status as a recognized nest predator, we also report agonistic behavior of a different Cerulean Warbler pair toward a Red-bellied Woodpecker foraging near the warblers' fledglings. Red-bellied Woodpeckers may be a more common nest predator of Cerulean Warblers than currently recognized, but further research is needed.

Feather sampling is often assumed to be harmless, but this assumption has not been tested. From 2008–2012, we recorded the behavior of 340 Common Tern (Sterna hirundo) chicks following the removal of a pinch of body feathers. Only 11.2% of these chicks ran after sampling and 69.4% showed no visible reaction to sampling. The probability of a chick running away increased with age. We therefore recommend that sampling be conducted as soon as possible after juvenal feathers emerge. There was evidence for individual differences in behavior: approximately 71% of chicks that ran after feather sampling also ran away when re-encountered on later dates, while other chicks rarely did so. We found no evidence that removal of feather samples increased chick mortality, supporting the assumption that this technique is minimally invasive, but small differences in mortality rates would have been difficult to detect.

In this study, we evaluated the interspecific agonistic responses of raptors and non-raptors, elicited by the presence of five raptor species (Circus cinereus, C. buffoni, Rupornis magnirostris, Elanus leucurus, and Geranoaetus melanoleucus) in the Pampas region of Argentina. We registered 62 agonistic interaction events, most of them involving two raptor species (58%). During these events we registered 122 attacks, 10 persecutions, and three cases of kleptoparasitism. Milvago chimango was the most important aggressor species among raptors, and Vanellus chilensis among non-raptor birds. Attacks in groups were more frequently performed by non-raptors (61.5% of the events involved two or more aggressor individuals) than by raptors (68.5% of the events involved only one aggressor). This study represents a primary approach to one scarcely explored aspect of raptor behavior in southern South America.

The Long-eared Owl (Asio otus) is a widely distributed predator with plastic foraging habits. Its diet has been studied across most of Europe and North America, but little information is available on intra-seasonal diet variation. We studied the winter diet of Long-eared Owls in a Mediterranean fragmented farmland. Diet was dominated by small mammals (mostly Apodemus spp.), with birds the second most abundant group. In our landscape, the amount of bird prey items in the diet was higher compared to values reported from other areas of Italy. There was relatively large variation in the diet among the three months of study. Our study confirms the pattern of higher Long-eared Owl diet diversity in a Mediterranean landscape compared to that reported for other regions of Europe where the diversity of prey species may be lower. The findings suggest that extensively-managed Mediterranean rural landscapes can provide habitat suitable for the Long-eared Owl, as they offer a wide diversity of food sources that may be exploited by this nocturnal predator.

We sampled blue crab (Callinectes sapidus) numbers in marshes on the Aransas National Wildlife Refuge, Texas from 1998–2006, while simultaneously censusing the wintering population of Whooping Cranes (Grus americana) on the refuge and surrounding habitats. This was done to determine whether mortality of wintering Whooping Cranes was related to the availability of this food source. Yearly variation in crab numbers was high, ranging from a low of 0.1 crabs to a high of 3.4 crabs per 100-m transect section. Significant non-linear increases in both juvenile and adult mortality in relation to decreasing crab abundance was observed. Results suggest that some threshold of crab abundance exists in which Whooping Cranes have higher survival on their wintering grounds.

Microbates cinereiventris is a polytypic and widely distributed species. Its reproductive behavior is only known based on the description of a single nest. Here, we present the first description of the eggs and nest of the subspecies M. cinereiventris peruvianus and the first description of the nestlings, feeding, and incubation behavior for the species. M. cinereiventris peruvianus has an open nest, primarily made of dry plant fibers and green moss. Nest attentiveness was 92.31 ± 0.20%, and a total of eight trips were recorded during the last 2 days of incubation. Nestlings hatched naked, were fed 1.58 ± 0.89 times per hour by both parents, and grew at a rate of 0.83 g per day during the first 5 days. M. cinereiventris share nesting characteristics with closely related species (M. collaris and Ramphocaenus melanurus).

We describe nests, eggs, and some breeding aspects of the Rusty-margined Guan (Penelope superciliaris) and Speckled Chachalaca (Ortalis guttata) in the Atlantic Rainforest of northeastern Brazil. Two active nests of P. superciliaris were found, the first was 50 cm above the ground and the second was 2.6 m. Both were bowl shaped and had three and two eggs, respectively. One egg from each nest was measured and weighed: 64.3 × 42.1 mm (61.5 g) and 55.5 × 38.0 mm (42.5 g). An active nest of O. guttata was found 3.2 m high on top of a tree. Initially, there was a single egg in the nest but two more were laid. The average egg measurements and weight were 55.0 × 38.4 mm and 43.3 g. The eggs of both species were rather similar with a dull white color, rough shell, and smeared with organic matter from the nest. We observed an incubation period of 29–30 days for the chachalaca, which was longer than previous estimates of this species. The guan nests were found in an advanced stage of development, which prevented accurate tracking of their incubation periods. Although the primary social reproductive strategy in most cracids is monogamy, it is possible that P. superciliaris is polygynous in our study area, justifying the absence of a male near the nest or even a nest territory.

I describe the nest of the Hooded Berryeater (Carpornis cucullata), an endemic of the Atlantic Forest of southeast Brazil. On the basis of observations of six nests, three main types of nest placement were identified: (1) nests supported by forks, (2) nest totally supported by a single horizontal branch, and (3) nests erected at the base of the dense mass of stems growing from bamboo nodes. All six nests were structurally similar, with several twigs forming a superficial web, which constituted the surface of the incubatory chamber. Below and around this web, there was a loose to dense layer of supporting thicker sticks. The six nests also had in common the presence of a flexible liana-like fern, which lined the nests' external margin in a variable degree. In some respects, the nest of the Hooded Berryeater is similar to the nest of the congeneric Black-headed Berryeater (C. melanocephala), though they differ conspicuously in that the latter is mostly composed of large, dry leaves in the lower layer.

We describe a hybrid between the Amazonian Motmot (Momotus momota) and the Rufous-capped Motmot (Baryphthengus ruficapillus), collected in northern Goiás, Brazil. In some characters (e.g., shape of the tail and facial mask) the hybrid is similar to B. ruficapillus, in others (e.g., measures and amount of blue in the plumage) it is intermediate between the two parents, and in others (e.g., color of the underparts) it is unlike any of them. Photographs document the occurrence of hybrids in two additional localities in Goiás. Complexity of the genetic control of plumage color in birds may explain the hybrid's characters, and rarity of B. ruficapillus may be a factor leading to hybridization between these species. This is the first known case of intergeneric hybridization in the Coraciiformes.