Field studies of the factors that influence reproductive success are crucial to life history theory. We investigate annual fledgling production by the monogamous, cooperatively breeding Red-cockaded Woodpecker (Dryobates borealis) in relation to breeder age, experience, and group size at Brosnan Forest, South Carolina, and evaluate several associated hypotheses. Productivity in both female and male breeders increased nonlinearly with age, peaked at 6 and 7 years, respectively, and then declined. We tested if the early increase in productivity with age was associated with age, per se (general skills), or breeding experience. We found for both males and females that the productivity of novice breeders increased significantly with age, indicating age effects independent of prior experience, but that experienced breeders were no more productive than novices the same age. We conclude that the basic skills that accrue with age, but not prior breeding experience, explain increasing success among young birds. The probability of a group nesting increased nonlinearly with female and male age, reaching 100% among females ≥ 7 and males ≥ 11 years old. We found support for both the constraint and restraint hypotheses for young males, but only for the constraint hypothesis among young females. Declining productivity with senescence counters the restraint hypothesis's prediction of increased effort late in life, while the maximal propensity to nest among older birds supports it. Differential survival failed to explain increasing productivity with age. Holding breeder ages constant, we found a linear effect of group size on annual fledgling production, with productivity increasing by 12% with each added helper through the largest group sizes. This suggests (1) no evidence of net compensation as group size increased, (2) no evidence of negative feedback from reproductive or resource competition in large groups, and (3) inclusive fitness is a selective force in helping.

The decline of the White Stork (Ciconia ciconia) in the Iberian Peninsula was averted within the last 30 years, partially due to an increase in food availability in landfills. In this study, we compared 2 colonies located at different distances from a landfill in southern Portugal, with the aim of assessing differences in stork diets. We also compared our current results with data from the same colonies before the landfill was built. Additionally, we studied storks' exposure to kleptoparasitism by Black Kites (Milvus migrans) as a potential factor affecting their feeding behavior in landfills. We analyzed 182 pellets collected in 2005 and 2010 in non-landfill colonies and from landfills only in 2010. We carried out >47 h of focal observations of storks feeding at the landfill. Pellet contents are primarily insects (15 families from 5 orders) as well as unidentified and inorganic materials. Our analyses of variance revealed significant local, seasonal, and annual differences in Coleoptera, Orthoptera, Hymenoptera, and total number of insects. Our observations at the landfill showed that storks feed on large amounts of organic material, mostly fresh meat and fish, which means that observational data differs from pellet data. Black Kites kleptoparasitize White Storks mainly at the beginning and end of the morning limiting their food intake and increasing the amount of time storks spend at the landfill. We conclude that foraging in landfills has provoked an important shift in the White Stork's diet, partially replacing these birds' natural food items and exposing them to potential new threats such as the ingestion of inorganic material and exposure to kleptoparasitism by kites.

Mutualistic interactions, such as animal pollination, structure biodiversity in the Neotropics. In coastal montane garúa (fog) forests of Ecuador, 2 mass-blooming plants attract up to 17 species of nectar-feeding birds, especially hummingbirds. We describe avian guilds and behavior at the 2 mass bloomers and use mist-netting capture rates to test 3 predictions: (1) capture rates of territorial hummingbirds will increase with flower abundance on the mass bloomer they defend, (2) hummingbirds known to mainly use other flowers will show no change in capture rate during mass blooms, and (3) field observations of interspecific interactions will be reflected in capture rates. We statistically modeled capture rates of bird species, species richness, and Shannon Diversity Index in response to flower abundance on the 2 mass bloomers during 16 flowering seasons (1996–2013). Capture rates of 8 nectar-feeding species increased significantly with increased abundance of white-flowered Psychotria hazenii blooms, while only one species, Speckled Hummingbird (Adelomyia melanogenys), increased significantly in response to red-flowered Stenostephanus clarkii flower abundance, and aggressively defended these flower patches. Violet-bellied Hummingbird (Damophila julie) showed the strongest capture rate response to increased abundance of P. hazenii flowers, and was the dominant territorial hummingbird around these shrubs. Endangered Esmeraldas Woodstars (Chaetocercus berlepschi) and Little Woodstars (Chaetocercus bombus) visited both mass bloomers, but had a statistically significant increase only with P. hazenii highest flower abundance suggesting that restoration to recover endangered woodstars will benefit more from plantings of P. hazenii than S. clarkii. We conclude that flower abundance and defendability structure avian pollinator networks at these mass bloomers more so than nectar quality, quantity, or secretion rates, all of which were similar.

This study confirms 2 independent accounts of previously undocumented hybridization between Magnolia Warbler (Setophaga magnolia) and American Redstart (S. ruticilla) through morphological and genetic analyses. Hybrids were discovered in 2 locations in eastern North America: Ottawa County, Ohio, USA, and Laval, Québec, Canada. The hybrids, one male and one female, showed plumage intermediate to both parental species. White eye arcs, yellow wash on the belly, narrow white wing bars, and black lores reflect the Magnolia Warbler parentage, while dark yellow-orange coloration on the sides of the breast and under the wing, yellow on the base of most of the secondaries, and pale yellow patches on the outer tail feathers reflect American Redstart. Sequences of the mitochondrial ND2 gene, the Z-linked muscle-specific kinase (MUSK) gene, and the myoglobin intron-2 (MYO2) confirmed maternal ancestry from Magnolia Warblers and paternal ancestry in American Redstarts for both hybrids. There is ample opportunity for this species pair to hybridize; they are congeners with broad range overlap, similar habitat preferences, song structure similarities, and plumage similarities in some age categories. Despite these conditions and the unusually high rate of hybridization within the Parulidae, this hybrid combination has never been documented before, and we suggest that this is a rare event that may be expected anywhere in their broad, overlapping ranges.

The Quailfinch (Ortygospiza atricollis) is a widespread African estrildid that features in specialist avicultural collections. However, the species is poorly known and has proven difficult to maintain in captivity, and as such, most captive stock represent wild-caught specimens. Here we report on the breeding ecology of a population of wild Quailfinches as observed at 62 nests in the 2012–2013 and 2013–2014 breeding seasons. Although Quailfinch bred during the wet season, incidental observations suggest rainfall patterns and the availability of suitable habitat for nesting, specifically habitat structure, may influence the onset of the breeding season at a local scale. Both sexes participated in all aspects of nest construction, including collection of material, construction, and maintenance. Nests were occupied for extensive periods prior to the commencement of laying, fulfilling a possible nest guarding or pair bonding function. Mean clutch size was 4.8 eggs (SD 0.2) and there were no significant seasonal differences in clutch size. Both sexes incubated and the incubation period lasted 14 d (SD 0.8). In common with many other estrildid species, there was considerable variation in the onset of incubation. Mean nest attendance during incubation was 83% and was similar between the sexes. The mean nestling period lasted 16.8 d (SD 0.8) and both sexes brooded and provisioned the nestlings with seeds and occasionally invertebrates. Growth was unusually rapid for estrildids, but within the range expected for ground-nesting passerines. The overall breeding success was 12% with predation being the main cause of nest failure.

Increased participation in mixed-species flocks is one hypothesized behavioral tactic used by forest birds to adjust to cold temperatures in winter. This phenomenon has been documented in temperate North America, but not at subtropical latitudes where temperatures are less extreme. To understand how temperature structures the size, richness, flocking propensity, and species interactions of subtropical mixed-species flocks, we performed paired mixed-species flock and point count surveys in upland hardwood forests in north-central Florida, USA. We described the composition of 92 mixed-species flocks across a ∼20 °C range of daytime temperatures, using linear mixed models and network analyses to test for effects of temperature. We found that both flock species richness and size were significantly smaller at higher temperatures while statistically controlling for effects of time of day, canopy height, and local site effects. Thirteen of 14 flocking species showed decreases in within-flock abundance with increasing temperature, although this effect was only significant for the nuclear Carolina Chickadee (Poecile carolinensis). Flock composition and species flocking propensities were less plastic than in temperate systems. By comparing metrics from 7 social networks corresponding to temperature ranges, we found that strength of flocking interactions was lower and that species were significantly less likely to co-occur with similarly foraging species at temperatures above 20 °C. Flocking propensities were lower for many species in the warmest temperature range. Thirteen of 14 species joined flocks in all 7 networks, and dissimilarity of social networks was consequently best explained by changes in species co-occurrence patterns rather than species turnover within flocks. In contrast to boreal flocking systems, changes to flocking behavior were prompted by unseasonably warm weather rather than cold spells, which suggests that warming winter temperatures could lead to breakdown of social behaviors in our system.

Sea surface temperatures (SST) in the Pacific Northwest of North America rose 1 °C during the last half of the twentieth century. Cannibalism, a behavior observed in diverse taxa, is often associated with low food supplies, which for marine animals can be precipitated by high SSTs. In an 8 year study, we found that in years of higher sea surface temperatures, Glaucous-winged Gulls (Larus glaucescens) breeding in a colony in Washington State, Salish Sea, USA, tended to exhibit higher rates of egg cannibalism by males, higher levels of every-other-day clutch-initiation synchrony by females, and longer egg-laying seasons than in years of lower SST. Clutch-initiation synchrony increased the odds that an egg survived cannibalism and may serve as an adaptive response to egg cannibalism. Short-term climate and resource fluctuations associated with El Niño Southern Oscillation (ENSO) events may select for behavioral plasticity in marine organisms, allowing long-lived individuals such as marine birds to switch between alternative life history tactics. The implications for long-term SST warming, however, remain unknown.

Descriptions of individual breeding bird biologies provide important insights to our understanding of avian life history strategies. The present study focused on the reproductive biology and nesting ecology of the Olivaceous Flatbill (Rhynchocyclus olivaceus) in the Parque Zoobotânico (∼100 ha) of the Universidade Federal do Acre, Brazil, between April 2015 and March 2016. We found 91 nests, of which 14 were active and 77 were abandoned. Due to multiple nest failure incidents, we only monitored a single nest throughout the breeding period from nest construction to offspring fledging. This nest was built in 14 d, eggs were incubated for 26 d, and nestlings remained in the nest for additional 21 d. The nest was classified as closed, retort-shaped, and pensile. We deconstructed one nest that had a weight of 65 g composed of twigs (31.6% of the total weight), fibers (28.9%), leaves (14.5%), bark (9.2%), bamboo pieces (9.2%), and tendrils (6.6%). We found the nests at heights of 1–9 m above the ground, with a preference for a 2–4 m stratum, built atop 25 different plant species. The 4 species that were the most frequently used as nest substrate were Protium unifoliolatum (n = 16 nests), Casearia sp. (n = 11), Siparuna guianensis (n = 10), and Couepia sp. (n = 9). The Olivaceous Flatbill breeds throughout the year, in both rainy and dry seasons, and it seems to be highly sensitive to human disturbance during the breeding season. The reproductive parameters recorded in the present study were consistent with those reported for other species of this genus, although most of the findings are novel for the Olivaceous Flatbill and provide important insights into its reproductive biology in the Amazon region.

Geographic variation in song characteristics within songbird species has the potential to reveal some of the complex interactions between ecology and behavior. The Connecticut Warbler (Oporornis agilis) is an uncommon and little studied Neotropical migratory wood warbler that breeds across the southern boreal forest in North America. The song of the Connecticut Warbler has remained poorly described and, prior to our study, no detailed spectrographic analysis exists. We document 20 distinct song variants in this species, based on differences in the structure and sequence of notes within repeated phrases, from across the breeding range. One song type, distributed across the entire breeding range, represented 36% of our samples. Preliminary evidence suggests a lack of geographic structure and no evidence of dialects or regiolects in the song types of this species. Our results highlight a unique distribution in song types within the Oporornis–Geothlypis complex, providing a baseline for future studies of geographic variation in this, and related, species.

The alarm calls of many vertebrates encode predator-specific information such as the type of predator or the urgency of the threat. When an alarm call is only produced in a specific context and elicits specific behaviors from the recipients it is referred to as functionally referential. The pervasiveness of functionally referential alarm calls across bird species, however, remains to be established. In this study, we first classified Northern Mockingbird (Mimus polyglottos) alarm calls and then assessed if parental birds produced different alarm calls for different predators or nestling stages. To classify alarm calls we first isolated parental calls that preceded nest predation events from mockingbird nest camera footage and analyzed them using Raven Pro. Using a PCA analysis, we identified 9 different alarm calls based on 18 different predation events that resulted in 494 alarm calls given. To determine if the alarm calls were predator- or nest stage-specific we conducted a multinomial logistic regression. One call was given exclusively in association with snakes and 2 were given almost entirely in association with cats. In response to American Crows (Corvus brachyrhynchos), mockingbirds mainly produced a fourth alarm call, which was also frequently associated with Cooper's Hawks (Accipiter cooperii). The remaining 5 alarm calls were associated with Cooper's Hawks. While we have strong preliminary evidence for predator-specific alarm calls in nesting Northern Mockingbirds, many of these calls are also given in other contexts, such as in intraspecific interactions, which would exclude them from being considered functionally referential. These results highlight the challenges of categorizing alarm calls as functionally referential and the need to further integrate functional reference with context-dependent communication.

I report on the strength of reversed sexual size dimorphism (RSD) in a local sub-population of Northern Pygmy-Owls (Glaucidium gnoma) in northwestern Oregon (2007–2012) in comparison to range-wide museum specimens examined by Earhart and Johnson (1970). Using Storer's Dimorphism Index (DI), RSD was higher among local breeding pairs (DI_mass = 6.64, DI_wing = 4.90, n = 20 pairs) and among all local specimens (DI_mass = 6.20, DI_wing = 4.39, n = 31 females, n= 23 males) than for specimens range-wide (DI_mass = 5.45, DI_wing = 4.30, n= 10 females, n= 42 males). RSD was also more distinct locally, because mass alone was diagnostic of the sexes at a threshold of 69 g and wing chord was nearly diagnostic, whereas range-wide there was greater intrasexual variation and intersexual overlap in both metrics. Locally, females weighed 75.3 ± 5.6 g (range 69.0–94.2 g), and males weighed 62.5 ± 2.5 g (range 58.5–68.5 g); all local males had wing chords <92 mm (89.2 ± 2.0 mm; range 85.0–91.5 mm), whereas for 90% of females wing chord was ≥92 mm (93.2 ± 1.3 mm; range 89.0–96.0 mm). Clutch size (F_1,4 = 1.822, P= 0.248, n= 20) and the number of fledged young (F_1,8 = 0.00, P= 0.619, n= 19) were independent of RSD among local breeding pairs. Vertebrate prey composition shifted seasonally and was similar at the 2 scales, with agile avian prey taken most frequently during the breeding season, when the evolutionary consequences of diet on RSD matter most. I found intersexual variation in prey composition at the local scale where males took avian prey more frequently than females. I concluded that RSD in pygmy-owls was stronger at the local scale and that intersexual differences in prey composition may be related to RSD in this species. This study highlights the value of examining multiple scales and seasonal variation in prey composition when evaluating the merits of RSD hypotheses. It also contributes to our understanding of one of the least studied owls in North America.

While the state of the art has been described for recording bird songs and calls, there are no described best practices for collecting and preserving the avian vocal organ, the syrinx. In addition to skins and skeletal preparations, field collection of tissues for DNA sequencing has become a common practice. Protocols for such tissue collection often involve accessing internal organs. Here we argue that collecting syringes, which also involves accessing the chest cavity, adds only minimal time to field or skeletal preparation and can be done without damage to the skeleton. Collecting syringes will enable studies of structure–function relationships in the production of calls and song that have not been previously possible. Three-dimensional X-ray computed tomography (CT) imaging techniques allow new insight into these relationships, but material of both male and female birds as well as juveniles is lacking for most avian taxa. Here, we present a guide to the removal and preservation of the avian syrinx and associated vocal anatomy in hopes of increasing their representation in biological collections. In this guide, we suggest that taking in situ measurements is ideal since dissection, fixation, and tissue staining can affect measurements of certain airway features such as tracheal diameter and bronchial length. Our guidelines demonstrate that removing a single wing, shoulder, and half of the pectoral girdle from the dorsal side of the thorax along with disarticulating the sternal and vertebral rib segments on one side of the body allows exposure of the complete airway without damaging the skeleton. We also provide recommendations for fixation, storage, and staining of specimens in preparation for diffusible iodine-based contrast-enhanced computed tomography (diceCT) scans that allow imaging of both soft tissue structures such as vocal folds and muscles as well as the cartilaginous rings that support these structures.

While it is well known that both sexes of many bird species vocalize, the importance and prevalence of female vocalizations is often underappreciated. In part, this is due to the paucity of field studies documenting their occurrence. Our knowledge of female vocalizations is particularly limited for the primarily monomorphic suboscines, for which obtaining vocalizations of known sex presents additional methodological hurdles relative to sexually dimorphic species. One solution is to collect a voucher specimen of an individual for which focal recordings have been made, with the sex of the specimen determined during its preparation. Using this approach, we documented a sex-specific vocal repertoire for the Dusky-capped Flycatcher (Myiarchus tuberculifer). We found that not only do females and males have distinct daytime vocal repertoires, but that females had a more diverse repertoire than males, vocalized more frequently, and that the male-specific vocalization was dependent on female vocalization in the context of a female-initiated stimulus–response duet. Although duetting has been anecdotally described for many species of tyrant flycatcher (Tyrannidae), this is only the second formal analysis of female song and duetting in this family and 1 of only 6 published examples for the New World suboscines. These findings deepen our understanding of female vocalizations in these groups and suggest that the female's leading role in territory defense through duetting should be investigated in other species. The “museum approach” employed in this study will be a useful tool to help document many of the potential cases of sex-specific vocal repertoires in other monomorphic species for which sexed and banded populations may be difficult to obtain.

Some songbirds produce only one or a few song types, but others sing large repertoires with many different song types. Birds with large repertoires can arrange these songs in a variety of distinct singing patterns that add a layer of complexity to their vocal production. Both large repertoires and singing patterns may communicate important information to conspecific males and females. Previous estimates of repertoire size of Red-eyed Vireos (Vireo olivaceus) range from 39 to 59. These estimates were based on a small number of recorded phrases per individual, and on single recordings of most individuals. I have made lengthy, multiple recordings over periods of days and weeks of 46 Red-eyed Vireos to revisit the question of their repertoire size. Repertoire size estimated for the birds I recorded varied between 17 and 341 phrase types, with a mean of 91. Fourteen birds for which I recorded at least 1,000 phrases had a mean repertoire of 154 phrase types. Previous estimates may have been low by a factor of 2–3 because of limited sampling. Plotting of phrase type vs. phrases sung for each bird showed a variety of singing patterns. Six birds sang a single limited repertoire of 17–47 phrase types. Nineteen birds sang a single repertoire, but new phrases continued to be added as more recordings were made, so these repertoires had no clear size limits. Twenty birds sang multiple groups or sub-repertoires of phrase types at different times, often changing between sub-repertoires during a single continuous bout of singing. Five birds sang frequent repetitions of a small number of phrase types selected from larger repertoires. The mean singing rate of the birds studied climbed from a low of 33 phrases/min at the beginning of the breeding season to a high of 46 phrases/min at the peak, and declined to 34 phrases/ min at the end of the breeding season. My study shows that Red-eyed Vireo repertoires are significantly larger than previously estimated, that singing patterns vary widely among individual birds, and that many birds group phrase types into multiple sub-repertoires, sung at different times.

The distribution of the White-tailed Hawk (Geranoaetus albicaudatus) in the United States is restricted to the prairies and savannas of the Gulf Coastal Plain of Texas. Although listed as a state threatened species, it remains one of the least studied raptors in North America. It appears to reach high densities on some Texas barrier islands despite the island vegetation communities being structurally simple and providing few nesting substrates. We compared vegetation and landscape characteristics for sets of White-tailed Hawk nest sites and random sites on 3 Texas barrier islands (Matagorda, Mustang, and North Padre) representing a gradient of low to high human presence and impact. We constructed model sets consisting of vegetation and landscape features measured at a random subsample of nest sites and random sites, then assessed model sets with logistic regression. Our best constructed model correctly differentiated 83% of nest sites from random sites on Matagorda Island, 70% on Mustang Island, and 50% on North Padre Island. Overall, it appears that the structure of nest substrates was important to White-tailed Hawk nest-site selection: shrubs categorized as densely structured with or without thorns accounted for 78% of nest substrates compared to only 13% of paired, random potential substrates. The most frequently selected nest substrates overall were yaupon (Ilex vomitoria; 43%) and Macartney rose (Rosa bracteata; 24%). If White-tailed Hawks are to be conserved on the barrier islands, a balance will need to be found between continued anthropogenic development, maintenance of habitat patches, and availability of suitable nesting substrates.

Pine plantations comprise about 7% of total world forest cover and are increasing across the globe. We compared settlement times, breeding densities, and the effects of time, habitat, and nest-site characteristics on the nest success of Eastern Wood-Pewees (Contopus virens) in red pine (Pinus resinosa) plantations and deciduous forest stands in south-central Ontario, Canada, in 2007 and 2008. Our goal was to evaluate the quality of these 2 habitats for this declining aerial insectivore. Pine plantations and deciduous forest stands were settled nearly simultaneously and at similar breeding densities, suggesting no preference for either habitat. Nest success in pine plantations (22%) was lower than in deciduous forests (35%), corresponding to higher counts of red squirrels (Tamiasciurus hudsonicus) and Blue Jays (Cyanocitta cristata) in plantations. Daily nest survival was lowest when nestlings were about 5 d old, but improved substantially as nestlings aged, and over the nesting season. In both habitats, increased nest visibility was correlated with decreased nest survival. In pine plantations, nest survival was higher where trees were more dispersed, while in deciduous forests, nests situated farther from tree trunks had higher survival rates. In both habitats, Eastern Wood-Pewees may use outward branches, when available, to detect movement and then evade potential nest predators. Although pine plantations provide breeding habitat for Eastern Wood-Pewees, management that increases hardwood understories and overstories may help to reduce visibility of Eastern Wood-Pewee nests and to reduce the populations of generalist songbird predators.

Rothschild's Swift (Cypseloides rothschildi) is among the least known South American swifts. Here we clarify its distribution and seasonality, and provide detailed natural history data and breeding information. We compiled 197 records of Rothschild's Swifts (museum specimens, citizen science initiatives, literature, and field observations) from Argentina and Bolivia; most from the breeding season (Oct–Mar, 177 records; 44 documented), a few thought to be on migration (Apr and Sep, 15 records; 3 documented), and fewer during the nonbreeding period (May–Aug, 5 records; 1 documented) with no records from July/August. Rothschild's Swifts are migratory, but the wintering quarters remain unknown. The distribution during the breeding season is broadly overlapping with the Austral Yungas of Argentina and Bolivia, with sparse records in Andean and extra-Andean ranges with forested and non-forested waterfalls. Our breeding distribution model indicated high presence probabilities in the Austral Yungas of Bolivia and Argentina. The breeding season during the austral spring and summer (late Oct/mid-Nov to mid-Mar/early Apr in northwest Argentina) began roughly with the early rains as in other Neotropical swifts. Our data from 8 breeding sites and from 8 nests that we studied in northwest Argentina regarding nest placement (near waterfalls), nest features (moss or moss and mud cups), eggs (single and white), and on the protracted development of Rothschild's Swift nestlings (∼55–60 d) and the sequence of plumage acquisition and behavior were coincidental with what is known from other Cypseloides. We provide behavioral information from a temporarily captive individual, which provided the first sound recordings of nestling/fledgling vocalizations of Rothschild's Swift—presumably the first available for any Cypseloides. It is unclear whether these vocalizations, recorded in captivity, represent developmental precursors of adult sounds or begging calls.

The green plumage of parrots confers a degree of camouflage amidst the canopy foliage the birds frequent. In parrots, green feather colors result from the juxtaposition of endogenously produced yellow pigments, termed psittacofulvins, and spongy structures in the feather barbs that produce a blue color. In rare individuals, the yellow pigments are missing, resulting in a blue phenotype, a variant plumage coloration. The Mexican Parrotlet (Forpus cyanopygius) is endemic to Mexico and the male sports a largely green body with turquoise-blue color on the underwing coverts, lower back, and rump. While inventorying the avifauna of the tropical dry forest at Sierra de Quila, Jalisco, in west-central Mexico, we captured a blue individual with no hint of green. Typically, in parrots, a blue phenotype results from a recessive mutation that prevents the production of yellow pigments thus revealing the underlying blue structural color. As far as we know, this is the first documented record of a blue (or cyanistic) Mexican Parrotlet. Declining numbers of parrotlets in Mexico could potentially increase the probability of birds becoming homozygous for the recessive mutation.

The Kelp Gull (Larus dominicanus) is a widespread and abundant seabird species inhabiting much of the southern hemisphere, where at least 6 subspecies are recognized. For the nominate subspecies L. d. dominicanus present in South America, limited information is available on its basic life history traits. In this note we present information on longevity and philopatry based on the resighting of 3 Kelp Gull individuals banded as chicks at their natal colony in central Chile. All birds returned to breed at their natal island and established their nests within 50–80 m of their natal subcolony. Maximum observed longevity ranged between 17.5 and 22.1 years. We consider this information on life history and behavior valuable for management purposes as this subspecies is rapidly increasing at some coastal regions of South America and it may become a problematic species to humans and other seabird populations.

The Swinhoe's Rail (Coturnicops exquisitus) is the world's smallest, and among the most poorly studied, Rallidae species. While the Japanese archipelago has long been considered a wintering area of this species, vocalizing Swinhoe's Rails have recently been observed during its breeding season in multiple distinct wetlands in northern Japan. During the summer of 2018, we investigated the breeding status of this species at a wetland in the Yufutsu Plain in central Hokkaido, where vocalizing Swinhoe's Rails have been recorded since 2012. To achieve our observations, we combined camera trapping and line-transect surveys with playbacks. Our surveys confirmed the presence of at least 1 family of Swinhoe's Rail and its abandoned nest. We also obtained a previous observation record of a family of this species from local birdwatchers at the Hotokenuma wetland in Aomori Prefecture. This study provides the first breeding evidence of Swinhoe's Rail in Japan, and suggests that this secretive, endangered rail species is a breeding summer visitor to northern Japan.

Bill deformities have been documented in many avian species across the globe and can be caused by environmental or genetic conditions that may also reflect ecosystem health. We describe the first case of bill deformity in the genus Tyrannus, in a young male Western Kingbird (Tyrannus verticalis) that fledged from a nest in an industrial park in Memphis, Tennessee, USA. The upper mandible of the bill was curved to the left and below the plane of the normal lower mandible making it unlikely that the individual would be able to forage normally and survive to adulthood. Genetic testing for evidence of hybridization with Scissor-tailed Flycatchers (T. forficatus) showed no sign of introgression, and it is unclear what caused the deformity.

Eucalypt plantations alter the physical and chemical conditions of the environment, and the value of such plantations for biodiversity conservation is controversial. Research on their potential effects on native Neotropical bird communities has focused on taxonomic diversity, while its impacts on other ecological aspects remain only partially explored. We used camera traps to compare habitat use and activity patterns of an understory bird assemblage between a native forest and an adjacent eucalypt plantation in the Colombian Andes. Six and seven understory bird species comprised the eucalypt plantation and the native forest assemblages, respectively. Habitat use of the White-throated Quail-Dove (Zentrigon frenata), Sickle-winged Guan (Chamaepetes goudotii), and antpittas was significantly lower in the plantation, whereas brushfinches used both forest types equally. Each species showed coefficients of activity that overlapped above 59%, suggesting the overall activity patterns of the understory birds were similar in both forest types. However, activity peaks of most species were slightly different between the 2 forests. Despite the fact that these areas are adjacent to one another, and that this eucalypt plantation has undergone 50 years of understory growth, our results indicate that this exotic plantation does not constitute a suitable habitat for most Andean understory birds. We found that eucalypt plantation effects on bird assemblages go beyond their taxonomic diversity and affect other ecological aspects such as their patterns of activity. Our study provides new insights on activity patterns of Andean birds and highlights the need for assessing the value of exotic plantations as a surrogate habitat for understory bird conservation.

We describe several cases of plastic use by the Loggerhead Shrike (Lanius ludovicianus), a declining grassland passerine that has not yet been reported interacting with anthropogenic material. Of 24 wild Loggerhead Shrike nests that were monitored over 2013 and 2019 field seasons in Ontario and Indiana, more than 20% contained incorporated plastic debris. Three instances of fledgling entanglement were recorded in Ontario as a result of loose plastic used as nesting material. We also describe an observation of a shrike handling plastic in a foraging-like behavior. Faced with a host of threats that include habitat fragmentation and roadside mortality, our observations suggest plastic debris presents yet another danger Loggerhead Shrikes must contend with in increasingly human-impacted environments.

Levels of conspecific brood parasitism (CBP) and quasi-parasitism (QP) are important parameters for the general understanding of alternative female mating strategies. We deployed double-digest RAD sequencing to assess CBP and QP in a south temperate population of Grass Wrens (Cistothorus platensis). CBP rate was low and varied annually (0–10%). No cases of QP were identified in our population. Grass Wrens showed similar levels of CBP when compared to other Neotropical songbirds. Given that females could increase their reproductive output by laying eggs in both their nests and in other females' nests, it is striking that CBP is so rare. Future work should evaluate counter-adaptations (egg pecking and rejection, nest desertion, and retaliation) that reduce the success of CBP.

Due to the low detectability of Northern Saw-whet Owls (Aegolius acadicus; hereafter, NSWO) throughout their annual cycle, standardized monitoring during migration allows for population assessments over time. We assessed age-class population trends in NSWO throughout eastern North America using banding data from 7 sites over a 25 year period. Using a mixed linear model, we did not detect any significant trends over time for the total owl count, adult owl count, and juvenile owl count from 1992 to 2017. During the period when all 7 sites were active from 2001 to 2017, trend estimates remained nonsignificant despite showing negative slopes. We confirmed this nonsignificant, negative trend through a similar mixed linear model of NSWO data from Christmas Bird Counts. Our results suggest that NSWO populations across eastern North America have been relatively stable since 1992 throughout their migration and winter ranges and demonstrate the value of standardized banding data for monitoring the regional population status of NSWO.

A female Kirtland's Warbler (Setophaga kirtlandii) was observed and captured on 12 February 2019 at the Font Hill Nature Reserve (18°02′N, 77°57′W) on the south coast of Jamaica, hundreds of kilometers southwest of its typical nonbreeding range. This is the first report of a Kirtland's Warbler in Jamaica. The individual was resighted in the same area twice after the initial capture, spending at least 7 weeks at the study site, suggesting this bird may have been wintering in Jamaica. Overall, it is unclear if this represents the expanding range of a recently increasing Kirtland's Warbler population or simply an errant migration.

Playa wetlands are important for maintaining biodiversity in otherwise nondiverse landscapes in the High Plains of the western Great Plains. Vegetation buffers around playas have been documented to reduce runoff of sediments and contaminants; however, there have been few assessments of the effects of buffers on bird communities. I conducted point counts during the breeding season and sampled vegetation at playa buffer sites and control playas to assess effects of buffers on breeding birds and their habitat. Relative abundance of wetland-dependent birds and total birds was substantially greater at buffered playas than unbuffered playas. I was not able to detect a difference in upland bird relative abundance between treatments. This was likely due to the habitat requirements of the most frequently detected upland birds: Common Grackle (Quiscalus quiscula) and Horned Lark (Eremophila alpestris). Buffered playas contained more visual obstruction and percent forb cover than control playas, but I was unable to detect a difference in percent grass or bare ground. Overall, playa buffers supported more birds and provided better habitat conditions for many bird species than unbuffered sites, and I suggest further research examining survival and reproductive output of birds using playa buffers.

We report the finding of a White-eared Hummingbird (Basilinna leucotis) nest during the winter. The observation took place on 9 February 2019 in San José del Pacífico, Oaxaca, Mexico, in the Sierra Madre del Sur. The hummingbird nest was located in the understory, 115 cm above the ground. The nest was placed within a plot of a pine-oak forest at 2,857 m a.s.l. and had 2 nestlings with complete juvenile plumage. Floral phenology is known to be a key factor that determines the biological cycles of hummingbirds, which rely heavily on nectar resources to fulfill their nutritional needs in the breeding season. Around the nest, we observed Salvia punicans Epling, a plant that blossoms during the winter months in the Mexican mountains and is visited by White-eared Hummingbirds. Previous winter nest records in Southern Oaxaca date from more than 50 years ago. We briefly discuss the implications of winter reproduction for the species and the potential commonness of this event.

Little is known about the foraging ecology and breeding biology of the Stygian Owl (Asio stygius robustus) across Central America. We located one Stygian Owl roost site in the Mountain Pine Ridge Forest Reserve in the Cayo District of Belize, where we collected pellets over a one-year period (n = 145; Mar 2009–Feb 2010). All identified prey items (n = 194) were passerines (69%), bats (19%), or beetles (12%). We used a proportions test and found seasonal variation in diet, with increased passerine prey consumed in the dry season (Jan–May) and increased beetle prey consumed in the wet season (Jun–Dec). This shift in diet may be influenced by temporal variation of passerine abundance and the emergence of beetles at the start of the wet season. In December 2010, we affixed an adult male Stygian Owl with a VHF transmitter, recorded regular movements using triangulation, and located an occupied nest with a single nestling in sub-montane pine forest habitat. The tagged male had a home range of 36 km² and was documented regularly flying up to 16 km from the nest site through broad-leaved forest to hunt in agricultural habitat, while roosting and nesting only in sub-montane pine forest. The use of human-created habitats, such as agriculture, could unveil threats not previously of concern for this species (e.g., pesticide use). Our findings further our knowledge on seasonal diet for Stygian Owls and highlight distinct habitat usage for both roosting and foraging, which has important conservation implications for an understudied Neotropical owl.

The Bornean subspecies of Rajah Scops-Owl (Otus brookii brookii) has not been documented alive in the wild since its discovery in 1892 and there are no photographs of the bird in life. We report the rediscovery of this subspecies in the montane forests of Mount Kinabalu (Sabah, Malaysia) at an elevation of 1,650 m and provide the first photographs of this subspecies in the wild. Almost all basic elements of this species' ecology remain unknown, including vocalizations, distribution, breeding biology, and population size. Additionally, phylogeographic patterns of montane birds in Borneo and Sumatra, as well as plumage characters, suggest that O. b. brookii may be deserving of species classification. However, the rarity of O. b. brookii has made quantitative phylogenetic analysis impossible. Properly resolving the ecology, distribution, and taxonomic standing of O. b. brookii could have important conservation implications.

Several of the first avifaunal surveys in Colombia were conducted in the lowland moist forests of the Middle Magdalena Valley, but for decades this region has been understudied. We present results of an avifaunal survey in a zone of Cantagallo, Bolívar, Colombia (Jun–Jul 2019), based on the collection of voucher specimens, associated tissue samples, and observational records. We report 165 species, 77 of which are represented with 266 voucher specimens. We found that the nearest documented records for 7 species are more than 100 km away. Moreover, our collection bridges more significant gaps in temporal sampling (mean = 71 years before our survey). Our field work resulted in the first tissue samples for 10 species in Colombia and 64 species from the department of Bolívar. The Middle Magdalena Valley's forests have almost vanished and the surveyed zone should be considered for protection.

We report the first record of Bronzed Cowbird (Molothrus aeneus) brood parasitism on a sedentary tropical population of the Blue-gray Gnatcatcher (Polioptila caerulea), which probably represents the subspecies P. c. deppei. Our observations represent the 46th known true host species parasitized by this cowbird species, the 104th host and victim, and the 3rd known brood parasite for the family Polioptilidae. “Victims” are all species parasitized by cowbirds and “hosts” are those species that hatch, feed, and successfully raise cowbirds. Our assignment of these records to the true host list are based on feeding behavior observations at a nest in Veracruz, Mexico. We provide additional information on nest characteristics of an understudied gnatcatcher population.

Andean Cocks-of-the-rock (Rupicola peruvianus; ACOR) are frugivorous, tropical lekking birds iconic to Andean cloud forests. Little is known about ACOR natural history outside of limited studies focused on their lekking behavior and diet. Given the persisting, detrimental effects of cloud forest deforestation, an increased understanding of ACOR natural history is critical for their conservation. Using capture-mark-resight/recapture (CMR) methods on R. p. sanguinolentus in northwest Ecuador, we determined the apparent annual survival of ACOR males and derived estimates for ACOR male longevity. The 2 top models estimated male ACOR apparent annual survival at 0.98 and 0.97, respectively, and our naïve estimate of survival was 0.87. Furthermore, we found banded ACOR males could persist at the lek for upwards of 14 years. Our results present key information on ACOR vital rates and offer a framework to understand those of related cotingids. Future studies should prioritize elucidating vital rates for ACOR females as well as specific habitat requirements of ACOR and related cotingids to inform specific conservation plans aimed at protecting these species.

We report 14 cases of banded female Costa's Hummingbirds (Calypte costae) fledging young from 2 or 3 broods in single breeding seasons during late February to mid-June in southern Nevada, USA. Successfully raising 2 broods in a single breeding season has been reported only rarely for this species, and raising 3 broods is previously unreported in the literature. We also report 8 cases of banded females simultaneously tending young and eggs from 2 nesting attempts. Females constructed a new nest and began incubating while (1) feeding large nestlings in the earlier nest (5 cases), or (2) feeding recently fledged young from the earlier nest (3 cases). One banded female accounted for 5 of these 8 cases. We also report 5 cases of autumn nesting, not previously documented for Costa's Hummingbird, including 5 young fledged from 3 nests in late November and early December. Our results suggest that multiple broods, simultaneous nests, and autumn nesting are viable breeding strategies for female Costa's Hummingbirds, some of which may be year-round residents at our study site in the Mojave Desert. We also suggest that multiple brooding and autumn breeding are facilitated by the availability of hummingbird feeders and cultivated exotic flowering plants in an urban setting.