Enhanced vigilance against predation is often an advantage of living in groups, but most studies have not examined individual-specific variation in the propensity to be vigilant among the animals within a group. We studied vigilance at the nest in colonially nesting Cliff Swallows (Petrochelidon pyrrhonota) in southwestern Nebraska in 2011 and 2012, and asked whether differences among individuals were consistent over time, whether vigilance varied among different colonies, and whether there were positive or negative fitness consequences of different levels of vigilance. We found significant among-individual variation in extent of vigilance and some variation among different colony sites. Vigilance also varied with date and nesting stage, but other phenotypic characteristics of a bird had no effect on vigilance. Differences among individuals in vigilance were not strongly related to their reproductive success that season, but more vigilant individuals were more likely to attempt intrusions into their neighbors' nests. Vigilance at the nest may be partly directed at monitoring conspecifics' activities in neighboring nests. This study is among the few that have investigated individual variation in vigilance behavior, a possible index of personality for Cliff Swallows, and the first to measure variation in vigilance for a colonial bird while breeding.

Dispersal decisions of songbirds are relatively well understood between breeding seasons, but far less is known about dispersal between nesting attempts and during the molting period. There are several non-mutually exclusive hypotheses for why birds disperse during breeding and molt including: (1) avoiding predation, (2) because of depleted resources, or (3) seeking higher quality habitat. In this study, we evaluated the above hypotheses by radio-tracking a Neotropical migrant, the Wood Thrush (Hylocichla mustelina), during breeding and molt. During breeding, 30% (7/23) of females moved territories within-season. Females were not more likely to move off-territory following nest predation, and dispersing females were not in poorer nutritional state than non-dispersing females prior to the move. However, females occupying nest sites with large trees, high canopy height and percent canopy cover, and low percent ground cover were more likely to move off-territory for their second nest to sites with few large trees, a low canopy height and cover, and high percent ground cover. During the molting period, 61% (28/46) of birds moved off-territory to molt. Molting areas were associated with more shrubs and fruiting trees compared with breeding territories. There were no sex or age effects as to whether a bird molted on or off their breeding territory. We suggest that off-territory movements during the nesting period are to seek more suitable nesting vegetation, rather than specifically avoiding predation or because of reduced resource availability. This study has additionally shown that, without radio-telemetry, detecting off-territory movements during breeding is difficult and neglecting to include these movements may result in an underestimation of annual productivity.

Nest predation and brood parasitism likely cause declines in many songbird species, yet the rate of these declines varies among species. Simultaneously studying co-occurring species with overlapping territories provides an opportunity to identify differences among the species that may explain differential reproductive success. We monitored nests of three co-occurring songbird species to determine whether the federally endangered Black-capped Vireo (Vireo atricapilla) experienced lower reproductive success than Northern Cardinals (Cardinalis cardinalis) and White-eyed Vireos (V. griseus) on private lands with and without trapping of brood parasites. We assessed if habitat metrics and nesting phenology were associated with nest success and frequency of brood parasitism by Brown-headed Cowbirds (Molothrus ater) to determine if these characteristics explain poor reproductive success. We monitored 188 nests in shrubland and ecotones with woodlands in central Texas from 2006–2008. We found species-specific differences in nest success and brood parasitism, year effects, and differential impacts of cowbird trapping. Black-capped Vireos nesting in locations without cowbird trapping experienced the lowest daily survival rate of nests (0.86) and period nest survival (0.01), whereas estimates in locations with cowbird trapping were similar to the other species (0.93 for daily and 0.11 for period nest survival). Nest initiation date was important for predicting brood parasitism, showing high probability of brood parasitism in the middle of the breeding season and low probability during the beginning and end of the season. Habitat metrics were not good predictors of nest success or brood parasitism. Management for conservation of Black-capped Vireos focused on vegetation manipulation may not increase reproductive success in the absence of cowbird trapping in some areas of the breeding range, because daily survival rate of nests was associated with cowbird trapping but not habitat metrics.

Breeding biology information, including nest survival estimates, are lacking for many nesting species in Puerto Rico. We studied the endemic Puerto Rican Bullfinch (Loxigilla portoricensis), and modeled daily nest survival to better understand the effects of several factors on daily nest survival. In 2009 and 2010 we monitored 37 bullfinch nests at two sites in southwestern Puerto Rico. Predation was the most important cause of nest failure. Ten nest survival models received approximately equal support. No temporal trends in nest survival were supported over others. Results suggested that available fruit is important for successful nesting, increased precipitation is related to higher nest survival, nest survival varied by site, and increased nest height is related to lower nest survival in bullfinches. Under the top model, daily nest survival rates for each site and nest stage ranged from 0.83–0.86% in 2009 and 0.80–0.93% in 2010. This information on nest survival and factors that influence it increases our understanding of the breeding biology of the bullfinch, and will ultimately help inform future studies and conservation efforts in southwestern Puerto Rico.

Populations of shrub-breeding birds are declining in eastern North America, and loss of habitat has been implicated in these declines. Seasonal use of habitat by shrub-breeding birds in the southeastern US remains understudied despite the fact that it is well documented that species resident within a region can shift habitat use dramatically between seasons. To better understand year-round habitat occupancy by shrub-breeding birds, we conducted bird counts and vegetation surveys during summer and winter 2008–2009 within Tuskegee National Forest, Alabama. We used multi-season occupancy models to examine use of habitat and to contrast seasonal occupancy patterns of four species of resident shrub-breeding birds—Brown Thrashers (Toxostoma rufum), Eastern Towhees (Pipilo erythrophthalmus), Northern Cardinals (Cardinalis cardinalis) and Carolina Wrens (Thryothorus ludovicianus). Brown Thrashers and Eastern Towhees are partially migratory—meaning some populations have separate breeding and wintering areas—whereas Carolina Wrens and Northern Cardinals are non-migratory. All four species showed seasonal changes in use of habitat between summer and winter, and all species were associated with both vegetation structure and certain types of cover. Further, partially migratory shrub-breeding species had greater site-turnover and increases in occupancy between summer and winter than non-migratory species. Our results suggest that: (1) management actions based on breeding habitat requirements will likely not create suitable winter habitat, and (2) management of resident shrub-breeding birds will require not only the creation and maintenance of certain types of cover, but also certain structural aspects of vegetation within habitats.

Many studies have suggested that early successional habitats are important for fall migrant and resident birds. In light of this, we studied habitat relationships, preferred fruiting shrub species, and fruit consumption by birds in early successional habitats during the fall at Iroquois National Wildlife Refuge, Alabama, New York, USA. We used transects to count birds in 12 shrub and 6 early successional forest sites during 2008–2009, and collected data to construct habitat models. We examined frugivory using a paired open/enclosed fruit branch experiment and by analyzing fecal samples of birds captured in mist nets. More fall songbirds were detected in shrublands than in forests across the 2 years, although forests with well-developed understories also had high detection levels. Total bird abundance was positively related to fruiting species richness and negatively related to small woody stem (0.0–2.5 cm) abundance. Abundance of American Robins (Turdus migratorius) was positively related to total shrub cover and fruit abundance on common buckthorns (Rhamnus cathartica), and negatively related to small and large (2.5–8.0 cm) stem abundance. Abundance of Gray Catbirds (Dumetella carolinensis) was positively related to fruiting shrub species richness. Abundance of Song Sparrows (Melospiza melodia) was positively related to gray dogwood (Cornus racemosa) fruit abundance, and negatively related to small stem abundance and bella honeysuckle (Lonicera × bella) fruit abundance. Fecal analysis suggested that birds as a whole disproportionately consumed fruit species relative to availability, and consumed more bella honeysuckle and common buckthorn than gray dogwood. Fewer fruits remained on open branches than enclosed branches, suggesting birds actively consumed fruits at our sites. Our results suggest that fall migrant and resident songbirds as a whole benefit more from mature shrublands that contain a diversity of fruiting shrub species than from early successional forests. While these characteristics may benefit the suite of fall migrants and residents at our location, appropriate habitat management may differ for other locations or migratory species.

Grassland birds are declining at an alarming rate and habitat limitation on the wintering grounds may play a major role in population declines. In an attempt to understand habitat needs and constraints of grassland bird species on their wintering grounds, we conducted the first-ever telemetry study to document the movements of a wintering grassland passerine bird in grasslands of the Chihuahuan Desert in northern Mexico. We attached radio-transmitters to 99 Vesper Sparrows in January of 2009 and 2010 and tracked them for up to 51 days. We estimated vegetation characteristics at foraging, roosting and random locations. We used kernel density estimators of the utilization distribution for each individual sparrow to estimate home range size. We found differences in average home range size between 2009 and 2010 (108.46 ± 36.43 ha and 30.91 ± 4.74 ha, respectively). Home ranges showed high levels of intraspecific overlap, with average pairwise overlap of 0.41, 0.70 and 0.79 among individuals at three study sites, as measured by the Bhattacharyya's affinity. Grasses and shrubs were shorter in foraging locations than in random sites within Vesper Sparrow core habitat, but we found no differences in grass cover and shrub cover. We suggest that movements of Vesper Sparrows are mostly limited to <1 km² during the winter and hypothesize that these movements are subject to constraints by food limitation and predation.

Grassland bird species frequently respond to habitat characteristics at multiple spatial scales when selecting nest sites. The Western Burrowing Owl (Athene cunicularia hypugaea) is a grassland bird species of conservation concern across much of its range, but most studies of its habitat needs have been restricted to relatively small geographical areas and have not integrated multiple spatial scales. Our study examined habitat characteristics at three spatial scales—local (near the burrow), colony, and landscape—across western South Dakota. We searched for Burrowing Owls in 107 prairie dog colonies from May to August 2011. We located nest burrows in owl-occupied colonies, and we randomly selected non-nest burrows in colonies that were not occupied by owls for comparison. We collected data for local habitat variables in the field. Ground truthing and aerial imagery were used to calculate colony and landscape variables. We used logistic regression to identify variables that impacted nest site selection. Variables at multiple scales were important, with percent tree cover within 800 m of the burrow and visual obstruction at the burrow having the greatest effect on nest site selection. Burrowing Owls in western South Dakota were most likely to nest in landscapes with little tree cover, perhaps to avoid large avian predators associated with trees. At the local scale, Burrowing Owls were most likely to nest in regions of prairie dog colonies with relatively low visual obstruction. Burrowing Owls may benefit from prairie dogs maintaining vegetation at a short height, which allows the owls to easily detect prey and predators. Maintaining active prairie dog colonies in open landscapes across western South Dakota and preventing the establishment of trees near prairie dog colonies is necessary to ensure preferred breeding habitat remains for Burrowing Owls.

Mexican Spotted Owls (Strix occidentalis lucida) occupy forest-dominated environments but also inhabit rocky canyonlands. I studied the owls' diet in canyon habitats in southern Utah and northern Arizona (1991–2007), and in mixed-conifer forest in the Rincon Mountains of southeast Arizona (1996–1997). I identified 3,315 prey items in regurgitated pellets from 38 pairs of owls in canyon habitat, and 383 prey items from 5 pairs in the Rincon Mountains. In canyons and forests, vertebrates dominated owl diets (97–99% of total prey biomass) with mammals accounting for 91–92% of prey biomass. In canyons, mammalian prey was primarily woodrats (Neotoma spp., 79% biomass), followed by white-footed mice (Peromyscus spp., 11%), and cottontail rabbits (Sylvilagus spp., 5%). In forest habitat, woodrats comprised 54% of biomass, followed by Botta's pocket gophers (Thomomys bottae, 13%), and cottontail rabbits (11%). For nine owl territories in three canyon regions in Utah, diets varied among the owl pairs with contribution to total prey biomass by woodrats ranging from 65–91%, typically followed by white-footed mice ranging from 13–19%. In both canyon and forest study areas, a variety of prey were consumed in addition to murids, including rabbits, pocket gophers, sciurids (Tamias spp.), heteromyids (e.g., Perognathus spp.), various bats (Vespertilionidae), shrews (Sorex spp.), small passerine birds, and numerous arthropods.

We report on the breeding biology of the White-throated Woodcreeper (Xiphocolaptes albicollis), a species endemic to the Atlantic forest of South America, based on 16 nesting attempts in 11 cavities (9 natural tree cavities and 2 nest boxes) in Misiones, northeastern Argentina. Natural cavities were 3.3–8.3 cm in diameter and 46–103 cm in depth, and generated by decay processes (not woodpeckers) at heights of 3–17 m in live trees 29–106 cm in diameter at breast height. White-throated Woodcreepers laid 2–4 eggs on alternate days, on a bed comprised of bark flakes, leaf fragments and seed pods. Incubation bouts (n  =  3) were more than 1 hr 40 mins. Incubation lasted 17 days and the nestling period 18–22 days, shorter than the congeneric Great Rufous Woodcreeper (Xiphocolaptes major). Both adults brought nest material, incubated the eggs, fed the nestlings, and removed fecal sacs; however, we suspect that the male contributed more to fecal sac removal. Both adults roosted in the cavity a few nights before eggs were laid, but only one adult did so during the incubation and nestling periods. Nestlings were fed arthropods and small vertebrates at an average rate of 3 visits/hr with no change in delivery rate over the nestling period. Adults defended their nests from four bird species but shared one cavity with a roosting female Helmeted Woodpecker (Dryocopus galeatus) throughout their incubation period. We confirm that the White-throated Woodcreeper exhibits biparental care like the Great Rufous Woodcreeper, the Dendrocolaptes and the Lepidocolaptes, but in contrast to Sittasomus, Dendrocincla and Xiphorhynchus. We recommend studies with banded individuals to determine the relative contribution of each parent.

Flightless Cormorants (Phalacrocorax harrisi), the only flightless members of their 27-member genus, are listed as vulnerable on the International Union for Conservation of Nature (IUCN) Red List. The world population of <1,000 breeding pairs is restricted to scattered small colonies along the coastlines of Isla Fernandina and Isla Isabela, Galápagos, Ecuador. No previous study has systematically examined daily activity patterns by these birds in relation to environmental variables. We made half-hourly behavior scan counts at a colony of Flightless Cormorants at Cabo Douglas, Isla Fernandina during the daylight hours of 7 consecutive days in May 2011. We used generalized linear models and multi-model inference to examine the response of colony occupancy and behaviors to hour of day, height of tide, temperature, humidity, wind speed, barometric pressure, solar elevation, and solar flux. We show that the behavior of Flightless Cormorants during our period of study was shaped primarily by time of day, wind speed, and solar flux; unlike many marine birds, they responded little to tide.

Results are reported from a citizen-science program to study the ecology, behavior, and reproduction of an invasive population of Red-vented Bulbuls (Pycnonotus cafer) in Houston, Texas. The most frequent behaviors are foraging (n  =  69), resting (n  =  45), and calling (n  =  29). The entire population occurred in urban areas. Bulbuls consumed berries (n  =  8 species), fruits (n  =  5), flowers (n  =  5), and buds (n  =  4); some insects are also included in the diet. Nine of the 20 species of identified plants consumed are exotics found within the native range of the bulbul, six are exotics found outside the native range, and five are native Texas species. The most common of the 35 species of plants that bulbuls perched in are bamboo (Bambusa sp.), crape myrtle (Lagerstroemia indica), edible fig (Ficus carica), and tallow (Sapium sebiferum). Flock size averaged 2.3 birds/flock (range  =  1–22) and the largest flocks (12–22 birds) are in late summer and early winter. Bulbuls are not migrants; peak observations are during spring and summer, with lower numbers during October. General biology is similar between Houston bulbuls, native populations in Asia, and other invasive populations in the Northern Hemisphere. This alien population is not a serious agricultural pest or disperser of weedy seeds, does not compete with native species, and has not expanded beyond the Houston region in the continental United States.

In many birds, females prospecting for high quality breeding resources have to inspect a number of males and their territories to make a good mating choice, yet in the face of competition with other females, the search time should be minimized. The sequential sampling of potential mates and territories by females is seldom witnessed. In a study of breeding Northern Lapwings, Vanellus vanellus, in Norway, we observed a female during the pair-formation period visiting seven territories in 105 mins, spending 15–20 mins on each of six territories pecking food from the ground and watching the resident male performing nest-scraping displays. One of the males was already mated, and on this territory the prospecting female spent only ∼2 mins. The observations show that female Northern Lapwings are potentially able to sample a high number of available territories in only a few hours.

Data concerning 303 nests of the Terek Sandpiper (Xenes cinereus) from 58 breeding sites in different parts of Russia and Ukraine were analyzed. Among them 196 were found in the western and 107 in the eastern part of this species' breeding range. In the eastern part, 61% of nests were placed in forests or within bushes, while in the western part only 8% of them had such location. Moreover, in the eastern part the species seems to avoid natural open habitats in spite of their availability, whereas in the western part of the breeding area nests were built mostly in open habitats, like meadows, pastures, or sandbanks dominated by sparse and low vegetation. Therefore, western and eastern populations of the Terek Sandpiper differ in nesting habitat selection. This is an exception among related species of the family Scolopacidae, for which different nesting habitats were reported only occasionally.

Because of their cryptic plumage and nocturnal habits, little is known about the breeding behavior of Chuck-will's-widows (Antrostomus carolinensis). Using temperature loggers and video-recordings, we quantified the incubation, brooding, and provisioning behavior of male and female Chuck-will's-widows in Adams County, Ohio, in 2011 and 2012. We located six nests, all 2-egg clutches laid on the ground. Four nests were successful, one was depredated, and one was abandoned. We quantified incubation behavior at all nests (mean  =  5.5 days; range  =  0.4–12.9 days). Adult Chuck-will's-widows incubated an average of 89.2% of the time, with females observed incubating more than males. Most incubation off-bouts (n  =  104) occurred at dawn (0400–0659; n  =  45) and dusk (1900–2200; n  =  48) and averaged 35 mins in duration. After hatching, the mean duration of brooding bouts was 20 mins (age of young  =  1–7 days). Both males and females provisioned young, and feeding rates were highest (P  =  0.003) during the hour immediately after sunset. The timing of off-bouts during incubation and provisioning visits after hatching suggest that Chuck-will's-widows in our study foraged primarily at dawn and dusk. Previous authors have noted that nightjars are visual predators and, therefore, their foraging behavior may be constrained by light levels.

Because Sharp-shinned Hawks (Accipiter striatus) are among the most secretive of North America's forest-breeding raptors, little is known about their breeding biology, including the characteristics of their nesting habitat. In 2009 and 2010, we searched forest stands in Kentucky and located 11 nests, all in pines (Pinus spp.). Nests were at a mean height of 18.6 ± 1.4 m in trees with a mean height of 23.7 m. Comparison of the characteristics of nest sites and randomly selected unused sites revealed significant differences (P  =  0.021). Discriminant analysis revealed that six variables (foliage cover, mean tree height, basal area, percent deciduous canopy cover, distance from edge, and distance from road) permitted the best discrimination between used and random sites. Sharp-shinned Hawks nested in areas closer to edges and in areas with denser stands of taller conifers and denser understory. All nests were in stands of young (∼25–50 years), even-aged conifers about 18–25 m in height. Nest sites were also closer to edges where stands of dense pines transitioned into areas with more, shorter deciduous trees and less foliage cover than nest sites. These adjacent areas may provide better foraging habitat for nesting Sharp-shinned Hawks because small birds, their primary prey, are more abundant in mixed stands than in dense stands of conifers where they nested.

Reports of interspecific parental behavior are rare but widespread among avian taxa. We present the first known case of interspecific parental care by a Wood Thrush (Hylocichla mustelina) at a nest of the Veery (Catharus fuscescens), documented by video at a long-term study site in northern Delaware, USA. We provide data on nest chronology, quantify parental behavior, and describe a copulation event between the Wood Thrush and the female Veery that was captured on video. Despite incurring no obvious fitness benefit, the Wood Thrush provided significant and prolonged nestling care including more feeding attempts and sanitation maneuvers than either Veery. We propose that these observations are a consequence of the normal adaptive behavior of the recipient species.

An Eared Grebe (Podiceps nigricollis) that lost a leg in an accident increased muscle mass in its intact leg by 28%. This allowed it to forage, run along the surface to take flight, and survive for about a year before dying in a weather-induced downing. Its ultimate survival probably depended on the species' predilection for hypersaline habitats, where passive invertebrates are abundant and can be captured easily on the surface without the need to dive. Similar phenotypic accommodation may have been realized in other similarly impaired Eared Grebes. However, it seems unlikely to be achieved in other grebe species, particularly fish-eating pursuit divers, which require two intact legs and feet for propulsion and underwater maneuverability.

Northern Bobwhites (Colinus virginianus) are predicted to maintain optimal covey sizes throughout the non-breeding season to avoid predators, thermoregulate, and forage efficiently. Arguably, population declines that reduce local bobwhite population densities could influence coveying behavior, which may then affect individual survival and population growth rates. We investigated changes in covey size and membership in a declining bobwhite population on private land in southwestern Ohio. Covey densities (range 0.25–1.63 coveys/km²) were lower than estimates from other areas of the bobwhite range. Despite an average 3.2% weekly decline in mean covey size during October–March, two unique coveys merged to form larger coveys on only six occasions and only one radiomarked individual changed covey affiliation (n  =  307 radiomarked individuals, n  =  57 coveys). Spatio-temporal separation of coveys and low daily movement rates (139.2 m/day) provided little opportunity for contact among adjacent coveys, possibly inhibiting mergers and inter-covey movements of individuals, particularly during winter. We postulate that low incidences of covey mergers and inter-covey movement by individuals were associated with spatial isolation of coveys because of low population densities on our study sites. Such density-dependent social structure would likely lower non-breeding season survival in low-density populations and therefore have implications for population viability.

We present the first nesting information for the Black Bushbird (Neoctantes niger), an enigmatic and poorly known member of the family Thamnophilidae. A hanging bulky cup nest was found in September 2011, in the buffer zone of Manu National Park, Peru. The nest contained a single white egg with scattered dark maroon spots and light streaks and was being attended by a male. The general shape of the nest resembled the deep pouch-shaped nests of other antbirds (e.g., Hypocnemis, Myrmotherula) but with clear differences in overall dimensions, thickness and amount of nesting material. More information is needed on nest architecture and breeding behavior for the Black Bushbird and all of its possible close relatives.

We report the first breeding record of the White Tern (Gygis alba) in México. We also provide notes on parental behavior of this species on Socorro Island, Revillagigedo Archipelago, México. We observed two adults feeding one nestling during the summer of 2012 at a nest located on the naval base on Socorro Island. The White Tern is considered a vagrant species in the Revillagigedo Archipelago. Although a breeding colony was mistakenly reported earlier, our report positively confirms for the first time the breeding status of this species in México

We describe an undocumented foraging strategy of the Willie Wagtail (Rhipidura leucophrys) interacting with grazing animals. This observation includes intentionally displacing a horse in order to depredate insects. Further observations of the feeding behavior and foraging tactics of wagtails are necessary to ascertain the frequency of this event in this species that has adjusted to living in cities and rural settings.

Larvae of bird blow flies are hematophagous intermittent parasites and they infect a variety of bird host species. In this study we focused on the prevalence of infestation in nests of Turdus merula in two sites with different climate. We collected 57 nests from Bratislava (Slovakia) which has a warmer climate and 37 nests from Leipzig (Germany) where there is cooler weather during the breeding season. There is no significant difference in the prevalence of infestation and in number of puparia between these two sites. The average number of infested nests was 18.68% while the average number of blow flies per nest was 10.0 ± 7.32 with 2.54 ± 1.83 larvae per nestling.