Since the first bird observatory was established over a century ago, hundreds have been established around the world. Classic observatories share a focus on capture and study of birds in the hand, particularly migrants. Many professionals were first inspired by working at a bird observatory, and researchers have long been using observatory data and facilities in collaborative studies. Results from observatories have made major contributions to knowledge of migration: timing, routes and destinations, body condition and local movement during stopover; as well as tracking long-term population change. Nonetheless, observatories are an underutilized resource for researchers, and this paper highlights the benefits they offer and opportunities for further cooperation.

We analyzed data from a woodland site for a 59-year period to determine whether changes in bird populations are related to changes in the diversity and relative abundance of woody plant species even when vegetation structure, degree of forest fragmentation in the surrounding landscape, and regional changes in bird populations are taken into account. Principal component analyses generated vegetation factors encompassing variables such as total basal area, shrub density, basal area of common tree species, and measures of tree and shrub species diversity. We also calculated a forest edge/forest area index based on GIS analysis of the landscape within 2 km of the study site. Poisson regression models revealed relationships between these covariates and population changes for 19 bird species and for seven groups of species characterized by similar migration strategies or habitat requirements. All groups of habitat specialists showed a positive relationship with the first vegetation factor, which indicates that they declined as total basal area and dominance of oaks and maples increased and as tree and shrub diversity decreased. This suggests that floristic diversity may be important for determining habitat quality. Bird species associated with the shrub layer and with hemlock stands showed positive relationships with the second vegetation factor, suggesting that the recent decline in eastern hemlocks (Tsuga canadensis) because of hemlock woolly adelgid (Adelges tsugae) had an adverse impact on these species. Forest migrants, shrub-layer specialists, long-distance migrants and permanent residents showed negative relationships with the forest edge/forest interior index, indicating that conservation efforts to protect bird communities should take the wider landscape into account. The strongest relationship for most species and species groups was with the first vegetation factor, which suggests that species composition and diversity of trees and shrubs may be especially important in determining abundance of many forest bird species.

Parent birds face a tradeoff between spending time incubating their eggs and foraging. The duration and frequency of breaks taken by incubating parents are potentially influenced by the ambient temperature, which affects both egg cooling rate and parental metabolism. We used remote temperature data loggers to obtain an extensive, continuous sample of incubation recesses, or off-bouts, taken by female Carolina Chickadees (Poecile carolinensis). We found that as ambient temperature increased, off-bout duration increased while off-bout frequency decreased. However, this relationship between ambient temperature and off-bout characteristics was not present at extremely cold or warm temperatures. Female chickadees also shortened the duration of off-bouts as embryos aged, and took fewer, longer off-bouts in the dark than during daylight. Our results suggest that the timing of off-bouts is influenced by the energetic constraints imposed by ambient temperature, although further research on nighttime incubation is needed. This study provides new information about the incubation behavior of Carolina Chickadees and helps clarify the complex influence of temperature on the balance between investment in offspring versus self-maintenance in intermittently incubating birds.

Bristle-thighed Curlews (Numenius tahitiensis, hereafter ‘curlews') breed only on low Arctic tundra in the southern Nulato Hills of the Yukon Delta National Wildlife Refuge (NWR) and on the Seward Peninsula, Alaska. Curlews use several distinct habitat types on the breeding grounds; however, quantified data of habitat use by curlews exist only for the Seward Peninsula. We investigated which available habitats on the breeding grounds were used most often by curlews in the Nulato Hills and compared availability with use to determine habitat selection using a land cover layer created in ArcGIS based on aerial photography and ground referenced locations. We also compared curlew habitat usage at our study site to habitats used on the Seward Peninsula. We used vegetation quadrats to determine plant composition within each habitat. We also determined percentage of habitat and plant composition within curlew territories. Curlews preferred shrub meadow tundra which consisted primarily of lichens (>50%), mixed with graminoid/herbaceous plants (∼13%) and few dwarf shrubs. Medium/tall shrub habitats, especially tall shrub thickets, were generally avoided by curlews on the ground, but the curlews were commonly observed flying and displaying over the shrubs. Low shrub tussock tundra and sedge wet meadows were occasionally used by curlews but not to the extent of shrub meadow tundra. The avoidance by curlews of areas with medium to tall shrubs was probably related to potential predation risks associated with reduced visibility in these habitats. Habitat selection was similar for both breeding populations of curlews, except curlews at our study site used shrub meadow tundra more frequently and low shrub tussock tundra and sedge wet meadow to a lesser degree than on the Seward Peninsula. Habitats differed in number of berry-producing plants. Berry-producing plants were predicted to be highest in the habitat curlews selected most (i.e., shrub meadow tundra); however, they were most abundant in habitats associated with tussocks.

We present field observations and genetic evidence of interspecific mate-selection and nesting resulting in successful hybridization between the Warbling Vireo (Vireo gilvus) and the Red-eyed Vireo (V. olivaceus). Two interspecific nesting pairs were found in western North America, each of which produced two fledglings. We examined the DNA of a salvaged fledgling from the nest of a mixed-species pair in Reno, Nevada, using mitochondrial and nuclear DNA analyses. The mitochondrial DNA of this individual indicated a Red-eyed Vireo mother, while its nuclear DNA was heterozygous and consistent with a hybrid origin. Phenotypic traits of the fledglings from the nest of a second mixed-species pair near Juneau, Alaska supported heterospecific parents for those offspring as well. We discuss these findings in the context of reproductive barriers that appear to result in little or no admixture across broad areas of sympatry in these two species.

Territorial systems of Neotropical birds remain poorly understood, especially considering the effect of interspecific interactions. Studies on territorial behavior provide information about demography and life history, and are useful for the refinement of conservation strategies. We assessed territories of six species of antbirds (Thamnophilidae) from August 2010 to May 2011 at Pedra Azul State Park, a protected area in southeastern Brazil, in a 30-ha sampling grid. Birds were captured, marked, and followed through the study area. Territory sizes of Plain Antvireo (Dysithamnus mentalis), Ferruginous Antbird (Drymophila ferruginea), Ochre-rumped Antbird (Drymophila ochropyga), White-bibbed Antbird (Myrmeciza loricata), White-shouldered Fire-eye (Pyriglena leucoptera), and Variable Antshrike (Thamnophilus caerulescens) were estimated by the convex polygon method. We found 46 territories of the six species. We compared and evaluated the effect of body size on territories among the species. Males and females were active in territory defense by emitting songs and calls. The mean territory sizes defended by the six species varied from 0.72–1.18 ha. We found empty spaces between territories and a high overlap rate among territories of different species, but no overlap within species. Thamnophilus caerulescens had the highest density and D. mentalis and D. ferruginea had lower densities. Body mass and distance to the forest edge had no effect on territory size. The territory assessment provided a precise density estimation of individuals in the study area.

Fraser Darling suggested that reproductive synchrony enhances reproductive success of colonial seabirds as a result of predator satiation. However, the cost of yearly reproductive synchrony is high for colonial species for which intraspecific predation is the primary cause of egg and chick loss. A few studies indicate that egg-laying synchrony on a daily time scale within the annual breeding pulse may be an adaptive response to intraspecific predation. Here, we report every-other-day clutch-initiation synchrony in densely nesting cohorts of Ring-billed Gulls (Larus delawarensis). This is the second known case of clutch-initiation synchrony on a daily time scale in larids, the first being for Glaucous-winged Gulls (L. glaucescens). In both Ring-billed Gulls and Glaucous-winged Gulls, the degree of clutch-initiation synchrony is inversely related to nearest neighbor distance. Further studies are needed to test whether clutch-initiation synchrony in Ring-billed Gulls is adaptive in the presence of cannibalism, or if it is simply a neutral byproduct of colonial nesting.

Songbirds have a high nest failure rate, with most failed nest attempts caused by predation. While songbird behavior before and during predation events has been documented, post-predation behavior has not. We observed post-predation behavior from 36 complete predation events (all fledglings or eggs taken by predator resulting in an empty nest) of nine songbird species by using video monitoring. We examined the time for the parent to abandon the empty nest and the number of return visits the parent made before abandoning the empty nest. Increased nestling age at the time of predation resulted in parents abandoning the nest sooner and making fewer return visits to the nest post-predation. There was weak evidence that parental behavior after predation differed based on the species of predator that destroyed the nest. Other post-predation behaviors included parents returning to eat eggshells, incubation of empty nests, and food provisioning. The extended time required to leave a nest after it has failed suggests birds have a compulsion that needs to be ‘switched off' prior to abandoning a nest. Why birds engage in such behaviors post-predation is unclear but indicates a lack of selection pressure to evolve an ‘immediate response' to predation. Presumably, delays in subsequent re-nesting attempts caused by such behaviors are minor but this hypothesis warrants further research.

Survival estimates for juvenile birds are rarely empirically derived and have been typically estimated as some percentage of adult survival. In particular, little information is available on survival when juveniles are independent of parental care or whether juvenile survival is sex biased. Additionally, little information is available about behaviors of juvenile birds that might be relevant to their survival. From 2010 to 2013, we radio tracked 71 independent juvenile Black-capped Vireos (Vireo atricapilla) in central Texas to estimate their survival and to quantify their behaviors. Using a known-fate model in program MARK, we calculated overall survival during the independent period to be 57% (86% for females and 28% for males). Males moved farther between consecutive locations than females and movement patterns varied substantially among individuals. Both sexes were frequently seen in association with conspecifics and heterospecifics. Half the males we tracked were observed singing, both sexes made many types of vocalizations, and the frequency of vocalizations did not differ between sexes. Whether behavioral differences contributed to survival differences between males and females will require further research. Our results indicate juvenile mortality is likely important for the population dynamics of this species and emphasize the need for studies of juvenile survival across a range of species and regions.

The genus Chlorospingus is distributed from central Mexico to northern Argentina. Despite its wide distribution, natural history information is sparse. We present the first detailed breeding biology information for C. flavigularis, plus descriptions of the nest, eggs, and other natural history information for C. parvirostris and C. flavopectus based on 26 nests monitored (22 from C. flavigularis, two from C. parvirostris, and two from C. flavopectus) in the buffer zone of Manu National Park, Cusco, Peru. Nests of C. flavigularis were bulky open-cups placed on a variety of substrates (e.g., ferns, moss). The clutch size of C. flavigularis varied between two to three eggs, but clutch size for C. flavopectus and C. parvirostris was consistently two eggs. The eggs of all three species were white with small light-brown speckles. Incubation and nestling period for C. flavigularis was 17 and 14 days, respectively, and daytime nest attentiveness was 60%. Nest architecture, clutch size, and eggs encountered for these species were consistent with previous reports for the genus Chlorospingus. More nesting behavior studies are needed to fill the knowledge gap regarding all species of Chlorospingus to help us understand nesting requirements for this cloud forest genus.

We provide the first detailed account of incubation and nesting behaviors of Carmiol's Tanagers (Chlorothraupis carmioli) based on 34 nests of the subspecies Chlorothraupis carmioli frenata found between 2008 and 2011 in Manu National Park at 400 and 1100 m above sea level. All nests were shallow cups with three layers. All nests had two white eggs with varying intensity of brown speckling. The parent spent 63.9 ± 11.6% (average ± SD) of the daylight period incubating and conducted 5.6 ± 2.3 (n = 73 days) off-bout trips per day that lasted 52.6 ± 22.9 min (n = 409 trips). The incubation period ranged from 15 to 17 days. Nestlings hatched weighing on average 4.2 ± 0.8 g (n = 8 nestlings) and gained 2.5 ± 0.1 g per day (n = 63 nestling-days). The nestling period lasted 11 days. Mass the day before fledging was 24.7 ± 2.1 g (n = 3 nestlings). Nest shape and composition, egg coloration, and clutch size of C.c frenata subspecies was very similar to the nests described for Central American subspecies C.c. carmioli. We additionally compared our results within the newly formed Habia-Chlorothraupis clade. Our results provide additional support for the phylogenetic relationship suggested by Klicka (2007) in which H. rubica is the closest relative of the Chlorothraupis genus.

Avian foraging behavior may vary among years because of changes in the abundance and availability of prey. We therefore aimed to study the foraging behavior of White-crested Elaenia (Elaenia albiceps chilensis), a Neotropical austral migrant, in relation to interannual variation in its food resources in a mixed forest of Patagonia. During two summers of contrasting rainfall patterns, we recorded foraging maneuvers, substrate use, and use of forest microhabitat (plant species and heights) where birds capture their prey. We also evaluated the abundance of the main food items consumed by this species: ripe fruit and arthropods. The first year was very rainy, when we recorded a lower supply of ripe fruits than in the second year, whereas the abundance of arthropods was similar throughout the study. During both years, the most frequent behavior of White-crested Elaenia was searching for food items while perched, capturing them from foliage using gleaning and sally-hovering maneuvers. Nevertheless, this species notably modified the use of foraging microhabitat between years. During the first year, elaenias used the canopy of the forest and foraged mainly in Nothofagus dombeyi trees, whereas in the second year elaenias used the entire profile of vegetation height and increased prey capture in shrubs of Aristotelia chilensis. Our results demonstrate the behavioral flexibility of this Neotropical austral migrant species and highlight the importance of considering the spatio-temporal variation of resources when evaluate the foraging behavior of birds.

Diet and behavior are essential aspects of ecological studies, and are even more informative if both aspects are studied together. We collected samples of feathers (n = 10 of unknown sex at Becasses Island in 2013) and of both feathers and blood at Staten Island (n = 5 males and n = 5 females in 2011 and in 2013) from Imperial shags (Phalacrocorax atriceps). In addition, GPS devices were deployed on two individuals at each location that allowed us to record one or two foraging trips each. Stable isotope composition of carbon and nitrogen in blood differed amongst years and between sexes, albeit marginally within each year at Staten Island. Feather stable isotopes of carbon and nitrogen did not differ amongst sexes or years at Staten Island and between Staten and Becasses islands to show individuals did not have significantly different diets amongst locations during pre-molt. Foraging behavior parameters did not differ between individuals as they all searched in shallow waters and close to shore. Individuals flew to their feeding grounds and searched intensively at the furthest point reached by diving interspersed with floating on the surface. These results show individuals feed on similar prey, at least during pre-molt, and would seem to behave in a similar way at both locations while breeding, though sample size is too small to generalize on their behavior. The differences in isotopic compositions amongst years for Staten Island could be showing the fluctuations that occur among seasons in the isotopic signatures of prey, and in consequence, in seabirds over time.

Parental investment is a unique balance between optimizing reproductive success and survival, yet how individuals vary their effort with respect to age and the contributions of their partner remains poorly studied. Here, we examine the provisioning of nestlings by Wood Thrushes (Hylocichla mustelina) at 38 nests in southern Indiana during the breeding season of 2013 to address the influence of adult age and sex on reproductive investment. We used video cameras to quantify an adjusted provisioning rate (provisioning rate = adult visits/hr/nestling × mean prey size × mean number of prey/visit) by individuals in both age-assortative (same age) and disassortative (different age) pairs (n = 33 pairs), hereafter referred to as pair type. Disassortative pairs delivered less prey than expected given nestling age, and sexes differed in their respective provisioning effort. In contrast, age-assortative pairs consistently provisioned more, and provisioning effort was comparable between the sexes regardless of parental age. These findings are contrary to studies where older breeders had a greater foraging efficiency and provided young with more prey. Our results indicate that adult age is not an accurate predictor of provisioning in Wood Thrushes and highlight the previously overlooked importance of age-assortative mating on parental investment in this system.

The Alder (Empidonax alnorum) and Willow (E. trailli) flycatchers are cryptic species, and their distribution outside the breeding season is poorly known, owing mostly to identification difficulties. Our new records suggest that large numbers of Alder Flycatchers overwinter in rivers crossing the Chaco region and in the foothill forests of the Yungas of Argentina, significantly increasing their southern wintering range. Records in northern Argentina span 3 November to 23 March. Key habitat for overwintering Alder Flycatchers in Argentina included stands of palo bobo (Tessaria integrifolia) along the Río Bermejo and tributaries, either in association with sparse shrubs of chilca (Baccharis salicifolia) or more rarely with canebrake (Gynerium sagittatum). Other habitats used were old shrubby ‘madrejones' with Tessaria scrub and sacha café (Sesbania virgata), very dense Baccharis salicifolia scrub next to flowing creeks in foothill Yungas and dry Chaco, and riparian forests dominated by palo flojo (Albizia inundata) and timbó (Enterolobium contortisiliquum). Seasonal flooding of these habitats did not affect the presence of Alder Flycatchers. Small territories of c. 20 × 20 or 25 × 25 m were defended in Tessaria stands. Alder Flycatchers fed mostly on insects in flight (aerial hawking), but also on green Lepidoptera larvae (upward sally-strikes), and on insects on leaves, and ripe fruits of tala (Celtis cf. ehrenbergiana) in forest understory (clinging). Vocalizations given by overwintering birds (fee-bee-oo, zwee-oo, wee-oo, churr, pit, double-peak, and kitter) were similar to those used while breeding. Alder Flycatchers collected in Argentina had significantly longer wings and wider bills than specimens from the sympatric Euler's Flycatchers (Lathrotriccus euleri) from Argentina with which it has been confused in museum specimens.

Populations of the Eastern Whip-poor-will (Antrostomus vociferus) are thought to be declining because of a range of potential factors including habitat loss, pesticide use, and predation. However, this species is nocturnal and, as a consequence, it is poorly studied, and its population status is not well assessed by traditional diurnal bird surveys. We used nocturnal road surveys to study habitat associations and distribution of Eastern Whip-poor-wills to better understand and contextualize their population status and to provide a framework for subsequent research and management. We used occupancy models to associate presence of Eastern Whip-poor-wills with habitat characteristics. Global models with habitat associations at a radius of 1600 m (1.0-ha area) were the best supported by the data, suggesting that this was the scale at which the species responded to the habitat parameters we measured. At this scale, Eastern Whip-poor-wills most frequently occupied areas lower in elevation and characterized by forested, herbaceous, and wetland cover types. In contrast, high elevation conifer forest communities had substantially fewer Eastern Whip-poor-wills. Detection rates were positively correlated with moon visibility and negatively correlated with noise. We used the results of our surveys to generate a regional model to predict distributions of Eastern Whip-poor-wills and that can be used as a framework for future management. Our results suggest that succession of agricultural fields and other clearings into forested habitats with dense understory may be a contributing factor to ongoing declines of Eastern Whip-poor-wills.

The North Island Brown Kiwi (Apteryx mantelli) is a nocturnal endangered species endemic to New Zealand. The protection of suitable habitat is key to the species' recovery; however, little is known about their habitat requirements. We studied the diurnal roosting behaviours of kiwis by intensely tracking 41 radio-tagged, non-breeding adults from May 2010 to February 2012 on Ponui Island, New Zealand. From these birds, we collected 3,997 roosting locations in three different macro-habitat types (scrub, forest, and swamp) and described 223 roosting burrows in the forest macro-habitat. Overall, we discovered that kiwis were roosting generalists; three quarters of the study population was found in more than one macro-habitat and just 5% used only a single type of micro-habitat. However, using compositional analyses, we found that they did show some clear preferences. On a macro-habitat level, kiwis preferred forest habitat over scrub or swamp. Furthermore, on a micro-habitat level, they preferred roosting inside trees, either living or dead, and holes in the ground over roosting in decomposing vegetation or holes associated with creeks. The least preferred micro-habitat type consisted of overhangs produced by ground slips. Kiwis were most likely to use long burrows with small entrances that were oriented downhill. Our findings suggest that priority should be given to protecting mixed landscapes with large, mature, dynamic native forests.

Adult Rough-legged Hawks (Buteo lagopus) are depicted and described in bird guides and handbooks as sexually dimorphic in plumage, although several authorities have reported that the sexes overlap in plumage. We examined photographs of 106 adult and Basic III Rough-legged Hawks that had been captured and measured, and more than 200 museum specimens to assess sexual dimorphism in five plumage characters and in wing chords. On the basis of museum specimens with gonad information on their labels, the sexes are distinguishable by wing chord, which is >420 mm in females and <418 in males. Most light-morph adults have the plumage of their sex as described in field guides and handbooks, but a few appear like the other sex. Gray barring on the back feathers and barring on the flanks (present in males, absent in females) are the best plumage indicators of the sex of birds in Definitive and Basic III plumages. Tail pattern was the most shared character and is not a reliable indicator of adults' sex.

The Speckled Rail (Coturnicops notatus) is one of the least known Neotropical birds. Despite the ongoing debate if its rarity is genuine or related to detection problems, its conservation status has been recurrently assessed as “least-concern.” Absence of voice recordings and thorough voice descriptions are the major limitations in determining its distribution and population size, which may bias the assessment of its conservation status. We present the first voice analyses of this species and two new records for southeastern South America based on individuals received by a wildlife rehabilitation center in southern Brazil. The first individual was found aboard a ship traveling from Uruguay to the Brazilian port of Rio Grande in October 2007, and the second was found in the Brazilian city of Pelotas in August 2015. At least three different types of voices of the latter individual were recorded and analyzed, all of which differ in pitch, timbre, and structure from the voices of other South American rails and crakes. One of these voices apparently is a contact call, the other a distress sound, and the third may be a form of territorial advertisement. Our recordings, voice analysis, and descriptions may help locate individuals in the field and increase our knowledge about this mysterious wetland bird.

I used 20 years of nest records and predation at silent control and begging-call playback nests to determine whether begging calls of Red-winged Blackbirds (Agelaius phoeniceus) attract predators. Survival analysis provided no evidence that vocal begging affected nest predation. Survival schedules during egg and nestling periods were not significantly different, and vocal begging activity was not significantly correlated with daily nest survival. I found that predation at 35 no-longer-active nests at which begging calls were played at natural volume, at a typical rate, and following a normal schedule was slightly but not significantly higher than at 35 silent control nests. Selection may have favored adaptations of nestling Red-winged Blackbirds' begging calls that reduce the risk of predation.

The Solitary Tinamou (Tinamus solitarius) is endemic to the Atlantic Forest. Little information is available about this bird species because of its low conservation priority and cryptic habits. Hunting and habitat loss are the main threats to the species, which is regionally threatened in southern and southeastern Brazil. We used camera traps installed along unpaved roads, at edges with roads, and in the forest interior in one of the last large remnants of the lowland Brazilian Atlantic Forest in southeastern Brazil to determine daily and seasonal activity patterns of the Solitary Tinamou. We obtained 256 records between June 2005 and December 2013 (sampling effort = 14,316 cameras-day). Solitary Tinamous were mainly observed away from roads, confirming the tendency of the species to occur more frequently in areas with greater canopy cover. Our data confirmed that photoperiod may influence daily activity patterns of the Solitary Tinamou, as the duration of daylight differs among the seasons. The species showed a total of 16 hrs of daily activity during the wet season with two main activity peaks during the day (0500 and 1800) and an intervening smaller peak (1300). During the dry season, the species showed a shorter duration of daily activity (13 hrs), and the activity peaks occurred either 2 hrs later or 1 hr earlier. Despite the difference in daily activity patterns between seasons, the number of records obtained was proportional to the sampling effort at each season, and the records were not correlated with climatic variables. The species was most often recorded between August and January, a time span that coincided with its reproductive period. It was less often recorded between March and May, a finding that could be related to the timing of the post-nuptial molting period. Our data serve to enhance current knowledge of activity patterns of T. solitarius and may be used in future studies relating temporal niche partitioning by the Solitary Tinamou with other frugivores or between the species and its predators.

Nest reuse is a common phenomenon in many passerine and non-passerine birds species. Although interspecific nest reuse has been reported in many African species, it is rare in passerines that nest in open, cup-shaped nests. Here, I report on interspecific nest reuse in larks (Alaudidae), specifically of a pair of Chestnut-backed Sparrow-larks Eremopterix leucotis using a nest previously occupied by Pink-billed Larks Spizocorys conirostris. It is possible that the Chestnut-backed Sparrow-larks selected a nest site in an area where predation seemed low as there were other successful nests or nests with nestlings in the near vicinity. The interspecific nest reuse reported here suggests opportunistic occupation of a previously used nest while at the same time saving the pair some energy during a period of peak activity and high energetic demands.

Destruction of conspecific and heterospecific eggs and nestlings occurs in several species of passerines. Two main hypotheses have been proposed to explain the adaptiveness of this behavior: as a mechanism to avoid competition or to gain access to reproductive opportunities. In Colombia, Southern House Wrens (Troglodytes aedon musculus) broke eggs and/or killed nestlings of Spectacled Parrotlets (Forpus conspicillatus, 24 cases), Apical Flycatcher (Myiarchis apicalis, one case) and of other House Wrens (four cases). Wrens attacked parrotlet nests in three contexts: 1) wrens took over and used a parrotlet nestbox within their territory, 2) wrens with an active nest attacked a neighboring parrotlet nest, or 3) the attacker was unknown but was inferred to be a wren. Wrens also attacked trial nests with natural and artificial wren eggs that were placed near active wren nests. These observations suggest that infanticidal behavior by wrens at this locality may be driven by competition for nest sites. In contrast, infanticide by House Wrens in Panama has been related to territorial takeover and mate replacement. The context and causes of infanticidal behavior are spatially and temporally variable, both within and between species.

The Great Rufous Woodcreeper (Xiphocolaptes major) feeds mostly on arthropods, but includes small vertebrates such as amphibians and reptiles in its diet, as well as eggs and nestlings of other songbirds. There are a few records of bats in the diet of the Great Rufous Woodcreeper, but it is not known how commonly they consume bats. During fieldwork in the Brazilian Pantanal, we recorded a Great Rufous Woodcreeper preying on a lesser bulldog bat (Noctilio albiventris). After striking the bat, the woodcreeper ingested thin strips of the prey's flesh. The use of tree cavities by the bats and Great Rufous Woodcreeper in the Pantanal may increase the chance of encounters between woodcreepers and bats, and suggests that this kind of predation event involving these two groups may be more common than reported.

In spite of recent developments in tracking technology, leg bands are still the main marking method in songbird population studies. Yet, band-related injury rates and the effects of such injuries on survival and reproductive success have rarely been documented in songbirds. Over a 9-year period, we banded 525 male Ovenbirds using a numbered aluminum band and three celluloid color bands. Of these, 322 individuals returned to our study area in at least one of the subsequent years, including four males (1.2%) missing a foot. In all cases, foot loss occurred 2–3 years after banding, suggesting indirect effects of bands rather than injuries sustained at the time of capture or banding. Among returning individuals, 91 were recaptured and only one had noticeable leg injuries that did not result in foot loss. Three of the four males missing a foot were able to fledge young, one of which produced young during two successive breeding seasons. The fact that injured males could hold territories overlapping their previous one and produce young suggests that they could forage efficiently. Although leg injuries may carry a cost over the longer term, two of the four injured males were re-sighted in our study area the year following the first observation of foot loss. Our results, along with those of other studies, suggest that the benefits of bird banding greatly outweigh the costs associated with potential injuries, at least in this ground-foraging forest songbird.

We documented an occurrence of infanticide on a young nestling Florida Grasshopper Sparrow (Ammodramus savannarum floridanus) while conducting a nest camera study on this critically endangered songbird in south-central Florida. The live nestling was removed from the nest by an adult and died on the ground within 5 hrs of eviction. We suspect that this was a case of parental infanticide based on the behaviors of the infanticidal adult, which were consistent with the breeding female at this nest. The adaptive or nonadaptive motivations for the deliberate eviction of a live nestling remain unknown. This is the first report of infanticide in the Grasshopper Sparrow and the genus Ammodramus.

We observed a fledgling abandonment and adoption event that subsequently led to an extended period of interspecific parental care between a male Black-and-white Warbler (Mniotilta varia) and two radio-tagged fledgling Golden-winged Warbler (Vermivora chrysoptera) siblings. Both fledglings were initially accompanied by their maternal Golden-winged Warbler until 5 and 9 days after fledging. At this time, a male Black-and-white Warbler began feeding both fledglings, and maternal care ceased. In the 23 days we monitored the fledglings between onset of interspecific feeding and independence, the male Black-and-white Warbler was observed with at least one of the fledglings on 20 of those occasions. Furthermore, the Black-and-white Warbler was seen feeding at least one of the fledglings on 16 of those visits. We photographed several feeding events. The Black-and-white Warbler remained with the fledglings until they successfully reached independence 28 days post-fledging.

Animals occupying human-dominated environments show the capacity for behavioral flexibility. Corvids are among the most intelligent synanthropic bird species. During a layover at Schipol Airport in Amsterdam, Netherlands, I photographically documented Eurasian Jackdaws (Corvus monedula) perching upside down from a building cornice. In contrast to other reports of hanging birds, these jackdaws did not forage or play while upside down and appeared to use the perching spot to observe their surroundings. Although Corvids and Psittacines are known to hang upside down, especially in captive situations, such behaviors are rarely documented in the wild, and never before in association with human-built structures.

Aberrations of plumage coloration are caused by hereditary and environmental factors and are not rare in wild birds, but few studies have estimated their frequency in natural populations. Here, we provide the first report of a white plumage aberration in an insular population of the White-necked Thrush (Turdus albicollis) on Ilha Grande, in southern Rio de Janeiro state, Brazil. Four (two males and two females) of the 123 individuals examined in 2013–2015 presented unusual white feathers on some part of the body (especially the hindneck), which may represent progressive graying or the result of injury. The frequency of the white plumage aberration recorded in our study (3.25%) is approximately three times higher than that expected in natural bird populations, and three of the four aberrant individuals were captured in the most disturbed forest site sampled. Further studies will be necessary to identify the true causes of the high frequency of white plumage aberrations detected in the study population, which may include diet, longevity, behavior, parasitism or other environmental factors.

The Bobolink (Dolichonyx oryzivorus) is the only landbird species that is known to stop every year in Galapagos while migrating; however, its stopover ecology while on the islands is unknown. In October 2015, we searched for and captured Bobolinks in the highlands of San Cristóbal. We found Bobolinks in two fields, separated by 9.15 km, at ∼425 m elevation. Average daily counts of Bobolinks on these two fields were 3.2 ± 1.8 and 4.8 ± 2.3 individuals. We caught nine individuals; body mass and fat reserves varied from 22.5–40.0 g and no fat reserves to 50–100% reserves, respectively. Both fields were dominated by grasses ranging in height from 30 cm to >100 cm, and included purple cuphea (Cuphea sp.). Other habitats we surveyed, where we did not observe Bobolinks, included closely cropped grass (5–10 cm), taller grasses with seed and with scattered to dense guava trees (Psidium guajava), and small (0.1–0.3 ha) corn plantations with seed. Six of the birds we caught had seeds of Drymaria cordata entwined in their feathers; while native to the Galapagos, this plant is highly invasive in other parts of the world.

Foreign objects have been observed in nests of ground nesting birds and have included such items as stones, driftwood, mammalian bones, and bottles. We discovered an American Oystercatcher (Haematopus palliatus) nest scrape containing a single, oblong stone while we were monitoring the nesting species from March to July 2015 off the coast of Citrus County, Florida. We report our observations of a pair of American Oystercatchers incubating this stone and discuss possible explanations for its presence in a nest scrape.