The Atlantic Lesser Frigatebird (Fregata trinitatis) is elevated to a separate species from Fregata ariel of the Indo-Pacific based on plumage differences and greater robustness of the rostrum and wing bones. The species now occurs only on the remote South Atlantic island of Trindade (South Trinidad) over 1,100 km east of mainland Brazil, although fossils establish that it once also occurred at St. Helena. Fregata trinitatis no longer breeds on the main island of Trindade and is only known to nest with certainty on a small rocky islet on the southern coast, where there may be fewer than 20 breeding pairs.

We report new observational and specimen data on the avifauna of Kolombangara, Western Province, Solomon Islands. These data, collected from 3–9 October 1974 and 13–21 May 2004, and supplemented with more recent observations, represent the first comprehensive survey of this globally significant island since 1927. All encounters of montane species are reported along with select species accounts for notable lower-elevation species. Numerous observations presented here suggest avifauna even more unique than previously reported. For example, we confirm a probable resident form of Peregrine Falcon (Falco peregrinus) and report the first observations and collected materials for a Blue-faced Parrotfinch (Erythrura trichroa) from Kolombangara. We observed all of the island's high-elevation endemics and found their relative abundances and patterns of occurrence to be consistent with those of an intact montane avifauna. Our findings suggest that despite large-scale modification of lowland habitat, montane forests on Kolombangara still maintain the full complement of endemic and other high elevation species described nearly 100 years ago, along with several additional taxa not previously recorded. However, incidental evidence suggests that forest change in the lowlands is impacting montane microclimates as indicated by extensive drying of epiphytic mosses at high elevations. Along with more recent collection of undescribed anurans, these findings confirm the global conservation significance of the montane forests and biodiversity on Kolombangara.

We studied the relationship between song repertoire size, territorial behavior, and nesting success in Pied Bush Chat (Saxicola caprata) in Haridwar (Himalayan foothills), India for three consecutive years (2013–2015). Our findings indicate song repertoire size is correlated with nesting success, but pre-nesting territory size, average territory size, and territorial conflicts are independent of song repertoire size. It may be inferred that larger territories are not necessarily better territories. The findings suggest that larger territory size is more susceptible to increased territorial conflict. Significant differences were apparent between territory size and territorial conflicts in the different stages of the nesting cycle. The findings suggest that larger territory size is more susceptible to increased territorial conflict. We propose that even if territorial conflicts are independent of song repertoire size, the amount of territorial conflict may be constrained by the stage of nesting cycle or size of the territory. Depending upon breeding requirements, male Pied Bush Chats tailor their territory sizes and territorial conflicts during the course of the breeding season.

We investigated singing patterns of Pied Bush Chats across years and nesting cycles. We recorded the seasonal singing activity of 25 males in their natural habitats in Haridwar, Himalayan foothills, India for three consecutive years. The vocal patterns, especially song repertoire size of males, remained largely constant, and this restricted annual variation suggests that the Pied Bush Chats are closed-end learners. Analysis of song bouts during different stages of the nesting cycle and across years indicates that the Pied Bush Chat is an immediate variety singer. The song output in terms of song complexity, song rate, song bout length, and percentage performance time was highest at the beginning of egg laying and during incubation compared to pre-nesting, nest building, and provisioning stages. Such singing peaks with respect to different stages of the nesting cycle indicated mate guarding by male Pied Bush Chats and announcement of fertility status of the guarded female.

It is often assumed that passerine birds conceal nests to reduce predation because nest predation is usually the primary cause of reproductive failure. We hypothesized that nesting success would be higher in nest cavities with more concealed entrances and therefore more likely chosen over less concealed cavities. We set 200 nest boxes in ∼100 territories of White-rumped Shamas (Copsychus malabaricus), territorial cavity nesters, in a seasonal evergreen forest in northeastern Thailand. Shamas were provided two boxes per territory, one with high and the other with low vegetation cover in front of the box entrance. Boxes were reset in new locations after a nest fledged or failed, providing 170 ‘choice' trials. We also compared vegetation characteristics of natural nest cavities with available natural nest cavities. Contrary to predictions, shamas placed nest material in the less concealed boxes significantly more often (89 boxes vs. 48), were significantly more likely to lay eggs in less concealed boxes (66 vs. 27), and eggs were significantly more likely to hatch in the low concealment treatment (38 vs. 8). Nest survival in the low concealment treatment was approximately twice that of the highly concealed boxes 36% (± 0.035) vs. 18% (± 0.042). Vegetation around natural nests (n = 26) was not significantly different from available randomly selected cavities (n = 52). Both used and available cavities had low levels of concealment. Cavity-nesting species may prefer less concealed sites because it is easier for an incubating/brooding female to detect approaching predators, allowing additional time for escaping and/or for mounting a defense.

Studies of geographic range shifts in response to climate warming that use data from Christmas Bird Counts or repeated state and provincial faunal atlases are better at detecting latitudinal shifts than altitudinal shifts because the coarse geographic scale of most citizen-science survey units masks the substantial elevational variation within their boundaries. To more directly measure altitudinal range shifts of forest-breeding bird species, we repeated an altitudinal transect survey conducted 40 years ago at Whiteface Mountain in the Adirondacks, New York, USA. We conducted roadside bird surveys at dawn and dusk at seven survey stations that ranged in altitude from 500 m to 1,425 m. We found considerable interspecific variation in the movement of altitudinal ranges, but document a preponderance of uphill shifts in both upper and lower boundaries of altitudinal breeding ranges. The shift of abundance-weighted mean altitudes for 42 species detected in both survey periods was 82.8 m. These shifts are correlated with a regional trend toward warmer summers from Adirondack weather station data collected over this same time period. Upper range boundaries have shifted more than lower boundaries, resulting in novel bird communities at some elevations (e.g., we found 13 species at 1,425 m vs 7 species at this altitude in 1974), resulting in a flattening of the altitudinal gradient of species richness. At low elevations we encountered several species that were not recorded on the transect in 1974, a trend we attribute to climate warming and anthropogenic habitat change at low altitudes. Our resurvey shows that there have been substantial upward range shifts in most bird species on Whiteface Mountain in the last four decades, and provides a basis for reassessment of altitudinal range dynamics at the southern edge of the North American boreal forest in the coming decades.

Habitat quality can have a profound effect on the condition and fitness of individual birds and on population demography. We investigated the effects of habitat metrics (invertebrate abundance and habitat type) on the condition (egg mass, adult mass, pre-fledged chick growth rates) of Piping Plovers (Charadrius melodus) nesting on Missouri River sandbars from 2005–2014. The amount of breeding habitat for Piping Plovers was variable throughout our study with more habitat available after flooding occurred in 2011. In addition, increased demographic rates (e.g., reproductive output, hatch year survival, and population growth) were observed in the post-flood period. We hypothesized that the condition of individuals would be related to habitat quality and that increased demographic rates observed on the Missouri River sandbars throughout the post-flood period would, at least in part, be related to increased condition. Egg mass, pre-fledged chick growth rates, and invertebrate prey abundance had similar trends, indicating that prey abundance was related to individual condition. This was especially true as the post-flood habitat aged. However, we found there was no difference in the condition of individuals on pre- and post-flood habitat types, suggesting that the condition of individuals did not appear to contribute directly to increased demographic rates during the post-flood period. Although the demographic effects of the flood-created habitat were positive for plovers, it is important to understand the effects of habitat on the condition of individuals, and the short- and long-term consequences of these effects that may ultimately contribute to demography.

Monitoring and conserving waterbirds, including Sora (Porzana carolina), in Missouri, is constrained by the lack of information on migration phenology. We performed nocturnal distance sampling surveys by ATV across 11 state and federal managed wetlands in Missouri, USA from 2012–2015 to compare the timing of Sora' autumn migration among years. Migration of Sora in Missouri began in the first week of August, on average it peaked on 25 September, and continued through the last week of October. We detected migration of Sora earlier in autumn than did previous work. We found the start and end of migration did not vary annually in 3 of 4 years. With our results, wetland managers should be able to better time their management for rails in Missouri.

The Horned Guan (Oreophasis derbianus) is endemic to humid montane forests of southern Mexico and Guatemala. This species is considered endangered because of their small populations, the loss and fragmentation of habitat, illegal trade, and overexploitation by subsistence hunters. We update information about the species' diet and foraging behavior by integrating the results generated during two and a half decades of research on the Horned Guan's ecology at the El Triunfo Biosphere Reserve, in Chiapas, Mexico, with additional published information compiled from other areas. Based on nearly 450 hrs of direct observations of free-ranging guans and 530 discrete feeding events, we found that during the breeding season Horned Guans feed primarily on fruits from six species of plants and leaves from one species. Horned Guans were not observed eating animal matter, corroborating its specialized frugivore-folivore habits. Our study increases the known plant taxa found in the Horned Guan's diet in El Triunfo from 40 to 63 ( Supplemental Material ()), and globally to 101 species ( Supplemental Material ()). For 48 taxa in El Triunfo, only fruits were consumed, while for eleven taxa consumption was restricted to leaves, and to flowers for one species; for four taxa both fruits and leaves were consumed. We found significant differences between males and females in the location of foraging on trees and diet composition. Young birds are fed fruits of Citharexylum mocinnii and leaves of Solanum appendiculatum by their mothers, both of which are rare in the diet of adult males. The conservation of the Horned Guan requires the long-term protection of suitable habitat that maintains the plant species important in their diet.

Diet studies provide information about a species' ecology, evolution, and behavior. The Araripe Manakin (Antilophia bokermanni) is a critically endangered, endemic, and sexually dichromatic species from northeastern Brazil. Little is known about its natural history, and as an endangered bird, information about diet may be crucial for conservation plans. We analyzed the diet of Araripe Manakins and tested if food items and foraging behavior differed for males and females. We caught and banded birds, and analyzed fecal samples. Using focal observations, we collected foraging behavioral data, including vegetation strata used, foraging bout duration and gathering method. Based on data gathered from 40 females and 54 males, we found that the Araripe Manakins' diet contains both plant and animal items including 10 different types of fruits and three orders of invertebrates. Clidemia biserrata was the most important plant item consumed, representing 80% of the diet. There was a substantial overlap of 68% of food items in the diets between sexes, which did not differ statistically. However, male and female diets were unique in some aspects: females consumed more items having a more diverse diet when compared to males. Males, however, consumed more Coleoptera, and these were the second most important item in their diets. Since male and female foraging behavior does not differ, this result suggests that males choose to consume more beetles perhaps to maintain plumage color, since beetles are rich in carotenoids. Results also provide important data about which plants can be used in the management or recovery of Araripe Manakins' habitats.

The United States Department of Defense (DoD) has a dual mission of maintaining military readiness and stewardship of its natural resources. The DoD invests more than $334 million on land and species management on their properties, which support high levels of biodiversity and harbor a disproportionate number of threatened, endangered, and at-risk species. The gopher tortoise (Gopherus polyphemus) occurs on 28 DoD installations in the southeastern United States. Because more than 350 species have been documented to use their burrows, the gopher tortoise is considered a keystone species. However, few species of birds have previously been documented as burrow associates. In this study, we compare bird species richness, visitation frequency, and behaviors at gopher tortoise burrows at two Department of Navy properties (Santa Rosa County, Florida) that differed in size, training intensity, habitat diversity, and proportion of habitat suitable for gopher tortoises. We detected a total of 33 species of birds and documented previously unreported behaviors of foraging, dust bathing, and wing-flashing display behaviors at tortoise burrows. Although species richness between sites was not significantly different, frequency of visitation was greater at the site with less military training activity. Our findings underscore the importance of even small military installations in supporting local biodiversity and the need to further explore gopher tortoise burrows as a potential resource for avifauna.

Information on reproductive biology is limited for many tropical birds, despite the importance of these data in areas such as ecology, taxonomy, and conservation. Hafferia zeledoni belongs to the Thamnophilidae family and was only recently elevated to the species level, and consequently little is known about its ecology and natural history. We found and monitored a dome-shaped nest of this species during 30 days. It was located on a steep slope in a sub-Andean forest, and both male and female participated in the incubation and care of nestlings. Night incubation was only performed by the female, and even though she also incubated during day, it was the male who spent more time on the nest during that period. The eggs were white with reddish blotches, and they measured on average 27.8 ± 1.2 × 19.7 ± 0.1 mm and weighed 5.84 ± 0.17 g. The two nestlings were naked with black skin and weighed 5.64 and 5.60 g at hatching, increasing to 28.61 and 31.60 g prior to fledging. We monitored the incubation behavior during 17 days, and the nestling period lasted 14 days. We compared our results with other members of the longipes clade finding similarities that support the newly established phylogenetic relationships. Our study provides the first description of the nest, nestlings, and incubation behavior of Hafferia zeledoni, and it provides new information on nest architecture that supports the dome nest radiation in this clade.

The genus Hylophilus sensu lato was recently recognized as polyphyletic and split in to several genera, including the monotypic genus Tunchiornis. We describe in detail the nesting features of T. ochraceiceps that could provide additional evidence to support the split of the genus. Nests were found at two stations in southwestern Perú, Manu National Park. We found three cup-nests covered externally with green moss and internally with thin and light straw fibers, with inner and outer major and minor axes of 48.6 × 49.2 mm and 66.6 × 61 mm, respectively, a wall thickness of 9.8 mm, and an inner depth of 38.7 mm. The eggs were creamy-white with dark-brown spots concentrated at the base and measured 18.3 ± 0.4 × 13.1 ± 0.3 mm with a mass of 1.73 ± 0.12 g. Overall nest attentiveness was 64% and the egg were incubated at 32.35 ± 3.11 °C. The incubation and nestling period lasted 15 and 11 days, respectively. The nest materials used by Tunchiornis are similar to Hylophilus but differ from Pachysylvia, which use dried leaves and bark. These results advance our understanding of the reproductive biology of this phylogenetically divergent group.

There is limited information on the breeding biology of members of the speciose genus Hemitriccus (Aves: Tyrannidae), published nest descriptions exist for only six of the 22 species. The Black-throated Tody-Tyrant (Hemitriccus granadensis) is one of these species that lacks information regarding its nesting biology. We provide the first nest, egg, nestling, and incubation behavior descriptions for the species with notes on its courtship behavior. We found three nests and observed one courtship display at three field sites, two in Colombia and one in Peru. The nest of H. granadensis is an enclosed “purse-like” pendant pouch inside of a moss ball suspended from a small branch with a side entrance and obscured by vegetation. Two nests had a single egg, which averaged 18.1 × 12.9 mm and 1.55 g. Egg appearance varied between nests, the egg at the Colombian site was tan and unmarked, whereas the egg at the Peruvian site was bright white with a few scattered, red specks. We cannot describe the full incubation period or nestling period because of egg infertility and nestling death. However, one nest was discovered with an egg that was incubated for 19 days. Nest attentiveness was 77.5% and average inner nest temperature differed between the Colombian (±SD) (23.79 ± 1.5°C) and Peruvian (17.27 ± 1.54°C) nests. We provide observations and video footage of the courtship display that match previous observations of this species. Overall, the nest shape resembles those of other Hemitriccus species, but clutch size differs from information published for the genus.

Historically, the genus Schiffornis has been placed in different families; currently, it is placed within the Tityridae family. Our study focuses on Schiffornis stenorhyncha, recently split from Schiffornis turdina. S. stenorhyncha inhabits lowland humid forests in some regions of Panama, Colombia, and Venezuela. Based on one nest found at the foothills of the Magdalena Valley in Colombia during one field season in 2014, we provide the first nest description for S. stenorhyncha. We describe the cup-shaped nest (internal length and width: 22.9 and 18.1 mm, thickness of the nest wall: 30 mm, cup depth: 56.6 mm, external length, width, and height: 139.4 mm, 144.2 mm, 115.7 mm) and the light cream with dark purple spotted eggs (two eggs with average measures of 18.3 × 23.2 mm and 4.49 g) of S. stenorhyncha and present nesting information including nestling descriptions, incubation, and nestling periods (21 and 20 days, respectively), and nest attentiveness information in different stages of the nest (4.72 trips a day during incubation and 1.25 trips per hour during the nestling stage). We compare our findings with other Schiffornis species and related species in the Tityridae family.

Disturbance because of human activity, including recreation on wildlands, can affect bird behavior which in turn can reduce breeding success, an important consideration for species of management concern. We observed Golden Eagles (Aquila chrysaetos) during the breeding season to determine whether the probability of flushing was affected by the type of recreationist, distance to encounter, eagle nest attendance, or date. We monitored eagles in 23 nesting territories from distant (600–1,200 m) observation points and recorded recreation activity within 1,200 m of eagles in the Owyhee Front of southwestern Idaho. In most (86%, n = 270) encounters, eagles did not flush in response to recreationists; however, whether an eagle flushed was affected by the type of recreationist and whether an eagle was at or away from the nest. Eagles were 60 times more likely to flush in response to recreationists that stopped a motor vehicle and transitioned to walking (11 of 17 passes) and 4.5 times more likely to flush in response to off-road vehicle (ORV) riders (17 of 121 passes) than during encounters with road vehicles (7 of 107 passes). Flushing was 12 times more likely for eagles away from nests (23 of 87 passes) than eagles at nests (13 of 183 passes). Eagles flushed at greater distances in response to recreationists that transitioned from motor vehicles to walking (lsmean = 620 m) than when responding to either ORV riders (lsmean = 525 m) or road vehicles (lsmean = 318 m). Flushing distances tended to decline throughout the breeding season to suggest seasonal changes in the costs and benefits of responding to disturbance. After flushing from nests, most eagles (77%) spent <40 mins away, but some (23%) spent >90 mins away from nests. Limiting recreational activities within 650 m and 1,000 m of nest sites may decrease nest-site flushing events by 77% and 100%, respectively. Because eagles seem most sensitive to humans transitioning between motorized and non-motorized recreation, land managers may strike a balance between access needs of recreationists and buffering eagles from disturbance by using a mix of trail closures and no-stopping zones that prevent transitions from motorized to walking activities.

Understanding sex-specific differences in behavior and survival is essential for informative population modeling and evolutionary biology in animal populations. Uneven sex ratios are common in many migrant passerine species; however, the underlying mechanisms remain unclear. We used molecular sex determination, nest monitoring, and radio telemetry of fledgling Ovenbirds (Seiurus aurocapilla), to determine if sex-specific patterns of production, survival or behavior were present prior to the first migration. We tested whether: 1) sex ratios were skewed towards males at fledging; 2) postfledging survival of males was higher than females; 3) distances moved over time were equal between sexes; and 4) if observed parental care was equal between sexes over time. We determined the sex of 33 hatch-year Ovenbirds in central Missouri in 2015 and followed 19 individuals using radio telemetry. We found no difference in sex ratios within broods, overall numbers of male (n = 18) and female (n = 15) nestlings, or in the survival of male (n = 8) and female (n = 11) fledglings followed with radio telemetry. However, we did find that sex affected the relationship between age and distance moved from the nest, suggesting females moved further from the natal site after independence from adults. These results provide a better understanding of postfledging ecology and support the common assumption that annual production of females is half of total productivity, a fundamental premise in most population growth models.

Understanding natal dispersal and rates of philopatry can help provide minimum estimates of juvenile survival, a vital demographic parameter for which little information is available. However, despite the large number of hatch-year migratory birds banded every year at their natal sites, few are resighted or recaptured. Here, we report on the return of 22 Swainson's Warblers (Limnothlypis swainsonii) banded as nestlings or fledglings between 1997–2008 at breeding sites in Arkansas, North Carolina, and South Carolina, USA. Of 284 nestling Swainson's Warblers banded, we found 13 (4.6%) exhibiting natal philopatry. Of 95 fledglings banded, we detected 9 (9.5%) in later years. The median distance moved from the original capture to an encounter location the subsequent breeding season for all second-year birds we detected was 1.5 km (range = 54 m to 15.4 km). The mark-recapture estimate for first-year apparent survival was 0.119 (SE = 0.032). Estimated recapture probability was between 0.55 and 0.65. Only one returning juvenile we detected was female. Assuming a 50:50 sex ratio, the annual apparent (i.e., minimum) survival estimate for first-year males was 0.238. Body mass, wing size, and banding date were not good predictors of whether a juvenile would return to the site the following year, and there was no evidence of differences among study sites. Because land use and hydrology limits suitable habitat, Swainson's Warbler populations at our study sites were mostly isolated from other suitable habitats and populations; thus, individuals of this species may benefit from natal philopatry more than most passerines.

The use of song by wood-warblers (Parulidae) with multiple song types has received little attention during migration. On the breeding area, the two song types serve to attract mates and defend territory, but the function(s) during migration, if any, are unclear. I studied the singing of Townsend's Warblers (Setophaga townsendi) during spring migration through southern Oregon and northern California. Males preferentially used Type II songs (79%) whether alone or in flocks of up to ∼20 individuals. Type I songs of wood-warblers tend to be acquired early in the hatch year while Type II songs appear to be subject to modification over an extended period of time. The preference for Type II songs in migration may reflect an important period in the development of Type II song. More than one dialect of Type I song was recorded within flocks indicating that flocks were composed of individuals from different breeding populations. Type II songs are recognizably similar in breeding populations from central Oregon to Alaska. The similarity of Type II songs across the range of the species may result from song refinement through interaction with other singing males while in transit.

The American Golden-Plover (Pluvialis dominica), a species of conservation concern, uses large agricultural fields during its spring passage through the mid-western United States. In west-central Indiana, large numbers of golden-plovers make a stopover in corn or soybean fields that were harvested the previous fall. Stopovers last for a number of days during which the birds feed and molt into alternate plumage. In recent years, wind energy facilities have been developed in the area with hundreds of wind turbines erected in fields used by the golden-plovers. During spring 2011 and 2012, we investigated patterns of golden-plover behavior at these facilities in Benton County, Indiana at a site where large spring aggregations of plovers have been observed for many years. Our results showed only limited behavioral avoidance of the turbines, and suggested that wind-energy development in this area was not significantly impacting migrant golden-plovers. However, we caution that additional studies could negate these somewhat tentative findings, and we urge that further evaluation precede possible expansion of wind energy development in the region.

Disturbance foraging – the use of disturbances created by other animals to locate cryptic or sedentary prey – is a widespread phenomenon, particularly in birds. In the Neotropics, a prominent example of disturbance foraging in birds is their relationship with army ants (Eciton burchellii). Numerous bird species attend army ant swarms and forage on the prey that the ants flush from the leaf litter. Here, I document a previously undescribed disturbance foraging association between two species of obligate ant-following birds and a small anteater, the northern tamandua (Tamandua mexicana). I observed both bird species approach and forage on fallen termites underneath the anteater, which was excavating a termite nest. The foraging association appeared to be a commensal relationship – the antbirds obtained a foraging benefit from the anteater, which was in turn unaffected by the birds. My observation suggests that ant-following birds may respond to other disturbances in addition to army ant swarms to find food.

Scavenging has been increasingly documented for difficult to observe species through advances in motion-triggered photography. Here, we document several instances of scavenging over multiple days by a Northern Hawk Owl (Surnia ulula) on a Canada lynx (Lynx canadensis) carcass. These observations are of particular interest because the owl visited the carcass 25 times, with the longest visit lasting >3 hrs. In addition, the owl routinely defended the carcass against Black-billed Magpies (Pica hudsonia). These observations suggest scavenging may represent a larger role in the diet of Northern Hawk Owls; further research is required in order to understand its importance for this and other raptor species.

North American geese (Anserini) are largely herbivorous, yet exploration and exploitation of a variety of food sources is well known. Utilization of a novel food source can be limited by many factors, including, but not limited to, general morphology and physiology, availability in the landscape, and energy balance constraints. Canada Geese (Branta canadensis) are documented to be exclusively herbivorous, yet herein we report observations over a two-year period of at least 8 different individual Canada Geese catching and eating fish. We hypothesize that this behavior represents an opportunistic exploitation of a readily available food source during a time when weather conditions limit foraging activities on the surrounding landscape. Our observations suggest the possibility of fish as a potential food source not previously recognized for Canada Geese.

Male birds of prey are usually smaller than females, known as “Reverse Size Dimorphism” (RSD). We quantified sexual size dimorphism in species that occur in Brazil, and suggest a bootstrap-based approach that allows an estimate of confidence intervals for dimorphism indices. We used body mass, total length, and wing length, measured from museum specimens and a few live birds, to quantify size. We gathered data from eight owl species, for which sample sizes were considered to be minimally adequate to provide reliable dimorphism estimates. We calculated a dimorphism index (DI) for each measurement and then these indices were reduced to a single latent variable using a principal component analysis. A clear trend toward positive DI values confirms RSD as a general pattern, except for negative values in Asio clamator (Striped Owl) for all measurements, for total length in Athene cunicularia (Burrowing Owl), and Ciccaba virgata (Mottled Owl), and for virtually equal to zero values in Pulsatrix koeniswaldiana (Tawny-browed Owl) for total length and A. cunicularia for wing length. Body mass was the most dimorphic trait in all species and DI values were consistent across all three traits. Wing length DI was the most precise index and total length DI was the least precise index. In descending order of overall RSD the species studied were Strix hylophila (Rusty-barred Owl), Megascops choliba (Tropical Screech-Owl), Glaucidium brasilianum (Ferruginous Pygmy-Owl), Tyto alba (Barn Owl), P. koeniswaldiana, C. virgata, A. cunicularia and A. clamator.

The Striated Caracara (Phalcoboenus australis) is a poorly known raptor associated with seabird colonies, restricted to the islands of southern South America, and with an estimated extant population of <2,500 mature individuals. We evaluated the number of breeding pairs, described the characteristics and spatial pattern of nest sites, and estimated breeding output of a population of Striated Caracaras in Franklin Bay, Staten Island, Argentina. We found one of the lower breeding density values reported for this species, although this population is associated with one of the biggest colonies of Rockhopper Penguins. The main material used for the construction of Striated Caracaras' nests was tussac grass, though only half of nests were placed in grassland. The spatial pattern for nest sites corresponds with global and local clustering. All successful Striated Caracaras' nests were at least 250 m from the nearest neighboring nest, were generally closer to the colony of Rockhopper Penguins than failed nests, and had more Rockhopper patches around them. Breeding success was 0.73 successful nests/active nests, productivity was 1.27 ± 1.01 young/active nest, and brood size was 1.75 ± 0.71 young/successful nest. The presence of invasive wild goats and red deer is proposed as a factor that could be restricting nest site availability in the study area.

Organisms with limited motility may use animal transport as a mechanism for dispersal. Migratory birds can provide a vehicle to move small organisms great distances, which may allow them access to areas that are otherwise inaccessible. During normal mist netting operations at a spring migration banding station along the northern Gulf of Mexico coast in Louisiana, USA, we encountered an Indigo Bunting (Passerina cyanea) with numerous snails, possibly Galba cubensis, underneath its breast feathers. While encounters of songbirds carrying snails appear rare, long-distance migrating songbirds represent a possible mechanism to transport small snails great distances to expand ranges, colonize new areas, or maintain genetic continuity.