We describe basic information about the nesting ecology of the recently discovered Blue-throated Hummingbird (Oreotrochilus cyanolaemus) based on a single nest found in Cerro de Arcos in the high Andes of southwestern Ecuador. The nest was located inside a small cave, attached to a rock wall, and was constructed with moss, rootlets, twigs, dry leaves, and black and white feathers, as well as soft down Puya sp. (Bromeliaceae) fibers. The nest contained 2 white, oval eggs. The fledglings left the nest to explore areas outside the cave 44 d after hatching; both fledglings already had the characteristic blue throat of male individuals. The Blue-throated Hillstar is a threatened species and its nesting area is currently affected by unmanaged tourism.

Nomadism is a type of movement lacking fixed spatiotemporal patterns, evident in species inhabiting variable environments. The irregular movement characterizing nomadic species often acts as a challenging barrier for scientists investigating their ecology. We provide an insight on the movement of a nomadic desert bird, the Spotted Sandgrouse (Pterocles senegallus), within and between different activity seasons. The data were obtained from 1 individual fitted with a satellite transmitter, which was tracked for ∼2.5 years. Three main activity seasons were detected during which the bird stayed in a specific area: pre-breeding, breeding, and winter. Nomadic behavior was evident during the pre-breeding and breeding seasons, whereas site fidelity was observed during winter (i.e., seasonal nomadism). Local scale fidelity with respect to roosting behavior was also evident among and within the 3 winters of tracking. Field observations carried out during the first breeding season enabled us to link the movement patterns of the bird with its behavior at different phases of the breeding season. Within and between activity seasons, the bird was engaged in short- and long-distance scouting forays. The long-distance ones occurred only during the pre-breeding season. In some of the scouting forays, the bird arrived at sites it had previously utilized, suggesting the existence of spatial memory and navigation capability. This fine-scale description of movement can uncover key features, which allow the survival and reproduction of nomadic birds inhabiting arid areas where the distribution of resources is largely unpredictable.

In birds, intraspecific killings are uncommon and occur in the context of cannibalism, nest site competition, new mate acquirement, or aberrant behaviors. However, in herons (Ardeidae), it has been rarely reported outside instances of siblicide. This report describes the first observation of an adult Reddish Egret (Egretta rufescens) killing a juvenile conspecific. The possible reason for the killing was the invasion of the adult's foraging territory.

Double brooding, a second breeding attempt following the successful fledging of a previous brood, has the potential to substantially increase annual reproductive success of a given bird species. Tree Swallows (Tachycineta bicolor) have a wide breeding distribution, which makes them suitable subjects for looking at effects of environmental variation on their breeding biology. One aspect of Tree Swallow breeding that is not well studied is double brooding. During this study, double brooding was frequent, ranging from 37% to 57% each year. Single broods and first broods did not differ from each other, however second broods had smaller clutches, fewer fledglings, and reduced hatching success. Double brooded females had a median date of first egg laying that was 5 d earlier than single brooded females. Based on other studies of double brooding in Tree Swallows, the observed differences may be attributable to factors such as reduced food supplies later in the season, female age, breeding experience, and/or nesting date. The results demonstrate the necessity for studying this species over a broader portion of its range to better understand its population dynamics and reproductive potential.

Little is known of the natural history of the Solomons Nightjar (Eurostopodus nigripennis) due to its restricted range and reclusive nature. Here we describe the breeding biology of E. nigripennis based on nests found in the Western Province, Solomon Islands, between June and October 2019. Four nests were discovered on 3 small islands: Tetepare, Hehevai, and Nanakatopa; the latter 2 are first island records for this species. We observed all stages of the species' nesting cycle, from egg to post-fledging care of juveniles by adults, each with a single nestling (n = 4). We describe the eggs, nestlings, and juvenile plumage of the species with additional detail on nesting habitat and document new breeding locations in the Western Province.

Termites are a protein-rich yet unpredictable and ephemeral food source known to attract a diversity of reptiles, mammals, and birds. Here we provide the first observation of birds feeding on an explosion of winged termites swarming through the canopy in Western Amazonia in Peru. During this observation made from the canopy, at least 11 canopy-dwelling bird species were observed, and this is the first record of all observed species participating in such an event. By understanding the combination of factors that trigger termite swarms and their opportunistic use by canopy birds, we might better predict how the changing environment will affect these events and availability to birds and other wildlife as a valuable protein source.

Animal communication carries the risk of signal exploitation by predators, and thus many prey species will adjust their signals into more discreet messages to conspecifics, or conspicuous antipredator cues. Although rails (Family Rallidae) use the visual display of tail flicking as a warning of vigilance toward predators, how these birds alter their vocal behavior based on perceived predation risk remains little studied. The calls of owls, predatory birds that consume a variety of rallid species and can home in on acoustic cues of their prey, can reduce singing in numerous bird species. We applied remotely activated broadcasts and autonomous recording units to study whether rails in the wetlands of the Lake Calumet region near Chicago, Illinois, would decrease their vocal activity rate following the broadcast of a rallid predator, the Great Horned Owl (Bubo virginianus). Contrary to predictions, Soras (Porzana carolina) significantly increased vocal activity when exposed to owl vocalizations and decreased vocal activity when exposed to a harmless control. Our results indicate that rails appear to increase their vocal activity as a potential alarm mechanism, likely to reduce predation risk by warning conspecifics.

The Eastern Black Rail (Laterallus jamaicensis jamaicensis) is listed as Threatened under the United States Endangered Species Act and as Endangered in 6 states along the Atlantic Coast. Black Rails are difficult to observe and documentation of definitive breeding evidence is limited. This, along with perceived overlaps between the breeding and migratory periods, has led to uncertainty about the breeding status of calling birds across a large portion of their range. To delineate breeding and migratory periods, I examined the phenology of breeding records (N = 170) and documented “presumed migrants” (N = 55) based on rails that hit radio towers, lighthouses, and buildings or were found in inner cities, on ships-at-sea, or on offshore islands. Nesting in Eastern Black Rails extends 3 months from mid-May to mid-August and peaks during the third week of June. Based on the available sample there is no evidence that egg dates vary with latitude along the Atlantic Coast. Presumed migrants were recorded from early March to early May and from early September to early November. Breeding observations and records of presumed spring migrants overlapped during the first 2 weeks of May. The overlap includes only 2.4% of breeding records. There was no overlap between records of presumed fall migrants and the breeding season.

It has been suggested that a high degree of relatedness could explain the occurrence of alloparental care in birds, but few studies have confirmed if there is a genetic relationship between foster parents and chicks. Using one case of adoption involving allofeeding and allodefense of a South Island Robin (Petroica australis) fledgling by a neighboring male, we assessed whether the adoption was the result of close kinship, care directed to offspring from an extra-pair copulation, or altruistic behavior toward non-kin. Our genetic analysis showed that the foster father was not the adopted fledgling's biological father, nor was he closely related to the chick. We conclude that his altruistic behavior may have been accidental, driven by a breeding male encountering the begging of an unrelated chick that had moved into his territory. The low level of adoption in this population (1.5% of 65 chicks) also supports the hypothesis that alloparental care in South Island Robins is likely to be the result of errors in kin recognition.

Black-chinned Hummingbirds (Archilochus alexandri) began nesting inside a hardware store near El Paso, Texas, in the spring of 2015. At least 12 nesting attempts occurred inside the store through 2020, and all but 1 of them fledged young (91.7% nesting success). Nests were followed closely in 2019 and 2020, when 7 nesting attempts produced 13 fledglings. One female raised 4 broods between mid-April and early September 2020; this female laid eggs for her second, third, and fourth attempts while young from each previous attempt were still in the nest. The high nesting success and productivity that we observed probably resulted from nesting indoors, where the 2 major causes of nest failure in this species, predation and extreme weather, were absent. Old nests remained intact for multiple years inside the store, which probably facilitated multiple brooding because females often reused old nests rather than built new ones for subsequent attempts.

Most examples of woodpeckers preying on vertebrates are thought to be opportunistic, and the wider role that some woodpeckers play as nest predators of other birds has not been appreciated until recently. To date, predation on nestling birds has been documented in at least 10 woodpecker species, including 5 of the 6 species of Melanerpes that nest in the United States. From 2018 to 2020, we documented 57 instances in which adult Lewis's Woodpeckers (Melanerpes lewis) provisioned young with nestling passerines (11.9% of 480 food deliveries), which constitutes the first verification of nest predation in this species. Among picids, nest predation is considered to be a widespread and typical foraging strategy only in the Red-bellied Woodpecker (M. carolinus) and Great Spotted Woodpecker (Dendrocopos major). We suggest that additional research will reveal that other woodpecker species routinely prey on nestling birds.

Academic journals, as well as birding magazines and newsletters, often publish reports of novel and/or unusual feeding behaviors observed by professional and amateur ornithologists. These reports, termed “feeding innovations,” have been used to test predictions in ecology, evolution, cognition, and neuroscience. I present here the latest version of the avian innovation database that has been collated since the mid-1990s, in order to facilitate work by researchers that have up to now had access to smaller versions that contained only innovation frequencies. The database includes descriptions, key words, and references to 4,455 innovations collated for 1,689 species in 166 families, obtained by systematically examining the short notes section and, in some cases, entire issues of 216 ornithology publications over periods that varied between 2 and 84 years. The database is intended as a tool for researchers to further study behavioral plasticity, opportunism, and cognition in birds.

Point counts are the most commonly employed methodology in bird surveys. Survey points are usually spaced ≥250 m apart to prevent double counting. In cases where they are used in small (<200 ha) geographic areas, this spacing results in a very small sample size, which may substantially underestimate species richness. Alternatively, locating survey points closer together may produce more complete species lists, but result in excessive double counting of individuals, yielding biased population estimates. We investigated this tradeoff in surveys of breeding birds in predominantly grassland habitats in 5 small (73–114 ha) national park units with survey points spaced at 100 m intervals. Sampling at this distance captured 70–90% of the estimated species richness at 4 of the 5 parks. Approximately half of the species observed were rare, occurring at ≤3 sites. Approximately one-third of all birds were observed far enough from the survey point to be counted at another point. Based on rarefaction curves, increasing the distance between survey points from 100 m to 200 m would result in a 27–48% reduction of observed species. Conducting multi-species bird surveys in small geographic areas using single-visit point counts that are widely spaced (e.g., ≥250 m) will likely underestimate species richness, even with the use of statistical species richness estimators. As a result, rare species will be undersampled.

Avian migration is a widespread, complex behavior that has long fascinated both scientists and the general public. Nonetheless, we have not identified the genetic and environmental controls of migration. Comparisons of migratory strategies within and among species suggest that these differences are associated with genetic and personality variation. Recently, studies have identified possible candidate genes for personality and migration in several avian taxa. Partially migratory species—those in which only some individuals migrate, while others remain resident year round—provide good study systems to test whether variation at candidate loci covaries with variation in migratory behavior. Using both a population genetic and a linear model approach, we tested whether genetic variation at 2 candidate genes (adenylate cyclase activating polypeptide 1, ADCYAP1, and dopamine receptor, DRD4) underlies variation in migratory behavior in the Western Bluebird (Sialia mexicana), a partial migrant, and the closely related Mountain Bluebird (S. currucoides), an obligate migrant, breeding in the Okanagan Valley, British Columbia. Our analyses suggested that DRD4, a gene usually associated with personality, might explain some of the propensity to migrate, but provided no evidence that ADCYAP1, a gene usually associated with the propensity to migrate, explained variation in migratory behavior in these species. Our results join a growing body of literature suggesting the effects of candidate genes are not generalizable across species or populations.

Changes in vegetation structure and species composition affect habitat use and behavior in most bird species by altering the distribution and abundance of their resources. We explore how the mating and foraging behavior of Cassin's Kingbirds (Tyrannus vociferans) varies by habitat type within a 2,450 ha urban park in Mexico City. The study site includes primarily water bodies, riparian vegetation, willow and Montezuma cypress stands, maize fields, and grasslands. We recorded kingbird behavior twice a week along 21 transects throughout 2012 and 2015. Courtship and reproductive behaviors were displayed in autumn (Sep) and early winter (Dec). Intraspecific agonistic behaviors were associated with courtship and mating events, particularly in 2015. Cassin's Kingbird generally favored open vegetation. The main foraging strategy in open habitats was flycatching but foliage gleaning became frequent when mistletoe plants produced fruits in infested willow stands. The use of mistletoe fruits, presumably a secondary diet item, coincided with the breeding season. In addition to these observations, our study is the first report of Cassin's Kingbird winter mating at low latitudes.

In temperate zone avian species, female song is typically less common and structurally complex than male song. Although anecdotal accounts suggest that female House Finch (Haemorhous mexicanus) song is less complex, it has never been compared quantitatively with male song. We analyzed songs from 2 House Finch populations in southern New York to investigate the degree of sexual dimorphism in complexity, as measured by concavity, frequency excursion, and length of song. We found that, although females sing at a significantly higher mean frequency and lower bandwidth, there is no significant sex difference in the structural complexity of song. Future research should investigate whether female House Finch song has an unrecognized function, or whether the retention of complexity is a byproduct of selection on a correlated trait.

In migratory stopover habitats, bird abundance and composition change on a near daily basis. On any given day, the local bird community should reflect local environmental conditions but also the environments that birds encountered previously along their migratory route. For example, during fall migration, the coast of the Yucatán Peninsula in Mexico receives birds that have just crossed the Gulf of Mexico and their abundance and composition may be associated with regional factors such as wind conditions experienced on previous dates. Other factors, such as local fruit availability, may also influence daily variation in bird abundance and composition. Using mist net data from 2 coastal national parks in the Yucatán Peninsula during fall migration in 2016 and 2017, we did not find a strong association between daily changes in bird abundance or community composition with wind conditions and ripe fruit availability. Thus, despite wind and fruit being known to be important to individual birds (influencing stopover duration and departure decisions), their effects might not scale up to be drivers of population and community level variation. On the other hand, we found that the 2 sites shared only about half of their species and those shared species had different temporal abundance patterns at each site. Site and year differences in temporal patterns of migration might arise because populations of the same species are on different migration routes and schedules. While bird arrival is not timed to hit peaks in fruit production in our study sites, whether bird–resource mismatch is a general characteristic of tropical coastal stopover habitats requires further research. If birds on migration have adapted to seasonal variation in food availability, they might be equipped to deal with the additional variability in food supply that is expected to occur with climate change.

Recent excavations from late Pleistocene to Historical period sites on the islands of Guadeloupe and Saint Martin yielded bones of the Burrowing Owl (Athene cunicularia). The osteological description of the remains combined with the location of fossil-bearing sites and historical accounts show this owl to have been present across the Guadeloupe islands in historical periods. This species has been identified in multiple archaeological sites, including those reported here, attesting to the near continuous distribution of this owl throughout the pre-Columbian period in the north of Lesser Antilles. Taken together, these results challenge the previous hypothesis of a relict distribution of the Burrowing Owl as a consequence of climatically induced modifications of the Caribbean environment since the last glaciation.

Basic population information is often lacking for recently recognized species, yet such information is essential for conservation and management. This study provides a detailed assessment of population size and habitat association in the Madeira Firecrest (Regulus madeirensis). Species abundance and habitat data were collected using a point transect distance sampling method. Estimates of density per habitat type were made, in conjunction with presence and absence data derived from the Madeira bird atlas, to estimate population size and habitat associations. We estimate the population size of the Madeira Firecrest to be 698,300 (95% CI: 523,540–869,960), which greatly exceeds the 10,000 individuals threshold for the IUCN “Vulnerable” category. Distribution and abundance were strongly associated with laurel and heath forest, with 56% of the population found in these 2 habitats. Historically, much of the native laurel and heath forest was lost on Madeira, but these remnant native forest habitats are now protected. Based on the large population size and successful management of the laurel forest habitat, our results suggest there is no immediate risk of a change in conservation status for the Madeira Firecrest.

Birds face many human-induced environmental challenges that we associate with population declines. Because of this, we need more ways to monitor populations before they become endangered. Several authors have proposed that fluctuating asymmetry, or nondirectional deviation from bilateral symmetry, could be used as an indicator of population declines. Fluctuating asymmetry is linked to developmental instability and stress associated with environmental challenges such as habitat loss in populations of birds and other animals. Two key premises of the argument for linking fluctuating asymmetry and population declines are that (1) fluctuating asymmetry changes over time, and (2) change over time results in overall population- or species-level differences in fluctuating asymmetry. I evaluated these premises by measuring tarsus and hallux lengths of museum specimens primarily from 1875–1950 in a pair of closely related species with different population statuses—the White-breasted Nuthatch (Sitta carolinensis) and the Brown-headed Nuthatch (S. pusilla). Since Brown-headed Nuthatch populations are decreasing whereas White-breasted Nuthatch populations are increasing, I predicted that Brown-headed Nuthatches would have increasing fluctuating asymmetry over time whereas White-breasted Nuthatches would have no change or decreasing fluctuating asymmetry over time, and this would result in Brown-headed Nuthatches having more overall fluctuating asymmetry in both morphological traits than White-breasted Nuthatches. The percent asymmetry of tarsi and halluces for Brown-headed Nuthatches were at least 1.5× higher than the corresponding values for White-breasted Nuthatches, which supported the second premise. However, since I also found that there was a great deal of interindividual variation and no change in fluctuating asymmetry over time in either species, it is still unclear whether fluctuating asymmetry could be used to help monitor populations for evidence of decline before they reach endangered status. Future studies should more broadly and deeply explore the associations between avian population declines and fluctuating asymmetry.

We analyzed changes in abundance of terrestrial birds on St. John, U.S. Virgin Islands, for a 32 year period during which 3 major hurricanes occurred. Using 1987 as a baseline year, because it followed a 27 year hiatus when no major hurricanes hit the island, we assessed the impact of hurricanes on vegetation structure and bird populations. Bird abundance was determined for 25 m radius circular plots that were surveyed each year of the study along the same transects. Percent cover of trees, shrubs, and herbs was measured in each plot in 1987, 1990, and 2019. All of the survey plots were in moist forest or dry woodland in Virgin Islands National Park. Of 13 common birds, 5 did not show marked and consistent declines in abundance following hurricanes even though the structure of vegetation on the island was heavily modified by storms. Three of these species are insectivores. Seven species declined or showed habitat shifts following Hurricane Hugo in 1989, but 5 of these populations subsequently increased and most recovered to close to their 1987 abundance during the 1990s. Six of these 7 species also declined or showed habitat shifts following Hurricanes Irma and Maria in 2017. The most marked declines in the aftermath of hurricanes in both 1989 and 2017 were for frugivores and nectarivores, especially hummingbirds. Most common bird species in Virgin Islands National Park were either resistant to the effects of severe hurricanes or resilient in the decade following a hurricane. However, more research is needed to assess the status of vulnerable species such as hummingbirds and rare resident species (Bridled Quail-Dove [Geotrygon mystacea] and Puerto Rican Flycatcher [Myiarchus antillarum]).

The genus Nonnula (Galbuliformes: Bucconidae) includes 6 species of nunlets, understory insectivores of humid Neotropical forest. Like the rest of their lineage (Galbuliformes, Piciformes, Coraciiformes, Bucerotiformes, Trogoniformes, and Leptosomiformes), Nonnula were speculated to nest in cavities or burrows, either underground, in mounds of leaf litter, in trees, or in arboreal termitaria. From 2014 to 2020 we studied 17 nests of Rusty-breasted Nunlet (Nonnula rubecula) at Cruce Caballero Provincial Park in the Atlantic Forest of Misiones, Argentina. From the outside, nests looked like the burrows excavated by relatives in Malacoptila, but nunlets excavated only the floor, carpeted it with leaves, built a roof frame of twigs and rachises, and finally covered the whole structure with leaf litter from the surrounding area. A clutch of 4 (occasionally 3) white eggs with mean dimensions 20.1 (SD 0.8) × 16.8 (SD 0.3) mm (2.8 [SD 0.3] g; n = 5) was laid on alternate days, and incubated 17–18 d. The pink, naked hatchlings, with eyes sealed shut, scrambled around the nest chamber and came to the tunnel entrance by day 3, similar to other Bucconidae. Two secretive adults incubated, brooded, and fed nestlings. Fledglings hopped out of the nest at 17–19 d, sometimes returned before leaving definitively, and apparently could not fly. The probability of a nest surviving the 42 d from laying to fledging was 0.40, comparable to some tree-cavity-nesting birds in our study area (but 95% confidence intervals were large: 0.11–0.69). There is no evidence that any Nonnula use tree cavities or excavate burrows. We propose that Nonnula are unique in their lineage in building a dome-shaped nest at ground level. This habit may have evolved from relatives that excavate underground burrows, surround the entrance with a collar of twigs, and cover the excavation site with leaf litter.

Anthropogenic climate change is affecting many bird species in a variety of ways, causing changes in their distribution, abundance, and food supply, and triggering responses such as shifting migration and nesting seasons. Most studies have focused on migratory birds that breed in temperate areas and little is known about effects of climate change on tropical birds. We used a 24 year dataset that included 1,632 nesting events of the Oahu Elepaio (Chasiempis ibidis), an endangered forest bird endemic to Hawaii, to investigate whether breeding phenology and performance were related to rainfall and whether a recent shift in the breeding season is related to changes in rainfall. Fecundity of the Oahu Elepaio was closely related to rainfall, with more offspring produced during years with higher rainfall. During the first 19 years of this study, from 1996 to 2014, all nests were initiated from November to June. From 2015 to 2019, up to 33% of annual reproduction occurred from August to October. Higher rainfall caused parallel increases in reproduction during the normal nesting season and the atypical season, with some birds nesting in both seasons. The change in breeding phenology of the Oahu Elepaio is unusual because it was not a gradual transition, but a sudden change of 6 months. The shift in breeding phenology coincided with unusually high summer and fall rainfall from tropical storms associated with a novel climate pattern in the northern Pacific Ocean from late 2014–2016 termed the warm blob. This pattern of warmer water and more frequent storms is expected to become more prevalent in the Central Pacific, so summer–fall breeding in the Oahu Elepaio is likely to continue and perhaps become more common. The Oahu Elepaio is flexible, adaptable, and may not be seriously affected by changing climatic conditions.

The bird life of the central Peruvian Amazon is poorly known. To better characterize bird diversity and distributions, we conducted 4 expeditions to this lowland area, totaling 114 field days in 2015, 2018, and 2019. We focused on sampling under-surveyed habitats, terra firme in multiple interfluves, and sites around a recent river avulsion, and we detected 657 bird species across 22 study sites. Our results include the first extensive inventories of blackwater wetland systems, Guadua bamboo tracts, and riverine islands in central Peru; revised information on distributions with respect to river barriers, including documentation of contact and putative hybridization between parapatric forms; 28 first regional records; and new details on poorly known taxa. Together, these results provide a more complete picture of avian diversity in an area characterized by high species richness, high habitat diversity, and biogeographic interchange.

Vast areas of North American grasslands have been lost and degraded, resulting in unprecedented declines of biodiversity. For example, 82% of North American grassland songbird species are experiencing population declines. Basic natural history, life history, and demographic data from different regions and time periods are essential for modeling population dynamics and developing effective conservation strategies for grassland birds. We monitored 392 nests to provide information on nesting biology, quantify reproductive success, and gain insight into the extent to which predation and weather influence nest survival of 7 grassland songbird species in southwest Saskatchewan, during 2010 and 2011. Clutch sizes of all species were within the range reported previously and declined as the breeding season progressed, particularly for Chestnut-collared Longspur (Calcarius ornatus), Vesper (Pooecetes gramineus) and Baird's (Centronyx bairdii) sparrows, and Western Meadowlark (Sturnella neglecta). Overall, 32–69% of the nests we monitored were depredated, and predation accounted for 91% of all unsuccessful nesting attempts. Daily survival rates were lowest during the nestling stage for 5 species, and nest survival estimates ranged from 16% to 48%. Nest survival of 4 species was influenced by the temporal effects of age and date. Chestnut-collared Longspur and Western Meadowlark nest survival increased through early to mid-incubation and declined thereafter until ∼3 d prior to fledging before increasing again. Nest survival of these 2 species, along with Sprague's Pipit (Anthus spragueii) and Vesper Sparrow, were lowest in late June to early July. We found no support for a strong effect of precipitation on nest survival. However, nest survival rates declined with increasing ambient temperature for Chestnut-collared Longspur and Horned Lark (Eremophila alpestris), the 2 study species with the most exposed nests, and were highest for Western Meadowlark nests when ambient temperatures were between 15 and 24 °C.

The Northern Saw-whet Owl (Aegolius acadicus) is a highly migratory owl that occurs throughout North America. Banding stations have studied the migratory habits of this species, but these studies rarely collect significant data regarding the origin of migrant birds captured in the midwestern United States. In the last 20 years Northern Saw-whet Owl ecology has been studied broadly; however, little is known how different populations may interact with one another. Many avian species with large geographic ranges often have populations that breed and winter in separate areas. Little has been documented to establish if this pattern exists in Northern Saw-whet Owls, a species where individuals are migratory, sedentary, and nomadic. Stable isotope ratios using deuterium δ²H in feathers have been successfully used to estimate the breeding origin of birds. We used stable isotope analysis of δ²H in conjunction with an isoscape map to determine breeding origins for Indiana Northern Saw-whet Owls. We collected 41 feather samples from migrating owls at 6 different banding sites across Indiana from October to November 2017. Because higher enrichment values in adult owl feathers complicate analysis, we only analyzed samples from young (hatching-year) individuals. After analysis and exclusion of birds identified as outliers, the model suggested that the birds originated along 44°N around the Great Lakes Region and as far east as Nova Scotia, Canada. When including outliers, the model suggested that individuals originated along 40°N between Iowa and New York. The outliers-excluded model remained more consistent with the known breeding range of this species than the outliers-included model. We successfully used this technique and our data suggests that the majority of Northern Saw-whet Owls originated from the Great Lakes Region. We recommend further investigation on the physiology and behavior of owls on the breeding grounds, which could aid in the ability to better understand differences in δ²H enrichment of this species. Better understanding of this would allow these models to be plotted more precisely onto the landscape.

The advance of urbanization in Neotropical countries has drastically changed or eliminated extensive areas of natural habitats. Despite these changes, some species breed in cities and adapt to urban conditions. Several variables, such as the type of nest, substrate, and height, as well as the distance to buildings at which nests are constructed, may affect nesting success of birds in urban habitats. Here we tested how these variables affect nest daily survival rate (DSR) of 6 bird species that constructed 3 different types of nests in a high human-density suburb of San José, Costa Rica. The first type includes platform nests built by 3 species of columbids, where at least 1 parent is always present at the nest; the second type includes cup-shaped nests, where both parents can be absent from the nest simultaneously, and is represented by a single species, the Clay-colored Thrush (Turdus grayi); the third type includes closed nests built by 2 species where at least 1 parent is always present. Species with all 3 types of nests display protective behaviors. We quantified nest variables (e.g., type of nest, substrate used to construct the nest, nest height, distance to buildings). The nests differed in their DSR, with a higher nest survival for columbids (3 species; 0.969, SE 0.011), followed by Clay-colored Thrush (0.942, SE 0.009) and closed-nest species (2 species; 0.942, SE 0.028). We found that nesting substrate was the most important variable explaining the DSR in columbids, but none of the variables had a significant effect explaining the DSR in the remaining 2 nest types.

I provide the first description of the nest and juveniles of the Coppery Metaltail (Metallura theresiae), a hummingbird endemic to Peru. The locality of Unchog, in the elfin forest of the Carpish mountains in Huánuco, is where I found this species nesting. My descriptions are based on 4 nests found on different occasions (April 2013, January 2014, and Jul–Aug 2014). Coppery Metaltail used mainly moss, lichen, lycopodium, and twigs as materials to build their nests. I found 3 nest locations: a tree branch, creek banks, and an abandoned hut. The mean internal diameter of nests was 34.45 mm long by 42.52 mm wide (n = 4). I only measured the depth of 3 of them (mean = 33.83 mm). Metaltail eggs were white and had a mean of 12.93 by 8.3 mm (n = 2). Fledglings (n = 2) were observed in July and one of them reached up to 144% the mass of an adult. I comment on other cases of nestling obesity for different species of hummingbirds. The Coppery Metaltail selects different substrates for nesting and might reproduce throughout the year.

The Eared Quetzal (Euptilotis neoxenus) is a Mexican endemic. It occurs from northwestern to west-central Mexico. It is considered threatened in Mexican environmental law. The lack of knowledge about its ecology and distribution during the nonbreeding season motivated our investigation. While inventorying the avifauna at Sierra del Águila and Sierra de Manantlán in west-central Mexico, we recorded the Eared Quetzal only from late October to early March. According to GBIF (n = 24 records), eBird (n = 4 records), as well as our own field findings (n = 14 records), this species can be observed year round occasionally in Arizona, the United States, and regularly from Chihuahua, Durango, Sinaloa, and Nayarit in Mexico. However, Eared Quetzals can only be recorded from November to May in the states of Jalisco and Michoacán. This suggests that at least some individuals of Eared Quetzal undertake migrations. Its potential distribution in central and southern Jalisco includes 9 forested mountain ranges. In addition to distributional data and evidence of migration, we provide noteworthy observations on its natural history.

We present information on the nests, eggs, clutch size, and nestlings of the Chestnut Seedeater (Sporophila cinnamomea), a migratory, globally vulnerable species restricted to the natural grasslands of South America. Despite its vulnerability, there is currently a remarkable lack of basic information on this species. We searched for nests from October to March 2018–2019 and 2019–2020 at 2 grassland areas in southern Brazil and monitored a total of 98 nests of 50 different breeding pairs throughout this period. Birds placed their nests on shrubs, clumps, and herbaceous plants, 42–51 cm above humid or dry ground, or water. Nests were low cups built out of native grass stems, inflorescences, and rootlets, held together with spider webs. Nests measured 4.86 cm (SD 0.40) largest internal diameter, 4.17 cm (SD 0.37) smallest internal diameter, 6.31 cm (SD 0.57) largest external diameter, 5.42 cm (SD 0.51) smallest external diameter, 4.04 cm (SD 0.45) internal height, and 4.74 cm (SD 0.52) external height. Clutches had 1–3 eggs. Eggs were mostly ovate, with a whitish to light beige background mottled with blotches and spots of darker beige and brownish tints. The mean egg size was 16.15 mm (SD 1.07) by 12.11 mm (SD 0.34) (n = 23). Results are part of ongoing research in the southern Brazilian grasslands, which aims to fill the gaps in the knowledge of the breeding biology of Chestnut Seedeater and thereby contribute to its conservation.