The extinct Laysan Rail or Crake (Zapornia palmeri) was a small, flightless rail endemic to Laysan Island in the northwestern chain of the Hawaiian Archipelago. I detail the collections made, including eggs, nests, juveniles, and numerous adults prior to its extinction. The juvenile plumage was seemingly well documented, but my study of a series of juvenile specimens collected in 1891 and 1896 provides hitherto undescribed molt changes, from downy chick to definitive plumage. Morphometric data show that sexual size dimorphism is present with males being slightly more robust in bill, legs, and feet. I provide a detailed review of the literature showing the chronology of events that led to the extinction of the species and how this easily could have been avoided.

Grebes are unique among birds in ingesting their own feathers. This behavior and the subsequent ejection of feathers as pellets have long puzzled ornithologists, who have tended to treat feather-eating and pellet-casting as independent behaviors rather than as complementary components of the digestive process. The diet of many grebes, including those with the most ancestral traits, is dominated by small invertebrates whose exoskeletons are resistant to digestion. Most birds eat grit to mechanically break down hard foods. Not so with grebes, which are chemical digesters. Feather-eating performs two main functions. The first is to retain food until it is fully digested; this is accomplished by a large feather bolus in the gizzard. The second, provided by a distinct group of feathers in the pyloric pouch, is to filter undigested or indigestible items from entering the intestine. Some of the gizzard bolus is probably regurgitated nightly, but the process is incomplete and undigested food can persist in the gizzard overnight and indigestible hard parts for several months. The pyloric plug is expelled irregularly. Inasmuch as feathers and other debris must eventually be discarded, pellet-casting is an inevitable consequence, not cause, of feather-eating. I propose that grebes originated as surface feeders and adopted feather-eating to enhance the efficiency of feeding on small arthropods or other hard-bodied taxa that are difficult to digest. This interpretation is relevant to understand the early evolution of grebes.

The use of tracking devices (tags) to investigate seabird movements and habitat use has grown rapidly over the last 30 years, but often tracking data are reported without assessment of the effects of tags. The extra mass and bulk may risk altering behavior, and effects likely vary depending on the size, anatomy, and foraging strategy of different species. A guideline that tags should not exceed 3% body mass is widely accepted by seabird researchers, but this guideline was developed for albatrosses and petrels. A review of tracking studies showed that alcids are more likely to be affected by tags than other groups. We found some evidence of a negative effect of tags on Parakeet Auklets' (Aethia psittacula; mean mass 266 g, tag 0.8–1.1% of body mass) reproductive success but not return rate or chick growth. Tagged Whiskered Auklets (A. pygmaea; mean mass 112 g, tag 1.8% of body mass) showed minor decreases in chick growth, and a 74% lower adult return rate during 2014–2015, despite no significant difference from control returns in 2013–2014. Our study demonstrated negative effects in alcids of tags well below the 3% guideline, confirming that limits for one group should not be uncritically applied to all seabirds. Mass of tags deployed should be kept to a minimum, but other factors (e.g., wing-loading, flight energetics, foraging strategy) may be equally important. To ensure the biological relevance of collected data, we strongly recommend that inclusion of tag effect experiments be considered essential in the design and approval of tracking studies.

The behaviors of animals can be highly variable across individuals and environments; however, recent studies have demonstrated that the behaviors of individuals in response to similar environmental stimuli are often highly consistent over time. We investigated consistency in nest building behaviors during a single breeding season in a population of Yellow Warblers (Setophaga petechia) in southeastern Ontario, Canada. We examined the first and second nests constructed by eight individually-marked females that were distributed among three breeding locations 1–3 km apart, to test whether individual female and location affected the similarity of nests using three methods. First, we compared morphological measures of nests among females and locations and found that nests built by the same female were more similar in their nest depth compared with nests built by different females. Second, we used human observers to rank nest similarity based on overall nest appearance (considering morphology and composition) and found that (1) nests built by the same female were more similar compared with nests built by different females, and (2) nests built by different females in the same location were more similar than nests built by different females in different locations. Third, we deconstructed all nests and compared nest composition among females and locations and found that nests built by the same female were composed of similar materials compared with nests built by different females. Our results suggest that individual females build nests consistently during a single breeding season, and that females breeding in close proximity build nests that are more similar in appearance compared with nests built by females nesting 1–3 km apart.

We studied the response of Water Rails (Rallus aquaticus) to conspecific and heterospecific playback to reveal any variation in reaction to playbacks of rail and crake and if and how these reactions change in intensity. Ten observation points, 100 m from each other within a reedbed, were selected. We made our observations three times a day over three days in three sessions (Apr, Jun, and Sept). We quantified the response of Water Rails to the playback of conspecifics and the heterospecifics: Common Moorhen (Gallinula chloropus), Corn Crake (Crex crex), Little Crake (Porzana parva), Spotted Crake (P. porzana), and Baillon's Crake (P. pusilla), in terms of phenological periods. We found that there is a difference in aggressive reaction between conspecific and heterospecific playbacks across all sessions and also within each session. The aggressive reaction decreases significantly in the direction (Water Rail = Common Moorhen) > (Corn Crake = Little Crake = Spotted Crake) > (Baillon's Crake), during the first session and (Common Moorhen) > (Water Rail) > (Corn Crake = Little Crake = Spotted Crake = Baillon's Crake) during the second session. We found that Water Rails react differently to conspecific and heterospecific calls. The reaction intensity changes from one session to another, and the level of reaction to different species also changes. Most of the aggressive reaction levels can be explained by nesting place and food competition but also nest parasitism behavior and body mass differences.

Avian malaria is a common disease in songbirds, caused by protozoa in the genera Plasmodium, Haemoproteus, and Leucocytozoon. These parasites can negatively impact bird health, survival, and reproductive success. Four species of songbirds were sampled for blood parasites during the reproductive season; the American Redstart (Setophaga ruticilla), the Gray Catbird (Dumetella carolinensis), the Cedar Waxwing (Bombycilla cedrorum), and the Red-eyed Vireo (Vireo olivaceus). The study aimed to determine parasite prevalence in these species, as well as to explore a relationship between infection and bird health, measured by body condition and blood parameters. We also tested whether age and sex had an effect on this relationship. Results detected a high parasite prevalence across all species using PCR (94%) but a much lower one using microscopy (37%), suggesting that parasite prevalence is high while parasitemia is low. Red-eyed Vireos were the only species with high prevalence and parasitemia. Parasite infection did not have an effect on body condition or any of the blood parameters tested (hematocrit and heterophil/lymphocyte [H/L] ratio). Because of variation in the reproductive strategies of the targeted species, we expected to find sex-specific differences in infection and health of redstarts and vireos (females having higher parasite prevalence and more health concerns than males) but no sex-specific differences in catbirds and waxwings. We also expected to find age-specific differences in infection and health in all species (juveniles having higher parasite prevalence and more health concerns than adults). Overall, age and sex did not have an effect on infection or health in any of the species, except for infected vireos, as females had a higher H/L ratio than males. This association could be attributed to the high parasitemia found exclusively in vireos. Time was tested as an additional factor and revealed a trend in waxwings, showing that birds caught later in the season (breeding) had higher parasite prevalence and lower body mass, hematocrit, and H/L ratio than birds caught earlier in the season (pre-breeding), consistent with infection by Leucocytozoon.

High arctic latitudes are characterized by short summers with continuous daylight, high seasonality, and low temperatures. In stable bird populations, mortality risks associated with the harsh climate and/or the long migration to reach the Arctic should be balanced by increased recruitment to the population through increased fecundity. We report on annual reproductive success of the American Robin (Turdus migratorius) nesting at its most northerly geographic limits in Ivvavik National Park, Yukon Territory, Canada during the 2010–2012 breeding seasons. Our objective was to determine whether fecundity was increased relative to similar populations breeding at more southerly latitudes. We also examined inter-annual variation in breeding parameters, which we predicted would vary because of interannual variation in local weather conditions. Clutch completion date, clutch size, and fledglings per nest varied significantly among years. No re-nests or double-brooding were documented. There was a significant decrease in incubation period and increase in nest success and clutch size with increasing latitude. Nests in Ivvavik National Park contained more fledglings per successful nest than nests farther south, and the nestling period (11 days) was the shortest recorded for this species. The lack of double-brooding appears to be at least partially compensated by higher fecundity during the single breeding event, at this northerly location.

In most dietary studies of fruit-eating birds, sampling methods consist of direct observations of foraging and fecal sample analyses, and the consumption of resource types is measured as the percent of occurrence in diet samples, or as counts (frequency) of ingested items. Since these measures are usually biased towards the overestimation of small and abundant resources, the amount of ingested mass is a more accurate measure of the crude energy and nutrients provided by a given food source. In this study, we use direct observations of foraging behavior to describe the diet of four frugivorous-insectivorous bird species during the breeding season in Southern Yungas forests, and we compare the number of ingested items and ingested dry mass as measures of fruit and arthropod consumption. In terms of ingested food dry mass, fruit consumption represented over 95% of the diet of the four bird species. The estimated proportion of fruit in the diet differed significantly among methods in three bird species. The comparison of two methods to quantify food consumption by birds allowed us to determine that, when gross amount of ingested matter is considered, the proportion of arthropods in the diet of frugivorous-insectivorous species is much smaller than previously reported. Our study suggests that the use of food dry mass is more appropriate than methods based on item counting to determine the importance of food items in the diet, since it avoids overestimation of resources which contribute comparatively little to the total energy and nutrients ingested. The comparison of these methods highlights the importance of using more reliable measurements of the contribution of different types of food to characterize the diet of frugivorous-insectivorous bird species.

Breeding populations of Mallards (Anas platyrhychos) have declined 38% in the northeastern United States over the past 17 years. One reason for this may be the reduction of a unique wintering habitat, artificial feeding sites. I hypothesize that artificial feeding sites improved over-winter survival and pre-breeding body condition of Mallards and were utilized by a sufficiently large proportion of the northeastern Atlantic flyway population to improve the population's average annual survival and/or fecundity, thereby impacting population dynamics. In Massachusetts, the number of artificial sites where people fed Mallards declined 44% since 1999. Other states do not conduct surveys of feeding sites, but Christmas Bird Counts provide additional data on populations of wintering Mallards. A sampling of urban centered count circles from northeastern states reveal a 48% decline in numbers of Mallards between 1993 counts and those in 2013.

Warming temperatures have been linked to advancing spring migration dates of birds, although most studies have been conducted at individual sites. Problems may arise ecologically if birds arrive or depart before or after associated food resources such as plants or insects reach critical lifecycle stages. Here, I compare mean first arrival dates of the Rufous Hummingbird (Selasphorus rufus), a prolific pollinator and long-distance migrant with the northernmost breeding range of any North American hummingbird, between 1895–1969 and 2006–2015 at eight observation locations in Oregon, Washington, and British Columbia. Historical arrivals were reported through the North American Bird Phenology Program, and recent arrivals were estimated from temporal occupancy patterns using eBird checklists. Results indicated that hummingbirds arrived 8 and 11 days later in the recent time period in two coastal cities in Oregon and 7–17 days earlier in northern, more inland cities in Washington and British Columbia. Fewer days were noted between arrivals in more northerly areas in the recent time period suggesting that birds may now be migrating faster than in the previous time period. Spring temperatures have increased in the past century in much of this region, and birds arrived earlier in years with warmer spring temperatures to suggest that migratory advances are climate-related. Later mean first arrivals reported in coastal regions of Oregon in the recent time period may suggest that Rufous Hummingbirds are bypassing coastal areas to take advantage of more predictable conditions along inland migratory routes or are shifting their breeding ranges northward, notions both supported by declining population trends observed in Breeding Bird Survey data. My results demonstrate a climate-related advancement of Rufous Hummingbirds in western North America and provide justification for the investigation of the ecological impacts of climate change on birds in coastal vs. inland environments. In addition, I provide a framework for comparing information from two extensive and emerging datasets to better understand the impacts of climate change on birds at broad spatial and temporal scales.

The Torrent Duck (Merganetta armata) is one of the four species of ducks that live in fast flowing rivers, and the only one inhabiting mountain rivers from Venezuela to Argentina. This study examines physical-chemical and biological environmental variables associated with different stages of the annual cycle of this waterfowl, to test the relationship between environmental variables and the establishment of territories by Torrent Ducks in the southern part of their range between November 2009 and April 2011. Territories were defined as sites where a pair of Torrent Ducks was found throughout the year, while non-territories were defined as sites where solitary birds were spotted in some seasons but not year-round. The variables that best explained the habitat use by Torrent Ducks were: 1) in spring, the energy of main prey items available per square meter of river, and 2) in fall, the flow rate. Higher food availability in spring and higher water flow in small rivers in fall were associated positively with paired Torrent Ducks' territory establishment. The future assessment of breeding success in territories with contrasting levels of food and water flow may allow for the determination of the importance of these variables for habitat selection, and the meaning that changes in precipitation caused by climate change may have on this species.

Whereas most host species parasitized by Brown-headed Cowbirds (Molothrus ater) accept cowbird eggs in their nests, others reject the foreign eggs or desert parasitized clutches. Chipping Sparrows (Spizella passerina) are a nest deserting host of cowbirds, but many of their nests continue to be incubated with cowbird eggs suggesting that cowbird eggs per se do not necessarily trigger desertion. We demonstrate that encounters with an adult female brood parasitic cowbird rather than with a cowbird egg in the nest, elicit nest desertion. We observed that a total of 33 (67.3%) of 49 nests were naturally parasitized in Illinois. Parasitized nests fledged less than one third of the number of host young than unparasitized nests did, indicating that parasitism is extremely costly in this species and that an evolved response to parasitism would likely spread through the population over time.

Reproductive behaviors such as mounting and copulation calls spread through gull breeding colonies via social facilitation. We showed that broadcasts of model copulation calls to breeding Glaucous-winged Gulls (Larus glaucescens) did not increase the overall numbers of bouts of head tossing or mounts, but they did coordinate the timing of subsequent head-tossing and mounting behaviors. By contrast, silent controls and non-gull sounds with similar spectral features and duty cycles did not coordinate the timing of either head tossing or mounts. Disturbances by humans, such as those occurring during an egg census, caused increases in head tossing in the short term but did not affect the number or timing of mounts. Eagle disturbances reduced the frequency of head tossing and mounting overall, and coordinated the timing of head tossing but on a longer time scale compared to the effect of a human disturbance. Our data demonstrate that the copulation call, without associated wing-flagging, is sufficient to cause the socially facilitated coordination of these reproductive behaviors in gulls, whereas other stimuli do not.

We studied the breeding biology of the Fire-tailed Myzornis (Myzornis pyrrhoura) in an alpine environment (3000–3800 m) of the Gaoligong Mountains in southwestern China during its breeding seasons in 2013 and 2014. Nests were built by both sexes and mainly contained moss and rhododendron flakes. They were located on vertical banks or rock faces, about 20–152 cm above the ground. This species was socially monogamous and sexually dimorphic both in plumage pattern and body size. Egg-laying was mainly initiated in mid-April and ended in early July, and the mean date of clutch initiation was 25 April in 2013 (n = 4) and 27 April in 2014 (n =5), respectively. The clutch size averaged 3.00 ± 0.15 (n = 10), and fresh eggs weighed 1.84 ± 0.19 g (n = 11). Males and females made virtually equal contributions in breeding activities, including incubation, provisioning, brooding, and nest sanitation. Incubation lasted for 15 days (n = 2) with a notably high nest attendance (eggs were incubated 99.48% of the time). The total provisioning rates were 6.52 ± 1.82 (range = 3.29–10.29) trips per hour, a rate that did not change significantly throughout the nestling period. Nestlings fledged at 19.67 ± 0.33 (n = 3 nests) days after hatching, when they were 19% heavier than adults. Growth of nestlings met logistic expectations except for tail length. Overall, the reproductive success rate was 42.86%. Compared with other lower-elevation breeding babblers, Myzornis had larger and heavier nests, fewer but larger eggs, and a longer nestling period. These life-history traits may facilitate its reproduction in the cold alpine areas of the Gaoligong Mountains.

The Sooty Antbird (Hafferia fortis) inhabits Andean foothills and lowland humid forest from Colombia to the western Brazilian Amazon. Despite its wide distribution, many natural history aspects are poorly known. The nest, eggs, and nestlings are described, with no additional nesting information available. Our study provides detailed behavioral information on the nesting biology of H. fortis based on seven nests that were monitored in lowland humid forest in southeastern Peru. Nests were large domes found mostly on slopes or in ravines. The clutch size was always two eggs. Both sexes share daytime incubation and feed the nestlings, but the female exclusively conducted nighttime incubation and brooding. Daytime nest attentiveness was 83 ± 9.5% (SD; n = 13 days), and was similar in both sexes. Nestling period was 13 days, and adults conducted 3.86 feeding trips per day, which increased as nestling developed. Nesting characteristics observed in H. fortis are similar to other Hafferia species, although there is little information about incubation and brooding behavior for the longipes clade, and in general for the Thamnophilidae. Additionally, we described an unusual nest defense behavior during a nocturnal attack by a snake (Oxyrhopus petola).

Breeding cavity-nesting seabirds on remote, oceanic islands are threatened largely by destruction of nest cavities and introduced predators. In response, artificial cavities are often implemented as a conservation strategy. Effective artificial cavity programs require recognition of specific nest-site characteristics, which can be major determinants of survival and persistence of cavity-nesting seabirds. In Bermuda, we monitored 158 natural and 178 artificial cavities of the White-tailed Tropicbird (Phaethon lepturus catesbyi) from 2013–2015 to determine if specific nest-site characteristics could explain cavity selection, nest survival, and predation by introduced rats (Rattus spp.) and the American Crow (Corvus brachyrhynchos). We found that tropicbirds preferred natural cavities lined with sand, and which had smaller entrances and were located on steeper cliffs. Occupancy of artificial cavities on the mainland varied across years and increased with cavity depth, whereas neither variable had any effect on artificial cavity occupancy on satellite islands. Clutch survival declined in cavities with rubble in nesting sand, and those with shallower cavity depths and larger entrance heights. Nestling survival varied by year, declined as the nesting season progressed, and increased with nestling age. Rat predation was significantly higher on mainland sites compared with satellite islands. Crow predation occurred only on offshore island sites, where natural cavities and shallower cavities with larger entrance heights were vulnerable. Rat and crow predation rates varied across years. Our results suggest multiple nest-site characteristics and temporal factors are important predictors of productivity in White-tailed Tropicbirds. Conservationists should simultaneously consider nest-cavity siting and dimensions, while they conduct biosecurity and predator control to improve the nest success of cavity-nesting seabirds.

We present the first record of the Ascension Frigatebird (Fregata aquila) for the Americas by retrieving coordinates from an individual equipped with a satellite transmitting device. As part of a wider study on the spatial and behavioral ecology of this species, we tracked a single juvenile frigatebird that entered into Brazilian waters as defined in the guidelines set forth by the Brazilian Ornithological Records Committee and the South American Checklist Committee. In total, this individual traveled ∼45,000 km over a 3.5-month period before transmissions ceased close to the exclusive economic zone of Sierra Leone. Based on the potential for this species to wander, the Ascension Frigatebird should be considered when attempting to identify any frigatebird in the Atlantic Ocean. Importantly, this record demonstrates the great potential for satellite telemetry to inform national ornithological and conservation organizations on the presence of pelagic seabirds that may otherwise be overlooked by visual surveys.

Caribbean Martins (Progne dominicensis) are common breeders on most Caribbean islands, where they regularly roost and nest in urban areas from February through August. However, from September through January, the basic ecology of this species—its migration and wintering locations—are largely unknown. In 2012, we deployed seven geolocators, and in 2014, we recovered one geolocator from a female Caribbean Martin on the Commonwealth of Dominica, a small eastern Caribbean island. Her wintering location was the western portion of the State of Bahia, Brazil, ∼3550 km southeast of Dominica. Although the location of the non-breeding grounds changed minimally, the fall departure date, migration route, and length of migration to western Bahia, Brazil, was different between years. In October 2012, the female followed a coastal migration route along the Atlantic coast of South America, then flew south to the non-breeding grounds. However in Oct 2013, she flew south from Dominica through Guyana, spent a few days in the Amazon rain forest, and then migrated southeast to the non-breeding grounds. These results provide insight into the repeatability of migration routes and wintering locations by this species, and serves as a first step in better understanding the Caribbean Martin's full life-cycle.

Western Chat-Tanagers (Calyptophilus tertius) are a rare and globally vulnerable songbird endemic to the island of Hispaniola. We conducted a radio-telemetry study of non-breeding Western Chat-Tanagers at two adjacent cloud forest sites in Sierra de Bahoruco in southwestern Dominican Republic during March and April of 2010. Male home ranges averaged 2.18 ± 0.25 ha in size (n = 4) and were significantly larger than those of females (0.88 ± 0.04 ha; n = 2). However, core use areas did not differ significantly between the sexes. We assumed that males and females with overlapping home ranges were mated pairs. At night, two putative pairs roosted an average distance apart of 15.8 ± 3.5 m (n = 7 observations).

Coprophagy by breeding birds, whereby parents eat the feces of their nestlings, is a common but rarely studied behavior. By eating feces, breeding parents may recycle nutrients. In many passerines, eating feces also reduces breeders' time away from the nest, saving energy and increasing brooding time. Here, we report the proportion of individuals that display coprophagy in a population of Dunnocks, Prunella modularis, in Dunedin (New Zealand), and evaluate whether coprophagy varies between sexes, and between two mating systems (monogamy and polyandry). We find that females consume fecal sacs significantly more frequently than males. We also find a non-significant trend for monogamous females to eat feces more often than polyandrous females. We conclude that two hypotheses – parental-nutritional and economical-disposal – could explain the differences in coprophagy between sexes. Our results also suggest that male Dunnocks may engage in coprophagy to recycle nutrients rather than for saving energy. Finally, we describe a novel observation of a nestling being fed with its own feces by an adult male.

The Dark-eyed Junco (Junco hyemalis) is one of the most abundant birds in North America and exhibits versatility in its selection of nest sites. Although typically ground-nesting birds, juncos also nest occasionally in trees, on buildings, and in natural recesses such as rock crevices. To our knowledge, juncos have never been reported nesting in a fully enclosed nest box specifically provided for songbirds. We report the first record of nest box adoption by Dark-eyed Juncos, supported by photographic evidence. A nest box containing a nest attended by a pair of Dark-eyed Juncos was monitored in 2016 in western Washington, USA, and reported to the Cornell Lab of Ornithology's NestWatch program, a national citizen-science program wherein volunteers submit data on wild nesting birds. The nest in question hatched successfully, and three nestlings fledged from the box. Cavity nesting in New World sparrows appears to be very rare, and we found only four additional observations of juncos utilizing natural cavity nests (i.e., a tree hole). Engaging the public to monitor large numbers of nests is the most likely approach to documenting novel nest sites, and citizen science provides the infrastructure for individuals to share observations.

We provide the first description of nest architecture and composition, adult construction behavior, and egg characteristics for the genus Rhytipterna. We provide these data for a nest of the Rufous Mourner (Rhytipterna h. holerythra) found under construction and followed through clutch completion and subsequent failure at La Selva Biological Station, Heredia, Costa Rica. Given the historically labile taxonomic placement of the genus Rhytipterna, our observations provide important additional lines of evidence further supporting its affinity to Myiarchus within the Tyrannidae. We highlight our record of the incorporation of shed reptile skins in the nest lining, only the second instance of this nest character within Tyrannidae outside of the genus Myiarchus. The phylogenetic distribution of this specialized nesting trait suggests the possibility of a single origin near the base of the subclade Tyranninae. Received 29 August 2016. Accepted 30 November 2016.

Nest usurpation is a behavior where one individual takes over the active nest of another individual of the same or a different species. The Grayish Baywing (Agelaioides badius) has been reported as an occasional inter-specific nest usurper. In previous studies, researchers have reported usurpation of nests of House Wrens (Troglodytes aedon) by Grayish Baywings. In this paper, we report that nest usurpation by Grayish Baywings is the second cause of breeding failure in a population of House Wrens in the Central Andes.

We describe a new predator-prey relationship between Herring Gulls (Larus argentatus) and Chimney Swifts (Chaetura pelagica) at a communal roost in Sault Ste. Marie, ON, Canada. In a season-long study in 2015, we document 38 instances of predation, an estimate which likely underestimates the extent of total predation pressure. Chimney Swifts were captured on-the-wing by Herring Gulls.

Red-winged Blackbirds (Agelaius phoeniceus) experience high rates of nest predation and are therefore expected to exhibit adaptations to reduce the risk of eavesdropping by predators. We used a simulated predator and observations of adult and nestling behavior to test predictions of the predator eavesdropping hypothesis. Females (n = 42) delayed their feeding visits significantly longer and took significantly longer to complete their round trips when a plastic American crow (Corvus brachyrhynchos) was 20 m from their nests than when a black wood block was at the same location, but time spent off territory foraging did not differ significantly. Nestlings (n = 35 broods) begged appropriately (in response to a female at the nest) significantly less and at significantly lower intensity when the plastic crow was 20 m from their nests than when the wood block was at the same location, but the crow had no significant effect on the amount or intensity of inappropriate (no female present) begging. These and other results demonstrate that adult and nestling Red-winged Blackbirds have evolved adaptations to reduce nest predation.

From 2010–2012, I studied nesting success and causes of nest failure at a colony of Barn Swallows (Hirundo rustica) where anecdotal evidence suggested the colony was declining in size. In 2010, many nests were destroyed, and indirect evidence suggested breeding adults were being depredated by a raptor. Using trail cameras, I captured video evidence of Barred Owls (Strix varia) depredating two nests, one containing chicks and the other eggs. During the study period, 72% (32/44; 2010), 51% (16/31; 2011), and 85% (17/20; 2012) of nests were depredated, and the number of nesting attempts declined by more than 50% over 3 years. The video evidence and plucked adult feathers suggests that Barred Owls were responsible for at least some of the predation. Barred Owls did not breed historically on the southern British Columbia coast but first appeared in 1966 and have become common breeders, while Barn Swallows have decreased in the same region by 5.64% per year since 1970. There may be many causes of local and regional population declines of Barn Swallows, but given their conspicuous nests, predation in less well protected nesting sites may be a localized cause of colony decline.

Increasing populations of Hooded Mergansers (Lophodytes cucullatus) (Heusmann et. al 2000) may be out-competing Wood Ducks (Aix sponsa) for nest boxes on some sites in Massachusetts. Hooded Mergansers' use increased from ≤2% of boxes in 1979 to 25% by 2013, while Wood Ducks' use increased from an average of 22% in 1979 to a peak of 65% by the mid-1990s and has since declined to 57%. We estimate that Hooded Mergansers may be important nest competitors on 13 of 51 study sites.