We studied the breeding biology of the Baywing (Agelaioides badius), a shared host of Screaming (Molothrus rufoaxillaris) and Shiny (M. bonariensis) cowbirds. We monitored 193 nests from December 2002 to March 2007 in the Province of Buenos Aires, Argentina. Baywings used a wide variety of nesting sites, mainly old nests of furnarids. Their breeding season lasted from late November to February and was closely matched by that of Screaming Cowbirds. The breeding season for Shiny Cowbirds started in late September but overlapped that of Baywings. Frequency and intensity of Screaming Cowbird parasitism were 93% and 5 eggs per parasitized nest, while for Shiny Cowbirds they were 16% and 1.4 eggs. Host clutch size was 4.0 ± 0.1 eggs and did not vary with time of breeding. Weight at hatching and age of maximum growth were similar for host and Screaming Cowbird nestlings. Shiny Cowbird nestlings had higher weight at hatching and lower age of maximum growth than the other two species. Screaming and Shiny cowbird nestlings had higher growth rates and asymptotic weights than host nestlings. Sex-specific growth curves of Screaming Cowbirds indicated males had higher growth rate and asymptotic weight than females. Only 19% of the nests produced fledglings. Host egg survival, hatching success, and nestling survival were 0.92, 0.88, and 0.94, respectively. Excluding nest failures, hosts fledged 0.78 chicks per egg laid. Baywings were smaller than Screaming and Shiny cowbirds, and experienced a high frequency and intensity of parasitism. However, the effect of parasitism on host hatching success and chick survival was low and comparable to that observed in larger hosts.

The Bobolink (Dolichonyx oryzivorus) is an obligate grassland species that is declining throughout its range in North America. There are few data available on Bobolink eggs and nestlings; this information is necessary for conservation planning efforts. Egg mass was recorded for 175 eggs from 37 nests in Québec and eastern Ontario in 2006–2007. Hatching asynchrony was evident with high between-clutch variation in egg mass. Egg mass did not differ with clutch size. Nest initiation date was positively correlated with smallest egg size and negatively correlated with within-clutch egg mass deviation. Nestling wing length, tarsus length, and mass were measured for 166 nestlings ranging from 2 to 10 days of age. Bobolink nestlings fledged below adult size and mass, achieving 87.7 ± 2.3%, 67.6 ± 1.5%, and 55.1 ± 0.4% of breeding adult tarsus length, mass, and wing length (± SE), respectively.

The Yucatan Wren (Campylorhynchus yucatanicus) is a highly restricted endemic species inhabiting the coastal scrub at the northern portion of the Yucatan Peninsula. We describe the breeding phenology and nesting success of this endangered species from April to September 2007 for a population at Ria Celestun Biosphere Reserve. We found 232 nests of which only 110 (47%) were active at either incubation or nestling stages. Yucatan wrens initiated nest building in late April, but clutch initiation occurred in early June and lasted until the end of July, resulting in a breeding season of 2 months. Nests were exclusively in coastal scrub and the transition between coastal scrub and black mangrove (Avicennia germinans) forest. Eleven species of trees were used as nesting substrate, but three included 75% of all nests found. Clutch size (x¯ ± SD) was 3 ± 1.5 eggs with incubation and nestling periods averaging 16 ± 1.0 days, and 16.5 ± 1.9 days, respectively. Mayfield estimates of daily survival rate for incubation and nestling periods were 0.968 ± 0.005 and 0.975 ± 0.005, respectively with nesting success of 46%. The average number of fledglings per successful nest was 2.5 ± 1.3. Predation was the main cause of nest mortality accounting for 54% of the active nests. Parental care was provided by both parents, but participation of a third individual feeding nestlings was recorded at three nests, providing evidence for occasional cooperative breeding. Increasing human development in the coastal region of the Yucatan Peninsula may represent a serious threat to conservation of the Yucatan Wren due to habitat restriction and high dependency on three species of trees as nesting substrate.

We provide details on the breeding biology of the Slate-throated Whitestart (Myioborus miniatus) from 126 nests found during seven breeding seasons, 2002–2008, at Yacambú National Park, Venezuela. Nesting activity peaked in late April and May. Only the female built the nest and incubated the eggs. Males rarely visited the nest during these stages. Mean clutch size (2.1 ± 0.04 eggs, n  =  93) was the smallest recorded for the Slate-throated Whitestart. Incubation and nestling period lengths were 15.3 ± 0.31 (n  =  21) and 10.8 ± 0.24 (n  =  7) days, respectively. Attentiveness (% of time on the nest) during incubation (59 ± 1.6%, n  =  52) was similar to other tropical warblers and much lower than northern relatives. This caused a relatively low egg temperature (34.40 ± 0.33° C, n  =  6 nests, 20 days) compared with north temperate birds. Both parents fed nestlings and increased their provisioning rates with nestling age. Growth rate based on nestling mass (k  =  0.521 ± 0.015) was faster than for other tropical passerines but slower than northern relatives. Predation was the main cause of nesting failure and rate of predation increased with age of the nest. An estimated 15% of nests were successful based on an overall Mayfield daily predation rate of 0.053 ± 0.007. This study confirms a strong latitudinal variation in life history traits of warblers.

Successful conservation of grassland bird populations requires basic information on their breeding biology; in particular, information from undisturbed native prairie over an extended period of time. We present data collected at Bowdoin National Wildlife Refuge in northcentral Montana on the reproductive biology of six grassland bird species that breed in mixed-grass prairie: Sprague's Pipit (Anthus spragueii), Savannah (Passerculus sandwichensis), Grasshopper (Ammodramus savannarum), and Baird's (A. bairdii) sparrows, Chestnut-collared Longspur (Calcarius ornatus), and Western Meadowlark (Sturnella neglecta). Basic measures of reproductive biology are presented, including estimates of nest density, phenology, fecundity, parasitism rates, and nest success, and how these and other characteristics varied across years. Nests (n  =  1,494) of the six focal species accounted for 98% of all passerine nests found during 1997–2007; Chestnut-collared Longspurs (51%) were the dominant breeding species. Total nest density across years ranged from 20 to 41 nests per 40 ha (CV  =  26%) on unburned sites. Mean clutch initiation date and clutch size varied little across years; however, clutch size tended to decrease over the course of a season, regardless of bird species. Daily nest survival rates did not differ markedly among bird species, but did vary substantially among years, suggesting that year-dependent factors were affecting nest success among all species similarly.

We evaluated foraging and nesting behavior, territory size, and nest success of Golden-cheeked Warblers (Dendroica chrysoparia), a federally endangered songbird, relative to mountain biking trail use. We conducted our study at two mountain biking sites and two control sites at Fort Hood Military Base and in Austin, Texas, in spring 2002 and 2003. Territories of male Golden-cheeked Warblers in biking sites (2.2 ha) were >1.5 times as large as those in non-biking sites (1.4 ha). Mayfield nest success in biking sites (n  =  33) was 35% compared to 70% in non-biking sites (n  =  22). Nest abandonment was three times greater in biking areas (15%) than non-biking areas (5%). Seven nests were depredated in biking sites, but only two nests were depredated in non-biking sites. Texas rat snakes (Elaphe obsoleta) were the most frequent nest predator at biking sites, accounting for 71% of the predations. We conducted behavioral observations of male Golden-cheeked Warblers in biking (n  =  139) and non-biking (n  =  204) sites. Males spent similar amounts of time in diurnal behaviors in biking and non-biking sites. We used video-camera systems to record female nesting behaviors at 17 nests in biking sites and 15 nests in non-biking sites. Nesting behaviors of females did not differ between biking and non-biking sites. The cumulative effect of disturbance from mountain biking trail use on Golden-cheeked Warbler foraging and nesting behavior appears to be minimal, but fragmentation and alteration of habitat by mountain biking trails may reduce quality of nesting habitat for Golden-cheeked Warblers.

The winter population ecology of American Kestrel (Falco sparverius), one of the most abundant and widely distributed raptors in North America, is poorly understood. We systematically searched a 225-km² area in Cape Coral, southwestern Florida, for American Kestrels during 14 winters (1 Dec–15 Mar, 1994–2008) to measure their annual apparent survival and to see if individuals returned to the same wintering area. We recaptured 101 of 2,958 banded kestrels during the study. We estimated annual apparent survival of 75% for males and 74% for females using a Cormack-Jolly-Seber model. These estimates are considerably higher than previous estimates for American Kestrels, but are similar to estimates reported for other species of Falco. Forty-six percent of the kestrels estimated to have survived were observed in the study area 1 year after recapture, based on year-specific color banding. All but six of 101 kestrels were recaptured within 1 km of where they were banded. Four of five kestrels banded as nestlings and subsequently recaptured in the study area were banded in southeastern Pennsylvania, suggesting migratory connectivity. Eighty percent of the kestrels trapped were females, but the proportion of females decreased annually (−3 ± 1% per year). Overall, the population decreased by an average of 7 ± 2% per year. Recent land-use change accompanied by increased human density and suburban expansion may be causing the observed trends.

Each year thousands of Pacific Black Brant (Branta bernicla nigricans) undergo flightless wing molt in the Teshekpuk Lake Special Area (TLSA), Alaska, in two distinct habitats: inland, freshwater lakes and coastal, brackish wetlands. Brant lose body mass during wing molt and likely must add reserves upon regaining flight to help fuel their 2,500 km migration to autumn staging areas. We characterized movements and habitat use by Brant during post-molt (the period immediately following the recovery of flight) by (1) marking individual Brant with GPS (global positioning system) transmitters, and (2) conducting a series of replicate aerial surveys. Individuals molting in inland habitats promptly abandoned their molt wetland during the post-molt and moved into coastal habitats. Consequently, inland habitats were nearly deserted by early August when Brant had regained flight, a decrease of >5,000 individuals from the flightless period of early July. Conversely, coastal molting Brant largely remained in coastal habitats during the post-molt and many coastal wetlands were occupied by large flocks (>1,000 birds). Our results indicate that inland, freshwater wetlands were less suitable post-molt habitats for Brant, while coastal wetlands were preferred as they transitioned from flightless molt. The immediacy with which Brant vacated inland habitats upon regaining flight suggests that food may be limiting during molt and they are not selecting inland molt sites strictly for food resources, but rather a balance of factors including predator avoidance and acquisition of protein for feather growth. Our data clearly demonstrate that patterns of habitat use by Brant in the TLSA change over the course of the molt season, an important consideration for management of future resource development activities in this area.

We tested the hypothesis that foraging for arthropods may be a viable source of energy when hummingbirds are competitively excluded from sources of nectar. We hypothesized that the Magnificent Hummingbird (Eugenes fulgens) relies more upon arthropods than the Blue-throated Hummingbird (Lampornis clemenciae) or Black-chinned Hummingbird (Archilochus alexandri) in southeastern Arizona. We were unable to quantify arthropod foraging by A. alexandri, but measured frequent arthropod foraging by both E. fulgens and L. clemenciae. E. fulgens engaged in more aerial flycatching than L. clemenciae, and their rate of flycatching attempts was higher than by L. clemenciae. Analysis of gut contents showed that E. fulgens consumes the greatest diversity of arthropods. Respiratory quotient measurements indicated E. fulgens catabolized a greater amount of fat/protein than the other species. Gut morphology of E. fulgens does not appear to differ from other hummingbirds suggesting hummingbirds in general may have the ability to use arthropods as an alternative energy source when access to floral energy is restricted. Our data are consistent with the hypothesis that the diet of E. fulgens includes more arthropods than other species with which they compete.

We quantified resident and migrant bird attendance at army ant swarm raids (n  =  48) in a neotropical montane forest. All observations were during seasons when Nearctic migrant birds are present. Bird species differed in army ant raid-attending behavior. Resident bird species attended 2 to 54% of raids, while migrants attended at lower maximum frequencies (2 to 21% of raids attended per species). Some resident and migrant bird species attended raids more frequently than expected based on capture rates in mist-net studies and point-count density surveys. Army ant raid attendance may be a regular element of foraging behavior for some resident species, and important in the wintering ecology of some Nearctic migrant species. The bird species that attended raids most frequently were predicted to show behavioral specializations for exploiting army ant swarms. Eight resident bird species (but no migrants) performed a specialized behavior, bivouac checking, by which birds sample army ant activity. Resident bird species' frequencies of raid attendance were positively associated with frequency of checking bivouacs (r  =  0.68). We hypothesize the absence of obligate army ant-following birds in montane forests has favored performance of specialized behaviors for exploiting army ant raids by some resident birds.

The Maroon-fronted Parrot (Rhynchopsitta terrisi) is a threatened species endemic to pine-oak (Pinus spp.-Quercus spp.) forests in “sky islands” of the Sierra Madre Oriental in Mexico. We measured parrot (n  =  10) home ranges during the breeding season (1999–2001) using radiotelemetry. Home ranges varied among years: 1999  =  12,379.05 ha, 2000  =  8,633.82 ha, and 2001  =  4,736.75 ha. Differences in home range size may reflect variation in distribution, abundance, and patchiness of food. Daily movements in 1999 were estimated as 23.6 km versus 13.7 km in 2000 and 26.8 km in 2001. Habitat preferences within the Pinus forest varied among nesting seasons. Preference in 1999 was for Pinus-Abies-Pseudotsuga forest and in 2000 and 2001 it was for Pinus forest and chaparral. This variation may be influenced by nesting behavior. Rapid landscape changes may necessitate planting and conserving pine forest to regenerate areas for long term conservation of Maroon-fronted Parrots.

We investigated how variation in fire severity (control or no fire; low, medium, and high severity fires) and interval (1–2 years vs. 3–6 years after fires) affected habitat and avian abundance, species diversity, richness, and evenness in the southern Appalachian Mountains. Fire severity and interval had significant implications for both habitat and avian communities. Species richness within 2 years of fires was on average 26% higher in areas receiving medium and high severity treatments than in unburned control units. Species diversity and species richness were markedly greater 3–6 years after fires within high severity treatments (12 and 44%, respectively), compared to unburned controls. Relative abundance and species evenness did not vary with fire severity or time since fire. The short-term effects of low severity fires, or high severity fires with short rotation periods (≤2 years) may have limited positive effects on avian communities. Facilitation of disturbance regimes including mid to high severity fires, which foster uneven-aged forests, can be an effective conservation tool for restoring avian communities.

We surveyed male breeding birds in five habitats (bottomland forest, maritime oak [Quercus spp.], pine [Pinus spp.] forest, maritime shrub, saltmarsh) of coastal Georgia, USA using distance-sampling methods to estimate population densities. We examined species-habitat relationships using indicator species analysis (ISA). Acadian Flycatcher (Empidonax virescens) in bottomland forest, Northern Parula (Parula americana) in maritime oak, Brown-headed Nuthatch (Sitta pusilla) in pine forest, Clapper Rail (Rallus longirostris) in saltmarsh, and White-eyed Vireo (Vireo griseus) in shrub habitat ranked highest for Partners in Flight (PIF) priority species by densities. The ISA indicated fewer PIF priority species were associated with saltmarsh, but more species (6) were unique to saltmarsh than any other habitat. Indicator species occurred more often in maritime oak than bottomland forest (8 vs. 6), but both habitats had similar numbers of PIF priority species (4). Shrub habitat covered the smallest area (∼0.2%) and had three PIF priority species, including Painted Bunting (Passerina ciris), the only PIF species with extremely high priority in this study.

We investigated avian use of clearcuts and two-age harvests during the post-breeding period in 2006 in the central Appalachians, West Virginia, USA with an information-theoretic approach to model selection. Cover variables appeared to be most important; e.g., vegetative vertical complexity had a strong positive relation with capture rates of mature forest birds and molting adults, as well as physical condition which supports a predator-avoidance hypothesis for habitat use. Basal area was a poor predictor of captures; residual trees near nets tended to depress capture rates. Food variables best explained capture rates for some species groups (e.g., early-successional insectivores and granivores, mature forest nesting adults, molting birds), but post-breeding habitat quality was based primarily on vegetative cover. Habitat use may depend on the bird's physical condition and molt status, and we found evidence for age-specific differences which may impact survival. Our study suggests important links between post-breeding habitat quality, molt status, physical condition, and bird age, and indicates a variety of response variables (relative abundance, survival, body condition) should be measured to assess avian habitat quality during the post-breeding period.

We conducted the first country-wide survey between 1994 and 2002 to examine the distribution, abundance, and conservation status of Sandhill Crane (Grus canadensis nesiotes) populations throughout Cuba. Ground or air surveys or both were conducted at all identified potential areas and locations previously reported in the literature. We define the current distribution as 10 separate localities in six provinces and the estimated total number of cranes at 526 individuals for the country. Two populations reported in the literature were no longer present and two localities not previously reported were discovered. The actual number of cranes at two localities was not possible to evaluate due to their rarity. Only four areas (Isle of Youth, Matanzas, Ciego de Avila, and Sancti Spiritus) each support more than 70 cranes. The remaining locations each have less than 25 individuals. Sandhill Cranes appear to be declining and have almost disappeared in Pinar del Rio and Granma provinces, and in northern Matanzas Province. Identified threats to the remaining populations include habitat modification (woody plant encroachment, agricultural expansion, and fire suppression), predation due to wild hogs (Sus scrofa), dogs (Canis lupus familiaris), mongoose (Crossarchus spp.), and poaching.

Dippers (Cinclidae) are the only passerines that find their prey almost exclusively under water. We examined the breast feathers of the five species of dippers for barb diameter and spacing. These results were compared with those measured for other bird families, both aquatic and terrestrial, to detect the presence of any adaptation in the structure of their plumage to their aquatic lifestyle. Barb diameters (2r) were about the same for all dipper species at ∼25 µm, but spacing (2d) varied from ∼150 to 215 µm. Dipper feathers exhibited large values for (r d)/r, the structural requirement for excellent water repellency, comparable to that of many other terrestrial birds including starlings (Sturnidae), swifts (Apodidae), and nightjars (Caprimulgidae). A slightly improved resistance to water penetration, indicated by a smaller value for (r d)/r, was observed for White-throated Dipper (Cinclus cinclus), whereas increased water repellency was found for both American (C. mexicanus) and Brown dippers (C. pallasii). Each of these three species is known to dive. No adaptations were observed for White-capped (C. leucocephalus) and Rufous-throated (C. schulzi) dippers, neither of which dive. The breast feathers of dippers have evolved excellent water repellency, but diving dippers show further adaptations for improved resistance to water penetration and water repellency to allow under-water foraging.

Open pit bitumen extraction is capable of causing mass mortality events of resident and migratory birds. We investigated annual avian mortality in the tailings ponds of the Athabasca tar sands region, in northeastern Alberta, Canada. We analyzed three types of data: government-industry reported mortalities; empirical studies of bird deaths at tailings ponds; and rates of landing, oiling, and mortality to quantify annual bird mortality due to exposure to tailings ponds. Ad hoc self-reported data from industry indicate an annual mortality due to tailings pond exposure in northeastern Alberta of 65 birds. The self-reported data were internally inconsistent and appeared to underestimate actual mortality. Scientific data indicate an annual mortality in the range of 458 to 5,029 birds, which represents an unknown fraction of true mortality. Government-overseen monitoring within a statistically valid design, standardized across all facilities, is needed. Systematic monitoring and accurate, timely reporting would provide data useful to all concerned with bird conservation and management in the tar sands region.

The Llanos is a significant waterbird site in the Western Hemisphere, but abundance and distribution of waterbirds across this vast region are poorly known, which hampers conservation initiatives. We used point counts along road routes in the Llanos region of Venezuela to examine abundance and distribution of waterbirds during 2000–2002 within five ecoregions across the Llanos. We detected 69 species of waterbirds and recorded 283,566 individuals, of which 10 species accounted for 80% of our observations. Wading birds (Ciconiiformes) represented the largest guild both in numbers of species (26) and individuals (55%), followed by waterfowl (26%), and shorebirds (11%). Five species comprised 62% of all individuals: Cattle Egret (Bubulcus ibis), White-faced Whistling Duck (Dendrocygna viduata), Black-bellied Whistling Duck (D. autumnalis), Great Egret (Ardea alba), and Wattled Jacana (Jacana jacana). Wading birds were particularly ubiquitous with at least 21 of 26 species recorded in each of the ecoregions. Species richness (66), proportion of waterbirds detected (54%), and mean number of birds per route (1,459) were highest in the Banco-Bajio-Estero savanna ecoregion. Our study provides the most comprehensive data set available on waterbirds in the Llanos of Venezuela and highlights regions of special conservation concern.

Migratory birds arriving in breeding areas should select territories that maximize reproduction and survival. Prey available prior to egg laying may be as important as prey availability for chicks later in the season. We sampled benthic and terrestrial prey items in Piping Plover (Charadrius melodus) foraging habitat soon after they arrived in breeding areas in New York during 2001–2003. Benthic invertebrates in the sand flats were abundant and available to adults, whereas terrestrial arthropods typically used later in the season were sparse in all cover types. Foraging adults selected intertidal sand flats over other microhabitats. One benefit of nesting near sand flats apparently is abundant food upon arrival in breeding areas. Protecting habitat between arrival in breeding areas and territory establishment is uncommon but warranted for this threatened species.

We report a male Cerulean Warbler (Dendroica cerulea) singing a highly accurate version of another species' song (Hooded Warbler; Wilsonia citrina), as well as a typical Cerulean Warbler song. We performed playback experiments to examine the manner in which this bird used, and responded to, the different songs. He responded aggressively (wing flicks and garbled song), and with his Cerulean Warbler song, to recorded versions of two different types of Cerulean Warbler songs, including a type that he was not observed singing. He did not respond in any manner to playback of Hooded Warbler song.

We describe the nest and eggs of two Philippine endemic passerines, the Rusty-faced Babbler (Robsonius rabori) and the Blue-breasted Blue Flycatcher (Cyornis herioti). We also describe a novel type of nest and nest placement for the Short-crested Monarch (Hypothymis helenae), and provide the first description of the eggs of this species. We discuss similarities among eggs and nests of these species with their relatives, and the need for more information regarding natural history and breeding habits for the Philippine avifauna.

The first of several nests (previously undescribed) of the Azure-crowned Hummingbird (Amazilia cyanocephala) was found on 20 February 2009 along the Río Pixquiac in Coatepec, Veracruz on the Gulf of Mexico side of the Sierra Madre Oriental of Mexico. The cup-shaped nest consisted of fibers and scales of tree ferns with the outside covered with liverworts and a few mosses and lichens. It was saddled on a thin, horizontal branch and had one “tail” of hanging liverworts, longer than the height of the nest cup, draped beneath the nest. It eventually contained two white, non-glossy eggs that were long-elliptical in shape, measuring roughly 13.5 × 7.5 mm. Other nests of the species discovered subsequently were similar in construction and placed on branches or substrates of different plant species. Observations of nest building, eggs, and incubation behavior at the first nest were generally consistent with descriptions for other Amazilia hummingbirds.

The Garden Emerald (Chlorostilbon assimilis) is endemic to southwestern Costa Rica and Panama, and knowledge about its' reproductive habits is limited. We describe the nest and nestlings of the Garden Emerald based on a nest found in La Amistad International Park. The nest was built on an anthropogenic substrate, and was similar to nests described for other emerald species. However, unlike other emeralds, the nest contained no lichens, mosses, or ferns. The nestlings resembled adult female plumage, similar to that for other nestling emerald species.

The Cipó Canastero (Asthenes luizae) is a recently described species from the Espinhaço Range, southeastern Brazil. We describe the nest, eggs, and nestlings of this species. Six nests were found in four different territories, two of which were active. All nests were in Vellozia nivea (Velloziaceae). Mean measurements were: height above ground  =  21.8 cm, entrance diameter  =  4.3 cm, nest length  =  23.5 cm, nest height  =  23.3 cm, and nest width  =  20.3 cm. Both active nests were parasitized by Shiny Cowbirds (Molothrus bonariensis).

We studied use of nest boxes by Great Tits (Parus major) in rural village gardens in a semi-arid area. Great Tits occupied 46.6% of the nest boxes, and used nest boxes within higher tree densities and with more tree species in the vicinity. Breeding success was greater in nest boxes with higher plant density, more plant species, and greater height of trees in the vicinity of the nest. The presence of children or dogs (Canis lupus familiaris) near nest boxes did not affect breeding parameters. Syrian Woodpeckers (Dendrocopos syriacus) enlarged 38.0% of nest box entrances during the first year. House Sparrows (Passer domesticus) occupied 41.0% of the nest boxes with enlarged holes and none of those with normal holes. Great Tits occupied both types, but significantly fewer pairs breeding in nest boxes with enlarged holes succeeded in fledging at least one young, probably due to their eviction by the larger House Sparrows.

The Resplendent Quetzal (Pharomachrus mocinno) is of particular conservation concern because of its iconic status in Central American culture. This species is a secondary cavity nester and modifies abandoned woodpecker nest sites in dead tree trunks (i.e., snags). We used 11 historical nest sites, reported in 1969, from Atitlan, Guatemala and 10 recent nest sites from San Gerardo de Dota, Costa Rica to examine if a relationship exists between nest and snag height. There were significant differences between Costa Rica and Guatemala in both nest height (6.3 vs. 10 m, respectively; t-test₁₄  =  −2.49, P  =  0.042) and snag height (8.1 vs. 14.0 m, respectively; t-test₁₃  =  −2.39, P  =  0.033). There was no difference in nest heights relative to snag heights for Costa Rica (0.76) and Guatemala (0.77; t-test₁₇  =  −0.20, P  =  0.84). One aspect of conservation efforts for this species has been placement of nest boxes to provide nesting sites for additional pairs. Our results provide a better understanding of placement requirements for nest boxes to encourage their use anywhere within the range of the species.

Nest parasitism in dabbling ducks is uncommon. Northern Shovelers (Anas clypeata) are considered infrequent parasites and Blue-winged Teal (A. discors) are rarely hosts to nest parasitism. We documented parasitism of a Blue-winged Teal nest by a Northern Shoveler. We reviewed 3,003 records from nests located in 1994 to 1997 in North Dakota and documented only one duck nest parasitized by a Northern Shoveler. Only nine of 1,494 Blue-winged Teal nests were parasitized. We found no evidence of Northern Shovelers parasitizing Blue-winged Teal nests in our nest records and only one account in the literature.

We used time-lapse video cameras and track plates to identify nest predators of Red-faced Warblers (Cardellina rubrifrons) and Yellow-eyed Juncos (Junco phaeonotus) in high-elevation (> 2,300 m) forests of the Santa Catalina Mountains in southeastern Arizona. Mammals, especially gray fox (Urocyon cinereoargenteus) and cliff chipmunk (Tamias dorsalis), were the principal nest predators of Red-faced Warblers and Yellow-eyed Juncos within our study system, accounting for 89% of all nest depredations. Our study is one of the first to use video cameras at real nests to document the prevalence of nest predators in montane forest ecosystems. Additional research is needed to learn if mammals are the dominant nest predators in other montane environments.

We report on a mixed brood of Great (Parus major) and Varied (Poecile varius) tits. The brood consisted of one Great Tit and five Varied Tits. Incubation and food provisioning to nestlings were by adult Varied Tits, but not by adult Great Tits. The foreign Great Tit nestling tended to receive more food than the average Varied Tit nestling. Provisioning of the foreign Great Tit by Varied Tits lasted even after fledging. We discuss the causes and outcomes of this rare phenomenon.

We videotaped an Eastern Phoebe (Sayornis phoebe) nest in central Kentucky on 22 June 2008 and documented a case of infanticide. An adult male phoebe, likely the resident male, was captured at the nest site on 21 June 2008. The resident female fed nestlings (3, ∼8 days of age) 69 times during a 4.1-hr taping session (0815–1221 hrs EDT) the next day, but the resident male was not observed at the nest. Beginning at 0923 hrs, an intruding phoebe (likely a male) occasionally visited the nest, sometimes pecking at, but not feeding, the nestlings; this phoebe initiated a vigorous attack at 1151 hrs, pecking and pulling the head of one of the nestlings for 25 min before pulling it out of the nest. The intruding phoebe returned after a short absence, just before the end of the videotape, and began attacking another nestling. The nest was empty when checked the next day. Suitable territories and nest sites may be limiting factors for Eastern Phoebes, and infanticide by non-breeding males may enhance their reproductive success if the resident female or a new female subsequently pairs with the male and initiates a new nest.

We report an observation of a Marsh Wren (Cistothorus palustris) eating a small fish. On 29 November 2008, a Marsh Wren was observed catching and consuming a small fish, probably a mosquitofish (Gambusia affinis), in a coastal marsh in Jefferson County, Texas. Marsh Wrens are known to eat invertebrates, primarily insects and spiders, and we believe this is the first record of a Marsh Wren capturing and consuming vertebrate prey.

The first instance of vocal mimicry is reported for the western subspecies of Curve-billed Thrasher (Toxostoma curvirostre palmeri). A Curve-billed Thrasher engaged in countersinging with a migrating Black-headed Grosbeak (Pheucticus melanocephalus) near Tucson, Arizona. Night-time singing by Curve-billed Thrasher is also documented for the first time. At least three responding Curve-billed Thrashers engaged in spontaneous song near Tucson, Arizona. Additional night-time singing was elicited by playback recordings