Registered users receive a variety of benefits including the ability to customize email alerts, create favorite journals list, and save searches.
Please note that a BioOne web account does not automatically grant access to full-text content. An institutional or society member subscription is required to view non-Open Access content.
Contact email@example.com with any questions.
We report results of a 4-year translocation effort to reestablish a breeding population of Evermann's Rock Ptarmigan (Lagopus muta evermanni) in the Near Islands group of the western Aleutian Archipelago. Habitat restoration was completed by eradication of introduced foxes from Agattu Island by 1979. We captured and moved 75 ptarmigan from Attu Island to Agattu Island during 2003–2006, and monitored 29 radio-marked females in the last 2 years of the study. We compared the demography of newly translocated birds (n = 13) with resident birds established from translocations in previous years (n = 16). Mortality risk was increased by translocation and 15% of females died within 2 weeks of release at Agattu Island. All surviving females attempted to nest but initiated clutches 8 days later in the breeding season and laid 1.5 fewer eggs per clutch than resident females. Probability of nest survival (x¯ ± SE) was good for both translocated (0.72 ± 0.17) and resident females (0.50 ± 0.16), and renests were rare. Probability of brood survival was higher among translocated (0.85 ± 0.14) than resident females (0.25 ± 0.12), partly as a result of inclement weather in 2006. Fecundity, estimated as female fledglings per breeding female, was relatively low for both translocated (0.9 ± 0.3) and resident females (0.3 ± 0.2). No mortalities occurred among radio-marked female ptarmigan during the 10-week breeding season, and the probability of annual survival for females in 2005–2006 was between 0.38 and 0.75. Translocations were successful because females survived, successfully nested, and recruited offspring during the establishment stage. Post-release monitoring provided useful demographic data in this study and should be a key component of translocation programs for wildlife restoration. Future population surveys and additional translocations may be required to ensure long-term viability of the reintroduced population of ptarmigan at Agattu Island.
We used 8 years of live recapture data (1998–2005) to estimate apparent annual survival for male (n = 237) and female (n = 296) Western Sandpipers (Calidris mauri) breeding on a 36-ha plot on the Yukon-Kuskokwim River Delta, western Alaska. Apparent annual survival (Φ) is the product of true survival and site fidelity, and estimates of Φ were corrected for the probability of encounter. Overall return rates (individual returned to the study site in a subsequent season) were lower for females (40%) than males (65%), as was Φ (± SE, females = 0.65 ± 0.05, males = 0.78 ± 0.03), and encounter rate (females = 0.51 ± 0.07, males = 0.74 ± 0.04). Results differed from previous estimates of Φ for this species as our estimates of Φ were higher for both males and females compared to estimates from another breeding site and two nonbreeding locations. Disparity among Φ estimates from breeding and nonbreeding areas highlights the need to delineate site-specific factors throughout the annual cycle that influence population dynamics of the Western Sandpiper.
Natal philopatry is rare in long-distance migrant shorebirds and requires long-term population studies to detect. We report on the rate of natal philopatry from a 18-year study of Semipalmated Plovers (Charadrius semipalmatus) marked as hatchlings to an arctic breeding site near Churchill, Manitoba. About 2% (27/1271) of banded hatchlings returned to the Churchill area to breed. There was no male/female bias in rates of philopatry: 17 male and 10 female hatchlings recruited into the local breeding population. The annual rate of recruitment of hatchlings varied between 0 and 10.7%. Age of first encounter on breeding areas ranged from 1 to 8 years (median age 4) suggesting either unusually delayed age at first breeding, or low detection rates for philopatric hatchlings. The maximum age of a recruited (known-age) hatchling was 9 years. Natal dispersal distances did not differ between males and females, and averaged 5 km between hatching and breeding locations. We used a time-since-marking mark-recapture model to calculate apparent survival of hatchlings. Apparent survival in the interval after first capture was φ1 = 0.0475 (95% CI: 0.030–0.075), whereas apparent survival (φ2 ) of birds during subsequent intervals was 0.866 (95% CI: 0.764–0.927). Low rates of natal philopatry suggest little advantage to site familiarity for juveniles, and agree with theoretical predictions for migratory species with widespread habitat availability.
I examined the breeding biology and nesting success of the Slate-throated Whitestart (Myioborus miniatus), a socially monogamous neotropical warbler, for five breeding seasons (2000–2004) in Monteverde, Costa Rica, near the center of its broad geographic range. Nesting was strongly seasonal, extending from late March through the end of June and coinciding with the end of the dry season and the onset of the rainy season in mid-May. Females constructed domed nests on open steep slopes or in banks along roads and trails. Mean clutch size was 2.9 eggs, and the mean incubation period was 14.2 days. Females performed all incubation of eggs and brooding of young nestlings, but both males and females fed nestlings and fledglings. Mean provisioning rate at nests when young were 5–9 days of age was 20.3 feedings/hr, and females fed young at a significantly higher rate than males (11.7 vs. 8.3 feedings/hr, respectively). Nestlings reached mean adult body mass of 9.5 g ∼ day 7–8, and mean age at fledging was 11.3 days. Parents fed juveniles for at least 4 weeks after fledging; the latest record of adults feeding fledged young was for 40-day-old juveniles. Daily nest survival rates showed strong annual variation and generally declined as the nesting season progressed. Mean daily survival rate was 0.968 and estimated overall nest success was 40.3% with a mean of 2.6 young fledging from successful nests. Predation was implicated in ∼85% of nest failures.
We studied clutch size, hatching and fledging success, and time necessary for chick Kelp Gulls (Larus dominicanus) to leave the nest throughout two breeding seasons (2004 and 2005) on Guararitama Island, São Paulo, Brazil. We followed 93 nests in 2004 and 97 nests in 2005. The average (± SD) clutch size was 2.09 ± 0.64 in 2004 and 1.93 ± 0.59 in 2005. Hatching success was 74% in 2004 and 53% in 2005, and fledging success was 54% in 2004 and 58% in 2005. Chicks grew quickly, following the linear equation y(t) = 61g 17.03g × age (in days), and began to fly at 40 days.
We present evidence of cooperative breeding in Society Kingfishers (Todiramphus veneratus). Groups of three kingfishers were observed cooperatively excavating nest cavities, incubating, and provisioning young. Three bird groups also comprised half of visual observations recorded during island-wide point transect surveys that occurred during the onset of breeding. Society Kingfisher densities were an order of magnitude greater than other Pacific kingfisher populations, which may lead to resource saturation and evolution of cooperation in this species. Our results lend insight into cooperative behaviors and facilitate conservation of birds in French Polynesia.
We examined Burrowing Owl (Athene cunicuaria) reproductive success at 144 nests in urban (n = 80) and grassland (n = 64) habitats in southern New Mexico in 2000 and 2001. Nest success was higher in grassland compared to urban areas (81 vs. 68%) but urban landscapes fledged more young per successful nest (3.85 vs. 3.07). Mean fledging success per nest was similar between habitats with 2.60 and 2.50 fledglings in urban and grassland habitats, respectively. Fledging success was categorized as failure, low, and high. Reproductive success in both habitats was associated with measures of owl density. High success in urban landscapes was associated with fewer surrounding nests, an index of larger nesting territories, and open space. Failure was associated with solitary nests. This suggests owls benefit from the presence of other nesting pairs as long as the density is not too high. High success in grassland habitats was associated with fewer surrounding nests, index of larger nesting territories, edge nests, and lower fledgling success of the nearest nest. Higher nest success, but fewer fledglings per successful nest, suggests competition for resources in this habitat.
Barn Owl (Tyto alba) diets were studied for 15 years in Utah. Ninety-eight percent of 111,016 prey items were mammals, heavily dominated by voles (Microtus spp.). Food-niche breadth (FNB) was 3.33 for the entire sample and varied gradually but significantly among the 15 years and among seasons. Frequency of prey in the diet did not vary significantly from year to year or among seasons. Mean daily temperatures did not vary significantly among years but annual precipitation totals and days when deep snow covered the ground varied significantly among years. Irrigation for agriculture may have partially mitigated annual precipitation fluctuations. Hay, one of the most important crops on the study area, increased over the study period and other crops decreased slightly in the amount planted. Hectares of hay planted, hectares of corn planted, and hectares of barley planted were the variables that combined to best predict annual FNB.
We collected data on breeding season diet composition of Red-shouldered Hawks (Buteo lineatus) in south Texas and compared these data, and those reported from studies elsewhere to examine large scale spatial variation in prey use in eastern North America. Red-shouldered Hawk diets aligned into two significantly different groups, which appear to correlate with latitude. The diets of Red-shouldered Hawks in group 1, which are of more northern latitudes, had significantly more mammalian prey and significantly less amphibian prey than those in group 2, which are at more southerly latitudes. Our meta-analysis demonstrated the dietary flexibility of Red-shouldered Hawks, which likely accounts for their broad distribution by exploiting regional variations in taxon-specific prey availability.
We studied the effects of brood parasitism by Brown-headed Cowbirds (Molothrus ater) and other factors on food provisioning rates of Swainson's Warblers (Limnothlypis swainsonii), a secretive and poorly understood species of conservation concern. We used time-lapse video systems to collect provisioning data at 25 nests, nine of which were parasitized by Brown-headed Cowbirds. We found strong relationships between feeding rate and brood size with increases from 2.0 feeding visits/hr for nests with a single Swainson's Warbler nestling to 3.0/hr for broods of four. We also found an effect of nestling age with 1.9 visits/hr early and 3.2 visits/hr late in the nestling period. The relationships between cowbird parasitism and provisioning were complex. Nests with brood size of one or three that contained a single cowbird nestling had greater provisioning rates (2.5 and 3.3 visits/hr, respectively) than non-parasitized nests (2.0 and 2.6 visits/hr, respectively). Nests with two cowbirds and no Swainson's Warbler young had greater provisioning rates (3.4 visits/hr) than those with two warbler young (2.4 visits/hr), or one warbler and one cowbird (2.6 visits/hr). The increase in provisioning rate with nestling age was more pronounced with two cowbird nestlings present than in nests with zero or one cowbird nestling. These results suggest that parasitized nests, especially those with multiple cowbird nestlings, can impose greater energetic demands on parents. Food limitation may constrain the ability of Swainson's Warblers to adequately care for both their own nestlings and cowbird young.
We used quantitative magnetic resonance body composition analysis and radiotelemetry to examine whether fat and lean body mass affected stopover durations of 11 birds captured during autumn migration in New York City, USA. Two Swainson's Thrushes (Catharus ustulatus), two Hermit Thrushes (C. guttatus), and seven Ovenbirds (Seiurus aurocapilla) were used in the study. Ovenbird stopover duration was significantly and negatively related to fat mass but unrelated to lean body mass. The same relationships were found when data from all three species were combined to increase sample sizes. Birds that departed within 1 day had fat stores upon capture that represented at least 11% of their total body mass whereas those with fat content <6% of total body mass remained for no fewer than 4 days. Arrival fat mass clearly influenced time birds spent at the site but lean body mass did not. Conditions for increasing or maintaining fat stores provided by urban stopover sites may affect the migration timing of birds.
We recorded fluctuations in a population of Orange-winged Amazon (Amazona amazonica) during 1 year at a roosting site on an island near Belém, Pará, Brazil. Parrots were counted from a boat by a minimum of three teams of two observers, each team oriented in different directions. Orange-winged Amazons were observed flying alone (14.2%), in pairs (75.7%), and small numbers in family groups (pairs with young) of three (8.7%), four (1.2%), or five (0.3%) individuals. The larger number of groups of three compared with groups of four and five individuals reflects the low survival rate of nestlings with generally only one surviving offspring per brood. The total number of parrots increased from April (3,899) to July (8,539), and began to decrease in August (5,351). This decrease was presumably due to onset of the breeding season, when paired individuals leave the roost in search of a nest, where they breed, nest, and rear young until the nestlings can fly.
Forster's Terns (Sterna forsteri) often forage alone or within mixed- species foraging aggregations. We investigated the relative costs and benefits of these two foraging strategies. Metrics used to assess differences in strategies included the number of attempts for prey (both successful and missed), capture efficiency, and capture rate. Forster's Terns foraging socially cue on presence and behavior of other aggregating species, especially Snowy Egrets (Egretta thula). Joining aggregations significantly increased their capture rate, but not their capture efficiency, compared to solitarily foraging terns. However, total aggregation size, influenced primarily by the two most abundant species, Laughing Gulls (Larus atricilla) and Snowy Egrets, affected tern behavior. For example, diving terns often collided with Laughing Gulls, causing frequent missed attempts for socially foraging individuals. Thus, large aggregation sizes had a negative effect on foraging success, perhaps because of interference and/or prey depletion. In contrast, solitarily foraging terns dove less often for prey but also missed less often. This may be why terns were observed foraging solitarily as aggregation sizes and congestion increased.
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.
The migration phenology of six species of coastal birds on Mustang Island, Texas, USA was examined for a 27-year period (1978–2005). First arrival date, last date of departure, and duration of stay were quantified for three winter and three summer residents. These three variables were analyzed for changes over time and correlation with local, regional, and global temperature indices. Mean local summer temperature increased 0.03° C/year (0.74° C overall), while mean local winter temperature increased 0.10° C/year (2.76° C overall). The three winter residents had a trend for increasingly later arrival, increasingly earlier departure, and decreased duration of stay over the 27-year period. These trends reflect a shortening of the winter season for these birds and are consistent with expected responses due to warming temperatures. The three terns representing summer residents had less homogeneity in temporal trends than the three winter residents. Correlations of local temperature with arrival and departure dates, and duration of stay yielded few significant results and no overall pattern. Only Double-crested Cormorant (Phalacrocorax auritus; a winter resident) and Least Tern (Sterna antillarum; a summer resident) had significant correlations between arrival date and arrival temperature.
I used a randomized, replicated, controlled study design to test the hypothesis that nest-site availability limits breeding densities of secondary cavity nesting species in even-age southern pine (Pinus spp.) forests. Breeding densities of secondary cavity nesters increased significantly on treated plots after nest boxes were introduced. Total number of nesting attempts also increased several fold post-treatment. These data indicate nest-site availability was a limiting factor for breeding densities of secondary cavity nesting species. The response of individual species to nest boxes ranged from moderately high (Great Crested Flycatcher [Myiarchus crinitus]), to low (Tufted Titmouse [Baeolophus bicolor], Eastern Bluebird [Sialia sialis]) to no response (Carolina Wren [Thryothorus ludovicianus]). At least three factors accounted for interspecific differences in this study: different levels of reliance on cavities excavated in snags, different body sizes, and differences in local population densities. The large number of unoccupied nest boxes (only 9% were used for nesting) suggests secondary cavity nesters were not limited solely by cavity availability but also by habitat quality. Prescribed burning appeared to facilitate discovery and use of nest boxes by birds in this study, consistent with the hypothesis that nest-site limitation is mitigated by habitat structure.
We quantified the impact of nesting and roosting House Sparrows (Passer domesticus) on nesting success of Cliff Swallows (Petrochelidon pyrrhonota) in colonies in western Arkansas in 2007 and 2008. Two sections of a large swallow colony under a bridge with House Sparrows were compared in 2007 to two sections with little House Sparrow usage. Nesting success of Cliff Swallows (percent of nests yielding at least 1 chick) was 61% in sections with low House Sparrow activity, significantly higher than the 30% in sections with high House Sparrow activity. House Sparrows defended a broad zone surrounding their nests from Cliff Swallow nesting attempts. We compared the proportion of nests used, clutch sizes, and brood sizes of Cliff Swallows in two colonies in 2008, one with and one without House Sparrow activity. In the colony without House Sparrow activity, 48% of old and new nests were used by swallows versus only 8% in the colony with House Sparrows. Swallow clutch sizes were similar in the two colonies, but swallow brood sizes in the colony with no House Sparrows were significantly higher, mean = 2.3 nestlings per nest (mode = 2; 75th percentile = 3) compared to 0.8 nestlings (mode = 0; 75th percentile = 1) in the colony with House Sparrows. This suggests Cliff Swallows are less successful when House Sparrows are present in colonies.
We evaluated home-range size and site tenacity of Le Conte's Sparrows (Ammodramus lecontii) during winter 2002–2003 at Brazoria National Wildlife Refuge, Texas. Twenty-six wintering Le Conte's Sparrows were radiomarked in 1- and 2-year post-burn units, and monitored for ∼10 days. Additionally, 1-ha plots on each 1-, 2- and 3-year (n = 15) post-burn units were flush-netted once monthly. Telemetry results indicated Le Conte's Sparrows were sedentary during winter with a 50% probability mean home-range of 2.41 ha (72% < 1 ha) and a 95% probability mean home range of 10.31 ha (44% < 1 ha and 55% < 1.5 ha). Home-range size did not differ between post-burn year 1 and 2 (P = 0.227). Le Conte's Sparrows appeared to exhibit a behavioral response to flush-netting (P < 0.001) with estimated capture probability of 0.462 and recapture probability of 0.056. Our findings suggest Le Conte's Sparrows remain fairly sedentary throughout the winter.
Sex allocation theory predicts that population sex ratios should be generally stable and close to unity, but individuals may benefit by adjusting the sex ratio of their offspring. For example, females paired with attractive males may benefit by overproducing sons relative to daughters, as sons inherit their fathers' attractive ornaments (“sexy son” hypothesis). Similarly, if compatible gene effects on fitness are more pronounced in males than females, genetically dissimilar mated pairs may enhance fitness by overproducing sons (“outbred son” hypothesis). We tested these hypotheses in Song Sparrows (Melospiza melodia) by examining offspring sex ratios of 64 complete families shortly after hatching (“early-stage”) and again shortly before fledging (“late-stage”) in relation to paternal song complexity and the genetic similarity of social mates. Neither early nor late-stage offspring sex ratio was related to parental genetic similarity. Nests of males with larger song repertoires contained more male-biased broods by the late-stage nestling period, but not in the early-stage nestling period. These findings suggest that attractive males may be better able to successfully raise male-biased broods, but not that females adaptively adjust primary sex ratios in response to their social mate's attractiveness.
Little emphasis has been placed on the influence of season and age on morphological measurements of swifts, which makes comparative mensural studies difficult in the Apodidae. This study provides information about the importance of morphological variation in measurements to the biology of the Biscutate Swift (Streptoprocne biscutata). I studied individuals captured at four colonies in southern Brazil. Mass varied with age, time of day, and season. Birds captured at dawn weighed 115.5 ± 9.9 g (n = 1,320). Mass was greater in fall and spring and lower in summer and winter. Subadults weighed less than adults during summer, fall, and winter. The wing measured 206.3 ± 5.2 mm (n = 812), and the tail measured 69.9 ± 4.6 mm (n = 802); both showed seasonal variation in length. The tarsus measured 25.9 ± 0.6 mm (n = 695), and the exposed culmen measured 9.94 ± 0.36 mm (n = 658). The Biscutate Swift has significant seasonal variation in several morphological measurements. This variation should be considered in studies comparing populations of this species, as well as those of other apodids.
Red-headed Woodpeckers (Melanerpes erythrocephalus) are one of the most easily recognizable bird species, but little is known about their social system and breeding activity due to their lack of sexual dimorphism. We observed a dense population of Red-headed Woodpeckers and found evidence of cooperative breeding. The habitat at our site may promote cooperative breeding because it has a high density of utility poles that woodpeckers use for nesting, roosting, and caching food.
The Collared Crescentchest (Melanopareia torquata) is an endemic bird of the Cerrado (Family: Melanopareiidae), and is listed in the State of São Paulo, Brazil as “endangered”. We studied the breeding biology of Collared Crescentchest at two nests in the State of São Paulo, southeast Brazil. Males were identified genetically and equipped with radio-transmitters. The incubation period was 12–16 days and the nestling period was 12–14 days. Nestling body mass was measured every second day for the first 10 days. Males participated in incubation and helped with nesting care. Measurements of eggs and nests are compared to those from the single previously known nest. These data are the first for any member of the Family Melanopareiidae.
Swainson's Warblers (Limnothlypis swainsonii) have been described as terrestrial leaf litter foraging specialists, and are thought to vacate flooded areas entirely. We report Swainson's Warblers occupying a flooded area in Arkansas and foraging on unusual substrates. We observed Swainson's Warblers feeding in novel ways in the tree canopy and on floating debris. This is the first report of Swainson's Warblers occupying and foraging in flooded habitat, and suggests this species may have more short-term flexibility in foraging substrate than previously thought. Return rates to flooded territories were reduced compared to years without floods and several marked individuals switched to an unflooded area protected by man-made levees. The altered hydrology of rivers constrained by levees may reduce habitat quality for this species.
We investigated the roles of food quality and predator avoidance in shaping foraging behavior of Northern Cardinals (Cardinalis cardinalis). Cardinals visited feeders near cover and feeders with sunflower seed significantly more than they visited those in the open and those with commercial wild bird seed mix. Cardinals with a choice between their preferred food and preferred location visited the sunflower seed feeder in the open significantly more than the mixed seed feeder near cover, despite their prior preference for feeding near cover. We recorded visits to these feeders over a 2-day period during which we played Cooper's Hawk (Accipiter cooperi) calls every 2 hrs. The overall visitation rate did not decrease significantly, nor did the visitation rate to feeders near cover increase significantly. However, the decrease in the visitation rate to feeders in the open approached significance. Overall, we observed a significant shift in the proportion of visits to feeders near cover (containing less preferred seed). We conclude Northern Cardinals are sensitive to both food quality and predation risk, and adjust foraging to prevailing perceptions of risk.
We found the first documented wild nest of a Coral-billed Ground Cuckoo (Carpococcyx renauldi) at Khao Yai National Park, Thailand in June 2007. The large stick nest was monitored for 24 days including 1095 hrs of video footage; it contained two eggs and was in dense vegetation 4.85 m above the ground. Nest attentiveness of adults was almost constant with both birds taking turns to incubate or brood. Food delivered to nestlings included lizards, nestlings, a snake, frogs, earthworms, and other invertebrates. Nest defense was observed against several known nest predators but the nest ultimately failed due to predation by a pig-tailed macaque (Macaca nemistrina). These observations provide insight into the breeding ecology of the only two congeners, C. viridis and C. radiceus, for which little is known of their ecology and both are endangered.
The endemic Chinese Grouse (Tetrastes sewerzowi) inhabits subalpine coniferous forests. Little is known about its diet in the breeding season, especially while birds feed on the ground. Analysis of crop contents indicated that willow (Salix spp.) was the primary food of males (>98% wet weight, n = 4), whereas Dragon spruce (Picea asperata) seeds and willow were the primary foods of females (both >40% wet weight, n = 2). Dragon spruce seeds, invertebrates (mainly ants), and forbs were frequently consumed by females, but seldom by males, possibly to meet the nutrient constraints of egg formation. We suggest the different diets of males and females of this monogamous species may be the result of females allocating more time to searching for scarce, nutritious food, whereas males spend more time in vigilance behavior.
Common Ravens (Corvus corax) are opportunistic generalist foragers. Ravens during winter, in some portions of their range, rely heavily on meat scavenged from carcasses. Ravens use a variety of strategies to find carcasses on the landscape, including keying on audible cues that suggest the presence of a food source. I documented Common Ravens investigating a simulated animal distress call on 13 of 17 trials, suggesting that investigating animal distress vocalizations may be one tool in the suite of foraging strategies used by ravens.
We report observations of Hooded Crows (Corvus cornix) hanging upside down in the wild, for both playing and harvesting acorns. This behavior was recorded in six different events at the same site (Villa Chigi's urban park in Rome, Italy) and, in two cases, involved two individuals at the same time. Hanging behavior has been observed mainly in captive Northern Ravens (Corvus corax) and in few cases in wild corvids. Our observations indicate hanging behavior can be used to obtain food. These observations confirm that corvids have enormous plasticity that can be adapted to obtain food.
I report the first observation of conspecific brood parasitism in the Dickcissel (Spiza americana). I monitored 302 nests during a study of the interactions between parasitic Brown-headed Cowbirds (Molothrus ater) and Dickcissels. This and a possible second case of conspecific brood parasitism may have resulted from females laying in nests after their original nests were destroyed in nearby hayfields.
We observed adult Kelp Gulls (Larus dominicanus) capture and eat Olrog's Gull (L. atlanticus) chicks in the Bahía Blanca estuary, Argentina. This estuary holds the largest breeding colony of Olrog's Gulls. There are no previously published reports of Kelp Gulls capturing and eating Olrog's Gull chicks. Our data support suggestions made by other authors about the possible existence of conflicts in colonies where both species breed in close proximity.
The Snares Penguin (Eudyptes robustus) breeds only on the Snares Islands, New Zealand, and is vagrant throughout the New Zealand region and southeast Australia. The only previous record outside this area was one in the Falkland Islands in 1988. We report the unusual occurrence of two Snares Penguins in the same colony in the Falkland Islands in 2008, and discuss identification issues. Vagrant penguins demonstrate the incredible dispersal ability of these flightless birds.
I present the first confirmed record of the Sapphire-throated Hummingbird (Lepidopyga coeruleogularis) at Punta Banco, southwestern Costa Rica. An adult male was seen and photographed perched on a twig at the border of a second growth forest tract. This observation extends the geographic distribution of this species from northern Colombia to southwestern Costa Rica.