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Swainson's Warbler (Limnothlypis swainsonii) is a species of conservation concern because of its small wintering range in the Caribbean Basin, relatively low population densities, and habitat fragmentation in its core breeding range in the southeastern United States. We investigated microsatellite DNA variation among 11 breeding populations from eastern Texas to Virginia and two populations from wintering areas in Jamaica and Mexico. Analyses of six polymorphic loci indicated a moderate level of gene flow among breeding populations, relatively small effective population sizes (<200 individuals in each sampled population), and subtle population variation. We detected no evidence of population bottlenecks in breeding or wintering populations. Bayesian assignment tests suggested that substantial mixing of breeding populations may occur in wintering areas. Genetic differences between the Mexican and Jamaican populations indicate they may be drawn from different subsets of breeding populations. Patterns of genetic variation among breeding and wintering populations suggest a network of local and regional conservation programs may be necessary to maintain genetic diversity in Swainson's Warbler.
The Canada Warbler (Wilsonia canadensis) is currently in decline in the northeastern United States and basic demographic parameters remain to be described. We studied marked populations (76 ASYs, 14 SYs, and 2 of unknown age) of Canada Warblers on two study sites from 2003 to 2006. We mapped 92 territories (including males returning in multiple years) of 71 males using handheld GPS and ArcMap. We compared the pairing and fledging success of older and younger males on both sites, a red maple (Acer rubrum) swamp and a young forest intensively harvested in 1985 with ∼10% residual standing trees used by males as song perch trees. Both sites had a high proportion of ASYs (84% ASY for all territorial males, 77.5% of all males including non-territorial individuals). Both pairing (91%) and fledging (78%) success was comparatively high suggesting these two sites were of high value to this species. A higher proportion of SYs were transients. Pairing success was lower for younger males which established territories, but paired SYs fledged at least one young at a rate comparable to older males. This study corroborates the benefits of age and experience to reproductive performance. The results suggest that both red maple swamps and post-harvest forests with thick subcanopy vegetation and emergent trees provide high quality habitat for breeding Canada Warblers.
We used radio-telemetry to locate night roosts of 54 Ovenbirds (Seiurus aurocapilla) wintering in a coastal second-growth scrub habitat in Jamaica. All Ovenbirds roosted within their daytime home range and most individuals roosted within the core of their diurnal home range. Sixty-six percent of individuals roosted within the 30% core use distribution (i.e., most heavily used portion of their home range) and 35% of individuals roosted within the 10% core. The average distance between roost sites for 29 individuals located on more than one night was 34 m and at least three birds roosted solitarily in the same location on different nights. Roost location relative to the 10% core area of diurnal home range did not differ between males and females, adults and immatures, or between individuals studied in subsequent years. The wintering Ovenbird population we studied appeared to roost solitarily. This study is the first to provide quantitative evidence that individual migrant songbirds in a tropical wintering population consistently roost at night within their foraging home range. These results suggest that roosting behavior is correlated with daytime space use patterns of the winter social system.
I studied the reproductive success of the Puerto Rican Vireo (Vireo latimeri) from 1998 to 2000 in Maricao State Forest, a montane reserve in the southwestern part of Puerto Rico. No parasitism by the Shiny Cowbird (Molothrus bonariensis) was found but 63% of 38 active nests were depredated with an overall daily nest survival of 0.932 ± 0.007 (± SE). Mean nest survival estimates following Hurricane Georges did not vary significantly before and after the hurricane. However, a return rate of only 39% was estimated for color-marked adults the year including the hurricane compared to 72% for the year without a hurricane. A 26% decline in density of territorial males was observed in the post-hurricane year.
We examined nest defense behavior of the Carolina Wren (Thryothorus ludovicianus) in response to avian intruders at the nest. Freeze-dried mounts of a brood parasite (female Brown-headed Cowbird [Molothrus ater]), nest predator (Blue Jay [Cyanocitta cristata]), and a control (Swainson's Thrush [Catharus ustulatus]) were presented at wren nests to examine if wrens were able to distinguish among these threats. The primary nest defense behavior of Carolina Wrens was alarm calls. Wrens spent more time alarm calling to the Blue Jay model than the control and Brown-headed Cowbird models suggesting cowbirds were not recognized as threats to the nest. Wrens were less likely to respond during laying stage trials, probably due to a lack of nest visitations at this time. Intensity of alarm calls did not increase from the laying to nestling stage for any of the models presented. Carolina Wrens are both socially and genetically monogamous, and males should invest heavily in care of young due to their high confidence of paternity. Males and females did not differ in the amount of time spent alarm calling to any of the models, and defended their nests from intruders with equal intensity as predicted by the confidence of paternity hypothesis.
We describe the nest and eggs of the Puna Tapaculo (Scytalopus simonsi) from Bolivia, and include observations of nest building, incubation, and parental care. The nest is similar to several other described nests in the genus in construction and placement: a domed cup nest of grasses in an excavated burrow in a vertical bank. Both male and female constructed the nest, brooded, and provisioned the young, typical of Scytalopus and tracheophone suboscines. This is only the second described Scytalopus nest constructed of grasses, probably an adaptation to its drier habitat near and above treeline. The growing body of Scytalopus nest descriptions suggests they do not exhibit generic level stereotyped nest structure and placement, unlike other tracheophone suboscines, which show strong phylogenetic signal in nest architecture.
Acorn Woodpecker (Melanerpes formicivorus) populations were sampled to evaluate geographic patterns of differentiation and connectivity across the species' range. We observed patterns of differentiation generally coincident with geographic patterns in plumage patterns with distinct subpopulations in Baja California Sur, northern Central America, southern Central America, and mainland Mexico north into the southwestern United States. We confirmed the existence of geographic genetic structuring of populations of this species, although shared haplotypes between Baja California Sur and mainland Mexico suggest that lineage sorting is not yet complete. The process of geographic differentiation and speciation is likely still underway in this group.
We studied the diet of the Acorn Woodpeckers (Melanerpes formicivorus) at La Primavera Forest, Jalisco, Mexico. This resident species had a diverse diet throughout all seasons. The diet included acorns of Quercus viminea, Q. castanea, and Q. laeta, which were stored primarily in granaries in live trunks of pine (Pinus spp.) trees. They also consumed acorns of Q. magnoliifolia and Q. resinosa by piercing and eating just the central part of the seed. Acorn Woodpeckers did not use acorns from species of oak in the same proportion as available. They also fed seasonally on insects (Coleoptera and Lepidoptera) and tree sap.
We used remote recorders to document temporal variation in acoustic signals of a population of Pileated Woodpeckers (Dryocopus pileatus) along the Choctawhatchee River in the Florida Panhandle, sampling seven different locations for 24 hrs once a week between mid January and mid April 2006. We found significant seasonal variation in the drumming behavior and vocal behavior of Pileated Woodpeckers. Drumming behavior peaked in mid March, just prior to onset of breeding activities. The three primary long-distance Pileated Woodpecker vocalizations, the cackle call, the wuk series call, and the wok call had similar patterns of seasonal variation. All four acoustic signals declined to low levels by early April when birds were nesting. The seasonal pattern of variation for all four Pileated Woodpecker acoustic signals had a similar pattern to that observed for song in many temperate passerines, and support the hypothesis that woodpecker calls and drumming displays are the functional counterparts to passerine song.
We investigated the influence of lunar and environmental factors on behavior of Common Poorwills (Phalaenoptilus nuttallii) in southern Arizona under a diverse set of natural and artificial conditions. Radio-marked poorwills were most active shortly after sunset during the new moon. Movements declined as evening progressed. Activity remained high for several hours after sunset when the moon was full. Poorwills were heard calling from March through October, but most calling occurred between early May and September. Only ambient light was correlated with number of poorwills heard calling. More poorwills responded to playbacks of conspecifics when the moon was full than when it was new. Poorwills did not change their response to conspecifics during full moon when playback of poorwill calls followed playback of Great Horned Owl (Bubo virginianus) calls but, during the new moon, fewer birds responded following the owl call. Poorwill behavior is strongly influenced by lunar conditions; their ability to detect and evade predators is important when calling advertises their location.
We conducted 262 call-broadcast point-count surveys (1–6 replicate surveys on each of 62 points) using standardized North American Marsh Bird Monitoring Protocols between 31 May and 7 July 2006 on St. Vincent National Wildlife Refuge, an island off the northwest coast of Florida. We conducted double-blind multiple-observer surveys, paired morning and evening surveys, and paired morning and night surveys to examine the influence of call-broadcast and time of day on detection probability. Observer detection probability for all species pooled was 75% and was similar between passive (69%) and call-broadcast (65%) periods. Detection probability was higher on morning than evening (t = 3.0, P = 0.030) or night (t = 3.4, P = 0.042) surveys when we pooled all species. Detection probability was higher (but not significant for all species) on morning compared to evening or night surveys for all five focal species detected on surveys: Least Bittern (Ixobrychus exilis), Clapper Rail (Rallus longirostris), Purple Gallinule (Porphyrula martinica), Common Moorhen (Gallinula chloropus), and American Coot (Fulica americana). We detected more Least Bitterns (t = 2.4, P = 0.064) and Common Moorhens (t = 2.8, P = 0.026) on morning than evening surveys, and more Clapper Rails (t = 5.1, P = 0.014) on morning than night surveys.
We studied variation in acoustic and temporal characteristics of the static male song of the Green Violetear (Colibri thalassinus) in a single population in Costa Rica. The static song of 19 males was extremely variable. The song has two elements: the first was delivered exclusively at the beginning of each song while the second was present once, twice, or three times in the song of different males. Low frequency (LF), song duration (ΔT), and high frequency (HF) varied significantly among most individuals. The male population of Green Violetear has four song types that differ in acoustic and temporal characteristics. The great inter-male song variation suggests this type of vocalization may be under sexual selection.
The invasive exotic Chinese tallow tree (Triadica sebifera) produces an abundant fruit crop, which is primarily bird-dispersed. The fruit pulp of tallow is lipid-rich, high in saturated fatty acids, and consumed by many bird species. Long-chained fatty acids can be difficult for many birds to digest and we investigated the ability of tallow consumers to assimilate energy in the pulp. We used the total collection method and compared apparent metabolizable energy (AME) of tallow fruit for three species of birds with differing fruit composition in their natural diets. All birds exhibited nitrogen deficits and lost body mass during the trials. Northern Cardinals (Cardinalis cardinalis) lost more mass (8.73%/day) than Yellow-rumped Warblers (Dendroica coronata) (5.29%/day) and American Robins (Turdus migratorius) (5.48%/day), and had larger nitrogen deficits (−120.1 mg N/g diet) than both species as well (−36.4 mg N/g diet and −68.9 mg N/g diet, respectively). Food intake relative to metabolic body mass was highest in Yellow-rumped Warblers (0.70 g-dry/g0.75·day). Northern Cardinal and American Robin food intake was lower and did not differ from each other (both species: 0.13 g-dry/g0.75·day). Nitrogen corrected values of AME were used to make species comparisons. Yellow-rumped-Warblers exhibited the highest values of AME (30.00 kJ/g), followed by American Robins (23.90 kJ/g), and Northern Cardinals (14.34 kJ/g). We suggest tallow may be an important winter food source for Yellow-rumped Warblers where their ranges overlap.
I examined how High Andean insectivorous birds partition resources in remnant Polylepis forest patches at three locations in the Cordillera Vilcanota, southern Peru. A number of distinctive guilds were identified within the bird community based on the manner and location of foraging displayed by each species. Important dimensions that enabled differentiation amongst guild co-members were those that supported the partitioning of resources between guilds. The significant disproportionate use of substrates and prey-attack maneuvers by birds indicated substrate specialization within the insectivorous Polylepis bird community. These specializations provide a means by which Polylepis insectivores fit syntopically along a resource gradient. Insectivores demonstrated a differential response to foraging in smaller patches, and changes in the foraging regimes of four guilds between large and small patches were frequent. The most abundant insectivores in small patches were the least diverse foragers; they compensated behaviorally for changes in patch habitat quality by using fewer substrates and prey-attack maneuvers. Guild members that shifted their foraging regime to use fewer attack maneuvers were also more tolerant of small patches. Small Polylepis patches have a significant role in fragmented High-Andean ecosystem functioning by providing essential foraging habitat for insectivorous birds.
Eight nests of the Giant Conebill (Oreomanes fraseri, Family Thraupidae) were found in Polylepis forest fragments in Cochabamba Department (Sacha Loma and Cuturi) of Bolivia during 2002–2004. The breeding period of the Giant Conebill extended from September to December at the beginning of the rainy season. The nests were open cups with an average outside width of 20 cm and a thick rim of 5.5 cm; the average clutch size was 1.86. Nests were constructed mostly with parts of Polylepis trees and a variety of mosses. All nests located were in the interior of forests, well camouflaged, and in trees with an average height of 3.16 m. Control of human disturbance, especially burning, is needed for protection of the habitat of the Giant Conebill.
Little is known about impacts to birds from collisions with windows at commercial buildings. We monitored bird mortality from striking windows at five commercial buildings on two college campuses in northwestern and southwestern Illinois. Bird mortality at Augustana College (northwestern), which was evaluated from 2002 to 2006, totaled 215 individuals in 48 species for an average rate of 55 birds/building/year. We calculated a mortality rate of 24 birds/building/year for 2004–2005 from 142 individuals within 37 species at Principia College (southwestern). Mortality of North American migrant (NAM) and neotropical migrant (NTM) birds was higher during migration than during summer or winter. We tested the hypothesis at Augustana that density of birds at a given location will be positively correlated with numbers of birds that die due to strikes with windows. Bird density only partially explained strikes with windows since mortality was also a function of landscaped habitat that attracted birds. Annual bird mortality at commercial buildings may be about five times higher than previous estimates. These buildings may place bird populations at high risk of strikes at windows.
Populations of the hematophagous mite, Dermanyssus prognephilus, within Eastern Bluebird (Sialia sialis) nests were manipulated using a pyrethrin-based insecticide to examine effects on nestling growth, selected hematological parameters, and fledging success. There was no difference in body mass, fledging success, estimated white blood cell counts, or hematocrits of infested versus non-infested nestlings. However, infested nestlings had a 25.0% reduction in hemoglobin and a 20.5% increase in immature erythrocytes. These findings suggest a physiological response to parasite feeding that may affect post-fledging survival.
Worthen's Sparrow (Spizella wortheni) is one of the most endangered species in Mexico. Its survival depends on appropriate conservation strategies and reliable information about the species. Our study on winter groups of Worthen's Sparrow flocking with other grassland bird species provides preliminary ecological and behavioral information on this species, and its relation to other migratory and resident bird species in La Perforadora Valley, Coahuila, Mexico. We observed flocking associations of Worthen's Sparrow with 16 other species. Ochiai's Association Coefficient indicated Worthen's Sparrow often associated with Vesper Sparrow (Pooecetes gramineus) (0.60), Black-throated Sparrow (Amphispiza bilineata) (0.33), Horned Lark (Eremophila alpestris) (0.27), and Western Bluebird (Sialia mexicana) (0.22). Worthen's Sparrow occurred more frequently in mixed than in monospecific flocks in winter. It foraged more frequently on the ground but also searched in shrub stems, branches, and foliage from perches, and at times hawked for flying insects from perches. Most perches were in the shrub stratum, but fences also were used. Worthen's Sparrow in mixed-species flocks spent more time in foraging activities than those in monospecific flocks.
We surveyed the coast of Chile between Isla Terhalten (54° 20′ S) and Islote Leonard (55° 44′ S) by boat during November–December 2005 to document breeding locations of Rockhopper (Eudyptes chrysocome chrysocome) and Macaroni (E. chrysolophus) penguins, and to count the number of nests during the early incubation period. A yacht-based observation recorded 1,000 Rockhopper Penguin nests at Isla Terhalten. Ground-based counts at Isla Noir estimated a total of 158,200 Rockhopper and 3,470 Macaroni penguin nests in 17 mixed colonies and one Macaroni Penguin breeding colony. The Rockhopper population on Isla Noir increased significantly from the previous estimate of 70,000 pairs, making this island the most important breeding site for the southern subspecies of Rockhopper Penguin. The new estimate for Rockhopper Penguins suggests a population increase over the last 20 years, consistent with recent data for the main colony in Argentina. Conservation status of the species and the factors potentially responsible for population declines elsewhere may need to be re-evaluated.
Breeding bird surveys indicate a long-term decline in numbers of scoters (Melanitta spp.) breeding in North America. Little is known about the breeding habitat and reproductive life history of White-winged Scoters (M. fusca) in their primary breeding areas in the boreal forest of Alaska and northern Canada. We characterized selection of nest habitats and attributes within those habitats by measuring variables at nests and random sites on the Yukon Flats National Wildlife Refuge, Alaska. White-winged Scoters avoided nesting in meadows, but nested in scrub or forested habitat types in proportion to their availability (χ25 = 9.7, P = 0.08). Nests of radio-marked females were farther from water and edge ( 210 ± 43 and 10 ± 4 m, respectively), and in slightly thicker cover ( 6 ± 4%) than nests located without aid of radio transmitters. Females selected sites with more variable and abundant overhead and lateral cover, and sites closer to edge and water than random sites. The results imply nearly random use of scrub and forested habitat types within the study area, but selective use of attributes within those habitat types. This generalist approach to nest site selection at a larger scale may be an adaptive response to reduce detection by nest predators. Nests located without use of radio-marked females may not be representative of the population of nests at a study site. White-winged Scoters often selected nest sites with dense cover far from water, which may increase nest survival. However, concealed sites are difficult for heavy-bodied birds to escape and females may be trading productivity against their own mortality.
Scoters (Melanitta spp.) exhibit extraordinary maneuvers during courtship flight, attitudes which are not commonly seen in flight. Scoters drop their legs and spread webbed feet during these maneuvers. There appears to be a correlation between how the feet of scoters meet the airflow and the maneuver in progress.
We report two incidences of Harlequin Ducks (Histrionicus histrionicus) entangling their bills in subcutaneously-attached anchor transmitters. We suggest caution should be exercised when using these transmitters.
Band-tailed Pigeons (Patagioenas fasciata) wintering at Hastings Reservation in central coastal California during winter 2006–2007 died in large numbers between January and March 2007. Laboratory analysis of carcasses indicated that Trichomonas gallinae was responsible for the die-off. During the height of the die-off, a survey of 2.5 km of suitable riparian habitat resulted in 373 pigeon carcasses being found. Based on a subsample of carcasses, mean turnover rate was 2.8 days with a 95% confidence interval of 2–10 days. Extrapolating to suitable habitat over the 52.7-km2 study area resulted in a conservative estimate of 43,059 dead pigeons, assuming a conservative carcass turnover rate of 10 days. This estimate of mortality is nearly three times the largest trichomoniasis mortality event previously recorded for Band-tailed Pigeons and at least twice the number harvested annually in the United States. Local mortality of pigeons in Monterey County, California may have been several times this estimate based on the presence of considerable similar habitat in the nearby Ventana Wilderness.
Arthur T. Wayne collected 58 Yellow Rails (Coturnicops noveboracensis) during seven winters between 1903 and 1918 at one locality on the Atlantic coast in Charleston County, South Carolina. The collection represents the largest known series of Yellow Rails from a single wintering site and provides information about the winter ecology of this species. There was no evidence that Yellow Rail numbers varied between winters. The sex ratio was significantly biased toward females suggesting the occurrence of differential wintering. Yellow Rails were collected mainly in wet (freshwater) fields with short dense grass, the same features of Yellow Rail habitats in coastal Texas. Yellow Rails were consistently located in the same habitats as LeConte's Sparrow (Ammodramus leconteii). Two other grassland species, Henslow's Sparrows (A. henslowii) and Sedge Wrens (Cistothorus palustris), had habitat occupancy patterns significantly different from that of Yellow Rails.
Water was released from a reservoir in May 2005 to restore the wetland of international importance at Zhalong, China. As a result, the water level on the floodplain rose rapidly. A pair of Red-crowned Cranes (Grus japonensis) was observed raising their nest to avoid submersion and loss of eggs. The nest and two eggs were tended by both adults, but the eggs did not hatch. Hatching failure may have resulted from low egg temperatures due to addition of wet and new nesting materials, and reduction of incubation time during the flooding event. Reservoir discharge should avoid the breeding period of waterbirds and discharge rates should be reduced.
We found evidence of birds nesting directly on glacier ice of the Quelccaya Ice Cap in the Cordillera Vilcanota, Perú at elevations up to 5,300 m. Observations during June and July over several years consisted of numerous nests not in situ having obviously fallen from the steep and dynamic, retreating glacier margin. A typical nest was a bulky structure of grass and twigs with a dry mass of 160 g. The inner cup was nicely formed and lined with fine grass, measuring 6–7 cm in diameter and 4–5 cm deep. Feathers and entire wings of White-winged Diuca Finch (Diuca speculifera) were observed in association with the nests; this was the passerine species most commonly seen in the area. The evidence indicates the glacier nests were built and used by White-winged Diuca Finch, probably during the Austral autumn when on-site automated measurements indicate the wet season ends and air temperatures have not yet decreased. This is the first well-documented case of high-elevation avian nesting on glacier ice.
The Rota White-eye (Zosterops rotensis) is an endangered species endemic to the island of Rota in western Micronesia. We monitored eight nests from 2003 to 2005, four of which produced at least one fledgling. Clutch size was two in each of five nests that were counted; the average number of fledglings from successful nests was 1.5 (n = 4). We filmed six nests and captured two nest predation events on video. A Mariana Crow (Corvus kubaryi), which is also an endangered species, was filmed taking nestlings from one white-eye nest. Another nest containing eggs was depredated by a rat (Rattus spp.); however, this may have occurred after the nest was abandoned due to the presence of the camera.
Predation is the primary cause of nest loss in most passerine species. While nest predation is important, the predator community and behaviors of parents and predators during predation events are poorly documented. I witnessed one and videotaped four predation events at nests of Western Slaty Antshrikes (Thamnophilus atrinucha) in central Panama. Predators included a snake (Pseustes poecilonotus), a monkey (white-faced capuchin [Cebus capucinus]), and three species of birds. Predators spent little time at the nest, yet some returned repeatedly to the same nest. Parents also returned several times to nests after the predation event and parental behaviors varied depending on the predator. Nest disturbance was not an accurate indicator of predator type.
We report the first records of Brown-headed Cowbirds (Molothrus ater) raised to fledging by Bachman's Sparrow (Aimophila aestivalis). Records are based on field observations of parasitized sparrow nests monitored during two separate avian reproductive studies. One record is of a Bachman's Sparrow nest in southwestern Florida in 2002 and four records are of unpublished data from sparrow nests in central Arkansas during 1983–1985. These observations suggest that Bachman's Sparrow can successfully raise cowbird young. Ours is also the first record of a parasitized Bachman's Sparrow nest in Florida.
We present the first observations of misdirected parental care by Savannah Sparrows (Passerculus sandwichensis) including a rare occurrence of simultaneous incubation. Two females simultaneously incubated eggs, brooded, and fed nestlings, and two males fed nestlings in one nest. These behaviors may have been prompted by strong parental instincts in combination with a stressful breeding environment mediated by hayfield management, as any genetic benefits were unlikely.
Grey Herons (Ardea cinerea) typically prey upon fish and other aquatic organisms with occasional reports of predating small birds. I report observations of one or more Grey Herons predating on Aldabra White-throated Rails (Dryolimnas cuvieri aldabranus) on Picard Island (Aldabra Atoll, Seychelles). Grey Herons were observed on two occasions having caught rails and, on another occasion, a heron was observed ambushing and pursuing rails with no success. Heron(s) were not observed ingesting the rails, as they flew or ran off with their prey, but it is likely the rails were consumed. These are the first observations of any form of predation on the Aldabra White-throated Rail, which is one of the largest recorded avian prey of the Grey Heron.
We observed a Northern Fulmar (Fulmarus glacialis) prey upon a live Common Murre (Uria aalge) off Cape Spear, Newfoundland, Canada on 4 November 2007. Active predation of Northern Fulmars on other seabirds has not previously been reported.
Boluses were collected from Black-crowned Night-heron (Nycticorax nycticorax) nestlings in 1992 to examine the impact of night-heron predation on a restored tern colony. Boluses (n = 101) were collected from 18 nests. Fish remains occurred in 89% of nests, sand shrimp (Crangon septemspinosa) in 50%, birds in 28%, and amphibians in 16% of nests sampled; mammalian, eel, squid, and marine invertebrate remains were also noted. Regurgitated bird remains were found in five nests and included four species, Common Terns (Sterna hirundo), Common Eiders (Somateria mollissima), Gulls (Larus sp.), and the legs of an unknown wading bird. Nestling night-herons from three nests were fed tern chicks, but 92% of tern chicks known to have been eaten were fed to nestling Black-crowned Night-herons in one nest. No tern chicks fledged in 1992 and night-herons were observed in the tern colony on multiple occasions. This study suggests that individual night-herons will specialize on waterbird prey. The subsequent removal of a specialist night-heron predator resulted in improved tern productivity.
This is the first report of the diet composition of Long-eared Owl (Asio otus) in the northern and central Negev desert, Israel. The diet consisted of 71.3% small mammals, 26.5% birds, 2.0% invertebrates, and 0.1% reptiles. There were no significant differences among the seven localities studied or among seasons in percent rodents or invertebrates in the diet. However, the proportion of psammophilious rodents within the diet was larger in settlements where the soil was sand or sandy-loess and smaller where the soil was loess or rocky. Percent birds in the diet did not differ among localities, but differed among seasons. Migratory birds formed a significantly larger part of the total birds consumed during migration than during the non-migratory months.
We document the first observed instance of polygyny in Flammulated Owls (Otus flammeolus) and the first among insectivorous raptors. Chronologies of the male's two nests, which were 510 m apart, were separated by nearly 2 weeks. Each brood initially consisted of three owlets, similar to the mean brood size in monogamous pairs. The male delivered considerably fewer prey to the secondary nest, compared with prey-delivery rates at nests of monogamous males during the nestling period. Evidence suggested that all owlets fledged from the primary brood, but only one fledged from the secondary brood. We were uncertain of the cause of polygyny, but a possible explanation is the Hayman Fire shifted the operational sex ratio of the owls in favor of females. The extent of polygyny in Flammulated Owls may be limited by costs to the reproductive success of secondary females.
I present the first published observations of the Giant Hummingbird (Patagona gigas) in the mountains of central Argentina. This species was recorded in early and late summer 2006 and 2007. This new range resembles other summer habitats of the species, which are in the Andes >500 km distant. A climatic envelope model configured with known locations obtained from the literature predicts a high probability of occurrence in its “new” range.
We report Giant Hummingbirds (Patagona gigas), regularly and deliberately, ingesting wood ashes and slaked lime in central Chile. These two minerals have high concentrations of calcium, which may be a scarce element in the nectar-based diet of the species. Both observations occurred during the post-breeding period suggesting the birds were females ingesting calcium-rich compounds to replace minerals lost during eggshell production.
We provide documentation on the first observations of nocturnal foraging by the Blue-crowned Motmot (Momotus momota). The motmot we observed mainly fed on sphinx (Sphingidae) moths; the capture rate seemed low for this fairly large prey.
We observed Grey Kingbirds (Tyrannus dominicensis) from late February to May 2007 stealing food items from the bills of Carib Grackles (Quiscalus lugubris). This behavior occurred at two baited walk-in bird traps on the grounds of Bellairs Research Institute of McGill University in St James, Barbados. Grey Kingbirds were not seen entering traps, but were regularly observed in tree branches near traps, often chasing Carib Grackles and Zenaida Doves (Zenaida aurita) as they exited the traps with food. We describe six instances of kleptoparasitism by Grey Kingbirds from Carib Grackles. To our knowledge, this is the first report of kleptoparasitism for this species.
Some ground-foraging birds, including most New World sparrows in the tribe Emberizini, uncover food items in litter by double-scratching, a backward hop that displaces the litter posteriorly. I report double-scratching by Yellow-headed Blackbirds (Xanthocephalus xanthocephalus), a species not previously known to exhibit this behavior. Double-scratching by one individual that was observed in detail occurred with the bill pointed downward with its tip near or touching the ground, as in other icterines but unlike the behavior in Emberizini. This individual, between double-scratches, also used bill-sweeping to displace litter. Double-scratching has a similar form in at least three of the four icterine species reported to show the behavior, suggesting the trait is homologous among these species. However, phylogenetic relationships imply that double-scratching evolved convergently in these taxa.