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We studied a newly established population of Kirtland's Warbler (Dendroica kirtlandii) in Adams County, Wisconsin, nesting in a red pine (Pinus resinosa) plantation. We found eight males and five females in Adams County in 2008 and 10 males and 10 females in 2009. Five of seven (71%) males color-banded in 2008 returned in 2009, and at least eight successful nests produced an estimated 33 young over the 2 years. Red pine comprised 66.9% of trees on the main site, 20.6% were northern pin oak/black oak (Quercus ellipsoidalis/Q. velutina), and 12.5% were jack pine (Pinus banksiana). Total tree density at the main site was 1,876 trees/ha, lower than generally reported in Michigan. Percent canopy cover and ground cover types were similar to Michigan sites. Lowest live branch height of jack pine was similar to Michigan sites, but lowest live branches of red pine at our site were closer to the forest floor. Significant red pine die-off at our site combined with substantial natural jack pine recruitment created a landscape matrix of openings and thickets that produced suitable Kirtland's Warbler habitat. We suggest young red pine-dominated plantations should be searched when surveying for Kirtland's Warblers as some lower-density red pine plantations could provide important supplemental habitat as the species expands its range.
Cerulean Warblers (Dendroica cerulea) have experienced one of the highest population declines of any neotropical-Nearctic migratory species in North America. We performed point counts and habitat assessments in areas used and unused by Cerulean Warblers in northern Alabama during the 2005 and 2006 breeding seasons to examine their avian associations and identify microhabitat features that best explained their occurrence. We detected on average ∼50 Cerulean Warbler males (total) in three disjunct populations during each breeding season. Areas used by Cerulean Warblers were characterized by avian communities with significantly higher species richness, diversity, and abundance compared to areas where they were not detected. Correspondence analysis related Cerulean Warblers to inhabitants of riparian, bottomland deciduous forests (e.g., Kentucky Warbler [Oporornis formosus], Acadian Flycatcher [Empidonax virescens], and Northern Parula [Parula americana]) and two edge specialists (Blue-winged Warbler [Vermivora cyanoptera] and Indigo Bunting [Passerina cyanea]) suggesting Cerulean Warblers in our study areas may be tolerant of some habitat disturbance within an otherwise largely forested landscape. Information theoretic criteria and canonical correspondence analysis indicated Cerulean Warblers preferred bottomland forests containing tall (> 29 m), large diameter, well-spaced (> 27 m2/ha) deciduous trees with greater canopy cover (≥ 90%), closer (< 20 m) canopy gaps, fewer snags (≤ 25/ha), and a moderately complex canopy structure.
The natural histories of Volcano (Selasphorus flammula) and Scintillant (S. scintilla) hummingbirds are poorly known. We describe aspects of their breeding behavior with emphasis on courtship displays and sounds that males produced for females. Males of neither species sang undirected song. Males of both species produced a display dive, in which they ascended ∼25 m in the air and then dove, swooping over the female. Both species produced a pulsed sound that was synchronized with abrupt tail spreads during the bottom of the dive. The second rectrix (R2) of both species was capable of generating the same sound in a wind tunnel, suggesting these sounds were made by the tail. The dive sounds of the Volcano Hummingbird were louder than those of the Scintillant Hummingbird. Male Scintillant Hummingbirds produced a wing trill in flight, and performed a shuttle display to females in which the wing-beat frequency reached ∼100 Hz. Males held territories in open areas during the breeding season. Not all territories included abundant floral resources, and abundant resources in closed habitat were not defended. The role of resources is unclear in the breeding system of these two species.
We studied the poorly understood Black Catbird (Melanoptila glabrirostris), a near threatened mimid, at Lighthouse Reef in northeastern Belize. A resident of coastal lowlands and offshore islands, this endemic species of the Yucatan Peninsula has been reported as extirpated from several localities and has declined in numbers at other sites. We found it relatively common on the larger of two islands that comprise Northern Two Cayes from 18 to 25 June 2005. It had not been reported there since first discovered at Lighthouse Reef in 1862 and was considered extirpated until we rediscovered it. The Black Catbird at Northern Two Cayes displayed fierce intraspecific territoriality and both males and females defended against aggressors. However, it exhibited no interspecific territoriality toward its nearest avian associate, the Mangrove Warbler (Dendroica petechia bryanti). It used wing-flashing in territorial defense, mating rituals, and while foraging on the ground. We estimated ∼10 pairs of Black Catbirds in a 3-ha study area in the buttonwood-coconut (Conocarpus-Cocos) ecosystem but made no attempt to estimate the size of an apparently larger population in the more extensive area of coastal scrub on the remainder of the island. The defended territory of the pair studied most extensively was 100 × 25 m, centering on a buttonwood (Conocarpus erectus) grove and included numerous coconut (Cocos nucifera) trees.
Reasons for the decline of the Mariana Crow (Corvus kubaryi) on the Western Pacific island of Rota are currently unknown, but a need to protect nesting habitat has been suggested. We examined 55 actual nest sites and 60 random sites from 1997 to 1999 to investigate habitat characteristics specific to crow nest sites. Both nests and random plots were predominantly in limestone forest habitat. Discriminant function analyses indicate actual nest sites were differentiated from random sites based on a higher percentage of canopy cover and mean DBH of papaya (Carica papaya) and woody vines, as well as a higher stem count of species associated with limestone forests. This resulted in correct classification of a potential site as nesting versus random in 92% of the cases. Actual nests were >300 m from buildings, while random sites averaged (± SE) 226.7 ± 71.6 m from a building. Actual nest sites were about twice as far from a road as random nest sites. Twenty-eight of the 55 active nests fledged young. Nests in native forests were associated with higher reproductive success than nests in more disturbed areas. These findings suggest that damage to habitat from anthropogenic or natural causes may be limiting nesting success.
Aspects of the breeding biology of the world largest Olrog's Gull (Larus atlanticus) colony, in the estuary of Bahía Blanca, Argentina, were assessed for 101, 66, and 47 nests in 2005, 2006, and 2007, respectively. Mean (± SD) clutch size in 2005 was 1.86 ± 0.73 eggs per nest and modal clutch size was two eggs (range = 1–3). The incubation period was 1.67 days longer for A-eggs than for B-eggs (27.44 ± 1.22 days vs. 25.77 ± 1.36 days, respectively; P < 0.001). Incubation length for C-eggs was 25.75 ± 0.96 days. The largest eggs were 31.5% (length), 21.3% (breadth), and 66.5% (volume) larger than the smallest eggs. Mean egg volume in 2006 and 2007 decreased with hatching order, but the magnitude of this change was more pronounced in 2007 than in 2006. Variation in all egg measurements was larger among than within clutches. Hatching success within three-egg clutches was 76.9% in 2005, 81.7% in 2006, and 91.3% in 2007 (P = 0.20). Total egg loss in 2005 reached 16.7% and complete clutch loss was 43.8% during the incubation period. Parameters quantified in this study provide a comparative benchmark for future research on factors affecting breeding parameters in Olrog's Gull from this and other colonies, and lay the foundation for developing effective conservation strategies for the species.
I studied the breeding biology, parental care, and nesting success of the Bolivian Swallow-tailed Cotinga (Phibalura flavirostris boliviana) in Aten, northwestern Bolivia, from October 2005 to February 2006. The incubation period ranged from 17 to 19 days and the nestling period was 25 to 30 days. Swallow-tailed Cotingas appeared to be monogamous during the entire nesting stage, from nest construction to fledging of nestlings, based on 10 nests with focal observations. Each parent took care of the nest every hour during the incubation period, but males spent more time at this activity than females. Both parents spent equal time taking care of the young during the nestling period. Nest care decreased as nestlings developed, the provisioning rate of parents increased, and length of foraging trips increased. The probability of daily survival between the nestling (0.9773) and incubation periods (0.9455) was not statistically significant; overall nesting success was low (20%). This work is the first detailed report of the nesting of this species in Bolivia.
The Shrike-like Tanager (Neothraupis fasciata) is a Cerrado bird considered as near threatened. Its life history is poorly known, especially its reproduction. We monitored reproduction during four breeding seasons (2003–2006) with 120 nests in a protected area in central Brazil. Nesting began at the end of the dry season and start of the rainy season. The incubation (13.0 days) and nestling (11.7 days) periods were shorter than for most neotropical birds, but similar to some other tanagers. Clutch size (2–3 eggs) was similar to most tropical birds. However, clutch size increased and nest initiation date advanced ∼30 days in a year of early precipitation compared to 3 other years with regular or late precipitation. The Shrike-like Tanager had breeding flexibility and ability to adapt to changes in temporal precipitation patterns.
We examined factors influencing Canada Goose (Branta canadensis interior) annual nest success, including the relative abundance of collared lemmings (Dicrostonyx richardsoni), arctic fox (Alopex lagopus) den occupancy, nest density, and spring phenology using data collected during annual Canada Goose breeding area surveys at Cape Churchill, Manitoba. Nest density and arctic fox den occupancy strongly influenced Canada Goose nest success. High nest density resulted in higher nest success and high den occupancy reduced nest success. Nest success was not influenced by lemming abundance in the current or previous year as predicted by the “bird-lemming” hypothesis. Reducing arctic fox abundance through targeted management increased nest survival of Canada Geese; a result that further emphasizes the importance of arctic fox as nest predators in this system. The spatial distribution of nest predators, at least for dispersed-nesting geese, may be most important for nest survival, regardless of the abundance of small mammals in the local ecosystem. Further understanding of the factors influencing the magnitude and variance in arctic fox abundance in this region, and the spatial scale at which these factors are realized, is necessary to fully explain predator-prey-alternative prey dynamics in this system.
Host-parasite interactions between Red-rumped Caciques (Cacicus haemorrhous) and Giant Cowbirds (Molothrus oryzivorus) were studied at 52 nests in the Atlantic Forest, Misiones, Argentina. Cowbird eggs (1–6) occurred in 27 of 38 cacique nests (71%) found during the egg stage. Giant Cowbird eggs were white and unmarked (85%), or marked and spotted over pale buff (15%); the marked eggs somewhat resembled host eggs, but were twice as large. Four host and three parasite eggs were found punctured and broken. Only three cowbird nestlings were observed, and resembled oropendola (Psarocolius spp.) nestlings more than those of Red-rumped Caciques. Botflies (Philornis spp.) infested cowbird and cacique nestlings, but there was no evidence of a cowbird-cacique preening mutualism.
We recorded parental provisioning rates of Varied Tits (Poecile various) at different altitudes (n = 17, 7, and 11 nest boxes at 300, 900, and 1,400 m, respectively) to examine if males and females cooperate in response to increased provisioning pressure due to nutritional demands of nestlings. Females provisioned nestlings more than males irrespective of altitude. Provisioning rates of males and females tended to increase with elevation, but the increase was greater for males. Provisioning was low early in the nestling period, and gradually increased reaching a peak between 9 and 10 days after hatching. The provisioning rate of females at the peak provisioning period (8–10 days) did not increase markedly at any altitude. Provisioning by males during the peak period increased and they contributed more during this period than at other times. The provisioning rate of males increased linearly with elevation. The provisioning rate of female Varied Tits also increased with elevation, but the increment ratio was lower than that of males. Changes in provisioning rates with elevation may be due to the need to invest more in parental care under unfavorable environmental conditions. Parents at high altitudes experience more difficulty provisioning, not only because of nestling growth, but also because provisioning is required more often. Thus, increased provisioning by males, which have a lower provisioning frequency relative to females, may be an investment to reduce foraging pressure on females and to ensure survival of nestlings.
Field surveys conducted between 4 September and 17 November 2008 resulted in the first comprehensive inventory of the avifauna of the outlying highlands of the Gran Pajonal and southern Cerros del Sira in central Peru. We report 462 bird species representing 52 families from above 900 m elevation. We describe the avian communities of humid montane habitats and savanna, and provide accounts for 22 species for which we obtained either new distributional data or information of taxonomic significance. We also discuss avian migration, reproduction, molt, and conservation in the region. Our results highlight the richness and uniqueness of the avifauna of the Cerros del Sira and Gran Pajonal, and reinforce the scientific and conservation importance of the eastern Andes and its outlying ridges.
Hybridization between Saltmarsh Sparrow (Ammodramus caudacutus) and Nelson's Sparrow (A. nelsoni) has been documented in areas where the two species occur sympatrically, increasing the difficulty of accurate species identification. We developed a DNA barcoding restriction fragment length polymorphism (RFLP) test to discriminate between Nelson's Sparrows and Saltmarsh Sparrows and applied it to 426 putative Saltmarsh Sparrows sampled from Maine to New York, USA. All individuals were identified in the field as Saltmarsh Sparrows based on morphology, but 34 (8%) had Nelson's specific mitochondrial DNA, indicating they were of hybrid origin. This discrepancy in morphological and genetic data highlights the difficulties associated with accurate field identification and may hinder conservation efforts by confounding attempts to identify and monitor “pure” populations. Mitochondrial DNA of Nelson's Sparrow was prevalent at the most southern point of the previously documented overlap zone and was also found in one individual 150 km south of the overlap zone. Our findings offer new insights into the extent of hybridization between the two species and underscore the need for further investigation into the consequences of hybridization on conservation of Saltmarsh Sparrows.
The White-collared Kite (Leptodon forbesiSwann, 1922), previously known by the holotype and three specimens from northeastern Brazil from the late 1980s, is considered by many as a juvenile variant of the Grey-headed Kite (L. cayanensis Latham, 1790). We present new morphological evidence from museum specimens of both species, including a previously misidentified specimen of L. forbesi, and field study to support the validity of the White-collared Kite as a species, now seen as endemic and severely threatened in northeastern Brazil. This species occurs only in remnants of the Atlantic Forest in the states of Alagoas and Pernambuco. It is distinguished from its congener by its white hind-collar, underwing coverts, and leading edge of the wings. The under surface of the secondaries show reduced black barring. The number of white and black tail bands is variable, and not a good diagnostic character. We also review all taxa described for L. cayanensis and show the described subspecies are not valid.
We examined behavioral interactions of raptors, Chihuahuan Ravens (Corvus cryptoleucus), and Lesser Prairie-Chickens (Tympanuchus pallidicinctus) at leks in the Texas Southern High Plains. Northern Harriers (Circus cyaneus) and Swainson's Hawks (Buteo swainsoni) were the most common raptors observed at leks. Only 15 of 61 (25%) raptor encounters at leks (0.09/hr) resulted in a capture attempt (0.02/hr). Mean (± SD) time for Lesser Prairie-Chickens to return to lekking behavior following a raptor encounter was 4.2 ± 5.5 min suggesting the disturbance had little influence on lekking behaviors. Lesser Prairie-Chickens engaged in different escape behaviors depending on raptor species and, generally, did not respond to ravens suggesting they are able to assess different predation risks. The raptors in our study area posed little predation risk to lekking prairie-chickens. Behavioral disturbance at leks appears minimal due to the lack of successful predation events, low raptor encounter rates, and short time to return to lekking behavior.
We studied songs of Black-throated Gray Warblers (Dendroica nigrescens) in a fragmented landscape in southwestern Oregon and northern California where each male sings a single Type I song consisting of two phrases. Fourteen variants of Type I songs were distributed in a complex geographic pattern across 19,400 km2 of the region. Variants differed in number of notes/syllables in the A-phrase (range 2–5), and the B-phrase differed in both the number and structure of syllables. Several variants occurred in well-defined areas and differed from neighboring songs; others overlapped adjacent variants or graded from one form to another across a narrow zone. Distinct variants could be identified, but the diversity of Type I songs and the pattern of distribution throughout the region does not describe a clear system of dialects. Geographic extent of the variants differed considerably; some occurred as small scattered populations occupying <250 km2 while the largest exceeded 3,000 km2. Variants in the most restricted area and having the most fragmented distribution had the least consistent structure among individuals both within local populations and across the range of the variant. Ridges >1,000–1,200 m in elevation served as effective barriers and separated sets of similar song variants. Fire also likely had a role in generation of variants as reflected by multiple variants occurring in areas lacking obvious geographic barriers.
Search behavior of arboreal insectivorous migrants was studied at three stopover sites along the northern coast of the Gulf of Mexico during spring migrations, 1993–1995. We examined if search behavior was affected by phylogeny, or by environmental factors. A sequence of search movements (hop, flutter, or flight) in a foraging bout was recorded for each migrant encountered. Search rate, frequency, and distance of movements were calculated for each species. Search rate was positively correlated with proportion of hop, but negatively correlated to flight distance. Hop distance was positively correlated to tarsus length, as was flight distance to wing length for the 31 species of migrants. Cluster analysis indicated closely related species generally have similar foraging modes, which range from “sit-and-wait” of flycatchers to “widely foraging” of warblers. Migrants tended to use more hops in dense vegetation, but more flights in areas with sparse vegetation. Migrants also used more flights when foraging in mixed-species flocks and during periods of high migrant density. Logistic models indicated warblers were more influenced by environmental factors than vireos, possibly because warblers are near-perch searchers and more affected by these factors.
Populations of Loggerhead Shrikes (Lanius ludovicianus) across North America have been declining, and factors responsible for this decline remain unclear. Few studies have focused on the availability and use of wintering habitat. Our objectives were to ascertain the size and characteristics of Loggerhead Shrike territories, and examine the hunting behavior of shrikes during the non-breeding season. We observed 1,372 hunting attempts by 19 shrikes; arthropods (65.3%) and other invertebrates (23.3%) were the most common prey. Characteristics of habitat at used and randomly selected, apparently unused isolated and continuous perch sites differed (P = 0.023 and P = 0.021, respectively). Used perches had less grass cover, more bare ground, and denser, shorter vegetation. We found no difference between characteristics of occupied and unoccupied areas (P = 0.34). Non-breeding territories in our study were larger (mean = 85 ha) than those reported for shrikes during the breeding season. The availability of suitable winter habitat does not appear to be limiting Loggerhead Shrike populations in Kentucky. However, most Loggerhead Shrikes winter south of Kentucky where densities are higher, and it is possible that availability of suitable habitat might be a limiting factor in some areas.
We investigated sex and age ratios of wintering Bicknell's Thrush (Catharus bicknelli) across a geographic gradient of sites on Hispaniola. The island-wide proportion male was 0.64 (n = 127), which is comparable to the known male bias in breeding areas. The proportion male varied geographically on Hispaniola, suggesting some level of habitat segregation. Male-biased ratios occurred at two sites whereas sex ratios at five sites did not differ from parity. The island-wide proportion adult was 0.72 and age ratios were significantly adult-biased at two sites. We assessed vegetative structure at all sites and the proportion of male thrushes increased significantly with density of understory vegetation. Age ratios were not associated with vegetation characteristics. Neither sex nor age ratios varied significantly with elevation. Our data suggest the possibility of sexual habitat segregation with males preferentially occupying cloud forest sites characterized by a thick understory of vines and saplings occurring at densities >10,000 stems/ha.
Use of ultraviolet (UV) light, which causes porphyrin pigments in feathers of some birds to fluoresce, provides a simple, effective means of distinguishing multiple generations of flight feathers in owls. This permits easier and more accurate classification of age of adult owls. This lighting technique has been used extensively with Barn Owls (Tyto alba) and Northern Saw-whet Owls (Aegolius acadicus) and works well on a variety of owl species at night in the field, and should have wide applicability among owl researchers. The relative ages of the feathers can be easily distinguished by the intensity of fluorescence they exhibit when the ventral surfaces of primaries and secondaries are exposed to UV (black) light. This allows rapid and accurate assessment of molt and, in turn, the assignment of an age classification for the owl.
We document a female Burrowing Owl (Athene cunicularia) that nested in Arizona and dispersed 1,860 km to Saskatchewan, where she successfully raised seven young during the same breeding season. The dispersal path between these two locations has not been documented previously. This is the longest distance ever recorded for breeding dispersal for any raptor within the same breeding season and possibly for any bird species.
A stand-replacing fire in 404 ha of jack pine (Pinus banksiana) and mixed pine forest in Michigan's Upper Peninsula in 2007 resulted in Black-backed Woodpeckers (Picoides arcticus) nesting at high density in 2008, the second possible nesting season post-fire. Nests were found within a 93-ha study area and a 19-ha stand (a subset of the 93-ha study area) in 199.5 survey hours concentrated in March–July. The 19-ha stand had six nests, a density of 0.31 nests/ha or 0.63 individuals/ha, while the 93-ha study area had 20 nests yielding 0.21 nests/ha or 0.42 individuals/ha. These nest densities are higher than previously reported in the literature for comparable stands, indicating a large influx of nesting woodpeckers post-fire. High nesting densities in this study may have resulted from: (1) optimal timing of the fire for wood-boring beetle exploitation of burned trees, (2) the discrete nature of burned habitat in the study due to impacts of salvage logging, or (3) our focus on regions of the burn where high nesting densities occurred, as the entire burned area (404 ha) was not included in nest density calculations.
We investigated factors that affect nest-site selection, egg success, and hatching success of Brown Pelicans (Pelecanus occidentalis) on Gaillard Island, Alabama, USA, a man-made island in Mobile Bay. Vegetation density at differing heights, and temporal and spatial variables were considered in the analysis. Brown Pelicans arriving earliest chose sites that were open on the ground, but with a layer of vegetation between 1 and 2 m above the ground. Egg success was related to arrival date, density of the highest vegetation layer, density of nests in a given area, and percentage of nests on the ground. Brown pelicans that arrived earliest appeared to choose more optimal nest-sites and had greater egg and hatching success.
Few descriptions exist of the nesting behavior of the Gray Trembler (Cinclocerthia gutturalis), and the only nest description of this species seems incongruent with what is known about nesting behavior of other species of Mimidae. We report the first definitively described nest of the Gray Trembler in St. Lucia, West Indies in June–July 2007. We observed construction of, incubation at, and feeding of nestlings in an open-cup nest, similar in architecture to nests of other mimids, contradicting previous reports that Gray Trembler nests are domed, constructed of dried grass, and on top of palm (Cocos nucifera) trees.
We videotaped nine ejections of real (n = 5) and artificial (n = 4) Brown-headed Cowbird (Molothrus ater) eggs by Warbling Vireos (Vireo gilvus). All eggs were ejected within 6 min. There were no significant differences in time used for any ejection behavior by egg type, although artificial eggs were probed longer before ejection. Eight vireos ejected the cowbird egg using visual cues only because none sat on its nest before ejection. One male ejected the cowbird egg after sitting on the nest for a few minutes; consequently, both visual and tactile cues were available for its decision to eject the cowbird egg. Most vireos identified the cowbird egg by sight and, in most cases, rapid ejection of the cowbird egg precluded the possibility of using tactile cues. Grasp-ejection was the only ejection method confirmed for real and artificial eggs. Two male vireos ejected cowbird eggs at two nests, which is the first documentation of successful ejection by male Warbling Vireos, and the third cowbird host for which males are known to eject cowbird eggs. The ability of males to eject cowbird eggs has important implications for the evolution of ejection behavior.
Conspecific egg destruction is an adaptive behavior that has typically evolved in multi-brooded, polygynous, or colonial avian species, and can be difficult to observe. We describe the first case of egg destruction in the Parulidae, which consists of mostly single-brooded and socially monogamous species. In this case, a female Cerulean Warbler (Dendroica cerulea) destroyed 5-day old eggs at a conspecific's nest. This act was likely committed to secure a breeding opportunity with a high quality male or to decrease local competition for resources. There is also the possibility this behavior may have been pathological and not adaptive.
We describe the successful predation of a black-bearded saki monkey (Chiropotes satanas chiropotes) by a Harpy Eagle (Harpia harpyja) in the Brazilian Amazon and briefly recap two past Harpy Eagle-primate predation interactions. The physiological limitations that raptor anatomy places on individuals during predation attempts are considered along with escape behaviors used by primates to exploit these limitations to increase their chances of survival. In particular, we focus on primate flight paths and startle vocalizations.
We observed three Common Ravens (Corvus corax) hunting for live sand crabs (Emerita analoga) during low tide on Netarts Spit, Oregon in mid-August 2010. One raven successfully extracted four crabs in five attempts during a 5-min period. The ravens hunted on a large sandy beach near the upper margin of the swash zone (the area covered by active wave action); the focal bird extracted buried crabs using an initial thrust of its bill into the sand to flip sand aside, and then followed with two or three additional jabs before removing a crab from the sand. Extracted crabs were pinned on their backs beneath a foot, whereupon the raven pecked at the ventral surface of the crab's body but did not consume the crab. The captured crabs were mature females, and the egg masses they carried appeared to be the target of the raven's attentions. Low tides in late summer appear to be particularly favorable conditions for profitable and successful hunting of sand crab by ravens. This is the first description of the method by which ravens hunt live crabs of any species, and is further evidence of the ability of ravens to exploit seemingly novel and hidden food resources.
We describe the first known instance of Black-billed Magpies (Pica hudsonia) nesting in a fully enclosed, pre-formed cavity. Magpies built an undomed nest of sticks in a nest box designed for Wood Ducks (Aix sponsa) near Olds, Alberta, Canada, in 2008. All nesting material was removed from the box after an apparently successful nesting attempt. Magpies built a new nest in the box and fledged at least four young in 2009. These observations indicate that cavity nesting is a distinct, novel behavioral trait that can arise in this species. We describe several potential costs of cavity nesting in this species, which may explain in part why this trait has not become established in any of the many studied magpie populations around the world.
Botteri's Sparrow (Peucaea botterii) occurs widely in the shrub-grasslands of southern North America. We report a breeding population of the species in the Sierra de la Encantada of northern Coahuila, Mexico, ∼80 km from the Big Bend area of Texas and >300 km from the nearest previously known breeding range in southern Coahuila and central Chihuahua. We captured three individuals, which show a mostly gray dorsal coloration, suggestive of the texana subspecies, occurring from southern Texas to northern Veracruz. The exact affinity of the northern Coahuila population still needs to be ascertained. The presence of Botteri's Sparrow in northern Coahuila may have been overlooked previously or may be part of a (temporary) range expansion. More work is needed to map the occurrence of Botteri's Sparrow in northcentral Mexico grasslands.
Over 250 bird species have been listed as victims of the Shiny Cowbird (Molothrus bonariensis), a well-known obligate brood parasite. Five of the nine species of Phacellodomus (thornbirds) have been listed as victims, but none has been reported rearing cowbird fledglings. I report observations of a pair of Orange-breasted Thornbirds (Phacellodomus ferrugineigula) rearing two fledgling Shiny Cowbirds in southern Brazil. These data add a new host for the Shiny Cowbird and constitute the first report of a species of the genus Phacellodomus as an effective host of cowbirds.