Henslow's Sparrows (Ammodramus henslowii) are reported to have irregular patterns of return to breeding areas. I present data supporting these reports at rangewide extents, while testing potential biases inherent in the North American Breeding Bird Survey data. Two measures of population variability were used to show that Henslow's Sparrows are less likely to use breeding areas predictably and consistently, but have similar variance in numbers at occupied sites relative to other sympatric grassland sparrow species. I illustrate how restricting analyses to single-observer-collected Breeding Bird Survey data results in subtle but significant effects not detected in data aggregated from multiple observers through the study period. The most conservative analysis (single-observer, restricted distribution) showed that Henslow's Sparrows exhibited lower prevalence of occurrence than Grasshopper (Ammodramus savannarum) (P < 0.001) and Savannah (Passerculus sandwichensis) (P < 0.001) sparrows but no difference in variation of abundance (P > 0.05). These results suggest Henslow's Sparrows are not returning to previously used breeding habitat from year-to-year. Grassland management should consider the behavior documented in this study and attempt to incorporate this facet of Henslow's Sparrow biology into decisions that involve broad-scale landscape design.

We examined the influence of woody vegetation on reclaimed surface mines on relative abundance of Grasshopper Sparrows (Ammodramus savannarum), Henslow's Sparrows (A. henslowii), Eastern Meadowlarks (Sturnella magna), Savannah Sparrows (Passerculus sandwichensis), Bobolinks (Dolichonyx oryzivorus), and Dickcissels (Spiza americana) as well as nest-site selection and nesting success of Grasshopper and Henslow's sparrows and Eastern Meadowlarks. Grasshopper and Henslow's sparrows were the most abundant grassland species on reclaimed mines. Numbers of Grasshopper, Henslow's, and Savannah sparrows, and Bobolinks were negatively associated with percent cover of woody vegetation within 100 m of survey locations. Only Grasshopper Sparrows responded to woody vegetation at nest-patch scales, as random locations had >2.5 times as much woody cover as nest locations. Daily nest survival (DNS) was negatively associated with amount of woody vegetation within 100 m of Grasshopper (DNS 0.76 ± 0.001 SE) and Henslow's sparrow nests (DNS 0.94 ± 0.020 SE), but only marginally negatively related to daily nest survival of Eastern Meadowlark nests (DNS 0.87 ± 0.006 SE). Avoidance of woody vegetation by grassland birds and the comparatively lower daily nest survival of Grasshopper and Henslow's sparrow nests near woody vegetation suggests managers of reclaimed surface mines who manage to conserve grassland birds should direct efforts towards reducing woody encroachment.

We studied the effects of breeding stage and behavioral context on the singing behavior of male Indigo Buntings (Passerina cyanea; n  =  15) during the 2004 breeding season in Madison County, Kentucky, USA, to better understand how males with a single-song repertoire vary the characteristics of their song to convey different information. Playback experiments were conducted in 2005 in territories of focal males (n  =  14) to further examine the possible effect of male-male interactions on singing behavior. We analyzed 10,919 songs of 15 male Indigo Buntings with songs consisting of a series of figures that were usually paired (i.e., phrases). Mean song duration was 2.30 ± 0.13 (SE) sec (range  =  1.44–3.40 sec) with males varying song duration by varying the number of figures and phrases in each song. Singing rates varied significantly (P < 0.0001) among breeding stages and were highest prior to pairing, suggesting singing has a role in mate attraction. Singing rates also differed (P  =  0.013) during playback experiments with rates higher during playback and post-playback periods (ξ  =  4.4 songs/min) than during the pre-playback period (ξ  =  2.9 songs/min). These results suggest that singing also has a role in territory defense. Songs of male buntings tended to be shorter prior to pairing and were generally longer in duration after pairing. Playback experiments revealed that bunting songs were longer (P  =  0.03) during and after playback (ξ  =  2.6 sec) than during the pre-playback period (ξ  =  2.0 sec). These results suggest male Indigo Buntings vary singing rates and song duration to convey different information, appearing to use shorter songs uttered at high rates to attract mates and longer songs to convey aggression during male-male interactions.

Onset of incubation was studied in three Hermit Thrushes (Catharus guttatus) and one American Robin (Turdus migratorius), all with four-egg clutches, at a high altitude site in the Sierra Nevada, California, USA. Behavior of laying females at the nest was measured from continuous recordings of internal egg temperatures of first-laid eggs. Full nocturnal nest attentiveness began immediately with the first egg. Daytime attentiveness increased steadily during laying as foraging time away from the nest decreased. On-off bouts by tending females in daytime increased in frequency and decreased in duration until the last egg was laid. Time on the nest could not be directly equated to occurrence of incubation because eggs were not uniformly warmed to exceed the temperature threshold required for embryonic development (physiological zero). Incubation began, both day and night, after laying of the second egg. It increased steadily thereafter with percentage of daytime devoted to incubation lagging well behind that of nighttime. Nest attentiveness and incubation temperatures reached maxima about the time of clutch completion and were continued during following days.

We studied the consequences of nest-site choice on nesting success under differing disturbance levels for the Rufous-bellied Thrush (Turdus rufiventris). We compared nest-site choice and nest success between a disturbed site and an undisturbed site in a montane subtropical forest in northwestern Argentina. We found no overall difference in daily predation rate (DPR) between the disturbed and undisturbed sites. However, DPR of nests on bromeliads was significantly lower at the microhabitat level than on other types of subtrates at the disturbed site. T. rufiventris used bromeliads for nesting more often than expected by chance at the disturbed site. DPR did not differ between substrates at the undisturbed site and T. rufiventris used all substrates according to their availability. Nests had higher predation at the disturbed site when DPR on non-bromeliad substrates was compared between disturbed and undisturbed sites. Nest fate was independent of nest height. Our results suggest T. rufiventris' flexibility in nest-site choice, as reflected by increased use of the safest sites, i.e., bromeliads, in the disturbed site compared to the undisturbed site, may allow this species to survive in an otherwise much riskier habitat. Our results illustrate how microhabitat-scale effects can mediate landscape scale effects.

We studied the breeding biology of the Taiwan Barbet (Megalaima nuchalis) in the Taipei Botanical Garden (TBG) during the 2008 and 2009 breeding seasons. Breeding pairs produced a mean of 1.8 broods per season and had a mean clutch size of 3.0 eggs. The mean incubation period was 13.8 days, and both parents shared incubation. The mean nestling period was ∼27.5 days, considerably shorter than that of other Asian barbets. The shorter nestling period may be related to the low fledgling success rate, multiple broods per season, and constant animal matter food in TBG throughout the entire nesting period. Ambient temperature influenced the amount of time spent by adults inside the nest cavity incubating eggs and brooding nestlings. Adult males provided more food to nestlings than adult females, while adult females cleaned the nest more often than males. The overall egg-to-fledgling success rate was low at 32.8%, because of infertile eggs and failure of eggs with embryos to hatch, abandonment, anthropogenic disturbances, predation, weather disturbances, and other unknown factors.

We present the first detailed information on the breeding biology of the Golden-faced Tyrannulet (Zimmerius chrysops). Information was gathered from 96 nests in Yacambú National Park, Venezuela during the 2002 to 2008 breeding seasons. The enclosed nest was similar to descriptions of nests of other species in the genus. Eggs were laid on alternate days with mean (± SE) clutch size of 1.98 ± 0.02 (n  =  45) and fresh weight of 1.616 ± 0.020 g (n  =  48). Only the female incubated and the incubation period averaged 16.9 ± 0.3 days (n  =  10). Nest attentiveness (% time on the nest) averaged 66.0 ± 1.6% (n  =  40) and increased from early to mid- and late-incubation. Incubation behavior yielded an average 24-hr egg temperature of 34.88 ± 0.45° C (n  =  7 nests, 43 days). The nestling growth rate constant for body mass (k  =  0.285 ± 0.011) was slow even for tropical tyrannids. The nestling period for nests where exact hatch and fledging days were observed ranged from 17 to 19 days with an average of 18.0 ± 0. 2 days (n  =  9). Both females and males fed nestlings at a rate that increased over the nestling period with a mean of 4.41 ± 0.65 trips/hr (n  =  10) during days 1 and 2 after hatching, and 14.93 ± 2.36 trips/hr (n  =  6) at pin-break (days 10–11). Daily predation rates were similar in egg-laying (0.052 ± 0.025; n  =  76.5 exposure days) and incubation periods (0.068 ± 0.010; n  =  575.5 exposure days), but were lower during the nestling period (0.039 ± 0.010; n  =  377.0 exposure days). The total daily predation rate (0.057 ± 0.007; n  =  989.0 exposure days) indicated only 12% of nests were successful. These breeding biology parameters for Z. chrysops differ substantially from other tyrant-flycatchers and temperate species, further highlighting the diversity within the Tyrannidae.

Relatively little is known about Arctic Warblers (Phylloscopus borealis) that breed in central Alaska. We monitored Arctic Warbler populations in two adjacent but distinct habitat types in central Alaska (high elevation, ‘open shrub’ and lower elevation, ‘dense shrub’). We collected 95 nests over three breeding seasons to learn more about nest-building behavior, nest mass, composition, fledging success, and nest parasites. Females were the sole builders of ground nests, which were primarily comprised of moss, grass, and a lining of moose (Alces alces) hair. Dry weight of nests was ∼20 g, but differed up to ∼3-fold within each habitat type each season. Nests from open shrub habitats were more massive and contained less moose hair lining than nests in dense shrub. Open shrub nests fledged more young during the most productive breeding season. We report the first record of the parasitic blowfly Protocalliphora tundrae in Arctic Warbler nests and for Alaska. Blowfly parasitism (55% of nests with hatchlings) was similar in both habitat types and did not correlate with fledging success, or nest mass. Nests with greater amounts of moss tended to have lower levels of blowfly infestation.

We located 39 Mississippi Kite (Ictinia mississippiensis) nests during the 2004 and 2005 breeding seasons in the White River National Wildlife Refuge in the Mississippi Alluvial Valley of Arkansas, USA. Radio transmitters were placed on seven adult and eight juvenile kites; 649 locations based on ground telemetry and 393 locations from aircraft were recorded for six adults (n  =  5 males, 1 female) and five juveniles (n  =  2 males, 3 females). The mean 90% kernel home range was 3,098 ha for adult kites (n  =  6) and 439 ha (n  =  5) for juveniles. Radio-marked Mississippi Kites significantly used mature forest (65.6%), second growth (15.5%), and water (10.0%) relative to availability (59.6, 11.5, and 7.1%, respectively). Agriculture fields (6.5%) and wetlands (1.5%) were used significantly less within the home ranges of kites relative to availability (17.6 and 3.9%, respectively). Tree height, diameter at breast height (dbh), and height of nest tree emergence above the surrounding trees were significantly greater for nest sites than randomly-selected overstory trees. Nest trees were significantly closer to the edge than randomly-selected trees. Most (57%) Mississippi Kite nests were in crotches of secondary branches in the nest tree. Conservation of super-emergent trees and mature forests is needed for nesting and foraging areas. Second-growth forest should be allowed to mature (>75 years) and uniform canopies should be avoided.

A tradition of shooting Common Loons (Gavia immer) for food and for bone fishing lures was established on Shackleford Banks, North Carolina, by the mid-19th century. This strongly ingrained tradition continued to be maintained, primarily by residents of nearby Harkers Island, when inhabitants of the banks moved inland about 1899. The practice probably arose because, on the east/west-tending Shackleford Banks, loons migrating northward in spring flew sufficiently low over land to be within shotgun range. Spring loon shooting, although illegal since 1918, grew to the point that dozens of hunters might be present on the banks on a given day. A strict law enforcement crackdown on this activity began in 1950, and the banks were effectively shut down for loon shooting. Loons continued to be shot opportunistically nearby, but a growing cultural intolerance of this practice brought the loon hunting tradition to an end. We document the existing memories and the few, scattered written sources concerning this unique local interaction between humans and birds.

We compared the distribution of migrant bird species between two islands in the Gulf of Maine to examine if differences in habitat resulted in differences in avian species composition and relative abundance during stopover. Ninety-one species were captured on both islands and those species captured on only one island were either breeding species or rare visitors to the islands. Differences in bird species distribution between islands were species-specific and consistent among sampling periods for nearly all species. Twelve species were captured more frequently on Star Island and 11 species more frequently on Appledore Island. Stopover species distribution appeared to be related to habitat structure, vegetation, diet, and habitat area. Scrub-shrub/open habitat breeding species and forest breeding species were not evenly distributed between islands. Island use was most closely associated with breeding habitat. All but two of the eight species that breed in scrub-shrub or open habitat were captured more frequently on Star Island. Ten of the species more common on Appledore Island breed in forested habitat. Nine of the 11 species more common on Appledore Island are area-sensitive in breeding areas, suggesting potential area sensitivity during migration. Differential habitat use indicates a large number of stopover sites in a wide variety of habitats are necessary to meet migration needs of passerine species.

I describe large volume morning flights of migrant songbirds in autumn along the south shore of Lake Pontchartrain, Louisiana, USA. These flights have at times exceeded 10,000 birds/hr since their discovery in 2002, ranking the site among the continent's highest volume regular migratory songbird concentration locations. Migrants move in “reverse” direction northeastward up a peninsula in Lake Pontchartrain, and fly across a 9-km water gap to reach the north shore, usually struggling into a headwind. Flights are dominated by Yellow and Yellow-rumped warblers (Dendroica petechia and D. coronata), Eastern Kingbird (Tyrannus tyrannus), Indigo Bunting (Passerina cyanea), Cedar Waxwing (Bombycilla cedrorum), and American Robin (Turdus migratorius) during their respective migratory peaks. These species have exceeded 800 birds/hr, and 70 other small landbird species have been recorded. Flights of >100 birds/hr were more frequent after nights with more hours of northerly winds.

Avian collision fatality data from studies conducted at 30 wind farms across North America were examined to estimate how many night migrants collide with turbines and towers, and how aviation obstruction lighting relates to collision fatalities. Fatality rates, adjusted for scavenging and searcher efficiency, of night migrants at turbines 54 to 125 m in height ranged from <1 bird/turbine/year to ∼7 birds/turbine/year with higher rates recorded in eastern North America and lowest rates in the west. Multi-bird fatality events (defined as >3 birds killed in 1 night at 1 turbine) were rare, recorded at <0.02% (n  =  4) of ∼25,000 turbine searches. Lighting and weather conditions may have been causative factors in the four documented multi-bird fatality events, but flashing red lights (L-864, recommended by the Federal Aviation Administration [FAA]) were not involved, which is the most common obstruction lighting used at wind farms. A Wilcoxon signed-rank analysis of unadjusted fatality rates revealed no significant differences between fatality rates at turbines with FAA lights as opposed to turbines without lighting at the same wind farm.

We studied androgen production during development in nestling Eastern Screech-Owls (Megascops asio) and hypothesized that gender and hatch order might influence serum levels of testosterone and androstenedione. Testosterone levels were highest immediately after hatching and declined significantly in the 4 weeks leading to fledging. The average level of testosterone for 1–7 day-old owls was 3.99 ± 0.68 ng/ml. At 22–28 days of age, the average testosterone level for nestling owls was 0.83 ± 0.18 ng/ml. Testosterone levels did not differ between males or females. The average testosterone level for male nestlings was 2.23 ± 0.29 ng/ml and 2.39 ± 0.56 ng/ml for female nestlings. The average level of androstenedione for nestling owls was 1.92 ± 0.11 ng/ml and levels remained constant throughout development. Levels were significantly higher in males than females. The average androstenedione level was 1.77 ± 0.16 ng/ml for male nestlings and 1.05 ± 0.24 ng/ml for female nestlings. Hatching order did not affect levels of either androgen. Our results provide a foundation for future studies of androgen production by nestling owls.

Development of the hypothalamic-pituitary-adrenal (HPA) axis and subsequent corticosterone (CORT) release in newly hatched birds is a balance between limiting exposure to the detrimental effects of CORT on growth and development, and the necessity of mounting an acute stress response. We measured the stress responsiveness of juvenile Chukar (Alectoris chukar) 20 to 60 days post-hatch prior to molting into full adult plumage. The integrated CORT response during 60 min of restraint in these individuals decreased with age. Comparisons to mean adult integrated CORT values imply the youngest juveniles have greater responses than adults while the oldest juveniles have reduced CORT responses. This pattern is currently an anomaly within the altricial-precocial range and suggests specific tradeoffs, such as molting into adult plumage, may affect timing of HPA suppression during development.

I summarize the 10-year composition dynamics of a riparian avifauna on the Arapaho National Wildlife Refuge, Colorado, USA. Only 15 of the 89 breeding bird species (19,393 individuals) were present each of the 10 years whereas 25 species were only recorded in a single year. Number of species in any given year ranged from 30 to 57 (34 to 64% of the 10-year cumulative species total). The number of species detected >1 and <10 years represented over half of all species with no pattern of either increasing or decreasing across years of study. Short-term definitions of species richness preclude the ability to define the major dynamic within an avian assemblage—species that use the site an intermediate number of years. Understanding the ecological prerequisites for these species should provide greater insight into current physical habitat and climate changes occurring on-site.

Avian mapping, also known as spot mapping or territory mapping, is a breeding season bird-survey technique that traditionally uses paper maps on which locations of birds are recorded. This method is often considered the most accurate in yielding a density, but has been criticized as being inefficient, time consuming, and inexact. We describe a novel digital-mapping method, incorporating a hand-held computer and high-accuracy global positioning system receiver (GPS), used in an ongoing boreal birds study. Digital mapping surpassed our expectations as to efficiency, flexibility, and work flow. We expect this method will become increasingly useful in many types of field studies, especially as costs decrease (currently ∼$2,100 for the field receiver used).

The Golden-cheeked Warbler (Dendroica chrysoparia), a member of the Parulidae, uses a two-category song system referred to as Type A and Type B. However, songs recorded from adult males in Bexar County, Texas, USA, did not resemble the typical A or B songs reported for this species. We report an analysis of these atypical songs from six adult males. Quantitative features of the measured songs and syllable structure suggest this atypical song is more comparable to a B song than an A song with some modifications. The atypical song has dropped a terminal syllable of the known B song, and selectively modified one of the syllables to include frequency modulations (up and down slurs). Further, the known B song was not heard in the investigated sites. We conclude the atypical song is a variant of the B song.

We tested the hypothesis that migrating birds use nocturnal conspecific song when selecting stopover habitat using data from the Yellow-breasted Chat (Icteria virens). We broadcast nocturnal song in unsuitable habitat (i.e., a manicured orchard) and alternated broadcast nights with nights where no song was broadcast. We caught significantly more individuals (8 males, 7 females) on mornings following treatments relative to control nights when no songs were broadcast (2.5 vs. 0 birds/morning, respectively). Eleven of 15 (73%) chats were removed from the nets after sunrise (mean  =  32 min after sunrise, range  =  5–60 min), and birds were captured on overcast, cloudy, and clear mornings. Only one bird was recaptured at the site, and only one male was detected singing at the site, suggesting individuals quickly left the area. Conspecific nocturnal songs for chats appear to be an important cue for selecting stopover habitat.

We report the first occurrence of the White-breasted Waterhen (Amaurornis phoenicurus) in Oceania based on discovery of a breeding population on Woleai Atoll, Yap, Micronesia. Islanders believe it first arrived on Woleai in the early 1970s, at a time when the species was beginning a period of range expansion that may be ongoing. Yap Outer Islanders report the waterhen is present also on nearby Eauripik, Ifaluk, and Faraulep atolls, where it arrived after it colonized Woleai. We summarize extralimital, nonbreeding dispersal of A. phoenicurus and report a recent first record for Palau.

The Wilson's Plover (Charadrius wilsonia) is widely distributed along the coast of the Americas. We present the first reproductive record in Baía de Todos os Santos, Brazil, broadening the southernmost limit of its breeding area along the Atlantic Coast to 12° 44′ S, 38° 45′ W. We recorded a family with a subadult in 2007, and a family with chicks and a nest in 2008. The female invested more time in incubation than the male in 96 hrs of diurnal nest observations. There were 102 interruptions during incubation due to the approximation of domestic animals (cattle and horses). The nest was abandoned 9 days after egg laying. An experiment with artificial nests suggests that 30% of Wilson's Plover nests may be destroyed by free-ranging domestic animals in this Baía.

We observed an occupied Harpy Eagle (Harpia harpyja) nest over three separate periods in eastern Venezuela. Both eggs in the clutch hatched on the same day, and two nestlings competed in the nest for 14 days before one succumbed. The female adult collected green branches 45 times over 60 days of observation. Green branch deliveries were positively associated with prey deliveries and our observations best support the ‘nest sanitation by covering prey’ hypothesis for the adaptive significance of green branch collecting. Prey delivery rate to the nest averaged one delivery every 2.4, 2.1, and 3.7 days in the three observation periods. Three-toed sloths (Bradypus tridactylus) and wedge-capped capuchins (Cebus olivaceus) were the most common prey items brought to the nest.

The Screaming Cowbird (Molothrus rufoaxillaris) is one of the most specialized brood parasites with only three known hosts: Baywing (Agelaioides badius), the main host throughout most of its range, and two alternative hosts in some areas of its distribution, Chopi Blackbird (Gnorimopsar chopi) and Brown-and-yellow Marshbird (Pseudoleistes virescens). We studied Screaming Cowbird parasitism in northeast Argentina where this parasite uses Baywings and Chopi Blackbirds as hosts. We monitored 69 nests of Baywings, 251 of Chopi Blackbirds, 31 of Solitary Caciques (Cacicus solitarius), and 30 of Cattle Tyrants (Machetornis rixosa). The frequency of Screaming Cowbird parasitism on Baywing nests was 80% and was 46% for Chopi Blackbirds. We recorded one event of Screaming Cowbird parasitism on one nest of Solitary Caciques and three events of Screaming Cowbird parasitism on one nest of Cattle Tyrants. The identities of parasitic eggs in both hosts were confirmed by sequencing the mtDNA control region. We propose these events of parasitism resulted from recognition errors by Screaming Cowbird females that regularly parasitize Baywings and Chopi Blackbirds. The nest of Solitary Caciques had been frequently visited by a pair of Baywings before Screaming Cowbird parasitism occurred, and the nest of Cattle Tyrants was near an active Chopi Blackbird nest that had been previously parasitized by Screaming Cowbirds.

We used video cameras to monitor 33 Dickcissel (Spiza americana) nests during 2003–2004 in the highly-fragmented, agricultural ecosystem of eastern Nebraska and western Iowa. Nine nests fledged young, 20 were completely depredated, three were partially depredated, and one was abandoned due to ants. Nine snakes, six small mammals, six common raccoons (Procyon lotor), two Brown-headed Cowbirds (Molothrus ater), and one American mink (Neovison vison) were documented as nest predators. These results suggest a diversity of predators is responsible for depredation of Dickcissel nests with snake predation being an important cause of nest failure.

Cavity-nesting birds may frequently compete for a limited supply of nest and roost cavities in trees, but interspecific sharing of these cavities has rarely been reported. The globally vulnerable Helmeted Woodpecker (Dryocopus galeatus), a little-known Atlantic Forest endemic, is believed to be threatened by nest-site competition; however, little is known about its ecology or natural history. I report an observation of a female Helmeted Woodpecker roosting with two White-eyed Parakeets (Aratinga leucophthalma) in their non-excavated (natural) nest cavity at Cruce Caballero Provincial Park, Argentina, and discuss possible implications for ecology and conservation of this rare woodpecker.

We attempted to collect diet samples using throat ligatures from nestlings of three songbird species in a riparian woodland in southeastern Arizona from May to August 2009. We had success with Song Sparrows (Melospiza melodia), observed adult Yellow-breasted Chats (Icteria virens) reclaim food from nestlings, and discontinued the use of throat ligatures when we observed an adult Abert's Towhee (Pipilo aberti) remove two, 3–4-day-old ligatured nestlings from its nest. Previous studies have reported problems (e.g., aggression toward nestlings by adults) with throat ligatures, but we are the first to document removal (and subsequent nestling mortality) in response to this technique. We urge investigators to exercise caution when using throat ligatures on species for which evidence of the safety and efficacy of this method are lacking, especially when nestlings are small in size relative to adults.