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Leapfrog patterns are a peculiar and little-understood phenomenon in which similar populations at either end of a geographic continuum are divided by dissimilar intervening populations. Leapfrog patterns may be important in allopatric speciation. Most documented cases of biological leapfrog patterns refer to morphological traits in passerine birds, and only few have been reported from outside the Andean region. More importantly, the biological basis of leapfrog patterns continues to elude biologists. We document a vocal leapfrog pattern—possibly the second such case documented—in the Maroon-chinned Fruit Dove (Ptilinopus subgularis) complex, adding to the few known examples of leapfrog patterns from outside the Neotropics and in non-passerines. P. subgularis is a Wallacean pigeon whose three taxa occur in a longitudinal continuum from Sulawesi in the west to the Sula Islands in the east. We used discriminant analysis and other statistical methods to demonstrate that terminal members of the complex differ in song from the geographically intermediate taxon but resemble each other more closely. Plumage in P. subgularis does not exhibit the same geographic distribution of variability, a pattern that agrees with the only other study reporting a vocal leapfrog pattern, and supports an earlier hypothesis that leapfrog patterns arise from stochastic phenotypic changes in geographically intermediate taxa. We combine the new insights on the distribution of vocal trait variation in P. subgularis with Pleistocene earth-historic information to revise species in the complex.
We constructed a phylogenetic hypothesis of the pattern of colonization of Philippine scops owls (Otus and Mimizuku). Two mitochondrial genes, ND2 and cytochrome b, were sequenced for 12 samples representing six Philippine endemic taxa: three endemic species, one of which has three endemic subspecies; and one endemic genus. Topology, branch length information, and sequence divergence were used to present the hypothesis for the pattern, direction, and sequence of island colonization events. Philippine scops owls are in two well-supported clades, consistent with at least two independent colonization routes. One route is represented by the montane clade of Otus sunia, O. longicornis, and O. mirus. The other clade is represented by three subspecies of the lowland O. megalotis. The basal position of Mimizuku gurneyi relative to the megalotis clade suggests early colonization of Mindanao. Branch lengths and sequence divergence data are congruent with the morphological differences among the megalotis races. The three races of megalotis differed in 15 of 16 morphological characters. Based on molecular and morphological evidence, we recognize the following Otus megalotis subspecies as full species: Luzon Lowland Scops Owl (O. megalotis), Mindanao Lowland Scops Owl (O. everetti), and Visayan Lowland Scops Owl (O. nigrorum). We also propose reassigning the Giant Scops Owl (Mimizuku gurneyi) to the genus Otus for phyletic consistency.
The Swallow-tailed Cotinga (Phibalura flavirostris) has traditionally been considered to consist of two subspecies, P. f. flavirostris of southeastern Brazil's foothill forest and, isolated by ∼2,500 km, a population of P. f. boliviana in central-western Bolivia. The plumage of the two taxa is distinctly different; boliviana males have a longer tail, and body plumage is significantly less sexually dimorphic. The iris of boliviana is mustard yellow, distinct from the blood red iris of flavirostris. P. f. boliviana has dull to bright orange-yellow feet whereas flavirostris has pink feet. Only one vocalization type is recorded for P. f. flavirostris, whereas at least five calls and a song are known for P. f. boliviana, which vocalizes significantly more often. The Brazilian P. f. flavirostris has strong seasonal movements, whereas P. f. boliviana has no seasonal movements. Given the diagnosable differences between the two taxa, it is highly probable they are separate lineages. P. boliviana qualifies as critically endangered for its declining small population due to continual habitat loss.
Many authors do not recognize the highland Andean Ibis (Theristicus branickii) as a species distinct from lowland Black-faced Ibis (T. melanopis). We considered this problem using a new system of quantitative criteria for species recognition. Andean Ibis differs from Black-faced Ibis markedly in proportions (shorter bill: mean 118 vs. 140 mm; longer tail: mean 215 vs. 185 mm), structure (no wattle), and color pattern (rufous-chestnut crown, face and nape rather than rufous-chestnut crown only; larger white vs. smaller rusty-buff belly-patch). We propose elevation of Andean Ibis to full species. It is rare in Ecuador and Bolivia, vagrant in Chile and only likely to be moderately abundant in Peru.
We compared 13 song features among three populations of Yellow-eyed Junco (Junco phaeonotus): J. p. bairdi from Baja California Sur, Mexico; J. p. palliatus from southeast Arizona, USA; and J. p. phaeonotus from Oaxaca, Mexico. Songs of J. p. bairdi differed significantly from those of J. p. palliatus in 11 of 13 features and differed significantly from those of J. p. phaeonotus in six of 13 features. Songs of J. p. palliatus differed significantly from those of J. p. phaeonotus in only four of 13 features. Discriminant function analysis clearly distinguished songs of J. p. bairdi from those of the two other subspecies, which were not clearly distinguishable from one another. Additional investigations using playback experiments and genetic analyses may be warranted to better evaluate the merits of promoting J. p. bairdi to species status.
We used Global Positioning System (GPS) satellite transmitters to estimate the breeding home ranges of Turkey Vultures (Cathartes aura) in Saskatchewan, Canada from 2005 to 2009. Breeding ranges calculated using 95% Minimum Convex Polygons (MCP) ranged from 47 to 953 km2 and averaged (± SD) 371 ± 340 km2. Fixed-kernel home ranges (95%) ranged from 49 to 1,992 km2 and averaged 648 ± 731 km2. These ranges include both the smallest and largest summer ranges reported for the species. Spatial variation in range size may have been due to differences in availability of food and the quality of the home ranges involved, amplified by the species' extremely low-cost soaring flight. Adults used all-night perches in varying locations up to 38 km from their nest house while traveling substantial distances to available carcasses to obtain food for their young. Identifying home range sizes for Turkey Vultures is a first step toward understanding how the species is increasing and expanding its distribution in Saskatchewan and elsewhere in Canada.
Conspecific brood parasitism (CBP) is a widespread alternative female reproductive tactic in birds. We monitored CBP and nesting biology of Mandarin Ducks (Aix galericulata) using nest boxes for six breeding seasons in Zuojia, northeast China. CBP occurred commonly (46.2% of completed clutches) during the study and frequency was positively associated with nest densities. The frequency of CBP declined as the nesting season progressed. On average, ∼2.5 females laid eggs in each parasitized nest. There were significant differences in clutch initiation dates and mean laying period between parasitized and un-parasitized nests; no difference was detected for the mean incubation period. Clutch size for un-parasitized nests decreased with advancing initiation date, but not for parasitized nests. The hatching rate for eggs in successful nests was 87.1%, and no significant difference was detected between parasitized and un-parasitized nests. The average number of ducklings that left from successful un-parasitized and parasitized nests was 8.4 and 15.4, respectively. Nest desertion was the main cause for nest failure and sibling trampling was the only cause of duckling loss before departure from nests
Egg and clutch size of Whiskered Terns (Chlidonias hybrida) in relation to their location within the colony were investigated at Jeziorsko Reservoir, central Poland. All nests (n = 125) in the colony were individually marked and mapped using a Global Positioning System. Four nest clusters were distinguished within the colony based on the patchy distribution of floating vegetation which delineated potential nesting areas. Early breeding Whiskered Terns nested in more central and denser parts of nest clusters and late breeders nested in more peripheral zones of the clusters (trend analysis: F = 20.47, df = 1, P < 0.001). Pairs which nested closer to the centers of clusters had larger clutch sizes (trend analysis: F = 5.70, df = 1, P = 0.019), but there was no relationship between clutch size and distance to the colony center (F = 0.38, df = 2, P = 0.69). Edge clutches had higher coefficient of variation in egg volume in comparison to more central clutches (trend analysis: F = 5.07, df = 1, P = 0.028). Terns nesting in intermediate densities laid eggs of the highest length and volume (trend analysis: F = 7.17, df = 1, P = 0.009; F = 6.35, df = 1, P = 0.014, respectively). We suggest that establishment of particular nest clusters in the Whiskered Terns colony at Jeziorsko Reservoir followed a central-periphery model.
We identified microhabitat features affecting nest-site selection and examined nest-site characteristics associated with success for the Grey-backed Thrush (Turdus hortulorum) in the Dagang Forestry Farm, Jilin Province, northeast China. We collected data from 79 nests from April to August 2008. Twenty-nine nests (36.7%) were successful, 47 (59.5%) failed due to predation, and the rest were either destroyed by storms or abandoned. The overall daily survival rate (DSR) was 0.9563 ± 0.0072. Nest attempts beginning late in the breeding season were more likely to be depredated. Averaged DSR of laying and late nestling (days 7–12 after hatching) periods were higher than those of incubation and brooding (days 1–6 after hatching). We compared habitat variables between nest and random sites and assessed the effects of nest-location and nest-patch characteristics on DSR. Grey-backed Thrushes selected nest sites with shorter ground cover and a high density of small trees and shrubs. DSR was positively related to distance from the nest to the main stem of the nest tree and negatively correlated with horizontal exposure. Further research should focus on identification of nest predators, implications of nest exposure and begging calls on nesting success, and breeding habitat requirements at different spatial and temporal scales of Grey-backed Thrush in fragmented landscapes of northeast China.
We monitored nesting attempts of White-throated (Turdus assimilis) and Clay-colored thrushes (T. grayi) over 4 years in southern Costa Rica to compare nest success in recently abandoned coffee (Coffea spp.) plantations, pasture, and along roads. Daily mortality rates of Clay-colored Thrush nests were lower in pasture (0.054 ± 0.014) than abandoned coffee plantations (0.096 ± 0.012). Daily mortality rates of White-throated Thrush nests were not influenced by land-cover type but were lower at highly concealed nests (0.058 ± 0.005) compared to less concealed nests (0.090 ± 0.017), and at nests that were on the ground (0.0580 ± 0.005) versus in vegetation (0.076 ± 0.007). Daily mortality rates for nests of both species were very low at an active coffee plantation where nests were monitored in 1 year (0.006 ± 0.004 and 0.015 ± 0.015, for White-throated and Clay-colored thrushes, respectively). Nests at the active plantation were heavily concealed which, along with results for White-throated Thrushes in abandoned coffee, indicates concealment has a strong influence on tropical thrush nest success. Nest success appears to be heavily dependent on factors that may influence both concealment and or habitat for predators. Nest success also appears to be strongly site-specific, making it difficult to provide general statements about the conservation value of different land-cover types.
We studied Swainson's Thrush (Catharus ustulatus) at two study areas of different latitudes to examine if parents provisioned their nestlings beyond daylight hours. We viewed 591 hrs of video from 37 nests. All nests were provisioned outside the dawn to dusk period but provisioning also continued through the night at the northern site. Night provisioners made an average (± SE) of 1.55 ± 0.18 fewer provisioning trips/hr during the pre-dawn to late evening periods compared to non-night provisioners. Night provisioners compensated with two additional trips/hr during the post-dusk period and 2.11 (95% CI: 1.61–2.77) trips/hr during the night period. Night provisioners did not experience improved reproductive success, which supports our conclusion that night provisioning was compensatory rather than ‘bonus’ energy. Nocturnal provisioning was best explained by increased day length, which corresponded to increased light levels during the night period that enabled parents to navigate and locate food. Swainson's Thrush extend a given provisioning effort over more hours as light levels permit rather than increasing energy delivery to their nestlings, which may provide time and energy for other activities.
We examined the provisioning behavior of male and female Grasshopper Sparrows (Ammodramus savannarum) during 2002 and 2003 by videotaping nests (n = 15) and subsequently reviewing tapes to quantify provisioning rates and identify prey items. There was no difference in provisioning rates of male and female Grasshopper Sparrows (P = 0.13) with mean rates of 2.16 visits/hr for females and 1.86 visits/hr for males. Provisioning rates for males and females combined varied with nestling age (P = 0.01) with rates lower for 1–4-day-old nestlings, increasing through day 6 and then declining for 7–10-day-old nestlings. Provisioning rates varied with brood size (P = 0.026) with rates higher for broods of five than broods of three or four. Most prey items delivered to nestlings were grasshoppers (Orthoptera, 68.1%).
We used information compiled by the U.S. Geological Survey's Bird Banding Laboratory and geographic information systems (GIS) analysis to identify trends in annual Northern Saw-whet Owl (Aegolius acadicus) movement across eastern North America. Analysis of 81,584 Northern Saw-whet Owl banding events revealed a southbound annual fall migration front with peak banding activity occurring progressively later in the season as latitude decreases. Northbound owls comprised <9% of owls banded and recaptured elsewhere in the same season, and <5% were recaptured northbound >100 km from banding location. There was no relationship between banding latitude and adult-to-juvenile ratio. However, the proportion of adults versus juveniles banded was not uniform among banding stations, suggesting age-differentiated migration patterns may exist. Information from multiyear foreign recaptures revealed that 72% of owls banded and subsequently recaptured at the same latitude in different years were recaptured <100 km from banding location. A similar trend was found in the Appalachian Mountains, the Great Lakes Basin, and the Atlantic seaboard. This indicates that Northern Saw-whet Owls may exhibit high migration route fidelity. These findings expand the Northern Saw-whet Owl information portfolio and illustrate the versatility of aggregate data sets as a tool for answering large-scale questions regarding migration.
The distribution of landbirds during migration in forested landscapes of eastern North America is poorly known. We describe (1) the distribution of landbirds in northern white cedar (Thuja occidentalis) dominated forests as a function of distance from northern Lake Huron in Michigan during spring and autumn migration, and (2) discuss factors that may affect the distribution of these migrants. Both long- and short-distance migrants in spring and fall were concentrated within 0.4 km of the Lake Huron shoreline. This pattern was particularly pronounced during spring when aquatic-hatched insects such as midges and their predators (e.g., spiders) are most common and occur in largest numbers near the shoreline. Both long- and short-distance migrant abundance was associated with midge abundance, after controlling for date, during spring migration but not during fall migration. Migrants may concentrate near the shoreline because of the barrier effect of Lake Huron and relatively abundant food resources, especially during spring migration. Terrestrial habitats adjacent to bodies of water, where aquatic-dependent invertebrates are relatively abundant may provide important stopover sites for landbird migrants. Our results suggest coastal areas within the Great Lakes region provide critical stopover habitat for landbird migrants and should be a focus of conservation efforts, especially given the increasing development pressure that threatens these areas.
We conducted mist-net surveys of migrating songbirds during fall migration 2007–2009 on the 1,300-ha Albany Pine Bush Preserve (APBP), a fire-managed inland pitch pine–scrub oak (Pinus rigida–Quercus spp.) barren in east-central New York. We banded 244 migrating passerines from 32 non-resident species in 8,610 net/m/hr documenting use of northeastern pine barrens as stopover sites for passerines with diverse breeding ecologies. We estimated the breeding site origin of six species (a kinglet, four warblers, and a sparrow) using stable hydrogen isotope measurements from flight feathers. There was a broad range of isotope ratios within each species indicating a large catchment area extending several hundred kilometers north and west of the stopover site. Over half the birds originated >750 km from the APBP. We found no evidence for geographical structure of the timing of migration through APBP; slopes of regression lines for capture date versus hydrogen isotope ratio from feathers (δDf) were not statistically different from zero. This contrasts with previous isotope research that reports both leapfrog and chain migration patterns by different warbler species at stopover sites in the western United States.
We investigated long-term trends in mean autumn capture dates of 19 species of migratory passerines including 11 long-distance migrants and eight short-distance migrants. Birds were captured between 1960 and 2007 at a banding station in southern Rhode Island. We detected annual trends in the highest ranked models with mean capture dates of seven species significantly delayed by an average of 3.0 days per decade; 38% of long-distance migrants and 50% of short-distance migrants studied significantly delayed migration. We found no evidence of long-term shifts in autumn migration timing for seven species and mean capture dates of five species exhibited non-linear annual trends. Mean autumn temperature was an important factor in explaining annual trends for eight species. Changes in annual capture rates for some species may have an equal or greater role than year or temperature in explaining long-term trends in autumn migration timing. Our analysis suggests that some migratory bird species are now departing the region later than in the 1960s. Important differences among species and regions are likely to influence species-specific responses to changes in climate patterns.
We used radiotelemetry to quantify habitat and spatial use patterns of neighboring Louisiana Waterthrush (Parkesia motacilla) along two streams in the Caribbean National Forest in Puerto Rico during 2005–2007. Home range sizes varied with younger birds having larger home ranges and core areas than older birds. All birds occupied some length of stream but a wide range of off-stream habitats were also used. Off-stream habitats included a range of disturbance from residential areas to small saturated pastures. Neighbors exhibited a wide range of overlap in home ranges (x¯ = 20%) and older birds had more overlap than younger birds. The greatest percent of foraging time was along streams (64.4%) followed by muddy substrate (26.5%), housing developments (7.4%), and roads (1.7%). The greater proportion of time foraging along streams indicates this is the preferred habitat for this species. Use of off-stream habitat indicates a strategy of exploiting food-rich ground substrates, and in particular those with high moisture.
The narrowing of the North American continent at the Isthmus of Tehuantepec creates an important geographic bottleneck for songbirds on their northward spring migrations. The Sierra de Los Tuxtlas, in the northwestern portion of the Isthmus, provide an ideal location from which to address questions of resource use and fuel acquisition during migration. We operated mist nets during morning and evening to capture passerines during spring migration in 2003 and 2004. Seven of 13 taxa had significant diurnal increases in body condition (an index of size-adjusted mass): Swainson's Thrush (Catharus ustulatus), Wood Thrush (Hylocichla mustelina), Magnolia Warbler (Dendroica magnolia), Kentucky Warbler (Oporornis formosus), Hooded Warbler (Wilsonia citrina), Worm-eating Warbler (Helmitheros vermivorum), and Ovenbird (Seiurus aurocapilla). All of these species, except Ovenbird, also had a significant increase in fat score. Indigo Buntings (Passerina cyanea) had a significant increase in fat score but not in condition index. A comparison with autumn migration at this site showed overall similarities in percentage of species gaining mass and in the amount gained, but there were seasonal differences within species. There was no relationship between increase in body condition and a mainland versus trans-gulf migratory strategy.
Molt strategies and plumage development by age and gender are poorly understood for resident tropical landbirds. We used data from six banding stations on Saipan, Northern Mariana Islands, and examination of 267 museum specimens to describe patterns of molt and to establish criteria for assessing age and gender of nine native resident landbird species on the island. Feather replacement sequences in the majority of Saipan's resident landbirds were typical of related species. Preformative molts occurred in at least eight of the nine species; these and definitive prebasic molts were incomplete to complete, and prealternate molt appeared to be absent for all species. We developed criteria for classifying gender of sexually dimorphic species using plumage cues, presence of brood patch or cloacal protuberance, and biometrics. We confirmed whether or not both brood patch and cloacal protuberance were reliable indicators of gender during breeding in monomorphic species. Distinct periods or seasons of molt are not well defined and can vary between years. Age classification of first-cycle birds based on molt limits, feather shape and condition, and extent of skull pneumatization is possible for most landbird species sampled on Saipan.
We documented the behavior of 13 parrot species at a geophagy site along the Tambopata River in southeastern Peru. These species use the lick in one or more multi-species aggregations composed predominantly of (1) large parrots and small macaws (81% of lick use), (2) large macaws (5%), or (3) parakeets and small parrots (5%). Monospecific flocks accounted for only 8% of lick use and lone individuals <1% of lick use. The multi-species aggregations sorted by body size and were generally composed of species with similar coloration suggesting that group composition was driven by a mix of competition and predation. Three species regularly used the lick in monospecific groups and these had the largest group sizes away from the lick, suggesting a causal relationship between intraspecific sociality and lick use in monospecific groups. All groups were wary when approaching the lick, probably due to the risk from landslides and predators. We suggest that clay lick use strategies are molded by predation risk and competition acting on a suite of species with varying body size, coloration, and gregariousness.
We describe the vocal repertoire of the Yellow-faced Parrot (Alipiopsitta xanthops) from recorded vocalizations and also flock sizes in Brasília (Brazil) during 2006. Vocal communication signals are both long-range and short-range sounds. We describe seven call types: flight call (long-range), long-range alarm call, congregation call (long-range), two agonistic calls (long-range/short-range), sentinel call (short-range), and a short-range alarm call. The flight call is equivalent to the functional song and contains the species-specific recognition code. Flight calls may also be uttered when perched and, when in quick series, function as long-range alarm calls. Long-range alarm calls become a high intensity congregation signal when several individuals overlap and, despite degradation and attenuation, may contain the species-specific code over distances of 800 m. The average (±SD) feeding flock size was 7.7 ± 8.2 individuals (n = 116) while the roosting flock size was 79.1 ± 10.5 individuals (n = 7). Short-range calls maintain communication while minimizing detection. High intensity vocalizations allow long-range communication, improving feeding efficiency through use of large areas and stimulating late afternoon roost congregations. Low intensity vocalizations maintain communications without providing the position of the parrot.
We studied seasonal profiles of circulating testosterone concentrations among male and female adult Tree Swallows (Tachycineta bicolor) breeding in nest-box colonies near Ames, Iowa, USA. Mean plasma testosterone in males was elevated during nest establishment (0.63 ± 0.86 ng/ml) and incubation stages (0.28 ± 0.26 ng/ml), and was significantly lower after hatching (0.03 ± 0.05 ng/ml) when males began provisioning nestlings. Male swallows do not incubate and high testosterone during the incubation stage may facilitate pursuit of extra-pair matings. Female testosterone concentrations were an order of magnitude lower than those of males (nest establishment, mean = 0.06 ± 0.09 ng/ml) and did not change significantly over the breeding season. These testosterone profiles support the hypothesis that elevated testosterone in males is associated with defense behaviors and obtaining additional mating opportunities during the first part of the breeding season, but is incompatible with parental care once the eggs have hatched.
Nesting activity of the White-collared Swift (Streptoprocne zonaris) was monitored from October 2001 to March 2002 to describe the breeding chronology of this species. Data were obtained from the colony ‘La Cueva de los Pajaritos’, near Mallín, Córdoba, Argentina. These are the first descriptions of the nesting chronology of this species in Argentina. The breeding season lasted 81 days from egg laying in early November to fledging in middle to late January. Clutch size ranged from one to two eggs which were incubated for an average of 22 days. Nestlings remained in nests for an average of 44 days and fledglings remained at the site for ∼5 additional days. These observations provide new information on nesting sites used by S. zonaris in Argentina, and provide the first documentation of the length of the breeding phases for the species in South America. The ‘apparently shortened’ length of incubation and nestling periods may be a geographical effect, due to this being the most southeastern known breeding colony for S. zonaris.
The Fulvous-breasted Flatbill (Rhynchocyclus fulvipectus) has an Andean distribution from Colombia and Venezuela to northeastern Bolivia between 750 and 2,300 m elevation. We describe the nesting behavior, nest, eggs, and nestlings of this species in the buffer zone of Manu National Park at Cock of the Rock Field Station, Cusco, Peru, from August through December 2009. We monitored seven nests using data loggers to describe incubation patterns and conducted direct observations of provisioning behavior. The two-egg clutch size and pear-shaped nest structure were consistent with previous reports. Incubation lasted 24 days (n = 1) and nestlings were in the nest for at least 29 days. We only observed one parent incubating (presumably the female) with average nest attentiveness of 64%, which decreased as the incubation period progressed. The adult made 10 to 15 foraging trips per day (n = 21) during incubation, when it spent on average (±SD) 32.9 ± 2.8 min during incubation bouts and 23.1 ± 6.3 min during foraging bouts (n = 3 nests). Nestlings were able to regulate their body temperature after the feathers were fully developed; however, their body temperature (37° C) was lower compared to adults. We confirmed Rhynchocyclus nests exclusively along creeks or rivers and also revealed long incubation and nestling periods, which may be more common than expected in tropical mountain areas. There was a decrease in nest attentiveness through time, contradicting previous findings on neotropical passerine species.
Temporal aspects of egg deposition are important factors governing avian reproductive success. I report hourly egg-laying patterns of the Pearly-eyed Thrasher (Margarops fuscatus) in the Luquillo Experimental Forest in northeastern Puerto Rico during 1979–2000. Initiatory eggs were laid by early morning (median = 0642 hrs, AST) and almost half of the eggs were laid by 0723 hrs. Many penultimate and eggs completing a clutch, however, were laid later in the morning and some not until mid afternoon (1429 hrs), thus extending egg deposition to 8 hrs. Delayed laying of the last eggs in a clutch may be an adaptive strategy triggering brood reduction to ensure survival of older and more robust siblings during periods of physiological stress and food shortages.
We provide the first known documentation of a male Least Bell's Vireo (Vireo bellii pusillus) breeding with a female White-eyed Vireo (V. griseus) and the first report of a White-eyed Vireo breeding in California at the San Luis Rey River, Oceanside, San Diego County. We discovered the pair building a nest on 12 May 2010. The female laid four eggs, and the pair successfully raised and fledged four nestlings. We collected DNA samples from each nestling and the female during the nestling stage and banded them with a numbered federal leg band for future identification. We obtained detailed nest measurements after fledging and monitored the territory for further nesting attempts. No additional nesting attempts were detected.
We report a Great-billed Hermit (Phaethornis malaris) with three testes, a condition known as triorchidism. This is the first case to our knowledge of triorchidism in Neoaves, the clade that contains ∼95% of avian species diversity. Triorchidism is inferred to be an exceptionally rare congenital abnormality in wild birds with developmental cause and evolutionary implications that are distinct from testicular asymmetry.
Nest reuse behavior in birds is rare because nests are ephemeral structures. We describe the first record of multi-season nest reuse by the Scintillant Hummingbird (Selasphorus scintilla). The nest was a multi-cup of four nests with newer nests placed on top of older nests. The nest was under the eave of a roof, which may have reduced nest disintegration and facilitated nest reuse.
We report re-encounter rates and dispersal distances of Red-eyed Vireos (Vireo olivaceus) re-encountered 1 year after banding in a large forest (∼ 4,600 ha) in southern Ontario, Canada. We re-encountered 12 (11%) of 109 banded individuals. Dispersal distances ranged from 40 to 9,870 m and were longest for hatch year (HY) bandings (median = 4,970 m, n = 3). Distances were similar between other age classes (SY: median = 225 m, n = 4; ASY: median = 220 m, n = 5), and males (median = 220 m, n = 9) and females (median = 250 m, n = 3). Our re-encounters of banded Red-eyed Vireos provide information on dispersal, detection rates, and methodology that could potentially improve future marking efforts and apparent survivorship estimates.
I observed 514 nest-box departures of 12 different individual Eastern Screech-Owls (Megascops asio), both males and females, at dusk in Falmouth, Massachusetts over a period of 12 years and compared their departure times to local sunset. Mean (± SD) delay after sunset was 21 ± 12 min, identical for males and females, but longer than those reported for more southerly locations. Females departed significantly earlier on overcast evenings. Females advanced their departure times during the nestling period by as much as 2.6 min/day, on average, over a 25-day period. The observed differences in departure delays among populations in Texas, the Washington, D.C. area, and Massachusetts may be an expression of differences in behavior among subspecies of M. asio.
Few documented reports exist that describe carrion-feeding by owls. We produce a conclusive record of carrion-feeding by Barred Owls (Strix varia) from photographs taken with a passive-infrared wildlife camera trap baited with the whole or partial carcasses of road-killed mammals (eastern gray squirrel [Sciurus carolinensis] and white-tailed deer [Odocoileus virginianus]). We recorded multiple pictures in two documented occurrences (one in Oct 2010 and the other in Dec 2010) over multiple days of a Barred Owl visiting both fresh and mostly-decayed carcasses. Attempts to lure owls to camera traps through use of tainted chicken and turkey meat were unsuccessful, and no additional owl pictures were obtained from unbaited cameras throughout 2010.