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We investigated the post-fledging ecology of the Northern Pygmy-Owl (Glaucidium gnoma) at two study areas in the Rocky Mountains of Montana and Idaho from 2002 to 2009. We observed 16 successful nesting attempts that fledged from two to seven young. Fledging dates ranged from 18 June to 5 August and all nests were vacated within a 2-day period. Post-fledging behavioral data were collected regularly from fledging through initiation of natal dispersal from five radiomarked family groups and opportunistically from three additional family groups. Post-fledging movement data were collected from eight family groups and two males that were suspected of nesting. Adults attended broods for 9 to 30 days (females) and 31 to 34 days (males) postfledging, after which they were not observed associating with their young. Young remained within the natal territory for 1 to 10 days following departure of adult males, after which they abruptly initiated natal dispersal. Areas used by family groups during the post-fledging dependency period ranged from 34.6 to 94.5 ha. Family groups were active throughout the day, but activity was notably more intense during crepuscular periods. Our earliest observations of young hunting occurred 9 days after fledging and 47% of all fledgling hunting attempts observed (n = 75) were successful. Adults and fledglings used vocalizations in contexts consistent with previous descriptions with the exception of an undescribed two-note vocalization that appeared to function as a contact call preceding prey deliveries.
Recent studies have suggested climate change could amplify the differences between arrival dates of male and female passerines. We investigated the generality of this finding and additional questions related to protandry by analyzing 32 years of banding data for seven species of migratory passerines. Six species exhibited significant protandry with males arriving on average between 2 and 6 days earlier than females. Only Baltimore Orioles (Icterus galbula) did not have significant differences between average arrival dates of males and females. The magnitude of protandry did not change in response to warming spring temperatures during the period of study, and none of the ecological variables examined explained variation in the amount of protandry. Males of all species studied were significantly larger than females. However, the magnitude of size difference also did not explain the amount of protandry observed. Arrival dates of males and females within each species tended to follow similar trends over time and sex ratios did not change over time for any species. Changes in sex ratios of Mourning Warblers (Geothlypis philadelphia)–more females in warmer years—however, were significantly related to mean temperature in the year of migration. Protandry may remain fairly consistent as the climate changes, although further research is needed to test the generality of this pattern.
We compared migrant bird recapture rate, stopover time, mass gain, and fat class between Star Island, New Hampshire and Appledore Island, Maine during spring and fall migration in relation to differences in relative species abundance between the islands; and examined potential movement of migrants between the islands. The average recapture rate in spring was 5.7% on Star Island and 3.6% on Appledore Island. Five species were recaptured more frequently on Star Island and one species more frequently on Appledore Island. There was no difference in mean minimum stopover time during spring (2.4 days on Star Island; 2.5 days on Appledore Island) and fall (2.9 days on Star Island; 3.2 days on Appledore Island). Three species had a longer mean stopover time on Appledore Island than Star Island. The island with the greater percentage of recaptures and longer stopover had more captures for a given species. Mass gains were significant for six species during spring (27.3%) and 10 during fall (38.5%) on Star Island, and five (22.7%) during spring and 13 (50.0%) during fall on Appledore Island. Five species had a difference in rate of mass gain between the islands. The between-island difference in species abundance was not reflected in between-island differences in mass gain, except for Red-eyed Vireo (Vireo olivaceus) during fall. There was no clear pattern in species differences in fat levels and differences in captures, stopover length, or mass gain between the islands. The fat-class and mass-gain results suggest habitat use, as measured by relative abundance, is not based on the ability to gain mass at the time of stopover. The notable fall mass gains for Red-eyed Vireo illustrate the availability of food resources for some species on both islands. Only 42 of 10,437 migrant birds banded moved from one island to the other. There was little evidence of movement between islands in a seasonally-appropriate direction for continued migration, or evidence indicating a shift between islands after initial capture.
We developed a field survey protocol based on the North American Breeding Bird Survey to evaluate the efficiency and reliability of a bird monitoring scheme in the Neotropics, known as NeoMaps. A team of 21 amateur and professional ornithologists conducted bird counts at 27 locations distributed throughout Venezuela between March and April 2010. Locations selected followed a stratified spatial sampling design derived from environmental and biogeographical variables. Two complementary survey protocols were implemented in consecutive days along 40-km-long roadside transects. Three-minute point counts were performed at 50 stops, 800 m from each other on day 1. Cumulative species lists were recorded at a selection of 10 stops sampled for 9 min each, divided into three consecutive 3-min periods on day 2. We recorded 593 species at the 27 sites combined, representing 57% of the 1,033 potential species, or 43% of all known Venezuelan species. An additional 83 species were recorded outside of the formal point counts, for a total of 676 species detected. Groups such as hummingbirds and most waterbirds had unusually low numbers of both species and individuals, probably due to an abnormally dry year. Our survey methods appear to be appropriate for surveying most common diurnal non-colonial species. This is the first large-scale, systematic bird survey in Venezuela or, to our knowledge, in any other tropical country.
The St Pierre and Miquelon Archipelago hosts the only French Leach's Storm-Petrel (Oceanodroma leucorhoa) colony. We conducted a survey during the 2008 breeding season to estimate the breeding population size on Grand Colombier Island. This survey included an estimation of burrow detection probability using a double-observer approach. We estimated that 3% of Leach's Storm-Petrels nests had failed before we started the survey. Nest occupancy probability was neither affected by slope nor vegetation type and was 0.546 ± 0.029. Burrow density was positively affected by slope and, consequently, was much lower on the plateau than on island slopes. Burrow detection probability was neither affected by observer nor by habitat and was 0.89 ± 0.01. We estimated the population to be 363,787 [95% CI = 295,502–432,072] breeding pairs, which is among the largest Leach's Storm-Petrel colonies in the northwestern Atlantic Ocean.
Saltmarsh Sparrows (Ammodramus caudacutus) are non-territorial, lack pair-bonds, and practice promiscuous mating behavior and obligate maternal care of young. Behavioral details of mating behavior and associated intermale aggressive behavior are poorly understood in the species. We report the results of an observational study of mating and agonistic behavior of individually marked breeding birds in New York. We witnessed 1,265 sexual and agonistic interactions within and among males and females from 1977 through 1985. We found no evidence of male mating aggregations, and male aggressive behavior was prevalent only in male-initiated sexual interactions. Females solicit matings from males during nest-building, but the behavior is inconspicuous and not associated with male aggression. Males spend the morning patrolling their home ranges, and chase or approach females they encounter anywhere in their breeding habitat. Males often concentrate patrol activity in the vicinity of nests under construction, but we found little evidence they know the location of most nest sites. Some males seek to forcibly mount females on the ground at any breeding stage, despite female resistance. Females thwart forced mountings in 57% of cases either by fighting with the males, or by uttering an aggressive call. When a more persistent male suppresses a female's resistance, she then crouches passively as he assumes a copulatory position on her back. We discuss this behavior in terms of female control of forced mountings, female choice of mates, and forced mating as a tactic of males that appear not to know the fertility status of females. Males have a large cloacal protuberance, which suggests sperm competition is strongly developed in the species. We caution that evolution of the unusual mating behavior in Saltmarsh Sparrows must be understood in relation to the different sexual behaviors of its closest relatives.
We compared the amount and type of acoustic competition experienced by Veeries (Catharus fuscescens) when they sang in the dawn chorus as opposed to when they sang in the dusk chorus. Veery songs tended to be masked more often at dawn than at dusk. Veery songs were masked 2.4 times per 10-song sequence at dawn and 1.2 times per 10-song sequence at dusk. A larger number of species were responsible for masking that occurred at dawn. At least 12 species masked Veery songs in our sample, and all identified species masked at dawn; only seven of the 12 also masked at dusk. These results represent the first empirical data documenting natural differences in acoustic competition at dawn and dusk. Acoustic competition may help explain why, in addition to singing at dawn, Veeries and other thrushes also have a pronounced dusk chorus.
We studied the population ecology of Pacific Wrens (Troglodytes pacificus) in 2003 and 2004 breeding across elevations from 100 to 1,300 m in coastal mountain forests in southwestern British Columbia, Canada to examine if this species is adapted to upper montane and subalpine habitats. We found fewer territories at high elevation, a higher proportion of unmated males, fewer nests per mated male, and no returns of banded adults or juveniles. The breeding season was 61% shorter (31 vs. 79 days), and mass of nestlings (at 11–12 days of age) and nest survival were lower at high elevation compared to lower elevation sites. Clutch size, incubation and nestling periods, parental provisioning rates of nestlings, and adult morphology did not vary with elevation. Annual fecundity measures declined with increasing elevation with no apparent compensatory increases in other vital rates such as survival of adults or offspring.
There is little information about nesting ecology of the federally endangered Black-capped Vireo (Vireo atricapilla) in the southern and western region of its breeding range, which is characterized by xeric thornscrub and patchy low-growing vegetation. We mapped territories and monitored 119 Black-capped Vireo nests across seven study sites in 2009 and 2010 in Val Verde County, Texas in the Devil's River region on the western edge of the Edwards Plateau. We observed 69 nests with cameras to identify nest predators. Clutch size was significantly smaller in 2009 (3.4 ± 0.82) than in 2010 (3.8 ± 0.43). Both nest depredation and parasitism by Brown-headed Cowbirds (Molothrus ater) were >10% higher in 2009 than in 2010. There was a large diversity of nest predators identified including Brown-headed Cowbird (n = 4), snakes (n = 4), and Greater Roadrunner (Geococcyx californianus) (n = 3). Species identified that have not been previously observed as Black-capped Vireo nest predators were bobcat (Lynx rufus), common raccoon (Procyon lotor), Greater Roadrunner, and the greater arid-land katydid (Neobarrettia spinosa). Productivity of Black-capped Vireos in the Devil's River area appeared to be heavily influenced by weather, particularly precipitation during the breeding season.
We describe the nest and eggs of the Marsh Antwren (Stymphalornis acutirostris), a recently described species which is the only member of the Thamnophilidae restricted to marsh habitats. We conducted 1,560 hrs of nest searching in tidal marshes of southern Brazil and found 178 nests. All nests were of dry fibers, straws, and silk. Nineteen plant species were used for nest attachment. All nests had a clutch of two white eggs with several irregular brown spots scattered over the entire egg, concentrated at the middle or the largest pole. The strategy of nest attachment to vertical structures used by the Marsh Antwren was previously unknown in the Thamnophilidae.
We present the first description of a breeding record of the Harpy Eagle (Harpia harpyja) in Belize, and describe the subsequent fledging of the juvenile. We discovered the nest on 27 November 2010 with a single 4–5 week-old chick, and began focal observations. The juvenile spent 56.3% of 71 observation days feeding, and the parents delivered food to the nest at a rate of one item every 2.04–3.33 days from late January to April. The most frequent food items were the common opossum (Didelphis marsupialis), white-nosed coatimundi (Nasua narica), and Yucatan black howler monkey (Alouatta pigra). We placed a satellite GPS-PPT transmitter on the juvenile Harpy Eagle on 14 April 2011 to track its movement patterns after fledging. Soon after, the parents stopped returning to the nest, the juvenile fledged, and for 28 days we delivered food to the young eagle in place of its parents. The abandonment of the juvenile by the parents may have been caused by low food abundance caused by drought conditions and/or placement of the transmitter may have had a role. The male subsequently returned to feed the juvenile. We believe these eagles represent one of the northernmost known extant breeding pairs of Harpy Eagles in the Americas.
We used video cameras in 2008–2009 to record provisioning activities at Dickcissel (Spiza americana) nests in and around Conservation Reserve Program field buffers in north-central Mississippi, USA. We simultaneously observed foraging flight distances of parents. Provisioning rate (P = 0.412), biomass (P = 0.161), and foraging distance (P = 0.159) did not increase with nestling age. Parents delivered larger items to meet demand associated with older nestlings (P = 0.010–0.001). This suggests energetic costs of changes in prey selection were less than costs of increasing the number or distance of provisioning trips. Presence of male helpers increased provisioning rate (P < 0.001) but not biomass (P = 0.992) because males brought smaller prey items (P = 0.001–0.021). Presence of observers 30 m from the nest reduced provisioning rates (P = 0.005) and biomass delivered (P = 0.066). Lack of habitat effects for any aspect of provisioning suggests grass field buffers provided nestling food resources similar to surrounding habitats. Use of continuous video monitoring of nest activity allows well-concealed activities including provisioning and male helping to be directly observed and better quantified.
We explored the relationship between Sprague's Pipit (Anthus spragueii) nest (n = 125) survival and the distance from their nests to grassland edge and other linear features on Bowdoin National Wildlife Refuge in north-central Montana from 1997 to 2007. Specifically, we studied the effect of distance to roads (secondary paved road and tertiary improved and unimproved dirt roads), an agriculture field, an active railroad right-of-way, and lacustrine shoreline on nest daily survival rate (DSR). The overall DSR was 0.95 ± 0.0057 (SE) with a 95% confidence interval of 0.94–0.96. We considered how models with distance thresholds (within 50, 100, 200, or 300 m) affected DSR while controlling for important covariates. None of the distance models improved the model over the minimum AICc model containing only non-distance covariates. There was no support for distance to any of the edges, including roads, having an effect on DSR relative to the minimum AICc model that contained three non-distance covariates.
We estimated the population density of the Helmeted Curassow (Pauxi pauxi) in Tamá National Park (TNP) Colombia, using visual counts between December 2006 and December 2008. We used six line transects (1 km each) equitably distributed in a natural forest between 800 and 1,200 m asl in the southern part of the park. The sampling effort was 588 hrs with a total distance of 490 km, a detection rate of 0.06 records/hr, and an encounter rate of 0.08 individuals/km. Only solitary individuals were recorded (n = 40); the estimated density was 4.8 individuals/km2. Most detections occurred in the lower strata of the forest (floor and sub-canopy) where hunters take advantage of curassows in the lower strata for successful harvest. The southern sector of TNP becomes important in the dry season. Our study suggests a large population is in TNP, but harvesting activities including removal of eggs, chicks, and juveniles, and hunting adults are affecting the reproductive rate and population of the species.
We studied the Red-billed Currasow (Crax blumenbachii) in Vale Natural Reserve, Linhares, Espírito Santo State, Brazil, using camera traps. We found the Red-billed Curassow present in the entire area of the reserve (∼ 22,000 ha) during 40 months of camera trapping (2005–2008). Most records were of single individuals, especially males, but pairs and even groups of individuals were also recorded. Males were paired with one and two females, suggesting polygyny in the species. The species was recorded throughout the day with one peak from 0500 to 0600 hrs and another after 1600 hrs. The daily activity pattern was similar for males and females. The number and widespread nature of the records suggests the local population of this species may be higher than previously thought.
The musculature of the pelvic appendage of the Chinese Grouse (Tetrastes sewerzowi) is described in detail. T. sewerzowi exhibits the same features as other tetraonids in the absence of M. adductor digiti II, and the relatively weak development of other intrinsic foot muscles, which are thought to be an adaptation to the extreme cold climate of the habitat of grouse. Myological modifications include weak development of the vincula between the flexor tendons to the digits (M. flexor perforans digiti III and M. flexor perforans et perforatus digiti III, M. flexor digitorum longus, and M. flexor hallus longus), the proximolateral insertion of M. flexor perforans digiti II, the well-developed middle head of M. flexor perforans digiti IV, and the ossification of the insertion tendon of M. extensor brevis digiti IV. These features are suggested to be associated with the requirement of finer control over the individual digits while moving on the tree, especially a thin branch.
Observations on birds feeding on fruits of the invasive shrub Lantana camara (Supirrosa) were conducted on Santa Cruz Island, Galapagos (Ecuador) in the Dry Zone during the 2009 dry season. The endemic ground finches Geospiza magnirostris (Large Ground Finch) and G. fortis (Medium Ground Finch) were recorded eating Lantana seeds with G. fortis the main consumer (>90% of records). Both finch species crushed the seeds and ate the embryos, discarding the exocarp and empty seed coats. They also dropped entire fruits to the ground, which could contribute to short-distance dispersal, but both finches also consumed fruits of L. camara on the ground. Density of L. camara seedlings under adult plants was higher in rockier areas than in bare soil since seeds were less accessible to predators and/or found more suitable microsites for germination and establishment. Both species of finches serve as short-distance dispersers, but mainly as seed predators of L. camara fruits.
Results of queries through public avian list-servers and a thorough literature search formed a data base to synthesize patterns of birds trapped in spider webs. Sixty-nine cases of birds, representing 54 species in 23 families, were reported trapped in webs. Hummingbirds were the most diverse family (9 species) and had the most cases of entrapment (n = 20). Archilochus colubris represented the species with the most cases of entrapment (n = 6). Mean mass and wing chord length of all species trapped were 11 g and 61 mm, respectively. Eighty-seven percent of all individuals had mass ≤15 g and 88% had a wing chord <90 mm. Phaethornis longuemareus and Mellisuga minima represented the smallest species (mass = 2 g, wing chord = 37 mm), and Streptopelia senegalensis was the largest (mass = 80 g, wing chord = 138 mm). Thirty cases of birds were entrapped without human intervention: 22 died and eight not wrapped in silk freed themselves. Those wrapped in silk invariably died unless freed by a human observer. One-half of all reported spider webs were of the genus Nephila, and all were orb weavers except for a single Latrodectus. Nephila clavipes entrapped nine species representing 14 cases, ranging from Mellisuga minima (mass = 2 g, wing chord = 37 mm) to Catharus ustulatus (mass = 23 g, wing chord = 93 mm). Patterns, causes, and consequences of birds entrapped in spider webs are discussed, including orb weavers as opportunistic predators of birds trapped in webs, and spider webs as a natural environmental hazard to birds.
We investigated nest site selection and breeding success of White Storks (Ciconia ciconia) in relation to geographical features, weather, and land use in western Turkey. Locations of nests in relation to altitude, distance to the nearest river and stream, slope, and aspect were examined between 2008 and 2010 in Sındırgı District. Population dynamics of breeding White Storks were surveyed in the central town in 1984, 1987, and between 1992 and 2010. White Storks nested in only 17 of 74 settlements. Twenty-six of 46 nests were occupied in 2010 with a mean density of 1.72 breeding pairs/km2. Settlements with nests were significantly lower (x ± SD) in elevation (283.3 ± 77.3 vs. 622.5 ± 230.7 m) and closer to the nearest river (1,646.2 ± 1,004.5 vs. 4,101.7 ± 3,231.5 m) than settlements without nests. No significant difference was found between the mean aspects of the settlements and the distances to the nearest stream between these two groups of settlements. The number of breeding pairs and fledglings had a significantly decreasing trend throughout the study period. The number of breeding pairs was positively correlated with the annual total area of crop fields and negatively correlated with the total area of fruit production. The number of breeding pairs was positively correlated with total and maximum precipitation in April, but breeding success was negatively correlated with mean total precipitation and mean maximum precipitation during the breeding season.
Two cases of prolonged incubation by White Storks (Ciconia ciconia) were observed in the same nest in 2009 and 2010 in southwest Poland. Incubation lasted at least 59 and 65 days, respectively; i.e., 84 and 103% longer than the average incubation period. Extended incubation was accompanied by other abnormal breeding behavior. The lack of observed copulation in either breeding season, an extremely short arrival-breeding interval, and early clutch reduction suggest the eggs were infertile. This is the first record of prolonged incubation in the Ciconiidae, and probably the first record of repeated prolonged incubation by wild birds.
We examined stopover site fidelity by Tennessee Warblers (Oreothlypis peregrina) at two Tennessee banding stations (Whigg Meadow and Big Bald) operated during fall migration, ∼1,000 km from the nearest breeding areas. We captured and banded 4,324 Tennessee Warblers at Whigg Meadow from 1999 to 2008 with 14 individuals (0.3%) recaptured in subsequent years. We banded 5,514 Tennessee Warblers at Big Bald from 2003 to 2008 where, despite relatively close geographical proximity to Whigg Meadow (<150 km between sites), no individuals were recaptured outside of the initial capture year. These inter-annual recaptures, to our knowledge, reflect the highest reoccurrence of a Nearctic-neotropical migratory passerine at a single stopover site. Our results provide evidence that passerine stopover site fidelity may occur at considerable distances from both breeding and wintering areas, and differ between geographically similar stopover sites.
A mated female was observed singing in a color-banded population of Common Yellowthroats (Geothlypis trichas) in New York State in 2011. This female continued to sing, often concurrently with her mate, for ∼1 week, at which time she completed nest construction and was not observed singing for the remainder of the season. Her song did not resemble any normal Common Yellowthroat song or vocalization. No previous publications have described female song in this species; common explanations for female song in other species include abnormally high testosterone levels, development of male-like characteristics with age, and increased territory defense demands at high densities. We found little support for any of these hypotheses, as our singing female was within the normal range for breeding density, testosterone, morphology, ornamentation, and several physiological parameters. We did not know the age of our female and could not discount old age as a cause of singing; however, other known-age, old females in the population were not observed singing. The potential explanations for singing seem inadequate in this case and the female may have been anomalous in some dimension that we did not measure, or a combination of factors may have contributed to the behavior. Alternatively, female song may be functional but only used in rarely observed social situations in this species.
I observed an exceptionally high density of Hermit Thrush (Catharus guttatus) nests (3.1 nests/ha) over two breeding seasons in an isolated 1.3-ha portion of an earthworm-free study site in the Chequamegon-Nicolet National Forest, Wisconsin. This density was much greater than the 0.1 to 0.6 nests/ha observed over the rest of the study area and exceeds by an order of magnitude most previously reported estimates for this species. The mean distance among Hermit Thrush nests in earthworm-free sites (215 m; 95% CI = 180–250 m) was lower than in invaded sites (250 m; 95% CI = 236–264 m); this difference was not statistically significant. Nest density did not differ significantly between categories. An abundance of suitable nest sites in a favored nesting substrate (clubmoss; Lycopodium spp.) could have contributed to the exceptionally high density of Hermit Thrush nests observed. High Hermit Thrush nest densities may occur in association with forest floor conditions that are characteristic of earthworm-free areas.
The Orange-eared Tanager (Chlorochrysa calliparea) occurs from southern Colombia to northern Bolivia between 900 and 2,000 m elevation. We describe for the first time the nest of the genus Chlorochrysa, based on five nests of C. calliparea, and provide information on incubation and nestling growth from August through December 2009 and 2010 in Manu National Park, Cusco, Peru. The Orange-eared Tanager has a distinct and unique nest location in clumps of moss hanging from horizontal branches, previously unknown among tanagers. The nest structure, however, was similar to that of most tanagers. We observed use of a nest-like structure as a dormitory, not previously reported for the Thraupidae. Clutch size was one egg and the nestling period was 21 days. The female made an average of 8.8 foraging trips/day from the nest which lasted on average 33.1 min with nest attentiveness of 58.9%. The small clutch suggests close affinity with mountain tanagers.
I monitored the breeding biology of House Sparrows (Passer domesticus) in a suburban colony in Cook County, Illinois, USA. I found a significant statistical correlation between clutch size and the base area of the nest box (r = 0.592, P < 0.0029) with mean clutch size varying from 4.49 eggs (in a ‘small’ nest box, 112 cm2 basal area) to 4.77 eggs (in a ‘large’ nest box, 221 cm2 basal area). Other measures of breeding success (hatching and fledging success, mean egg mass, and nestling condition) had no statistically significant relationship with nest-box size. Measures of nest site preferences, as suggested by earlier date of first egg of season or by greater number of broods per season, also show no statistically significant correlation with nest-box size.
We report an unusual case of a monogamous pair of Northern Flickers (Colaptes auratus) initiating a second clutch while there were still nestlings in the first nest. The male and female incubated at both nests but only the male fed nestlings at the first nest. The second nest attempt was abandoned after the first nestlings fledged, possibly because the two broods were too synchronous in timing for the male to contribute sufficiently to both. Double-brooding has not been previously documented for Northern Flickers.
Evolutionary theory predicts birds should adjust the sex ratio of their broods in response to external factors that differentially affect the reproductive value of each sex. We examined the brood sex ratio in the Lilac-crowned Parrot (Amazona finschi) in relation to climate, hatching date, and hatching order. We used polymerase chain reaction amplifications to identify the gender of 66 nestlings from 32 clutches spanning 7 years. There was a tendency to produce more female offspring in years of high nestling survival following high rainfall with a slight female-bias in third-hatched nestlings. We found no significant associations between brood sex ratio and rainfall, hatching date, or hatching order within clutches. Our results suggest the examined factors provide insufficient differential costs or benefits of offspring gender to promote sex ratio bias in this monomorphic species.
We present the first documentation of nestling care by multiple male feeders at nests of the Veery (Catharus fuscescens) in a Mid-Atlantic Piedmont forest in northern Delaware. This is only the second confirmation of this behavior in a Nearctic-neotropical migrant songbird. Five of six nests (83%) were attended by a male that concurrently fed nestlings at a second or third nest. Three of six nests (50%) were attended by one female and two males. No females were observed at more than one nest. We monitored >140 Veery nests at our study site since 1998, and believe the dense breeding habitat and single-brooded nature of the Veery have inhibited our ability to confirm this behavior prior to 2011. Our data suggest this behavior is widespread in our study population.
We observed Eastern Meadowlark (Sturnella magna) nests in Conservation Reserve Program grasslands in east-central Illinois to examine the influence of the surrounding agricultural landscape on nestling diets. Esophageal ligatures were applied to 3- and 6-day old nestlings to examine food items brought to the nest. The most common items were spiders (44% of total volume; primarily wolf spiders [Hogna spp.]), followed by orthopterans (23%; crickets, grasshoppers, and katydids), and lepidopteran larvae (18%, primarily cutworms). Adult Eastern Meadowlarks foraged more often than expected in soybean fields.
Darters (Anhingidae) are among the most territorial Pelecaniformes, but most of the observed aggression is between males and limited primarily to the breeding season. We observed three instances of agonistic interactions between two female Anhingas (Anhinga anhinga) foraging in a pond of an urban park in southeastern Brazil. A foraging resident female chased another female as soon as it caught sight of the latter approaching, which caused the intruder to dive and retreat. The resident female vocalized toward the site where the intruder disappeared while still in the water. The resident then vocalized from a perch from time to time toward the pond while drying its feathers. We played back its recorded call and the bird vocalized toward us suggesting this vocalization was territorial. Agonistic behavior at foraging sites merits further observation to learn whether it is restricted to particular individuals and/or periods.
The House Crow (Corvus splendens) is a bioinvader to the Red Sea region and has been shown to negatively impact indigenous species. We describe attempts by House Crows to acquire an ordinarily inaccessible, high quality food source by mobbing Western Osprey (Pandion haliaetus) in large coordinated groups. The crows mobbed perched Osprey that had successfully caught fish in 176 observed attempts to steal the otherwise inaccessible food source. However, crows succeeded in forcing Osprey to abandon fish on only seven occasions (∼4%). The crows then jointly fed on the abandoned fish. The consistency in mobbing Osprey and the low rate of success suggests House Crows are aware of the energetic value of fish.
Howell et al. (2003) proposed modifications to the system of molt terminology for birds developed by Humphrey and Parkes (1959) to address a perceived inconsistency in the Humphrey-Parkes (‘H-P’) system that Howell et al. (2003) termed the ‘first basic problem’. These modifications have been adopted by mainstream ornithological literature, but are premature and unnecessary. The recharacterization of the prejuvenal and first prebasic molts, and resulting plumages, by Howell et al. (2003) is: (1) not supported by scientific studies, (2) inconsistent with several factors that support classification of these molts and plumages under the H-P system, and (3) contrary to the fundamental purpose of that system. Moreover, the H-P system can be interpreted in a manner that resolves the ‘first basic problem’ without recharacterizing the prejuvenal and first prebasic molts and resulting plumages. The H-P system also can be interpreted to start the first molt cycle with commencement of the initial acquisition of contour feathers and provide a fixed point to start a nomenclature of molts and plumages. The four molt strategies identified by Howell et al. (2003) may be explained by variability in conventional first prebasic and first prealternate molts and are not dependent on adoption of their proposed modifications of the H-P system. Ornithologists are encouraged to re-examine the modifications to the H-P system proposed by Howell et al. (2003) and to resolve existing conflicts in North American molt terminology by adopting the proposed interpretations of the H-P system identified in this paper.