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We describe a new species of Scytalopus tapaculo (Aves: Passeriformes: Rhinocryptidae) from the temperate humid montane forests (2,400–3,200 m) of Junín Department, Peru. This species has a unique song that differs strikingly from that of any known Scytalopus species, consisting of a rapidly repeated series of ascending phrases. Phenotypically, the new species is uniformly blackish in color and small-to-medium in size, most similar to members of the allopatric S. latrans complex. At least six species of Scytalopus occur along an elevational gradient on the eastern slopes of the Andes in Junín; in the vicinity of the type locality, the new species replaces S. femoralis at 2,400–2,500 m, and is replaced by S. acutirostris at 2,900–3,200 m. Throughout its elevational range, the new species is broadly syntopic with the larger S. macropus. This species is currently known from a single river drainage; although it probably occurs more broadly, it is likely a range-restricted species endemic to central Peru.
Rohwer et al. (2009) present isotopic evidence of migratory double breeding by five species of birds that were breeding in July and August in northwestern Mexico. The presence of old brood patches in these species, combined with their late breeding in Mexico, suggested that these species had bred earlier in the north. Here we present data showing that Orchard Orioles and Yellow-breasted Chats breed as commonly in coastal Sinaloa in late May and early June as they do later in the summer; further, many females of these species examined in early June 2011 had downy ventral apteria, indicating that they were breeding for the first time in their annual cycle in Sinaloa. Thus, the old brood patches observed in these species in July and August, when they are still breeding in northwestern Mexico, may reflect earlier breeding attempts by those same individuals in Mexico. Yellow-billed Cuckoos seldom call and are uncommon in northwestern Mexico until late June and likely do not begin breeding until July. For Yellow-billed Cuckoos there had been no description of how the ventral apterium changes with breeding, so Rohwer et al. (2009) assumed that it followed a passerine pattern of re-feathering during the post-breeding molt. To test this assumption we examined the ventral apterium in cuckoo specimens collected throughout the winter and found that it remains featherless throughout the year, including immediately after the complete mid winter molt. Thus, the bare ventral apteria of cuckoos arriving in northwestern Mexico in June and July do not constitute evidence of prior breeding in that year.
Felicity L. Newell, Aaron N. K. Haiman, Desirée L. Narango, Julie Means Elder, Linda Daily Leonhard, Jennifer Philhower-Gillen, Angela M. Johnson, Amanda D. Rodewald
We document the first confirmed cases of polygyny and double brooding in the Eastern Wood-Pewee (Contopus virens). During an intensive study of the effects of shelterwood harvesting on canopy-nesting songbirds in southeastern Ohio, 2007–2010, we color-banded 79 Eastern Wood-Pewees and monitored 237 pewee nests. In 2007, we confirmed a color-banded male provisioning at two concurrently active nests; the male was polygynous in at least two consecutive years. In 2009, we observed an unbanded female feeding fledglings and subsequently shaping a nest from which young had recently fledged; the female successfully fledged two broods from the same nest. In addition to confirmed observations, we identified several other probable cases of polygyny and double brooding. In our upland oak system, we estimated rates of polygyny from 6–22% with the greatest occurrence of polygyny during a dry spring in 2007; rates of double brooding may have been as high as 6–12%. Males appeared to benefit from polygyny, because males paired with two females fledged twice as many young compared to monogamous males, without any apparent negative effect on return rate. Overall, we did not find negative effects on reproductive success for females paired with polygynous males, although we were not able to consistently differentiate between primary and secondary females. Polygyny appeared to be related to either territory quality and/or male quality with nests of polygynous males located in preferred nest sites while provisioning rates were greater at polygynous compared to monogamous nests. In addition, we only found experienced males paired with two females. Both males and females benefited from double brooding, fledging twice as many young as single brooded pairs, but in our system double brooding appeared to be limited by high levels of nest predation early in the breeding season.
Many aspects of the breeding biology of Afrotropical forest birds are poorly known. Here we provide a description based on the monitoring of 1461 active nests over eight breeding seasons about one or more aspects of the breeding biology for 28 coexisting understory bird species on the Amani Plateau in the East Usambara Mountains, Tanzania. Mean nest height and mean distance of nest from forest edge varied widely among species with most species constructing nests across a broad vertical and forest edge to interior gradient. However, there were important exceptions with all sunbird species and several dove and waxbill species constructing nests in close proximity to the forest edge. For 17 common species for which we recorded two or more active nests, mean clutch size across species was 1.9 eggs per clutch, the lowest site-specific mean clutch size yet reported for a tropical forest bird community. For nine bird species, a subset of the 17 common species, length of breeding season, defined as the difference between the earliest and latest recorded incubation onset date, ranged from 88–139 days. Most of these nine species displayed a unimodal distribution in incubation onset dates across a breeding season which extended from the end of August through middle January. In summary, a wide variation exists in most aspects of the breeding biology within an understory forest bird community in the East Usambara Mountains.
We provide the first detailed nesting biology information for the Yellow-breasted Warbling-Antbird (Hypocnemis subflava), a member of the recently split Warbling Antbird complex. We found seven pouch-shaped nests with two eggs or nestlings within Manu National Park, SE Peru. Long incubation sessions (93.7 ± 7.78 minutes, range = 4–480 minutes, n = 18 days) were untaken by both parents and high diurnal nest attentiveness (% of time on the nest) averaged 85.8 ± 1.4% (n = 16) as a result of taking fewer short foraging trips (6.3 ± 0.6 trips/day, range = 3–11; n = 14) that lasted 16.19 ± 1.78 min (range = 1–91; n = 18). Incubation behavior produced an average inner nest temperature of 32.3 ± 0.24 °C (n = 15 days) and average egg temperature of 36.4 ± 0.09 °C (n = 3). Individual nests at different elevations exhibit differences in incubation behavior. The nestling period was 11 days (n = 1) and both parents brooded and fed the nestlings. Nest shape, location, and composition were similar to other species in the complex, but egg coloration was variable among species.
The Spectacled Tyrant (Hymenops perspicillatus) is a flycatcher that inhabits open lands, grassy areas near water bodies, marshes, fields and pastures in southern South America. Our aim was to describe the breeding biology of Spectacled Tyrants in native tall grasslands, specifically by studying their reproductive phenology and breeding success. The study was developed in the southeastern Pampas region, Argentina. We conducted nest searching and monitoring during the 2010–2011 and 2011–2012 breeding seasons. We found 88 nests. The breeding season was from mid-October to late January. Clutch size was 2–3 eggs, mode = 2. Incubation and nestling periods were 15.8 ± 0.7 days and 14.7 ± 0.6 days, respectively. Nest predation was higher during the incubation period than during laying and nestling periods. The probability of nest success from egg-laying to fledging was 0.24. This species shows life-history traits in accordance with other South American temperate birds.
We present detailed information on the breeding biology of a migratory population of the Tawny-bellied Seedeater (Sporophila hypoxantha), a typical member of the “capuchinos” group. Data were collected for 69 nests from 2007–2010 in areas of hilly dry grasslands in southern Brazil. Breeding begins in early November, a week after the seedeaters arrive, peaks in late November, and lasts until late February, when individuals migrate north. Females build small open-cup nests in small shrubs (mainly Vernonia chamaedrys and Eupatorium polystachyum), 41.9 ± 0.8 cm (range 27–60 cm, n = 38) above the ground. Clutch size is two (91%) or three eggs (n = 43), which measure 16.22 ± 0.51 mm by 11.93 ± 0.28 mm (n = 10), and incubation, which is performed by the female, lasts 12 days. Average nest attentiveness during incubation was 60 ± 5% (n = 5) with 20–31 min on-bouts. Males help feed the nestlings beginning on the fifth day after hatching. Provisioning visits/hr averaged 4.6 ± 0.7 (n = 6) and females brooded after feeding the young in 48% of the visits when nestlings were 1–4 days old. When nestlings were 6–9 days old, the average visits/hr increased (8.95 ± 1.8, n = 11; z = −2.5, P = 0.012), with brooding after feeding in 14% of the visits. Nestlings fledged after 9–10 days. The basic reproductive characteristics of the migratory population are very similar to those found in the resident population in the Formosa region, Argentina, but the breeding season, time spent building the nest, and length of visits to the nest during the nestling stage were shorter.
Prescribed fire is a frequently applied land-management tool for the preservation and maintenance of southern pine woodlands. Many avian species benefit from the use of prescribed fire in pine woodlands; however, the effect fire has on nesting site characteristics is not well understood for many disturbance-dependent species. We located nests of Bachman's Sparrows (Peucaea aestivalis) in mature longleaf pine (Pinus palustris) forests managed using frequent prescribed fires (return intervals ≤2 years). Vegetation characteristics were measured at each nest (n = 37), within a 0.04-ha area immediately adjacent to nests, and at different time intervals following burns within a larger 20-ha area surrounding nests. We examined vegetation characteristics within the 20-ha area 2, 6, 12, and 18 months after prescribed burns to compare post-fire plant succession with site characteristics associated with nest sites. Nest sites had lower amounts of grass standing crop, grass ground cover, and higher amounts of woody vegetation than found in the 0.04-ha area immediately surrounding nests. Vegetation structure at nests sites was similar to the structure measured across the 20-ha area <6 months following burns, but vegetation structure at ground level began to deviate ≥6 months after fires such that ≥50% of the values differed from the values recorded at nest sites. Results point to the importance of open vegetation structure at ground level and the need for frequent burning to maintain appropriate nesting habitat. Vegetation characteristics associated with nest sites appear to be highly ephemeral and tightly linked to conditions at ground level. As such, suitable nest sites likely represent a subset of areas occupied by singing males.
The functional consequences of nest size variation in cavity nesting birds have been thoroughly investigated in recent years. However, it is unknown whether recent nest-building experience influences subsequent nest architecture. By providing Eastern Bluebirds (Sialia sialis) with either deep or shallow nest boxes for their initial nest of the breeding season, we tested whether the height of their subsequent nest in the same breeding season reflected the height of their initial nest or whether they built nests to match their current nest cavity regardless of their previous nest height. We found that second nests built in deep boxes were significantly taller than first nests built in shallow boxes by the same females. This difference could be because of nest date, cavity depth, or experience. We tested each possible driver and found that cavity depth better explains variation in nest height than either nest date or prior experience. We conclude that, for this multi-brooded secondary cavity nesting passerine, the roles of learning and experience are secondary to the importance of behavioral plasticity.
Little is known about the post-fledging period in most bird species, and almost nothing has been reported for the family Emberizidae, including New World sparrows. We report here, for the first time, the sizes (wing length and body weight) of, and the distances traveled by fledgling Grasshopper Sparrows within their hatch summer in a restored Atlantic Coastal grassland in Maryland. In the years 2002–2009, we recaptured 24.3% of the 799 banded nestlings in the grasslands at least once within their hatch year. Body weight was not correlated with wing length, wing length did not change with time of recapture, and the average fledgling gained weight by 14% in 100 days. Smaller than average birds were missing from late summer recaptures. As expected, the distance traveled increased significantly with time, but the average fledgling was recaptured 346 m from its nest. The average time of recapture was 33 days after fledging; the youngest recapture was 5 days after fledging and it dispersed a net 580 m from its nest; the longest and fastest distance recorded was 1,615 m from the natal nest in no more than 20 days; the longest recorded retention was 97 days by a local that moved a net distance of 753 m. We conclude that most fledglings in this population of Grasshopper Sparrows remain within their natal habitat for most of the months prior to their pre-formative molt, and that at least 1∶4 of them survive at remarkably high rates.
Scissor-tailed Flycatchers (Tyrannus forficatus) are insectivorous Neotropical migrants that breed in the south-central United States. We examined their fine-scale (circles 300 m in radius centered on observed flycatcher locations) associations with different land cover types in south-central Texas. Scissor-tailed Flycatchers use a sit-and-scan foraging strategy; therefore, we expected the species would be positively associated with open land cover types (vegetation with little or no canopy) such as grassland, pasture/hayfield and cropland, and negatively associated with forest and shrubland given that the latter could obstruct visual scanning. We conducted 44 surveys from 9 May 2011 to 15 December 2011 by slowly driving (30 km/h) rural roads throughout 15 counties in south-central Texas and 3 near the coast of the Gulf of Mexico. Using ArcGIS, we quantified the percent cover of four general land cover types (urban/developed land, forest/shrub, grassland/pasture/hay, and cropland) within 300 m of each flycatcher location. Statistical analysis involved comparing the land cover of the flycatcher locations to a set of random points along the same routes. On average, flycatcher locations had significantly more grassland/pasture/hay than did random points (38.8 vs. 31.2%) and significantly less forest/shrub (29.9 vs. 36.7%). Therefore, although flycatchers may associate with open land cover at a rate greater than its overall availability, they generally occupy locations that have a mix of open and closed land cover. Knowledge of flycatcher habitat use at a fine-scale could be useful to the successful conservation of this species.
We evaluated sites on an industrial forest in central Arkansas that American Woodcocks (Scolopax minor) used for courtship during their spring migration. Our main objective was to determine the vegetation characteristics used by male woodcocks on their courtship sites within early successional pine stands. We quantified use within three stages of early successional pine stand; pine seedling (1 year old), young-pine sapling (2–3 years old), and old-pine sapling (4–5 years old). We used crespuscular surveys as an index to the number of woodcock using each stand. We completed surveys in January–March 2010 and 2011 on eight stands of each stage (n = 24) during 7–10 day sampling periods across spring migration. We quantified the vegetation structure of each stand including the percent of bare ground, standing herbaceous, flattened herbaceous, shrub, coarse woody debris, and canopy cover and horizontal density. We found that woodcocks used stands with greater shrub, standing herbaceous, and flattened herbaceous cover. This is different from other studies in the southern United States that have shown woodcocks to use areas with sparse vegetation and increased bare ground. We suggest this disparity occurred because previous studies assumed constant detection between stands with different vegetative structure, whereas we completed detection tests to determine how vegetative structure may influence detection between stand types and incorporated these differences in detection into our analyses.
In Florida, roughly 18,000 ha of treatment wetlands called Stormwater Treatment Areas (STAs) have been constructed on agricultural land to reduce phosphorous loads to the Everglades. Little is known about how avian communities in these STAs compare to those present on other similar land types. In 2008–2009, point counts were conducted seasonally in the STAs, nearby croplands, and natural Everglades marsh to compare avian communities among these habitats. Overall, avian densities were nearly three times greater in STAs than in the croplands and 38 times greater than in the natural marsh. Local species richness in the STAs was 78% greater than in croplands and nearly four times greater than in the natural marsh. Although natural marshes may have more structural complexity than the croplands and STAs, their oligotrophic status probably limits their ability to support a large bird community. Avian densities varied seasonally among habitat types; avian density was greatest in the winter in STAs as a result of high densities of migratory waterfowl. The STAs may be providing wintering habitat to a significant portion of the North American waterfowl population, including as much as 8% of the breeding population of American Coots (Fulica americana). If the trend of increasing numbers of treatment wetlands continues, it has the potential to alter the distribution of wetland birds, a group that has previously suffered population declines because of habitat loss.
Neighbor-stranger discrimination is the ability to recognize and respond differentially to familiar and unfamiliar conspecifics. This type of recognition is common in species that aggressively defend territories, such as the colonially nesting Great Black-backed Gull (Larus marinus). This species has a large agonistic signal repertoire, which includes the “yeow,” a short-range threat vocalization. A playback experiment was used to determine whether Great Black-backed Gulls are capable of recognition on the basis of this call type. Subjects maintained alert postures for significantly longer in response to unfamiliar yeows than to those of their mates or neighbors. To my knowledge, this is the first study to demonstrate neighbor-stranger discrimination on the basis of a threat vocalization.
Delayed plumage maturation (DPM) in young males (in their second year of life: SY) of some species of birds has been found to reduce aggression directed at these younger males. Tree Swallows (Tachycineta bicolor) are unusual because it is SY females rather than males that display DPM; however, the functional significance for DPM remains equivocal. During the breeding season, we tested whether both male and female Tree Swallows behaved differently towards SY and older (after second year: ASY) female Tree Swallow models. When presented as a territory intruder, we predicted that ASY models would receive more aggression from resident pairs if ASY females are perceived as a greater competitive threat. When presented as a territory owner, we predicted that SY models would experience more territorial intrusions if SY plumage is perceived as a signal of inexperience in territory defense. When models were presented as intruders, resident females were more aggressive towards ASY models compared to SY models. When presented as territory owners, ASY models received more aggression than SY models from intruding Tree Swallows, although we suspect that intruders were neighboring Tree Swallows with already established territories, as opposed to birds seeking to settle within the territories of our models. Overall, our results suggest that DPM in female Tree Swallows is an adaptive trait that potentially reduces intrasexual competition for SY females during the breeding season.
The Ryukyu Scops Owl, Otus elegans, is distributed over a 1,200-km area, only inhabiting islands. Within this range, I studied this species across 20 continental islands in the Ryukyu Archipelago and two oceanic islands. Although most studies recently use quantitative continuous measurements of many specific aspects of the vocalization, I introduced a new method, “typological analysis” to visually classify variation of spectrograms according to the shape of syllable in the owl species, examining their dialects in relation to their geographical distribution. In the typological analysis, hoot, syllable, and element types were defined according to the number of syllables, the degree of timescale overlap of the first and second elements in the second syllable, and relative differences of duration and frequency of two elements in the second syllable, respectively. Although frequencies of hoot and element types in each island population were significantly different between the island groups north and south of the Kerama Gap across the archipelago, hoot and element types were shared between the island groups. Furthermore, typological variation occurred in syllable types, however there were no differences in frequencies of syllable types between the island groups. Geographic structure in vocal parameters as steep clines with stepped variation is represented as a dialect. According to the definition, this study found that no unique dialects in hoots occurred between the different island populations of Ryukyu Scops Owls. The Kerama Gap might act as a biogeographical barrier, contributing to the differentiation between owl hoots according to spectrotemporal analyses; however, the typological analysis detected the distribution of typological characteristics of hoots on the small islands north of the Kerama Gap that contradicts this concept of a biogeographical barrier. Because the typological analysis needs to visually examine each individual by careful attention to detail, it is a good method for discovering minor geographic variations and patterns in bird vocalizations.
The Cerulean Warbler (Setophaga cerulea) is a North American landbird showing a high rate of population decline. Estimates of its annual adult survival rate are needed to evaluate its current population status. Annual return rates of 104 color-banded adult male Cerulean Warblers were used to estimate minimum annual survival from 2008–2011. The study site was a large oak-hickory forest bordered by a mosaic of forest tracts and agricultural land in southwestern Michigan. Cormack-Jolly-Seber (CJS) live recapture models yielded an annual survival estimate (Φ) of 0.59. This estimate lies in the range of available CJS survival estimates for other Neotropical migratory species with different population trajectories. In addition, this survival value confirms sink population status for Cerulean Warbler breeding populations studied at widespread locations in the breeding range (all λ < 1.0). Inter-year breeding dispersal was frequently <1.0 km, but seven banded males made breeding dispersal movements among years >1.0 km. Previous studies have suggested that some adult male Cerulean Warblers make very long-distance breeding dispersal movements among years, suggesting realized annual survival rates are higher than reported. The annual adult male survival rate reported here is similar to the only other value obtained from a breeding population of this species. In aggregate, these findings suggest that reduced breeding ground productivity is a probable cause of the long-term population decline of the Cerulean Warbler. Conservation efforts focused on this imperiled songbird species might focus on increasing this demographic factor, perhaps via reforestation of the breeding grounds.
The McKay's Bunting (Plectrophenax hyperboreus) is one of the rarest passerine species in North America and breeds solely on St. Matthew and Hall islands in the remote Bering Sea, Alaska. We examined the nesting ecology of this poorly studied species on St. Matthew Island in 1982, 1983, and 2003. We found that the high breeding density of the McKay's Bunting may account for the lower clutch size and number of young fledged per successful nest compared to its sister species, the Snow Bunting (P. nivalis). The proportion of eggs that successfully hatched was higher for McKay's Buntings than Snow Buntings breeding at other Arctic locations in North America. Daily nest survival declined during egg-laying and incubation and increased throughout the nestling period. Nesting chronology was earlier in 2003 compared to the 1980s; however, daily nest survival was similar between decades. To assess how McKay's Buntings are responding to climate-mediated changes to physical and biotic conditions, we recommend monitoring the species' reproductive rates and population size.
Based on 805 observations of 63 species, we identified the main breeding seasons of avian trophic guilds in New Caledonia. Most omnivorous and carnivorous birds had undefined breeding periods with moderate peaks during the warm/dry season and the hot/rainy season. In contrast, nectarivorous, frugivorous, granivorous and insectivorous species had marked breeding seasons that started at the beginning of the warm/dry season and ended in the hot/rainy season. Introduced species also reproduced during these periods, regardless of the trophic guild to which they belonged.
The temporal and spatial patterns of avian brood parasitism can critically influence host fitness, the coevolution of parasitic strategies and host resistance, and their reciprocal effects on population dynamics. This study examined spatial patterns of Brown-headed Cowbird (Molothrus ater) parasitism on Eastern Phoebe (Sayornis phoebe) hosts in 2009–2011 near Ithaca, NY, USA, and compared them with published data from 1999–2002 at the same nest sites, encompassing a period long enough for a turn-over of most of the breeding adult host and parasite populations. Relative to non-parasitized nests, host nests, that were more likely to be parasitized annually in 2009–2011, had also been parasitized more often during years 1999–2002. These findings are consistent with the hypothesis that Brown-headed Cowbirds, even across generations, show a consistent preference for particular Eastern Phoebe nest sites, although it remains unclear what the relative roles of the biological traits of the hosts occupying those sites versus the ecological and physical characteristics of the actual nest sites may be in yielding these patterns. Nonetheless, the results imply that knowing the site-specific historys of parasitism of reusable nests and breeding sites can be used to predict variation in the risk and future impact of cowbirds on this host species.
We present the first nest description for the Lawrence's Thrush (Turdus lawrencii), found on 9 February 2011 in the lowland tropical forest at the Tiputini Biodiversity Station, Orellana province, Ecuador. The nest was situated 1.6 m off the ground, tucked in the hollow end of a broken dead tree. The open-cup nest conformed to the shape of the depression in which it was built, and averaged 13.0 cm in diameter and 6.6 cm in depth. The inner cup diameter averaged 8 cm and the maximum depth was 4 cm. The nest was constructed of moss, leafy liverworts, and fungal rhizoids held together with mud. During 6.5 hrs of observation on 13 and 14 February 2011, we observed the female feeding the nestlings while the male remained in the vicinity of the nest. We conclude that the nest composition of Lawrence's Thrush is typical of other thrush species, and based on our limited behavioral data we also conclude parental care is comparable to other Turdus species.
As part of monitoring a population of Canada Geese (Branta canadensis maxima) in southern Quebec, two siblings hatched in the same nest in 2008 were later observed breeding together. The geese were first seen as a pair in spring 2011, and we found their nest the following year 437 m from their natal nest site. The sibling pair had lower hatching success than other pairs of the same age cohort. To our knowledge, this is the first report of sibling pairing in the wild for a goose species. Adoption is common in geese, and siblings reared in different family groups may be unfamiliar to one another, which may be the case for the observed sibling pair. Since geese are perennial monogamous birds, full siblings are produced each year, providing further possibility for inbreeding, but we found no pairing among siblings of different ages. Natal dispersal was more important for males and this could contribute, with kin recognition, to inbreeding avoidance.
Habitat fragmentation is particularly severe in the Lower Rio Grande Valley (LRGV) of Texas, where greater than 90% of the native wetland habitat has been replaced by agriculture and urban development. The Brownsville Common Yellowthroat (Geothlypis trichas insperata), a rare subspecies of the Common Yellowthroat restricted to this area, is a good model for studying the effects of this extensive fragmentation on avian genetics and ecology. In this study, three hypotheses addressing genetics and habitat fragmentation were tested: (1) the density of Brownsville Yellowthroats is greatest along the Rio Grande rather than away from the river; (2) individuals found on or near the Rio Grande are more closely related than individuals farther away; and (3) a source-sink metapopulation model is best fit to describe the population dynamics of this subspecies. We used 15 microsatellites to examine the genetic diversity of 128 individuals from Cameron and Hidalgo Counties (Texas) sampled during 2008–2009. The densities of yellowthroats at sites near the Rio Grande were not significantly different from densities at sites farther from the river. Genetic analysis indicated that individuals were as related to each other as would be expected in distant relatives and indicated the presence of a single, admixed population. The results suggest that the Brownsville Common Yellowthroat is able to move freely among isolated habitat patches and that wetlands along the Rio Grande do not act as an exclusive corridor for this species.
Billions of birds are estimated to be killed striking clear and reflective windows worldwide, and conservation, ethical, and legal reasons justify preventing this unintended human-associated avian mortality. Field experiments reveal that to be effective, UV signals used to prevent bird-window collisions must minimally reflect 20–40% from 300–400 nm. Field experiments reveal 3.175 mm parachute cord hung in front of clear and reflective windows separated by 10.8 cm and 8.9 cm are effective bird-window collision preventive methods. The results of the parachute cord experiment and those of previous studies support the importance of applying collision prevention methods to the outside window surface reflecting the facing habitat and sky. Comparison of field and tunnel testing experimental protocols to evaluate bird-window collision preventive methods suggest that tunnel testing is useful for initial assessment but not as a definitive measure of effectiveness.
Avian nests face a wide variety of nest predators, which pose different risks that could select for the ability of parents to notify conspecifics of nest predator type. We previously demonstrated that the Japanese Tit (Parus minor) produces acoustically distinct mobbing calls for different nest predators (crows and snakes), thereby eliciting different and appropriate anti-predator responses not only in parents, but also in nestlings. However, the variation in mobbing call behavior may have been caused by differences in the experimental methods used, whereby each nest was presented with either a mounted crow or a live caged snake. In the present study, we observed a total of seven natural encounters of Japanese Tits with crows (n = 4) and snakes (n = 3) near their nests. Consistent with the previous experiments, Japanese Tits produced distinct mobbing calls, namely, “chicka” calls for crows (4/4) and “jar” calls for snakes (3/3). Thus, we conclude that mobbing calls of Japanese Tits signal nest predator type to both parents and nestlings.
We observed feigning behavior by a male Red-crowned Crane (Grus japonensis) in Heilongjiang province, China. The male crane pretended to be injured to draw a larger intruder away from the young. The Red-crowned Crane held his quivering right wing pointed down at the ground, stretching his neck out, running quick short steps with an exaggerated limp (broken-wing ruse). Then, he spread both quivering wings and tail and ran with quick short steps (trailing wing ruse). These ‘injury feigning’ behaviors have not been recorded previously in this species, and this is only the third observation of these behavior in cranes (Gruidae).
Scavenging is a common behavior in many animal species and can increase the fitness of individuals and populations. Scavenging has been documented more commonly in recent years with advances in technology, including in difficult to observe avian species. Four North American owl species have been documented scavenging, and here we relate the first documented scavenging by a Western Screech-Owl (Megascops kennicottii), which was video-documented with a motion-triggered camera. The screech-owl visited a Virginia Opossum (Didelphus virginiana) carcass seven times over an 11-hr period, with the longest visit lasting 7 mins (mean = 3.14 ± SD 2.34 mins); during the visits the owl actively fed on the carcass. The most common prey of Western Screech-Owls are small mammals, insects, arthropods, and small birds. No mesocarnivore or large mammal has ever been detected in diet studies of screech-owls, though screech-owls have been shown to attack and kill prey larger than themselves. The importance of carrion in owl diets is largely unexplored, and the scavenging behavior of owls could be more significant than currently believed depending on its availability and the presence of competing scavengers. Further research is needed to establish the commonality of scavenging by owls, and its various ecological effects.
Migratory and non-migratory Whooping Cranes (Grus americana) historically inhabited southwestern Louisiana until they were extirpated in 1950. Little is known about the feeding habits or dietary items of these cranes except for anecdotal evidence from local residents provided to R. P. Allen for his influential 1952 work on Whooping Cranes. Other populations of Whooping Cranes have been characterized as opportunistic omnivores, consuming small vertebrates, invertebrates, and plant material. In 2009, southwestern Louisiana was selected as a reintroduction site for Whooping Cranes. We report on four observations of reintroduced Whooping Cranes depredating at least two different species of turtles (common snapping turtle and mud turtle), which have not been previously reported as a dietary item for this species.
Mallards (Anas platyrhynchos) have been observed foraging on intertidal Pacific sand crabs (Hippidae, Emerita analoga) in the swash zone of sandy beaches around Coal Oil Point Reserve, California, and several other beaches on the west coast since at least November 2010. Unlike foraging shorebirds, Mallards do not avoid incoming swashes. Instead, the incoming swash lifts and deposits them down the beach. Shorebirds and diving ducks commonly feed on sand crabs, but sand crabs appear to be a novel behavior and food source for Mallards. Previous surveys of beaches did not report foraging Mallards on regional beaches, whereas foraging Mallards were common in contemporary (recent) surveys and anecdotal reports. Observations of this potentially new behavior were separated by as much as 1,300 km, indicating that this was not a local phenomenon. Mallards foraged singly, in pairs, and in flocks. An expansion of diet to sand crabs carries risks of exposure to surf, human disturbance, high salt intake, and transmission of acanthocephalan and trematode parasites for Mallards but has the benefit of providing a dependable source of animal protein.
Japanese weasels (Mustela itatsi) artificially introduced to Miyake-jima Island, a peripheral island of Japan, in the early 1980s increased predation on bird nests. We investigated the breeding biology of Japanese Bush Warblers (Horornis diphone) before and after the weasel introduction. Nest height was higher after than before the introduction, while clutch size did not differ significantly between the periods. These results suggest that introduced carnivores affect not only nest predation but also the nest site selection of birds.
Nestling birds attract parental care with begging that often includes the display of colorful gapes and rictal flanges. The evolution of mouth coloration has been attributed to both the enhanced visual conspicuousness of colorful mouths and the potential for color variation to reveal information about nestling quality. For both hypotheses, the visual contrast between the gape and rictal flanges is potentially important to parents' perception of color. We observed, and then quantified with digital photography, striking within-tissue variation in the carotenoid-based coloration of rictal flanges in three passerine species. Yellow flange tissue was most saturated near the gape, indicating higher carotenoid deposition there than in more lateral regions of the tissue. This within-flange color patterning may have important visual consequences and could have evolved in the context of communication between offspring and parents.
Cinereous Warbling-Finch, Poospiza cinerea, is a poorly-known bird endemic to the Cerrado region and ‘Vulnerable’ to extinction. It has been suggested that this species may be nomadic because of its rarity and low density. We tested this suggestion throughout observations of two banded individuals in a ‘campos rupestres’ site at Serra do Cipó, state of Minas Gerais, Brazil. We also described some aspects of its natural history, including a preliminary estimation of the home range size. Estimated home ranges of the pair were 15.02 and 16.56 ha using two different methods. Home range comprises mainly rocky outcrops, with low-height vegetation, used for foraging on small arthropods. The pair showed year-round residency and long-term site fidelity for at least 3.5 years, thus contradicting the nomadism hypothesis.
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