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Nest predation has driven the evolution of specialized behaviors that decrease the probability that a predator encounters a nest. We collected descriptions from the literature of a behavior wherein male and female adults fly to their nest as a pair, with one bird flying onward or veering off while the other enters the nest. We suggest that the most likely function of this behavior is to decrease the risk of nest predation from visual nest predators. In this hypothesis, visual nest predators are distracted by the flying bird and thus fail to observe the bird arriving to the nest entrance (and the nest itself), although the putative adaptive value of this behavior remains to be confirmed. While this behavior has been sporadically noted in the natural history literature, few ornithologists are aware it is found across multiple taxa, especially in the Neotropics. We show that this behavior occurs in at least 28 species across 5 distinct families (and 11 genera) of passerines. We propose a classification scheme for this and similar behaviors and discuss factors hypothesized to promote the evolution of this behavior (e.g., mate guarding, building enclosed nests). We call this behavior “coordinated misdirection” (or “desvío coordinado” in Spanish) because it depends on the cooperation of at least 2 birds, and its presumed function is a visual misdirection—a ruse to draw the observers' attention away from the nest. Finally, we encourage future research so that the evolutionary history of the behavior can be explored and the behavior can be analyzed under a life history framework.
We present the first detailed account of the breeding biology and egg description of the Restinga Tyrannulet (Phylloscartes kronei). Restinga Tyrannulets build their nests (n = 10) 0.7–3.0 m above ground level. The nests were closed and ovoid, with an interior of dry grass leaves and an exterior covered with moss, all adhered with spider webs to fix the nest material. Nest chambers were lined with plumose seeds. Nest construction lasted ∼19 d and was apparently accomplished exclusively by females. We recorded a clutch size of 2 to 3 white eggs (15.9–16.8 × 12.7–13.1 mm). Incubation was performed only by females and lasted ∼12 d (constancy of incubation = 0.4), but both adults fed the nestlings and fledglings and removed fecal sacs from the nests. Nests and eggs were within the general pattern found for genus Phylloscartes. Female P. kronei had a more important role than males during the breeding period and seemed to be solely responsible for nest construction, which differs from reports for other Phylloscartes species.
Electrocutions of birds on power structures is a global conservation concern that has not been thoroughly reported in all areas where it occurs. Here we provide information from citizen scientists describing 3,400 avian carcasses of at least 79 species found at the bases of 57,486 electrical pylons in Hungary. Of these carcasses, 3% were found at the bases of pylons retrofitted to reduce electrocution risk. On average, one carcass was found per 15 nonretrofitted pylons surveyed compared one carcass per 89 retrofitted pylons, an 83% difference in frequency. Electrocutions included 4 species of conservation concern in Hungary: Red-footed Falcons (Falco vespertinus), European Rollers (Coracias garrulous), Saker Falcons (Falco cherrug), and Eastern Imperial Eagles (Aquila heliaca). Only 3 of 104 (3%) electrocutions involving these species occurred on retrofitted pylons. Across birds of various sizes (small ≤25 cm long, medium 26–49 cm long, and large ≥50 cm long), differences in electrocution frequencies on nonretrofitted and retrofitted pylons were smallest for small birds, apparently because small birds could walk across the unprotected gaps in coverage directly below energized conductors. In this study, citizen scientists documented the breadth of the electrocution problem in Hungary but were not trained to record detailed pylon-specific configuration details. Rather, each pylon surveyed was categorized into one of 8 general configurations. Pylons with terminal connections were the most dangerous, accounting for 8% of pylons and 24% of electrocutions. Future mitigation may benefit from professional scientists conducting detailed analyses of how electrocutions occurred on retrofitted pylons.
With the exception of sites along coastal Texas, southeast Oklahoma, and coastal South Carolina, the winter distribution and abundance of Yellow Rail (Coturnicops noveboracensis) is poorly understood. Along the northern Gulf Coast region, winter occurrence is suspected based on a scattered collection of museum specimens and anecdotal observations, although the extent of this species' distribution is uncertain. To address this lack of information, we performed systematic rope-dragging surveys at night targeting Yellow Rails at 17 wet pine savanna patches (size range 1.9–83.3 ha) and one high salt marsh site (13.1 ha) located along coastal Alabama and Mississippi during the winter/spring seasons (Dec–Apr) of 2011–2013. For all sites combined, we flushed 123 Yellow Rails over 117.4 survey hours, yielding 1.0 rail/h. Of these, we captured and banded 61 rails (50%). The sex ratio for birds, discernable through morphometric measurements (n = 40 ind.), was ∼1:1 male-to-female. The relative abundance of Yellow Rails increased in relation to the size of the area surveyed and was higher at sites burned within 3 years. Across sites, each additional hour of survey effort increased the number of birds detected by 0.66 rails/h. Our findings indicate Yellow Rails overwinter in wet pine savanna habitats along the northern Gulf Coast region, providing additional information supporting the ecological importance of these dynamic coastal communities for this and other imperiled grassland obligate species.
Fragmentation and degraded habitat conditions can result in increased competition for critical resources, altered mating systems, and can eventually result in population declines or extinction. We investigated the degree to which habitat degradation and habitat loss impacted the breeding ecology of Greater Prairie-Chickens at 3 study sites across relatively intact grasslands in Kansas, USA. Across all 3 study systems, we found similar rates of multiple mating by females at 14–20% of broods. In addition, we found evidence for facultative nest parasitism of conspecific females. Prairie-chicken females inhabiting more intact and less fragmented landscapes with a higher probability of survival did not engage in parasitic egg laying, whereas ∼17% of females inhabiting a more fragmented and isolated landscape engaged in parasitic egg laying. Parasitic egg layers tended to be older females that parasitized nests of yearling females. Parasitic egg layers only laid parasitically after an initial nesting attempt failed. Parasitic laying females all renested and hatched their own clutches. When counting parasitically laid eggs, parasitic egg-laying females laid significantly more eggs than nonparasitic egg layers and, as a result, had 25% greater fecundity. This case study across the relatively intact grasslands of Kansas highlights how land use and management can influence adaptive life history traits and population stability. Consequently, understanding these relationships will be essential to developing effective future conservation and management plans for prairie-grouse.
The genus Lanio is distributed from southern Mexico to northern Brazil. Until now, nesting information has been limited and scattered among Lanio species. Nests descriptions are available for 3 of the 4 species, and only L. versicolor has nestling descriptions. No information is available on incubation and feeding behavior or incubation and nestling periods for any Lanio species. We present detailed nesting biology information for L. versicolor, such as incubation and nestling behavior, eggs and nest thermal dynamics, and nestling feeding behavior, and also present the first evidence of cooperative breeding for the genus Lanio based on 11 nests monitored in the buffer zone of Manu National Park, Cusco, Peru. Nests were cup-shaped, and all had a leaf located above the nest. The clutch size was 2 eggs, white with maroon or wine-colored spots covering the shell surface. Incubation and nestling periods were 15 and 11 d, respectively, and daytime nest attentiveness was 78%. Nest architecture, clutch size, and nestling period were consistent with previous reports for the genus Lanio. We found similarities in the nesting biology of Lanio spp. with other species of the Tachyphoninae subfamily. Our study significantly increases the information available for the genus Lanio and provides novel and important information of cooperative breeding for a Neotropical mixed-species flock “leader” species. Yet, more studies are needed to fill the large information gap on nesting of tropical birds such as the species in the genus Lanio.
First discovered in northern San Martín department, Peru, in 1976 by O'Neill and Graves (1977), the Long-whiskered Owlet (Xenoglaux loweryi) has been an enigma to Neotropical ornithologists. Before 2007, it had only been encountered twice more, and only as mist net captures. Finally, in the past decade, the species has been found with regularity in the field, allowing us to gain knowledge of its life history. Here, we provide information on the known distribution, natural history, additional specimen data, and conservation status of this enigmatic bird.
We quantified patterns of male and female parental care of the Swallow Tanager (Tersina viridis) in the activities of nest building, incubation, and feeding of nestlings during 4 reproductive seasons in Morrinhos, Goiás. The first individuals arrived in late June and the last individuals departed at the end of November, but incubation and feeding of nestlings occurred primarily in September and October, respectively. Males did not participate in incubation, but they contributed to nest building (24%) and feeding nestlings (55%; n = 8 nests). The results demonstrate biparental care and a socially monogamous breeding system for Swallow Tanager; however, low male involvement in total parental care, especially in incubation, and marked sexual dichromatism suggest the occurrence of extra-pair fertilization (EPF).
Begging by nestling passerines is an important way to communicate their state of hunger to parents. We examined whether experimentally increased nestling begging vocalizations can quickly alter parental provisioning rates in European Starlings (Sturnus vulgaris). We predicted that an increase in begging volume heard by parents during the experimental treatment would result in a significantly higher number of provisioning visits compared to the pre-playback control of natural begging levels. Total number of parental provisioning visits during 1 h control and experimental trials were compared for 23 broods of 14-day-old nestlings. Begging calls of each brood were recorded when nestlings were 13 days old; the loudest calls from each brood were made into a 3 min loop and projected continuously the next day during the experimental trial. As predicted, parents provisioned at a significantly higher rate during the experimental trials than the control trials. European starlings are sensitive to begging calls made by their offspring and respond quickly to any changes in their begging vocalizations.
We used sequences of the mitochondrial ND2 gene, the nuclear TGFB-2 intron-5, and differences in plumage pattern to assay geographic variation in the Red-bellied Woodpecker (Melanerpes carolinus). Ten population samples from throughout its range indicated that ∼23% of the mitochondrial genetic variation was distributed among populations, largely due to the occurrence of a clade of haplotypes restricted to the Florida peninsula with a local frequency of 82%. In a hierarchical analysis, 37% of the mtDNA genetic variance was distributed between the Florida peninsula and elsewhere. A strong signal of population growth was detected in the non-peninsular portion of the range. Otherwise, geographic variation in haplotype frequencies was minor, with no evidence of isolation-by-distance. Nuclear intron data showed little variation among populations (Fst = 0.007). These results suggest recent secondary contact of 2 differentiated taxa following expansion from allopatric Pleistocene refugia. We modeled the transition in haplotype frequencies along the Florida peninsula as a zone of neutral introgression; the estimated width of that zone was 435 km, and its center was near present day Ocala. Variation in plumage pattern along the peninsula previously had been used to describe a subspecific taxon, M. c. perplexus. We used variation in the forehead pattern of adult males from along the east coast of the United States to model this phenotypic transition; the zone had an estimated width of >2,500 km and an approximate center in the Florida Keys. Taken together, the geographic patterns in mtDNA and plumage variation suggest the populations of Red-bellied Woodpeckers on the Florida peninsula differentiated from those elsewhere during isolation; they are now in secondary contact in a well-known suture zone and represent 2 phylogenetic species connected by wide molecular and morphological zones of introgression.
The northward range expansion of Tufted Titmice (Baeolophus bicolor) has increased their contact with Black-capped Chickadees (Poecile atricapillus). Tufted Titmice and Black-capped Chickadees were observed foraging naturally in 3 Connecticut forests and at a residential bird feeder to assess the degree of foraging niche overlap and competition between the 2 species during winter 2015–2016. Chickadees spent significantly more time in the outer portion of the upper canopy than did titmice, which used different subsections of the canopy fairly evenly. Chickadees also foraged in shrubs significantly more than did titmice. Titmice spent much of their time foraging on the ground, which chickadees largely avoided. These differences may be explained by the ability of larger titmice to better forage on larger branches and to flip leaves to forage on the ground. The larger size of titmice may also explain their dominance to chickadees at the bird feeder. Given a choice between safflower seeds, black oil sunflower seeds with shells, and black oil sunflower seeds without shells, both species took some of each, but titmice most often chose safflower seeds while chickadees most often chose black oil sunflower seeds without shells. Although chickadees and titmice showed some overlap in their food choices and foraging locations, the significant differences we found may mitigate competition between these species, at least under the environmental conditions of this study. As titmice continue to expand their range northward, competition may be greater in areas with harsher winter conditions and less human-supplied bird seed.
Dendrocincla woodcreepers (Furnariidae: Dendrocolaptinae) are known for their foraging associations with army ants and mammals and for their emancipated males, which provide no parental care. Little is known of the natural history of the Plain-winged Woodcreeper (Dendrocincla turdina), an Atlantic Forest endemic. In Paraguay (2000–2002) and Argentina (2000–2016), we nearly always found Plain-winged Woodcreepers foraging in association with black capuchin monkeys (Sapajus nigritus), unless they were attending a nest, when they foraged alone, often by sally-gleaning. In our main study area, Parque Provincial Cruce Caballero, encounter rates of both monkeys and Plain-winged Woodcreepers increased dramatically after 2012. We found 2 nests, 1 with 2 eggs and the other with 2 nestlings, both in deep, nonexcavated tree cavities in shady forest understory. One secretive adult attended each nest; there was no evidence of a pair bond with another adult. During incubation, nest attentiveness was 62%, on-bouts were mean 35 (SE 5) min (range 3–83; n = 21) and off-bouts averaged 16 (SE 1) min (range 8–28; n = 24). The adult brought lichens and a few other nesting materials throughout the incubation period and sometimes used them to cover the eggs when it left the nest. Once the eggs hatched, nest attentiveness declined rapidly, although the adult roosted with the nestlings until they were 14 days old. Nestling diet included arthropods (especially Orthoptera, Lepidoptera, Hemiptera, and Coleoptera) and vertebrates (bat and frog) but differed between the 2 nests, suggesting opportunism. The adult brought food much more frequently around sunrise (7.93 [SE 0.69] visits/h) and sunset (8.03 [1.19] visits/h) than during the rest of the day (3.26 [0.22] visits/h). Nestling development was slower than for coexisting Dendrocolaptinae with biparental care, and the nestlings fledged when 26–27 days old. Uniparental care is unusual in forest insectivores but has arisen at least twice in Dendrocolaptinae and seems to be associated with hiding of eggs, secretive behavior, and slow nestling growth.
Both weather and parental care can influence avian reproductive success, yet few studies have investigated these 2 factors simultaneously. Examining these factors under a common framework is informative because they may interact to influence overall productivity; for example, weather could directly influence nestling survival or could act indirectly by influencing rates of provisioning. To tease apart these possibilities, we used piecewise structural equation modeling and path analysis to assess the relative influence of local weather (temperature and rainfall) and rates of provisioning on the fledging success of Mountain Bluebirds (Sialia currucoides) breeding in nest boxes. Both ambient temperature during the nestling period and provisioning rates influenced fledging success, but this finding was dependent on nest box entrance type. Bluebirds nesting in boxes with a hole-shaped entrance had higher overall fledging success than those using boxes with a slot-shaped entrance and exhibited a positive association between fledging success and provisioning rates but a negative association with temperature. Bluebirds nesting in boxes with a slot-shaped entrance experienced reduced fledging success, and success was only weakly associated with provisioning rates. Reduced fledging success for birds nesting in slot boxes may be due to increased exposure and higher susceptibility to stochastic events (e.g., storms), which may also mask any effects of parental effort on success rates. Based on these findings, we recommend the use of nest boxes with hole-shaped rather than slot-shaped entrances when managers and conservation groups establish new bluebird routes or replace existing boxes.
Geographic variation in mating signals is of interest to evolutionary biologists because the consequences of spatial divergence may lead to behavioral discrimination, assortative mating, and speciation. Birdsong is a mating signal of songbirds, and geographic variation in the form of small-scale dialects or large-scale regiolects has been documented in many species. We studied macrogeographic variation in song of the MacGillivray's Warbler (Geothlypis tolmiei) to determine the pattern of song variation in this species. Hypotheses used to explain the evolution of song divergence were also examined. We found extensive individual variation in the cultural units and physical parameters of song that overwhelmed differences among populations. We did not find dialects in the breeding range but did find a pattern of clinal variation with song differences increasing with increasing geographic distances among populations. Hypotheses that explain patterns of song divergence in other species did not apply to MacGillivray's Warblers. Selection for novel songs that facilitates individual recognition may be important in this species that breeds in extremely dense vegetation. Extensive individual variation among male tutors within and among populations may also inhibit dialect formation and perpetuate song diversity in future generations.
Selection of nest sites directly influences reproductive success for Greater Sage-Grouse (Centrocercus urophasianus); thus, regional evaluation of how this species selects nest sites is necessary for effective habitat management. We evaluated fine-scale nest site selection of Greater Sage-Grouse in the Centennial Valley of southwest Montana. We conducted vegetation surveys at nest sites (n = 90) of radio-tagged Greater Sage-Grouse and paired random locations across 2 breeding seasons (2014–2015). The majority of nests were located under mountain big sagebrush (Artemisia tridentata ssp. vaseyana), three-tip sagebrush (A. tripartita), and basin big sagebrush (A. tridentata ssp. tridentata) shrubs. We used generalized linear models and information theory to evaluate competing hypotheses about nest site selection. Our top model indicated that nest site selection was primarily associated with nest shrub morphological characteristics and cover provided by the nest shrub. Mountain big sagebrush and three-tip sagebrush provided twice the amount of lateral cover that basin big sagebrush shrubs provided. Our results suggest that herbaceous cover was unimportant at fine scale nest site selection of Greater Sage-Grouse in our study area. Managers should focus on conserving large intact stands of mountain big sagebrush and three-tip sagebrush habitats because they provided the most lateral cover and supported the majority of nest sites.
The Upland Goose (Chloephaga picta) is a ground-nesting bird that has suffered a precipitous population decline in the last 60 years. We monitored Upland Goose nests with camera traps in Santa Cruz province, Argentina, to study nest disturbances that could reduce reproductive success. We studied female behavior following nest disturbance by predators, livestock, or humans and compared it with situations when females leaving the nests voluntarily. At least 34% of nests were depredated, 92% of them by culpeo (Pseudalopex culpaeus) and gray (Pseudalopex griseus) foxes; only 29% of the monitored nests were successful. Livestock sniffled, licked, and nuzzled the incubating female and the nest contents, and 2 nests were trampled. Off-bout duration was affected by the identity of the intruder. The lengths of predator and human off-bouts were similar and higher than those of foraging and livestock off-bouts. To boost reproductive success, we recommend livestock exclusions and predator control on nesting areas to discourage fox predation. Nests monitoring protocols should include as few and widely spaced visits as possible, restricted to a few people. Given the ecological similarities between the Upland Goose and congeners, including the critically endangered Ruddy-headed Goose (Chloephaga rubidiceps), we extend these recommendations to all Chloephaga spp. breeding areas.
This is the first empirical ecological study on the critically endangered Yellow-crested Cockatoo (Cacatua sulphurea) in a nonnative urban habitat of Hong Kong, southern China. The exotic Hong Kong population creates a conservation paradox in which efforts toward protecting the endangered species would conflict with the preservation of recipient communities and habitats. The diet and feeding ecology of Yellow-crested Cockatoo were investigated to better understand the interaction between the exotic population and its inhabiting urban environment. The results indicated that the cockatoos mainly exploited 11 plant species and 4 food types, most of which were exotic plant species. They had a moderate Levin's niche breadth of 0.41, suggesting that the birds were generalist feeders with flexible diet in a nonnative urban environment. They preferred to feed solitary or in small flocks, consistent with the low conspecific attraction rate in feeding. Conspecific attraction might increase the foraging efficiency of Yellow-crested Cockatoo. Cotton tree (Bombax ceiba) was ecologically significant to Yellow-crested Cockatoo; it not only provided the birds with different food types throughout the year, but also served as the major venue for take-away food. Our findings will help bridge the knowledge gap in the feeding ecology of urban exotic parrots and provide valuable information on how to manage or conserve the endangered alien species.
Charles R. Brown, Mary Bomberger Brown, Stacey L. Hannebaum, Patricia K. Hosack, Abigail J. Kucera, Catherine E. Page, Stephanie A. Strickler, Gigi S. Wagnon
Extreme climatic events can often lead to intense selection and serve as catalysts for rapid evolutionary change. Cold and rainy weather during a 6-day period in spring 1996 led to massive mortality of Cliff Swallows (Petrochelidon pyrrhonota) in western Nebraska and selected for birds with shorter wings and tails, larger skeletal traits, lower levels of fluctuating asymmetry, and less phenotypic variance in all traits. Here we investigate whether the same patterns of selection occurred during 2 subsequent cold and rainy weather events in this population in 2004 and 2017. Directional selection on morphological traits in 2004 was generally the same as in 1996, but in 2017 selection on tarsus length and outer tail feather length was in the opposite direction. As in 1996, selection during both events reduced phenotypic variance in most traits. The results illustrate the potential for extreme weather events to act as drivers for fluctuating directional selection on morphological traits and for periodically removing phenotypic outliers.
We studied genetic similarity between adults and nestlings in putative social families (i.e., 2 adults and a chick) of a seabird that provides obligate biparental care, the Australasian Gannet (Morus serrator), in New Zealand. We detected DNA fingerprint mismatches in 12% of 26 nests between the chick and 1 of the 2 attending adults sampled. No parent–offspring genetic mismatch was detected in nests with 4-week-old or younger and sedentary nestlings, whereas adult–nestling mismatches were detected only in nests with 5-week or older and more mobile young sampled. We conclude that the genetic mating system of this sulid species is predominantly monogamous.
Motion-activated cameras captured images of 2 Keel-billed Toucans (Ramphastos sulfuratus) on and near the ground in two 900 m2 experimental forest restoration plots located in the Los Tuxtlas Biosphere Reserve, Veracruz, Mexico, during July 2015. Toucans have been known to forage widely for fruit in fragmented landscapes. Our cameras indicated that they additionally foraged on and near the ground for insects or other animal prey in relatively predator-free forest patches. As key agents of dispersal of large-seeded old-growth trees, toucans and other large frugivores were likely responsible for recruitment of animal-dispersed tree species of mature forest in our experimental plantings, even in stands of wind-dispersed trees or controls where animal-dispersed tree species were not planted.
Nest reuse is a relatively uncommon practice among passerines, particularly among multiple species. In June 2016 we documented a Sage Thrasher (Oreoscoptes montanus) nest in the Upper Green River Basin, Wyoming, being reused by a Loggerhead Shrike (Lanius ludovicianus) pair within the same season. The shrikes made structural changes to the nest, including removing nearly all sticks supporting the nest's exterior. The repurposing of an open-cup nest by a Loggerhead Shrike within the same breeding season has never been documented, and interspecific nest reuse by passerines in general is rare. The pervasiveness of this behavior, however, is poorly understood because instances are likely underreported.
We first observed Sora (Porzana carolina) swimming and diving under water while capturing them with hand nets at night. Since that time, we have observed the behavior several times and documented it with photos and video. Rails are among the most elusive birds. Despite living in wetlands, water depth has often been discussed as a factor limiting habitat use by rails, with the assumption that when water levels are too deep, rails walk on top of floating or emergent vegetation. Here we present new photo and video evidence that confirms previous observations that Sora are adept at swimming and diving in deep water wetland environments, which should alter how we think about their ability to avoid predators and use deeper water habitats.
Barred Owls (Strix varia) are generalist predators that take a variety of birds, small mammals, herps, fish, crustaceans, insects, gastropods, and other invertebrates as prey. Here we document 2 different Barred Owl individuals that ingested rough-skinned newts (Taricha granulosa) as prey in northern California. Few vertebrate predators are known to feed on newts of the genus Taricha because they carry a potent defensive neurotoxin (tetrodotoxin) lethal to most vertebrate predators. Our examples suggest that Barred Owls may prey on newts in some areas and that consuming newts is not always lethal to Barred Owls.
Behavior of young birds can have important consequences for population dynamics. We investigated the autumnal post-fledging movements of 3 White-tailed Sea Eagles (Haliaeetus albicilla) hatched in Kazakhstan. All 3 eagles traveled south, flying on average 25–108 km/d. Movement was nonrandom, with eagles generally traveling near mosaics of forest, open areas, and water, and rarely using areas with little vegetation. As the first study of movements of White-tailed Sea Eagles in arid Central Asia, this study provides insight into potential limiting factors and how these birds interact with their environment during long-distance movements.
The Greater Roadrunner (Geococcyx californianus) is a medium-sized predatory bird that occurs widely across the southwestern United States. Despite its prevalence in this region, studies examining the nesting and behavioral ecology of this species are limited. In 2015 and 2016, we examined relatively unknown aspects of roadrunner natural history by using infrared video cameras to observe antipredator behaviors associated with Greater Roadrunner nest defense. Nest predation accounted for all nesting failures in our study. The Great Plains rat snake (Pantherophis emoryi) accounted for 70.0% of nest predation. We observed rat snakes entering the nest and consuming eggs or nestlings for >6 min before roadrunners flushed from nest sites. We also observed 53.3% of roadrunners actively defending nest sites from snake predators and zero defending nests from coyotes (Canis latrans), likely because of the predator size. Active defense sessions in our study lasted 1 min 20 s (95% CI 1 min 17 s) and consisted of 12.0 (95% CI 3.4) bill strikes per min of active defense. We observed no successful nest defenses because partial nest contents were lost during each event; however, >50% of predation events with an active defense session resulted in preservation of at least one viable egg or chick, indicating nest defense was a valuable behavior. Examining nest defense behaviors in larger, predatory birds may elucidate risks and rewards associated with nest defense that may not be observed in studies focusing primarily on passerines.
Eciton burchellii is a Neotropical army ant that influences the ecology of many associated animal species, including their prey and species that attend the ant's foraging raids. At least 29 bird species are obligate specialists on foraging at army ant raid fronts, and additional species across diverse avian orders follow army ant raids in a facultative manner. These facultative ant-following birds include species of raptors in Accipitriformes, Strigiformes, and Falconiformes. The most frequently documented raptors that follow raids are forest-falcons in the genus Micrastur. Micrastur falcons add a unique type of predation to raids, catching larger arthropod species that would otherwise likely escape the ants, and also prey on small fleeing vertebrates, such as lizards and other ant-following bird species. Here we present an observation of a Collared Forest-falcon (Micrastur semitorquatus) attending an E. b. parvispinum raid and flying toward a Ruddy Woodcreeper (Dendrocincla homochroa) at the raid front, as well as capturing a fleeing snake from the raid front. To our knowledge, this is the first report of a snake falling prey to a raptor at an army ant raid front.
By many metrics hummingbirds are excellent fliers, but few species are known to undertake long flights over open water. Here we report 33 sightings of Green-backed Firecrowns (Sephanoides sephaniodes) crossing the Corcovado Gulf in Chilean Patagonia. Sightings ranged between 1.2 and 12.6 km from shore and occurred in a variety of weather conditions. The high frequency of offshore encounters suggests that either the Green-backed Firecrown performs a seasonal migration between Patagonian islands and fjords or a high level of connectivity exists between geographically separated metapopulations.
The Bumblebee Hummingbird (Atthis heloisa) is an endemic bird to Mexico. Its natural history is poorly known, particularly its breeding biology. We provide novel and complementary information that enriches the biological knowledge on the species. We describe a nest of the Bumblebee Hummingbird found in Northern Oaxaca and characterize the nest site. The nest was mainly assembled with mosses and lichens; however, we recorded females transporting hairs of the invasive fern Pteridium sp. and seeds of the bromeliad Catopsis sp. for nest construction. Males were noisy and conspicuous while females were secretive; thus, we suggest considering differences in detectability among sexes when studying the species. Males exhibited courtship displays that consisted of several vertical movements over females while adopting a horizontal posture, erecting the tail, emitting a bee-like sound, and fanning out the feathers of the throat toward the females. The Bumblebee Hummingbird is considered a sedentary species, but we suspect it performs altitudinal movements in search of cloud forests during spring and summer and humid pine-oak forests during winter and autumn. Although the literature indicates that this hummingbird reaches breeding conditions between April and July, we recorded intense breeding activity only during January and February. It is not clear if such variation is regional or if the species could breed multiple times during the year.
The Upland Sandpiper (Bartramia longicauda) is a migratory shorebird with main wintering areas in Argentina and Uruguay. The migration route from the wintering to the breeding areas has been described as passing through the Amazon basin, but some records suggested that the western slope of the Andes is part of the regular route. To assess if this area is regularly used by the species, we encouraged volunteers to be part of a Citizen Science project in Chile to conduct listening points at night, allowing us to gather records from extensive areas. In 2 years, we collected 80 records of Upland Sandpiper from Arica to La Serena, confirming that northern Chile is part of the regular route. This migration strategy might be a result of the current winds, which blow from east to west in March and April on the South American continent and from south to north following the Pacific coast. These results change our understanding of the Upland Sandpiper migration through South America, adding a new, important area where the species must be considered for energetic project assessments.
Although they eat seeds, pulp, petals, pollen, and nectar, parrots are rarely recorded as eating leaves, with only one species being fully folivorous. In terra firme forest in south-central Brazilian Amazonia, we recorded apparent folivory over a several sequential days by the Blue-headed Parrot (Pionus menstruus) on young leaflets of Swartzia polyphylla (Fabaceae). Closer examination, however, showed that the majority of processed leaves also contained small caterpillars, so that we consider this to be a record of highly selective insectivory, which is also uncommonly reported in parrots. We speculate that such events may be more common than realized and act as dietary supplements for a seed-based diet.
The Snail Kite (Rostrhamus sociabilis) is a raptor of conservation interest. Here we report on 15 nests of the species in a wetland in Cuba. Nest detection was conducted using 150 observation points. The number of eggs/chicks, height of the nest, and diameter of the tree at breast height were recorded. The closest distance to roads and towns was measured. Nests were located over a period of 7 months. Of the nests found, 67% contained eggs and/or chicks; 40% contained only eggs, 33% contained only chicks, and 20% contained both. Nests were built on shrubs in inland lagoons. The minimum distance between nests and nearest roads was 0.7 km and from the nearest village was 1.3 km. These results can be used as a tool for the management and conservation of the population in the wetland.
Relatively little is known about the longevity of free-living landbirds, especially in the tropics. We used mark-recapture data for birds originally banded in 2005 and 2006, and later recaptured between 2011 and 2016, to estimate minimum longevity for 20 species from southeastern Peru. The oldest recorded longevity was 10 years, 6 months for a Black-billed Treehunter (Thripadectes melanorhynchus). Another notable record was for a Russet-crowned Warbler (Myiothlypis coronata; 9 years, 2 months). Our estimated minimum longevity records generally reflect the findings of other researchers, indicating that tropical birds are often markedly site faithful and long-lived.
The “capuchinos” form a monophyletic group within the Neotropical seedeaters of the genus Sporophila and are typically smaller than the other congeners. Many of the 12 species of this group are endangered, but reproductive information is scarce for most of them. Here we present the descriptions of nests, eggs, nestlings, and nesting habitats for the Pearly-bellied Seedeater (Sporophila pileata). From 2012 to 2017 we found 83 nests constructed in herbaceous plants present in open marshlands, 15–73 cm above water or humid ground. Nests were deep cups built of grass stems, inflorescences, and rootlets, attached with spider web. Nests measured 59.3 ± 4.7 mm outside diameter, 50.7 ± 6.5 mm outside height, 41.6 ± 3.2 mm internal diameter, and 35.7 ± 3.3 mm internal depth. Eggs were oval with white, grayish, or greenish background color with black and brown spots mainly in the obtuse pole. They weighed 1.2 ± 0.1 g and measured 16.3 ± 0.8 per 12.2 ± 0.3 mm. Clutches consisted of 1–3 eggs. Our study sites represent the northernmost reproductive areas ever documented for a migratory capuchino.
One of the least known aspects of the biology of diurnal birds is their nocturnal behavior, which limits our knowledge on their circadian cycles and total home ranges. We studied the nocturnal behavior of the Pale-breasted Thrush (Turdus leucomelas) in a suburban area in Brazil to investigate the relationship between the night roost and diurnal home range (DHR). Birds returned every night to the same roosts in tall trees with dense canopy. In contrast to their nesting habits, birds did not use buildings as nocturnal roosts. In 4 of 9 cases, night roosts were completely outside the DHR. When they were inside the DHR, night roosts were not close to the core area of the DHR. Our results, together with data for a few other bird species, show that considering nocturnal roosting behavior is essential for a more accurate estimate of home ranges of diurnal birds.
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