The Kona Grosbeak (Chloridops kona), last seen in 1892, was restricted to a small mid-elevation area on the leeward (Kona) side of the island of Hawaii. It was reported to feed almost exclusively on the fruits of the naio tree (Myoporum sandwicense), which are extremely hard, requiring a force of perhaps 400 newtons or more to open. The morphology of the skull and mandible of the Kona Grosbeak was accordingly much more modified for the hypertrophied adductor musculature needed to crack naio fruits than its closest relative, the Wahi Grosbeak (Chloridops wahi), which has been found as fossils on most of the other main Hawaiian islands. The Wahi Grosbeak is here hypothesized to have fed on less resistant seeds, such as those of the Hawaiian prickly-ash (Zanthoxylum spp.). Naio is widely distributed in diverse habitats in the Hawaiian Islands but its fruits were apparently an energetically viable food source only on relatively young (ca. 1200 year old) aa lava flows on the dry side of Hawaii, where the plants produce abundant flowers and fruit on a year-round basis. The Kona Grosbeak therefore appears to have evolved in less than the ca. 400,000 years since Mauna Loa became high enough to create a rain shadow and develop younger aa flows and associated vegetation.

Research on sexually selected male traits has intensified over the last two decades and there are now many species of birds for which male traits associated with extra-pair mating success have been identified. Some of the more commonly studied species have been examined in multiple populations; however, there is often little consistency in results between studies. In paired analyses of Tree Swallows breeding in Wisconsin, we found that successful extra-pair sires were more experienced breeders, heavier, had fewer lice holes in their feathers, had longer wings and tended to be in better condition than the male they cuckolded. Our results are similar to those from a population of Tree Swallows studied in Ontario but differ from a population studied in British Columbia. Such variation among populations may arise if environmental heterogeneity influences the information content, reliability, or importance of particular male traits as signals of male quality. Taking these factors into consideration will help us understand how selection on male traits varies between populations and the role of extra-pair mating in sexual selection.

Millions of birds die each year during migration. Most of this mortality goes unobserved and conditions surrounding the actual events are often not thoroughly documented. We present a case study of substantial migrant casualties along the shores of southwestern Lake Michigan during May 1996 when we found 2,981 dead birds of 114 species, mostly migrant passerines. An unusual sequence of events allowed us to document the circumstances surrounding this migratory bird kill. Bird carcasses appeared on the southwestern shores of Lake Michigan in the days following storm systems that produced high rain and in one case, hail. Encounters between birds and precipitation over open water were recorded by weather radar, and were followed by winds that drifted dead birds toward highly populated shorelines where the kill was observed and documented. Climatologically, May 1996 was exceptional for producing weather conditions that both killed birds en masse and allowed the mortality to be documented. As a result, this is one of the more thoroughly documented instances of a weather-related mass mortality event during migration.

Call-broadcast surveys are frequently used to elicit responses of secretive marsh birds and produce greater detection rates than passive surveys. However, little is known about how detection rates of birds from these surveys differ by season and time of day. We conducted call-broadcast surveys for eight focal species at 56 wetlands throughout Iowa from 15 May–13 June 2010 (early season) and from 15 June–10 July 2010 (late season). Our focal species were Pied-billed Grebe (Podilymbus podiceps), American Bittern (Botaurus lentiginosus), Least Bittern (Ixobrychus exilis), King Rail (Rallus elegans), Virginia Rail (Rallus limicola), Sora (Porzana carolina), Common Gallinule (Gallinula chloropus), and American Coot (Fulica americana). Surveys were conducted in the early morning (30 mins before sunrise to 3 hrs after sunrise) and late evening (3 hrs before sunset to 30 mins after sunset) in accordance with the North American Marsh Bird Monitoring Protocol. We evaluated marsh bird detection rates as a function of a) time of day (morning and evening survey periods), b) season (early and late in the breeding season), and c) wetland size for four species with the greatest detection rates (Pied-billed Grebe, Least Bittern, Virginia Rail, and Sora). We also evaluated the above effects for two species groups; all eight species pooled and all rails pooled. We found significant (P < 0.05) effects on the number of detections for Pied-billed Grebe in response to time of day, time of season, and wetland size; Sora, Virginia Rail, all rails, and all species had an effect of time of season only. Understanding seasonal and time-of-day differences in detection rates, as well as area dependence of secretive marsh birds, will refine existing monitoring protocols by allowing researchers to maximize detection probabilities of target species.

Recent advances in radio-transmitter technology have produced sub-gram transmitters which allow small birds to be radio-tracked so that researchers can ascertain information on species movement and behavior to inform conservation and management plans. However, the ability to study some species remains limited by practical problems with transmitter attachment. As a result, improvements in design may be hindered by underreporting of retention rates and attachment issues. We monitored retention rates for glue-attached radio-transmitters on two bird species in southern Ontario with different life histories. Mean retention time for Chimney Swifts (Chaetura pelagica) was ≥25.1 days (± 12.8 SD, n  =  12, May–Aug 2010 and 2011), while for Bobolinks (Dolichonyx oryzivorus) we estimated mean retention time at under 24 hrs (n  =  15, May–Jul 2011). We discuss potential reasons for this disparity and suggest improvements to transmitters and attachment methods for short-term use on small birds where tag retention and damage may be problematic, as Bobolinks were capable of removing transmitters and breaking antennas which, in some cases, rendered the devices inoperative. We collated retention estimates from published studies that marked birds with glue-attached radio-transmitters; these studies used a wide range of methods with varying success on different species, however, few studies specifically examined the effects of alterations in glue attachment methods on retention. We encourage researchers to report retention rates to improve the use of resources in other studies and enable advancements that will augment the potential of existing radiotelemetry technology.

Mexican Spotted Owls (Strix occidentalis lucida) are common in older forests within their range but also persist in many areas burned by wildfire and may selectively forage in these areas. One hypothesis explaining this pattern postulates that prey abundance increases in burned areas following wildfire. We observed movement to wintering areas within areas burned by wildfire by four radio-marked Mexican Spotted Owls in the Sacramento Mountains, New Mexico. These movements occurred during the winters of 2004–2005 and 2005–2006, with some owls migrating in both winters and others in only one. Wintering areas of these owls occurred within the perimeters of two wildfires that burned in May 2000 and April 2002, respectively. We estimated relative prey abundance and biomass during December 2006 within paired burned wintering areas and nest core areas used by these owls. Species richness and relative abundance of small mammals were greater in the burned wintering areas than in the associated nest core areas for all four owls, and estimated prey biomass ranged from 2–6 times greater in burned wintering areas relative to the paired nest core areas. Burned wintering areas used by these owls were similar in elevation to their nest core areas, and likely experienced similar weather conditions during winter. These results suggest that wintering owls moved to areas with greater food resources, rather than to areas with milder weather. They further suggest that relative prey abundance was greater in burned wintering areas than in the nest core areas >5 years post-fire, and that these burned wintering areas provided important habitat for Mexican Spotted Owls in our study area during an energetically stressful season.

We studied a small isolated population of Mexican Spotted Owls (Strix occidentalis lucida) from 1996–1997 in the Rincon Mountains of Saguaro National Park, southeastern Arizona, USA. All mixed-conifer and pine-oak forest patches in the park were surveyed for Spotted Owls, and we located, captured, and radio-tagged 10 adult birds representing five mated pairs. Using radio-telemetry, we examined owl home range characteristics, roost habitat, and monitored reproduction within these five territories. Breeding season (Mar–Sep) home range size for 10 adult owls (95% adaptive kernel isopleths) averaged 267 ha (±207 SD), and varied widely among owls (range 34–652 ha). Mean home range size for owl pairs was 478 ha (±417 ha SD), and ranged from 70–1,160 ha. Owls that produced young used smaller home ranges than owls that had no young. Six habitat variables differed significantly between roost and random sites, including: percent canopy cover, number of trees, number of vegetation layers, average height of trees, average diameter of trees, and tree basal area. Radio-marked owls remained in their territories following small prescribed management fires within those territories, exhibiting no proximate effects to the presence of prescribed fire.

In California, oak woodlands are being converted into vineyards, resulting in a loss of songbird nesting sites. Although many vineyards contain wooded riparian habitat, no previous research has examined the avian species composition in oak-vineyard landscapes. We compared the avian communities associated with vineyard, edge, and riparian habitats and examined to what degree the riparian habitat in vineyard landscapes continues to support birds associated with native oak woodland habitat that spanned the region before agricultural intensification. We further tested whether the presence of nest boxes in vineyard and riparian areas altered avian species composition in the landscape. Mist nets were used to survey the avian community in vineyard, edge, and riparian habitat at four sites during the breeding season. Permutational ANOVAs, using presence-absence data from captures, identified habitat, study sites, and time over the breeding season as highly significant main effects that explained differences in species composition. Establishment of songbird nest boxes did not alter the species composition. Two-thirds of the birds identified as woodland species in prior studies were found in riparian areas adjacent to vineyards, including five watch-list species. Overall the species composition of birds using riparian habitat was greater and significantly different from those found in the vineyard. This highlights the importance of maintaining natural areas like riparian habitat in agricultural landscapes.

Urban habitat has become more and more important for birds because of rapid urban development and reduction of natural areas, and the responses of birds to season in urban habitats is important to research in urban avian ecology. We examined whether bird communities varied with season in terms of community attributes, composition of species and species groups, and nestedness in highly urbanized Hong Kong, which is positioned on one of the main migratory routes, and thus has great conservation value for birds. We studied 30 urban parks, and had 3,815 observations of 31 species in the breeding season (May–Aug 2010), compared to 3,972 observations of 53 species in the nonbreeding season (Nov 2010–Feb 2011). Eurasian Tree Sparrows (Passer montanus), Red-whiskered Bulbuls (Pycnonotus jocosus), and Japanese White-eyes (Zosterops japonicus) were the most abundant species in both seasons. Bird species richness and diversity in the nonbreeding season were significantly higher than in the breeding season. Migrants accounted for 5.0% of total abundance and 28.3% of richness in the nonbreeding season. Compared to the breeding communities, the avian communities included more insectivores (4.2%), insectivore-frugivores (4.8%) and herbivores (10.5%), but fewer granivores (8.4%) and species that feed on the ground (10.7%) appeared in the nonbreeding season. Moreover, multi-response permutation procedures analyses showed the composition of species and species groups differed significantly between the two seasons. Bird communities were highly nested in Hong Kong, but the degree of nestedness was close for the two seasons. We found there are obvious seasonal patterns in the bird community of Hong Kong, and an understanding of this can provide basic, essential information that park managers can employ to conserve a more diverse ecosystem in Hong Kong and even in other cities.

Scytalopus, the largest genus of tapaculos (Family: Rhinocryptidae) typically build mossy globular nests within bank or tree cavities. Only 23 of the 40 recognized species' nests have been described, and of these only one has incubation patterns described. We provide the first description of the nest architecture, eggs, incubation behavior, and nestlings of the Trilling Tapaculo (Scytalopus parvirostris). The globular nest was mostly built of dark rootlets, and was lined with fern scales, hyphae, and feathers placed within the cavity of a rotting tree 1.5 m off the ground. The nest contained two white eggs. Nest attentiveness averaged 91 ± 0.5% per day, with an average of 12.6 ± 0.3 trips per day. Incubation bouts on the nest averaged 54.6 ± 2.9 mins and foraging trips averaged 8.8 ± 0.7 mins. Combined daily nestling growth rates averaged 18 ± 2% weight, 9 ± 2% tarsus, and 16 ± 3% wing (n  =  4 days).

Egg mass production is costly, but hatching from heavier eggs could be beneficial for the nestling's phenotype and fitness. Egg mass could be influenced by proximate causes, like food abundance, female condition, environmental conditions, and/or by ultimate causes, such as females depositing resources differentially within a clutch to increase the biological fitness of some eggs. Yolk mass, although poorly studied, is the source of nutrients for the embryo, so its mass should be more influential for the nestlings than total egg mass. We used a technique that allowed us to measure yolk size without destroying the eggs. We studied yolk mass in 212 eggs of White-rumped Swallows (Tachycineta leucorrhoa) and found that yolk mass was influenced by laying order, with last laid eggs having heavier yolks than first laid eggs, and the pattern was consistent with egg mass variation. Food abundance also affected yolk mass: when insect availability was high the yolks were heavier. We conclude that embryos in the last laid eggs have more resources from which to develop, and excluding food abundance, neither environmental conditions nor female's condition affected yolk mass. We encourage other researchers to study yolk mass given that multiple variables affected total egg mass.

Forest edges are often associated with a high risk of brood parasitism by Brown-headed Cowbirds (Molothrus ater), but the extent to which this vulnerability changes across the breeding season is poorly understood. We evaluated temporal variability in the relationship between distance to habitat edges and risk of brood parasitism. From 2008–2010, we monitored parasitism of 347 nests of Northern Cardinals (Cardinalis cardinalis) at 19 forested sites within the urbanizing landscapes of central Ohio. For each nest, we measured distance to the nearest edge (e.g., road, residential area, mowed field, agriculture, and natural area) and recorded when clutches were initiated. We found that risk of parasitism associated with edges varied with time of season. Early in the breeding season, risk of parasitism declined with increasing distance from edges. However, late in the breeding season, nests farther from edges had higher rates of parasitism. These patterns suggest that early in the season, cowbirds search for forest nests along residential and agricultural edges, whereas later in the season, cowbirds search the interior. Our results show that managers should consider temporal factors in generalizing about the risk that edges pose to nests.

The cleaning of display courts is used by several forest lekking birds to possibly serve as an anti-predation strategy against terrestrial predators. Using a pit viper replica in the leaf litter 10–20 cm from the court (camouflaged predator) and in the central cleared area of the court (non-camouflaged predator) of the White-bearded Manakin Manacus manacus we tested experimentally the anti-predation hypothesis. We also described the phenology of court cleaning by lekking males, and tested the relationship between court cleaning and the frequencies of display bouts by males, visits to courts by females, and the amount of debris falling on courts. Results showed that court cleaning had a defensive role against terrestrial predators, optimizing the time of detection of potential terrestrial predators in the cleared courts. Court cleaning was positively correlated with court visits by females, which may be related to the improvement of a male's plumage conspicuousness by enhancing the plumage contrast against the cleared court, as already demonstrated for M. vitellinus. If this is the case, then court cleaning may serve a dual role, as an anti-predation strategy and to enhance sexual exhibition by lekking males.

We studied the nestling diet of two reedbed specialist passerines, Reed Parrotbill (Paradoxornis heudei) and Oriental Reed Warbler (Acrocephalus orientalis) in a tidal reedbed in the Changjiang River Estuary, China. Reed Parrotbills delivered mainly Homoptera, Diptera, and Leptidoptera to their nestlings, and Oriental Reed Warblers delivered mainly Diptera, Hymenoptera, Araneida, and Lepidoptera to their nestlings. More than 98% of the diet of nestling Reed Parrotbills consisted of wingless items and >97% consisted of concealed items, indicating that Reed Parrotbills are limited in their ability to catch winged prey capable of strong flight and rather they retrieve prey from within reed shoots using their large and strong beaks. About 85% of the diet of nestling Oriental Reed Warblers consisted of winged items and >99% consisted of exposed items, indicating that Oriental Reed Warblers are limited in their ability to retrieve prey from within reed shoots and depend on their flight ability to catch prey capable of flight. Oriental Reed Warblers had significantly more taxonomic categories of prey in their diet, significantly wider diet niche, and significantly higher diversity in nestling diet than Reed Parrotbills. Our study demonstrates that although these two species breed sympatrically in reedbeds as reedbed specialist, Reed Parrotbills and Oriental Reed Warblers use different strategies in their exploitation of food resources.

The last, self-sustaining population of Whooping Cranes (Grus americana), the Aransas-Wood Buffalo population, has overwintered almost exclusively along the Gulf Coast of Texas, USA, in and around the Aransas National Wildlife Refuge during recent decades. In late autumn and winter 2011–2012, Whooping Cranes were observed several hundred kilometers from coastal wintering grounds, with at least 13 Whooping Cranes in central Texas, south-central Kansas, and central Nebraska from November 2011 to early March 2012. Notably, family groups of Whooping Cranes were observed around a Texas reservoir, Granger Lake, over a 3-month period. An extreme drought, coupled with record warm temperatures in the southern and central United States, may have interacted to influence behaviors and distributions of Whooping Cranes during winter 2011–2012. Such observations suggest that Whooping Cranes may be more opportunistic in use of wintering habitat and/or more likely to re-colonize inland historical sites than previously thought. Continued documentation of Whooping Cranes overwintering in areas other than the Texas coast and/or altering timing of migration will be important for protection and management of additional winter habitat as well as for informing population estimates for the Aransas-Wood Buffalo Population of Whooping Cranes.

Several authors have suggested that male Calliope Hummingbirds (Selasphorus calliope) perform their dive and shuttle displays on “dispersed leks” where the dramatic aerial displays of several individuals can be seen or heard from a single location. To expand on the limited information available on breeding territorial behavior, I provide detailed time budget data from 3 years of observation of males in a 20-year-old seed-tree cut in Montana. Males spent the vast majority of their time (76%, on average) perched on dead willow branches that extended upward to 4–5 m in height, and an average of 90% of perch time was spent at no more than three perch sites. Most of the rest of the males' time (15%, on average) was spent off territory, where they conducted a good portion of their feeding. About 6% of a male's time was spent performing energetically demanding dive and shuttle displays, which were directed primarily toward females, but also toward other bird species perched within the male's territory. Displays directed toward females were sometimes followed by copulation while she was perched. This is only the second geographic location where male Calliope Hummingbirds are reported to have congregated in what appears to be a dispersed lek. We still know little about how common the clustering of breeding territories is, whether such clustering is limited to early successional habitat, and whether relatively few males obtain most of the copulations in such clusters, as would be expected in a classic lek breeding system.

Despite being widespread and abundant, little is known about the breeding ecology and natural history of the Eastern Wood-Pewee (Contopus virens), in part because nests are often high in the canopy, difficult to view, and adults are monomorphic. We monitored nests of Eastern Wood-Pewees and recorded the feeding rate of nestlings by adults as part of a larger study on breeding demography of Eastern Wood-Pewees across a gradient of savanna, woodland, and forest in the Missouri Ozarks in 2010–2011. We monitored 287 nests between 26 May and 22 August and conducted feeding rate observations for 54 nests with nestlings. There was an 88-day nesting season with peaks of nest activity on 24 June and 22 July. We recorded 19 cases of double brooding and nine cases of within-season nest reuse. Seasonal fecundity was 2.2 fledglings per territory. The frequency of parental feeding visits increased with nestling age. These are additional observations of nest reuse, nesting cycle lengths, and breeding season length for Eastern Wood-Pewees; future demographical research of marked individuals will continue to fill in gaps in breeding ecology for this common and widespread flycatcher.

New Caledonian Crows (Corvus moneduloides) manufacture the most complex foraging tools used by nonhuman animals. Not only do they shape multiple tool designs of different complexity out of raw material using distinct, design-specific manufacture techniques, they are the only species to incorporate hook technology. The three different hook tool designs that they cut out of barbed Pandanus spp. leaves are suggested to have evolved by a process of diversification through cumulative changes rather than independent invention. Here, I describe three examples of an oversized version of the so-called ‘narrow’ pandanus tool design in an area where narrow tools are also made. My observation of the way a crow used one of these oversized tools in the wild suggests that they may be efficient for foraging in especially deep probe sites. The co-occurrence of two different designs originating from a very similar manufacture technique is consistent with diversification. Furthermore, qualitative data suggest that shape variation in the three previously described pandanus tool designs might be associated with ecological function. These findings strengthen the possibility that pandanus tool designs are an example of rudimentary diversification developed in close association with functional requirements.

The study investigated behaviors of Least Grebes Tachybaptus dominicus during the breeding season. Agonistic postures and interactions and courtship rituals already mentioned by other authors are described in more detail and new pair bonding displays detected, especially Parading in Z posture and the Diving ceremony, are added to our knowledge of the species. The results are discussed in relation to the prevalent phylogenetic hypothesis for the grebe family.

Several hypotheses have been proposed to explain infanticide in animals, but the behavior has only been observed in a few bird species. I describe video evidence of infanticide by a female Red-winged Blackbird (Agelaius phoeniceus) at a nest in Valley Forge National Historical Park in Pennsylvania. A female Red-winged Blackbird was seen pecking and pulling at the sole remaining 5-day-old nestling and eventually pulled the nestling from the nest until it fell to the ground. A female Red-winged Blackbird later returned to the nest with food 1 hour after the infanticide and made several visits with food in its bill. The last visit to the empty nest occurred 7 hours after the infanticide occurred. There were not sufficient plumage differences between the feeding and attacking bird to determine conclusively that they were different birds. The occurrence of infanticide could be explained by several hypotheses and might be more common in Red-winged Blackbirds than has been reported. For example, infanticide in Red-winged Blackbirds could increase male parental investment as is seen in other polygynous species. Misplaced aggressive behavior under stressful conditions; however, is also a possible explanation for this single case of infanticide.

We conducted field work during May–July 2005 in the Mexican states of Nuevo León, Tamaulipas and San Luis Potosí. We observed breeding activity of Black-capped Vireos and found active nests in northwestern Nuevo León and southwestern Tamaulipas. These findings represent the first documented nests for those states, and for the latter state, the first records of Black-capped Vireos nesting below the Tropic of Cancer. Our findings suggest that the breeding range of Black-capped Vireos should be extended approximately 520 km to the southeast of the previous known nesting area near Ocampo, Coahuila.

Breeding within a seabird colony can have positive and negative effects for smaller passerine species. For example, they may profit from the anti-predator behavior of the seabirds as well as from the influx of food and nutrients brought into the community. However, these possible benefits might be offset by seabird predation. For instance, gulls are not only fierce defenders of their colony, but also opportunistic feeders. Here, we report predation of Glaucous-winged Gulls (Larus glaucescens) on Sooty Fox Sparrows (Passerella iliaca fuliginosa), Song Sparrows (Melospiza melodia), and a European Starling (Sturnus vulgaris), observed on Mandarte Island, British Columbia, Canada. These observations provide new evidence for dietary supplements of Glaucous-winged Gulls and for a disadvantage of passerine life in a Glaucous-winged Gull colony.

We directly recorded predation of Black-legged Kittiwake chicks (Rissa tridactyla) by a Peregrine Falcon (Falco peregrinus) using a remote time-lapse camera. Between 20 July 2013 and 23 July 2013, all four nests in the camera's field of view failed. A peregrine was recorded depredating chicks in two of these four nests. Periods of adult desertion at the other two nests strongly suggests chicks in these nests were depredated as well. Predation happened at night, a rarely documented behavior of the peregrine. Along with giving insights into peregrine hunting behavior, the use of remote cameras allows us to determine nest fate. Determining sources of chick mortality is invaluable for identifying causes of variability in productivity rates of colonial breeding birds.

Predation at the nest is the largest source of reproductive failure for many species of passerine birds, and so it is important that we understand the details surrounding such predation events. With the advent of small video and temperature recorders, nests can now be monitored remotely and predator identity can be assigned. Using remote data collection techniques, we report the unusual observation of a White-throated Sparrow nestling being taken by a juvenile Sharp-shinned Hawk. Normally, Sharp-shinned Hawks focus their efforts on fledgling birds; however, if they do take nestlings, they tend to be from arboreal-nesting species. Since the White-throated Sparrow is a ground-nesting passerine, we suspect that a combination of nest location, nest structure, vegetation structure within the territory, and age of the nestlings made this nest an ideal target for an opportunistic young Sharp-shinned Hawk.

A Leach's Storm-Petrel (Oceanodroma leucorhoa) initially banded on Tenerife, Canary Islands, Spain in October 1995 was recaptured on Bon Portage Island off the south tip of Nova Scotia, Canada in August 2009, 13 years and 10 months later, and some 4,660 km and 51° longitude away. Recoveries on breeding areas of seabirds that were originally banded on wintering areas are exceedingly rare. This record appears to constitute the first winter-summer recapture of a Leach's Storm-Petrel.