| prevalence of hematozoa in overwintering american redstarts (setophaga ruticilla): no evidence for local transmission. | we examined american redstarts (setophaga ruticilla) for protozoan blood parasites on their wintering grounds to determine whether transmission of these parasites occurs prior to spring migration. a total of 73 blood smears from 37 birds were examined for presence and intensity of infection. thirty-six birds were sampled in the fall, soon after arriving from northern breeding grounds, and the spring prior to departure. two (5%) of the samples collected in the fall were positive for haemoproteus ... | 2004 | 15137497 |
| a molecular comparison of plumage and soil bacteria across biogeographic, ecological, and taxonomic scales. | we used molecular methods to determine the microbial community of soil and avian plumage across biogeographic, ecological, and taxonomic scales. a total of 17 soil and 116 feather samples were collected from five avian species across multiple habitat types within one neotropical and one temperate locality. hypotheses regarding patterns of microbial composition relative to acquisition and dispersal of plumage bacteria in the ecosystem were tested by comparing microbial communities within and betw ... | 2007 | 17334855 |
| linking breeding and wintering grounds of neotropical migrant songbirds using stable hydrogen isotopic analysis of feathers. | recent studies have shown that stable hydrogen isotope ratios (δd) in the tissues of animals often correlate with δd of local precipitation. here we examined the relationship between δd in feathers and growing season precipitation for neotropical migrant songbirds breeding over a continent-wide isotopic gradient. δd values were determined on feathers of 140 individuals of 6 species of wild insectivorous forest songbirds (setophaga ruticilla, empidonax minimus, vermivora peregrinus, catharus ustu ... | 1996 | 28307604 |
| social information and community dynamics: nontarget effects from simulating social cues for management. | artificially creating social stimuli may be an effective tool for facilitating settlement by rare and/or declining species into suitable habitat. however, the potential consequences for other community members have not been explored and should be considered when evaluating the overall utility of using such management strategies. i report on nontarget, community-wide effects that occurred when manipulating social cues of two competitors that are species of concern in the western united states, th ... | 2008 | 18839770 |
| species interactions and population density mediate the use of social cues for habitat selection. | 1. the perspective that populations and communities are structured by antagonistic interactions among individuals has dominated much of ecology. yet how animals use social information to guide decisions, such as habitat selection, may be influenced by both positive and negative interactions among individuals. recent theory also suggests that the way animals use social information may be substantially influenced by population density, which alters the potential costs and benefits of such behaviou ... | 2007 | 17439476 |
| a review of the zumpti species group of the genus harpyrhynchoides (acariformes: harpirhynchidae)--ectoparasites of passerines. | the zumpti species group of the genus harpyrhynchoides (harpirhynchidae), parasites of passerines, is revised. a key to the species of this group is provided and data on host associations and geographic distribution of its constituent species are summarized. this group includes six previously recognized species: harpyrhynchoides alaudinus bochkov, 2000, h. brevis (ewing, 1911) comb. nov., h. heatherae bochkov and galloway, 2013, h. rubeculinus (cherny and sixl, 1971), h. vulgaris bochkov and gal ... | 2014 | 25543798 |
| winter habitat quality but not long-distance dispersal influences apparent reproductive success in a migratory bird. | long-distance breeding and natal dispersal play central roles in many ecological and evolutionary processes, including gene flow, population dynamics, range expansion, and individual responses to fluctuating biotic and abiotic conditions. however, the relative contribution of long-distance dispersal to these processes depends on the ability of dispersing individuals to successfully reproduce in their new environment. unfortunately, due to the difficulties associated with tracking dispersal in th ... | 2016 | 27349098 |
| climate and density influence annual survival and movement in a migratory songbird. | assessing the drivers of survival across the annual cycle is important for understanding when and how population limitation occurs in migratory animals. density-dependent population regulation can occur during breeding and nonbreeding periods, and large-scale climate cycles can also affect survival throughout the annual cycle via their effects on local weather and vegetation productivity. most studies of survival use mark-recapture techniques to estimate apparent survival, but true survival rate ... | 2015 | 26811763 |
| experimental reduction of winter food decreases body condition and delays migration in a long-distance migratory bird. | many tropical habitats experience pronounced dry seasons, during which arthropod food availability declines, potentially limiting resident and migratory animal populations. in response to declines in food, individuals may attempt to alter their space use to enhance access to food resources, but may be socially constrained from doing so by con- and heterospecifics. if social constraints exist, food declines should result in decreased body condition. in migratory birds, correlational evidence sugg ... | 2015 | 26378315 |
| habitat features and long-distance dispersal modify the use of social information by a long-distance migratory bird. | the processes by which individuals select breeding sites have important consequences for individual tness as well as population- and community-dynamics. although there is increasing evidence that many animal species use information acquired from conspecics to assess the suitability of potential breeding sites, little is known about how the use of this social information is modified by biotic and abiotic conditions. we used an automated playback experiment to simulate two types of social informat ... | 2015 | 26061822 |
| inter-annual variation in american redstart (setophaga ruticilla) plumage colour is associated with rainfall and temperature during moult: an 11-year study. | carotenoid-based colouration plays an important role in sexual signaling in animals as an honest indicator of individual quality during mate choice and competitive interactions. however, few studies have examined how natural variation in weather conditions influences inter-annual variation in the expression of ornamentation, potentially through affecting the dietary availability of carotenoids. in this study, we examine variation in the expression of carotenoid-based plumage colouration in relat ... | 2015 | 25433695 |
| color expression in experimentally regrown feathers of an overwintering migratory bird: implications for signaling and seasonal interactions. | plumage coloration in birds plays a critical role in communication and can be under selection throughout the annual cycle as a sexual and social signal. however, for migratory birds, little is known about the acquisition and maintenance of colorful plumage during the nonbreeding period. winter habitat could influence the quality of colorful plumage, ultimately carrying over to influence sexual selection and social interactions during the breeding period. in addition to the annual growth of color ... | 2014 | 24834321 |
| experimental and observational studies of seasonal interactions between overlapping life history stages in a migratory bird. | prior to reproduction, migratory animals are at the juxtaposition of three life history stages in which they must finish the non-breeding stage, initiate and complete migration, and prepare for the onset of breeding. however, how these stages interact with one another is not fully understood. we provide evidence that, for migratory birds that begin breeding development prior to departure from non-breeding sites, the level of breeding preparation can drive migration phenology, a critical behavior ... | 2013 | 24128687 |
| the effects of experimental irrigation on plant productivity, insect abundance and the non-breeding season performance of a migratory songbird. | migratory bird populations are often limited by food during the non-breeding season. correlative evidence suggests that food abundance on territories varies among years in relation to rainfall, which affects plant productivity and arthropod biomass. at the font hill nature preserve in jamaica, we used an irrigation experiment to test the hypothesis that rainfall affects the condition of wintering american redstarts (setophaga ruticilla) via intermediate effects on plant productivity and arthropo ... | 2013 | 23372825 |
| winter rainfall predicts phenology in widely separated populations of a migrant songbird. | climate change is affecting behaviour and phenology in many animals. in migratory birds, weather patterns both at breeding and at non-breeding sites can influence the timing of spring migration and breeding. however, variation in responses to weather across a species range has rarely been studied, particularly among populations that may winter in different locations. we used prior knowledge of migratory connectivity to test the influence of weather from predicted non-breeding sites on bird pheno ... | 2013 | 23161154 |
| range-wide effects of breeding- and nonbreeding-season climate on the abundance of a neotropical migrant songbird. | geographic variation in the population dynamics of a species can result from regional variability in climate and how it affects reproduction and survival. identifying such effects for migratory birds requires the integration of population models with knowledge of migratory connectivity between breeding and nonbreeding areas. we used bayesian hierarchical models with 26 years of breeding bird survey data (1982-2007) to investigate the impacts of breeding- and nonbreeding-season climate on abundan ... | 2011 | 21939075 |
| rainfall-induced changes in food availability modify the spring departure programme of a migratory bird. | climatic warming has intensified selection for earlier reproduction in many organisms, but potential constraints imposed by climate change outside the breeding period have received little attention. migratory birds provide an ideal model for exploring such constraints because they face warming temperatures on temperate breeding grounds and declining rainfall on many tropical non-breeding areas. here, we use longitudinal data on spring departure dates of american redstarts (setophaga ruticilla) t ... | 2011 | 21450737 |
| does stress response predict return rate in a migratory bird species? a study of american redstarts and their non-breeding habitat. | in vertebrates, the adrenocortical stress response activates an emergency life-history stage, which is thought to promote survival by helping individuals escape life-threatening situations. although the adrenocortical stress response promotes many behavioural and physiological changes, it remains unclear whether this stress response actually translates into higher survival in wild vertebrates. we measured the adrenocortical stress response of non-breeding american redstarts (setophaga ruticilla) ... | 2009 | 19605397 |
| non-breeding season events influence sexual selection in a long-distance migratory bird. | the study of sexual selection has traditionally focused on events and behaviours immediately surrounding copulation. in this study, we examine whether carry-over effects from the non-breeding season can influence the process of sexual selection in a long-distance migratory bird, the american redstart (setophaga ruticilla). previous work on american redstarts demonstrated that overwintering in a high-quality habitat influences spring departure dates from the wintering grounds, advances arrival da ... | 2009 | 19203918 |
| improved estimates of certainty in stable-isotope-based methods for tracking migratory animals. | the use of stable-hydrogen isotopes (deltad) has become a common tool for estimating geographic patterns of movement in migratory animals. this method relies on broad and relatively predictable geographic patterning in deltad values of precipitation, but these patterns are not estimated without error. in addition, deltad measurements are relatively imprecise, particularly for organic tissue. most models for estimating geographic locations have ignored these sources of error. common modeling appr ... | 2008 | 18488615 |
| phylogeography of a widespread north american migratory songbird (setophaga ruticilla). | genetic analyses for many widespread north american species have revealed significant east-west differentiation, indicating that many survived through the pleistocene in 2 glacial refugia-1 in the eastern and 1 in the western part of the continent. it remains unclear, however, whether other areas may have served as important glacial refugia. moreover, many such species exhibit widespread genetic similarity within eastern and western regions because of recent expansion from small refugial populat ... | 2010 | 18468988 |
| natal dispersal driven by environmental conditions interacting across the annual cycle of a migratory songbird. | natal dispersal, the process through which immature individuals permanently depart their natal area in search of new sites, is integral to the ecology and evolution of animals. insights about the underlying causes of natal dispersal arise mainly from research on species whose short dispersal distances or restricted distributions make them relatively easy to track. however, for small migratory animals, the causes of natal dispersal remain poorly understood because individuals are nearly impossibl ... | 2008 | 18287030 |
| optimal conservation of migratory species. | migratory animals comprise a significant portion of biodiversity worldwide with annual investment for their conservation exceeding several billion dollars. designing effective conservation plans presents enormous challenges. migratory species are influenced by multiple events across land and sea-regions that are often separated by thousands of kilometres and span international borders. to date, conservation strategies for migratory species fail to take into account how migratory animals are spat ... | 2007 | 17710150 |
| continent-wide variation in feather colour of a migratory songbird in relation to body condition and moulting locality. | understanding the causes of variation in feather colour in free-living migratory birds has been challenging owing to our inability to track individuals during the moulting period when colours are acquired. using stable-hydrogen isotopes to estimate moulting locality, we show that the carotenoid-based yellow-orange colour of american redstart (setophaga ruticilla) tail feathers sampled on the wintering grounds in central america and the caribbean is related to the location where feathers were gro ... | 2007 | 17443954 |
| hydrogen isotopic variation in migratory bird tissues of known origin: implications for geographic assignment. | continent-wide variation in hydrogen isotopic composition of precipitation is incorporated into animal diets, providing an intrinsic marker of geographic location at the time of tissue growth. feathers from migratory birds are now frequently analyzed for stable-hydrogen isotopes (deltad) to estimate the location of individuals during a preceding molt. using known-origin birds, we tested several assumptions associated with this emerging technique. we examined hydrogen isotopic variation as a func ... | 2007 | 17370093 |
| social cues facilitate habitat selection: american redstarts establish breeding territories in response to song. | for migratory songbirds nesting in northern temperate forests, a short breeding season demands that males rapidly establish territories. because critical insect and vegetation resources are unavailable during spring arrival, we suggest that conspecifics serve as settlement cues for males new to a local population. to test conspecific attraction, we conducted playback experiments with american redstarts setophaga ruticilla. experimental results demonstrate that song playbacks strongly attract con ... | 2006 | 17148397 |
| assessing habitat quality for a migratory songbird wintering in natural and agricultural habitats. | as tropical forests are cleared, a greater proportion of migratory songbirds are forced to winter in agricultural and disturbed habitats, which, if poorer in quality than natural forests, could contribute to population declines. we compared demographic indicators of habitat quality for a focal species, the american redstart (setophaga ruticilla), wintering in jamaican citrus orchards and shade coffee plantations with those in four natural habitats: mangrove, coastal scrub, coastal palm, and dry ... | 2006 | 17002761 |
| sampling variability and estimates of density dependence: a composite-likelihood approach. | it is well known that sampling variability, if not properly taken into account, affects various ecologically important analyses. statistical inference for stochastic population dynamics models is difficult when, in addition to the process error, there is also sampling error. the standard maximum-likelihood approach suffers from large computational burden. in this paper, i discuss an application of the composite-likelihood method for estimation of the parameters of the gompertz model in the prese ... | 2006 | 16634310 |
| tropical winter habitat limits reproductive success on the temperate breeding grounds in a migratory bird. | identifying the factors that control population dynamics in migratory animals has been constrained by our inability to track individuals throughout the annual cycle. using stable carbon isotopes, we show that the reproductive success of a long-distance migratory bird is influenced by the quality of habitat located thousands of kilometres away on tropical wintering grounds. for male american redstarts (setophaga ruticilla), winter habitat quality influenced arrival date on the breeding grounds, w ... | 2004 | 15002772 |
| arrival fat and reproductive performance in a long-distance passerine migrant. | long-distance passerine migrants deposit substantial fat stores to fuel their migratory journey. many of those migratory birds arrive at their northerly breeding grounds with larger fat stores than were necessary to reach their breeding area. both male and female american redstarts ( setophaga ruticilla) arrived to breed in michigan's upper peninsula with fat, and females arrived with more fat than males in 2 out of 3 years. we test the hypothesis that migrants arriving at the breeding grounds w ... | 2003 | 12647139 |
| linking winter and summer events in a migratory bird by using stable-carbon isotopes | for migratory birds, early arrival and physical condition on the breeding grounds are important determinants of reproductive success and fitness. differences in arrival times often exceed a month, and later arriving individuals are often in poorer condition. habitat-specific isotopic signatures indicate that the quality of winter habitats occupied by american redstarts (setophaga ruticilla) determines their physical condition and spring departure dates, which in turn result in variable arrival s ... | 1998 | 9836637 |
| corticosterone levels as indicators of habitat quality: effects of habitat segregation in a migratory bird during the non-breeding season. | during the non-breeding season, many species of territorial migratory birds exhibit a non-random pattern of habitat distribution, with males and females occupying different habitats. in this study, we examined possible physiological consequences arising from such habitat segregation in one migrant passerine species, the american redstart (setophaga ruticilla), on its non-breeding grounds in jamaica, west indies. for 2 years, we measured concentrations of corticosterone, at the time of capture (b ... | 1998 | 28308538 |
| diurnal and individual variability in the foraging behavior of american redstarts (setophaga ruticilla). | the foraging behavior of american redstarts, setophaga ruticilla (aves: parulidae), was examined from dawn to dusk in the nestling phase of their breeding cycle in a northern hardwoods forest in new hampshire, usa. based on a sample size of nearly 3000 foraging acts, we found that redstarts hawked more and foraged lower at midday than early in the morning, coincident with a statistically significant increase in the abundance of flying insects in the lower strata of the forest at that time of day ... | 1978 | 28309123 |