| microbes in tree swallow semen. | a frequently hypothesized but poorly studied cost of multiple mating in birds is that exposure to pathogenic sexually transmitted microbes (stm's) can lower reproductive success. conversely, female birds may benefit from high frequencies of copulation and multiple copulation partners if they receive cloacal inoculations of beneficial stm's that can either protect them against future encounters with pathogens and/or serve as therapy against present infection. we examined the semen of 30 male tree ... | 2000 | 10941730 |
| dioxins and congener-specific polychlorinated biphenyls in three avian species from the wisconsin river, wisconsin. | sediments from the wisconsin river. wi. usa are contaminated with 2,3,7,8-tetrachloro-p-dioxin (tcdd) and polychlorinated biphenyls (pcbs). wet weight concentrations of tcdd and pcbs in eggs were at background levels and highest in the piscivorous = 7 pg/g tcdd a hooded merganser (lophodytes cucullatus; geometric m ean nd 0.92 microg/g pcbs) a nd lowest in the omnivorous wood duck (aix sponsa) (< 1 pg/g and 0.07 microg/g); concentrations in eggs of the insectivorous tree swallow (tachycineta bic ... | 2002 | 12166666 |
| reproductive effort reduces long-term immune function in breeding tree swallows (tachycineta bicolor). | we examined whether strategies of reproductive allocation may reduce long-term immunocompetence through the effects of manipulated effort on secondary or acquired immunity. we tested whether increased reproductive effort leads to reduced immune function and survival by manipulating brood size in tree swallows (tachycineta bicolor) and exposing breeding females to a primary and secondary exposure of sheep red blood cells to elicit a humoral immune response. females raising enlarged broods produce ... | 2003 | 12964994 |
| digenetic trematodes, acanthatrium sp. and lecithodendrium sp., as vectors of neorickettsia risticii, the agent of potomac horse fever. | neorickettsia (formerly ehrlichia) risticii, the agent of potomac horse fever (phf), has been recently detected in trematode stages found in the secretions of freshwater snails and in aquatic insects. insectivores, such as bats and birds, may serve as the definitive host of the trematode vector. to determine the definitive helminth vector, five bats (myotis yumanensis) and three swallows (hirundo rustica, tachycineta bicolor) were collected from a phf endemic location in northern california. bat ... | 2003 | 14627451 |
| accumulation in and effects of lead and cadmium on waterfowl and passerines in northern idaho. | waterfowl and passerines in northern idaho in 1987 had high levels of lead in their blood and tissues that originated primarily from mining and smelting activities. four canada geese (branta canadensis) and one common goldeneye (bucephala clangula) found dead contained 8 to 38 microg/g (wet mass) of lead in their livers. these levels exceed the lower lethal limit of 5 microg/g in experimental birds. two of the canada geese (one each from the contaminated and reference areas) died with ingested l ... | 1995 | 15091521 |
| effects of oil sands tailings compounds and harsh weather on mortality rates, growth and detoxification efforts in nestling tree swallows (tachycineta bicolor). | oil sands mining companies in alberta, canada, are evaluating the feasibility of using wetlands to detoxify oil sands process material (ospm) as a reclamation strategy. reproductive success, nestling growth, survival and ethoxyresorufin-o-deethylase (erod) activity were measured in tree swallows (tachycineta bicolor) on experimental wetlands. in 2003, harsh weather triggered a widespread nestling die-off. mortality rates on the control site reached 48% while they ranged from 59% to 100% on recla ... | 2006 | 16297515 |
| polychlorinated biphenyl congener patterns in tree swallows (tachycineta bicolor) nesting in the housatonic river watershed, western massachusetts, usa, using a novel statistical approach. | a novel application of a commonly used statistical approach was used to examine differences in polychlorinated biphenyl (pcb) congener patterns among locations and sample matrices in tree swallows (tachycineta bicolor) nesting in the housatonic river watershed in western massachusetts, usa. the most prevalent pcb congeners in tree swallow tissue samples from the housatonic river watershed were ballsmitter zell numbers 153, 138, 180, 187, 149, 101, and 170. these congeners were seven of the eight ... | 2006 | 16377044 |
| species differences in the sensitivity of avian embryos to methylmercury. | we injected doses of methylmercury into the air cells of eggs of 26 species of birds and examined the dose-response curves of embryo survival. for 23 species we had adequate data to calculate the median lethal concentration (lc(50)). based on the dose-response curves and lc(50)s, we ranked species according to their sensitivity to injected methylmercury. although the previously published embryotoxic threshold of mercury in game farm mallards (anas platyrhynchos) has been used as a default value ... | 2009 | 18421496 |
| Selenium accumulation and reproduction in birds breeding downstream of a uranium mill in northern Saskatchewan, Canada. | Selenium (Se) concentrations in aquatic invertebrates and bird eggs collected along the treated effluent receiving environment of the Key Lake uranium mill in northern Saskatchewan were significantly greater than from nearby reference areas, and in some cases (e.g., eggs of common loons-Gavia immer) were higher than commonly used thresholds for adverse reproductive effects in birds (i.e., 5 µg/g dry weight in diet; 12-15 µg/g dry weight in eggs). Mean Se concentrations in tree swallow (Tachycine ... | 2011 | 21927945 |
| external heart deformities in passerine birds exposed to environmental mixtures of polychlorinated biphenyls during development. | necropsy-observable cardiac deformities were evaluated from 283 nestling passerines collected from one reference site and five polychlorinated biphenyl (pcb)-contaminated sites around bloomington and bedford, indiana, usa. hearts were weighed and assessed on relative scales in three dimensions (height, length, and width) and for externally visible deformities. heart weights normalized to body weight (heart somatic index) were decreased significantly at the more contaminated sites in both house w ... | 2006 | 16519318 |
| breeding success of tree swallows along a gradient of agricultural intensification. | the intensification of agricultural practices has been identified as the main cause of population decline in farmland birds since the 1960s in both europe and north america. although the links between species richness or abundance and various components of agricultural intensification are well established, the mechanisms underlying these trends have rarely been addressed along a gradient of intensification or have been quantified at only one spatial scale. here we quantified the influence of lan ... | 2008 | 18686577 |
| incubation stage and polychlorinated biphenyl (pcb) congener patterns in an altricial and precocial bird species. | the composition of polychlorinated biphenyl (pcb) congeners was compared between non-incubated and embryonated eggs of tree swallows (tachycineta bicolor) and little terns (sterna albifrons) to determine if measurable changes in pcb congeners occurred during the embryonic period. there was no indication of changes in pcb congener patterns over the incubation period in tree swallows in 1999 and 2000 at a site with very high pcb exposure or a site with more modest pcb exposure. additionally, conge ... | 2014 | 25213805 |
| avian wildlife as sentinels of ecosystem health. | birds have been widely used as sentinels of ecosystem health reflecting changes in habitat quality, increased incidence of disease, and exposure to and effects of chemical contaminants. numerous studies addressing these issues focus on the breeding period, since hormonal, behavioural, reproductive, and developmental aspects of the health can be observed over a relatively short time-span. many body systems within individuals are tightly integrated and interdependent, and can be affected by contam ... | 2013 | 23260372 |
| impacts of acid rainon aquatic birds. | studies of toxicological and ecological effects of acidification on aquatic birds in europe and north america are reviewed. heavy metals are deposited by acid emissions, which also increase solubility and mobility of heavy metals in soil and water. aluminium is leached from soil and mobilized from lake sediments under acid conditions; it removes susceptible fish and invertebrate species and contaminates remaining invertebrates. it is not highly toxic to birds, but may interfere with their regula ... | 1989 | 24249190 |
| mercury in breeding saltmarsh sparrows (ammodramus caudacutus caudacutus). | environmental mercury exposure of birds through atmospheric deposition and watershed point-source contamination is an issue of increasing concern globally. the saltmarsh sparrow (ammodramus caudacutus) is of high conservation concern throughout its range and the potential threat of mercury exposure adds to other anthropogenic stressors, including sea level rise. to assess methylmercury exposure we sampled blood of the northern nominal subspecies of saltmarsh sparrows (a. c. caudacutus) nesting i ... | 2011 | 21792662 |
| metal concentrations in three species of passerine birds breeding in the hackensack meadowlands of new jersey. | the new jersey meadowlands is an important natural area, a diverse mosaic of wetland habitats positioned within the heavily urbanized ny city metropolitan area and the ny/nj harbor. persistent contaminants may pose threats to wildlife inhabiting these habitats, affecting reproduction, egg hatchability, nestling survivorship, and neurobehavioral development. metals of concern in the meadowlands include arsenic, cadmium, chromium, lead, and mercury. these metals were analyzed in feathers and blood ... | 2008 | 18191831 |
| mercury concentrations in eggs of red-winged blackbirds and tree swallows breeding in voyageurs national park, minnesota. | most investigations of the environmental effects of mercury (hg) have focused on aquatic food webs that include piscivorous fish or wildlife. however, recent investigations have shown that other species, including passerine songbirds, may also be at risk from exposure to methylmercury (mehg). we quantified hg concentrations in eggs of two species of songbirds, red-winged blackbirds (agelaius phoeniceus) and tree swallows (tachycineta bicolor), nesting in voyageurs national park, minnesota, usa. ... | 2016 | 26801652 |
| dietary exposure of three passerine species to pcdd/dfs from the chippewa, tittabawassee, and saginaw river floodplains, midland, michigan, usa. | dietary exposure of house wrens (troglodytes aedon), tree swallows (tachycineta bicolor), and eastern bluebirds (sialia sialis) to polychlorinated dibenzofurans (pcdfs) and polychlorinated dibenzo-p-dioxins (pcdds) near midland, michigan (usa) was evaluated based on site-specific data, including concentrations of residues in bolus samples and individual invertebrate orders and dietary compositions by study species. site-specific dietary compositions for the three species were similar to those re ... | 2011 | 20145996 |
| passerine exposure to primarily pcdfs and pcdds in the river floodplains near midland, michigan, usa. | house wren (troglodytes aedon), tree swallow (tachycineta bicolor), and eastern bluebird (sialia sialis) tissues collected in study areas (sas) downstream of midland, michigan (usa) contained concentrations of polychlorinated dibenzofurans (pcdfs) and polychlorinated dibenzo-p-dioxins (pcdds) greater than in upstream reference areas (ras) in the region. the sum of concentrations of pcdd/dfs (sigmapcdd/dfs) in eggs of house wrens and eastern bluebirds from sas were 4- to 22-fold greater compared ... | 2010 | 19894014 |
| polychlorinated biphenyls, dioxins, furans, and organochlorine pesticides in spotted sandpiper eggs from the upper hudson river basin, new york. | in 2004, spotted sandpipers (actitis macularia) were studied on the hudson river near fort edward south to new baltimore, ny and on two river drainages that flow into the hudson river. concentrations of 28 organochlorine pesticides, 160 polychlorinated biphenyl (pcb) congeners, and 17 dioxin and furan (pcdd-f) congeners were quantified in eggs collected on and off the hudson river. the pattern of organochlorine pesticides and pcdd-f congeners did not differ significantly between eggs collected o ... | 2010 | 19809875 |
| agricultural intensification is linked to constitutive innate immune function in a wild bird population. | immunity represents an important defense mechanism against pathogens and is intimately linked to fitness. previous studies have found significant interindividual variation of immune responses in wild populations and have emphasized the importance of ecological factors in explaining this variability. a deterioration of environmental conditions, such as agricultural intensification, can modify resource availability and, as a result, alter immune functions. the aim of this study was to investigate ... | 2017 | 28277952 |
| experimental relationships between levels of corticosterone in plasma and feathers in a free-living bird. | integrated measures of corticosterone (cort), such as from feathers (cortf), have intuitive appeal because they incorporate both the duration and amplitude of glucocorticoid secretion. an association between cortf and plasma cort has never been shown in wild birds, and it is unclear as to when and if these measures should be correlated, given that they are fundamentally different yet related measures of physiology. we hypothesized that cortf should correlate with instantaneous measurements of pl ... | 2013 | 23913947 |
| maternal transfer of mercury to songbird eggs. | we evaluated the maternal transfer of mercury to eggs in songbirds, determined whether this relationship differed between songbird species, and developed equations for predicting mercury concentrations in eggs from maternal blood. we sampled blood and feathers from 44 house wren (troglodytes aedon) and 34 tree swallow (tachycineta bicolor) mothers and collected their full clutches (n = 476 eggs) within 3 days of clutch completion. additionally, we sampled blood and feathers from 53 tree swallow ... | 2017 | 28688298 |
| heritable variation in circulating glucocorticoids and endocrine flexibility in a free-living songbird. | phenotypic flexibility is a central way that organisms cope with challenging and changing environments. as endocrine signals mediate many phenotypic traits, heritable variation in hormone levels, or their context-dependent flexibility, could present an important target for selection. several studies have estimated the heritability of circulating glucocorticoid levels under acute stress conditions, but little is known about the potential for either baseline hormone levels or rapid endocrine flexi ... | 2017 | 28665031 |
| spatiotemporal exploratory models for broad-scale survey data. | the distributions of animal populations change and evolve through time. migratory species exploit different habitats at different times of the year. biotic and abiotic features that determine where a species lives vary due to natural and anthropogenic factors. this spatiotemporal variation needs to be accounted for in any modeling of species' distributions. in this paper we introduce a semiparametric model that provides a flexible framework for analyzing dynamic patterns of species occurrence an ... | 2010 | 21265447 |
| pcbs and dde in tree swallow (tachycineta bicolor) eggs and nestlings from an estuarine pcb superfund site, new bedford harbor, ma, u.s.a. | while breeding tree swallows (tachycineta bicolor) have been used as biomonitors for freshwater sites, we report the first use of this species to assess contaminant bioaccumulation from estuarine breeding grounds into these aerial insectivores. eggs and nestlings were collected from nest boxes in a polychlorinated biphenyl (pcb) contaminated estuary, the new bedford harbor superfund site (nbh, massachusetts, usa), and a reference salt marsh, fox hill (fh, jamestown, rhode island, usa). sediments ... | 2009 | 19924974 |
| variation in immune function, body condition, and feather corticosterone in nestling tree swallows (tachycineta bicolor) on reclaimed wetlands in the athabasca oil sands, alberta, canada. | in the athabasca oil sands region of northern alberta, mining companies are evaluating reclamation using constructed wetlands for integration of tailings. from may to july 2008, reproductive performance of 40 breeding pairs of tree swallows (tachycineta bicolor), plus growth and survival of nestlings, was measured on three reclaimed wetlands on two oil sands leases. a subset of nestlings was examined for i) feather corticosterone levels, ii) delayed-type hypersensitivity response, and iii) innat ... | 2010 | 19850385 |
| compromised immune competence in free-living tree swallows exposed to mercury. | mercury is a pervasive environmental contaminant and a well-documented immunosuppressor. however, little is known about the effects of mercury contamination on health of free-living vertebrate populations. the south river in virginia, usa was heavily contaminated with industrial mercury from 1929 to 1950, and recent studies have documented high levels of circulating mercury in riparian songbirds breeding below the site of contamination. here we used two standardized immune assays, mitogen-induce ... | 2009 | 19322655 |
| digit ratio in birds. | the homeobox (hox) genes direct the development of tetrapod digits. the expression of hox genes may be influenced by endogenous sex steroids during development. manning (digit ratio. new brunswick, nj: rutgers university press, 2002) predicted that the ratio between the lengths of digits 2 (2d) and 4 (4d) should be sexually dimorphic because prenatal exposure to estrogens and androgens positively influence the lengths of 2d and 4d, respectively. we measured digits and other morphological traits ... | 2008 | 18833568 |
| adult tree swallow (tachycineta bicolor) survival on the polychlorinated biphenyl-contaminated housatonic river, massachusetts, usa. | tree swallows (tachycineta bicolor) were captured and banded at six sites that differed in polychlorinated biphenyl (pcb) contamination levels in the housatonic river watershed, western massachusetts, usa, from 2000 through 2004 to test the prediction that apparent survival rates of females in more contaminated areas were lower than those from less contaminated areas. we also tested whether plumage coloration affected over-winter survival and whether concentrations of pcbs in eggs differed betwe ... | 2007 | 17521155 |
| evaluating cytochrome p450 in lesser scaup (aythya affinis) and tree swallow (tachycineta bicolor) by monooxygenase activity and immunohistochemistry: possible nonlethal assessment by skin immunohistochemistry. | six-month-old lesser scaup (aythya affinis) and nestling tree swallows (tachycineta bicolor) were injected intraperitoneally with beta-naphthoflavone (bnf) in corn oil or in vehicle alone. liver samples were taken and stored at -80 degrees c until microsome preparation and monooxygenase assay. skin samples were placed in buffered formalin for subsequent immunohistochemical (ihc) analysis for cytochrome p4501a (cyp1a). lesser scaup treated with bnf at 20 or 100 mg/kg body weight showed approximat ... | 2006 | 17022400 |
| spatial, temporal, and dietary determinants of organic contaminants in nestling tree swallows in point pelee national park, ontario, canada. | point pelee national park of canada in southwestern ontario, an important migratory route and vital breeding area for many birds, has localized areas of organochlorine (oc) pesticide contamination from agricultural production during the 1950s and 1960s. during 2001 and 2002, we investigated movement of persistent contaminants through the food web with the insectivorous tree swallow (tachycineta bicolor) as a sentinel. the a priori site classifications, contaminated or reference, were based on so ... | 2005 | 16445099 |
| thyroid function in nestling tree swallows and eastern bluebirds exposed to non-persistent pesticides and p, p'-dde in apple orchards of southern ontario, canada. | this study examined the associated effects of pesticides and persistent residues of p,p'-dde on thyroid function in 16-day-old tree swallows (tachycineta bicolor) and 12-day-old eastern bluebirds (sialia sialis). apple orchards sprayed with pesticides in current use and reference sites were chosen for study in southern ontario, canada, during 2000-2001. we assessed thyroid hormone concentrations (plasma and muscle thyroxine [t4], and triiodothyronine [t3]) and the response to a challenge with th ... | 2005 | 15943111 |
| health of tree swallow (tachycineta bicolor) nestlings exposed to chlorinated hydrocarbons in the st. lawrence river basin. part ii. basal and stress plasma corticosterone concentrations. | sixteen-day-old tree swallows (tachycineta bicolor) were collected in 1999 and 2000 from nine sites within the vicinity of the st. lawrence river in canada and the united states to determine if organochlorine contaminant concentrations correlated with corticosterone levels. basal plasma corticosterone levels were determined in chicks reared in nest boxes, and stress plasma corticosterone levels were determined in chicks after exposure to a 10-min standardized stress test. mean basal plasma corti ... | 2003 | 14555399 |
| health of tree swallow (tachycineta bicolor) nestlings exposed to chlorinated hydrocarbons in the st lawrence river basin. part i. renal and hepatic vitamin a concentrations. | sixteen-day-old tree swallows (tachycineta bicolor), near fledging, were collected in 1999 and 2000 from nine sites representing a gradient of dioxin concentrations, within the vicinity of the st. lawrence river in canada and the united states, to determine if organochlorine contaminants correlated with vitamin a levels measured as retinol and retinyl palmitate. mean concentrations of hepatic retinol ranged from 3 mg /kg to 13 mg /kg, and from 0.35 mg /kg to 1.5 mg /kg for renal retinol. mean co ... | 2003 | 12775516 |
| high levels of extra-pair paternity in an isolated, low-density, island population of tree swallows (tachycineta bicolor). | molecular genetic studies have suggested that apparently nonbreeding males ('floaters') may account for a significant proportion of extra-pair paternity (epp) in avian populations. attempts to determine the influence of breeding density on epp are therefore confounded by the presence of a subpopulation of floaters whose numbers are difficult to estimate. to study epp in a tree swallow (tachycineta bicolor) population with few floaters, we chose a nestbox grid on an island with an excess of avail ... | 2001 | 11380885 |
| patterns of organic contaminants in eggs of an insectivorous, an omnivorous, and a piscivorous bird nesting on the hudson river, new york, usa. | belted kingfisher (ceryle alcyon), spotted sandpiper (actitus macularia), and tree swallow (tachycineta bicolor) eggs were collected in 2004 from the upper hudson river, new york, usa. this area is one of the most polychlorinated biphenyl (pcb)-contaminated locations in north america. multivariate analyses indicated among species differences in the concentration and composition of pcb congeners, polychlorinated dibenzo-p-dioxin (pcdd), and dibenzofuran (pcdf, pcdd-f when combined with pcdds) con ... | 2010 | 20872693 |
| mercury and other element exposure in tree swallows nesting at low ph and neutral ph lakes in northern wisconsin usa. | the primary objective of this study was to determine whether tree swallows (tachycineta bicolor) demonstrate similar responses to lake ph and mercury (hg) contamination in northern wisconsin as do common loons (gavia immer). similar to common loons, hg concentrations in the blood of tree swallow nestlings were higher, hg concentrations in eggs tended to be higher, and egg size tended to be smaller at low (<6.2) ph lakes. in contrast to common loons, tree swallow nestling production was not lower ... | 2012 | 22325433 |
| cliff swallows petrochelidon pyrrhonota as bioindicators of environmental mercury, cache creek watershed, california. | to evaluate mercury (hg) and other element exposure in cliff swallows (petrochelidon pyrrhonota), eggs were collected from 16 sites within the mining-impacted cache creek watershed, colusa, lake, and yolo counties, california, usa, in 1997-1998. nestlings were collected from seven sites in 1998. geometric mean total hg (thg) concentrations ranged from 0.013 to 0.208 microg/g wet weight (ww) in cliff swallow eggs and from 0.047 to 0.347 microg/g ww in nestlings. mercury detected in eggs generally ... | 2008 | 18166988 |
| life-history and phenotypic traits of insectivorous songbirds breeding on reclaimed mine land reveal ecological constraints. | studies assessing impacts of industrial activities on wildlife typically examine population- or community-level responses. however, changes in measures such as species abundance or diversity are driven by cumulative responses of individuals to disturbance, and may take time to detect. quantifying individual responses could allow us to foresee and mitigate future population declines resulting from industrial activities, while providing ecologically informative indices to assess quality of reclaim ... | 2016 | 26930317 |
| resource selection plasticity and community responses to experimental reduction of a critical resource. | resource selection plasticity and behavioral dominance may influence the ability of a species to respond to changes in resource availability, particularly if dominant species have highly specialized resource requirements. we examined the response of several dominant and subordinate cavity-nesting species to a reduction in the availability of an essential resource (nesting cavities) using the novel experimental approach of blocking the entrances to high-quality cavities. we monitored nest abundan ... | 2008 | 18481522 |
| microbial and environmental effects on avian egg viability: do tropical mechanisms act in a temperate environment? | the viability of freshly laid avian eggs declines after several days of exposure to ambient temperatures above physiological zero, and declines occur faster in tropical than temperate ecosystems. microbial infection during preincubation exposure has recently been shown as a second cause of egg viability decline in the tropics, but whether microbial processes influence the viability of wild bird eggs in temperate ecosystems is unknown. we determined the microbial load on eggshells, the incidence ... | 2011 | 21661574 |
| stress and immune responses of nestling tree swallows (tachycineta bicolor) and eastern bluebirds (sialia sialis) exposed to nonpersistent pesticides and p,p'-dichlorodiphenyldichloroethylene in apple orchards of southern ontario, canada. | to determine the relative effects of pesticides in current use and persistent residues of p,p'-dichlorodiphenyldichloroethylene (p,p'-dde), we examined endocrine and immune responses in tree swallow (tachycineta bicolor) and eastern bluebird (sialia sialis) chicks from pesticide-sprayed apple orchards and reference sites in southern ontario, canada, during 2000 to 2001. nests were exposed to as many as seven individual pesticide applications and up to five mixtures of pesticides during the egg-i ... | 2004 | 15648768 |
| certainty of paternity and paternal investment in eastern bluebirds and tree swallows. | extra-pair paternity is common in many socially monogamous passerine birds with biparental care. thus, males often invest in offspring to which they are not related. models of optimal parental investment predict that, under certain assumptions, males should lower their investment in response to reduced certainty of paternity. we attempted to reduce certainty of paternity experimentally in two species, the eastern bluebird, sialia sialis, and the tree swallow, tachycineta bicolor, by temporarily ... | 1998 | 9632472 |
| effects of in ovo exposure to 3, 3',4,4'- tetrachlorobiphenyl (pcb 77) on heart development in tree swallow (tachycineta bicolor). | tree swallow (tachycineta bicolor) eggs from two uncontaminated sites, patuxent research refuge (prr), md and cobleskill reservoir, ny were dosed with pcb 77 to evaluate effects on the developing cardiovascular system. to ensure embryonic viability, treatments were administered into the air cell at embryonic day (ed) 2.5 including: untreated (control), vehicle (filtered sterilized fatty acid mixture), 100 ng/g and 1,000 ng/g egg. eggs were dosed in the field with 0.2 μl per egg, returned to the ... | 2017 | 28767159 |
| integrated population models reveal local weather conditions are the key drivers of population dynamics in an aerial insectivore. | changes to weather patterns under a warming climate are complex: while warmer temperatures are expected virtually worldwide, decreased mean precipitation is expected at mid-latitudes. migratory birds depend on broad-scale weather patterns to inform timing of movements, but may be more susceptible to local weather patterns during sedentary periods. we constructed bayesian integrated population models (ipms) to assess whether continental or local weather effects best explained population dynamics ... | 2017 | 28573381 |
| wind and rain are the primary climate factors driving changing phenology of an aerial insectivore. | while the ecological effects of climate change have been widely observed, most efforts to document these impacts in terrestrial systems have concentrated on the impacts of temperature. we used tree swallow (tachycineta bicolor) nest observations from two widely separated sites in central alaska to examine the aspects of climate affecting breeding phenology at the northern extent of this species' range. we found that two measures of breeding phenology, annual lay and hatch dates, are more strongl ... | 2017 | 28446701 |
| seasonal patterns in reproductive success of temperate-breeding birds: experimental tests of the date and quality hypotheses. | for organisms in seasonal environments, individuals that breed earlier in the season regularly attain higher fitness than their late-breeding counterparts. two primary hypotheses have been proposed to explain these patterns: the quality hypothesis contends that early breeders are of better phenotypic quality or breed on higher quality territories, whereas the date hypothesis predicts that seasonally declining reproductive success is a response to a seasonal deterioration in environmental quality ... | 2017 | 28405278 |
| an evaluation of feather corticosterone as a biomarker of fitness and an ecologically relevant stressor during breeding in the wild. | feather corticosterone (cort) levels are increasingly employed as biomarkers of environmental stress. however, it is unclear if feather cort levels reflect stress and/or workload in the wild. we investigated whether feather cort represents a biomarker of environmental stress and reproductive effort in tree swallows (tachycineta bicolor). specifically, we examined whether individual state and investment during reproduction could predict feather cort levels in subsequently moulted feathers and whe ... | 2017 | 28214946 |
| patterns of diversity and spatial variability of β-defensin innate immune genes in a declining wild population of tree swallows. | assessing the genetic variation and distribution of immune genes across heterogeneous environmental conditions in wild species is essential to further our understanding of the role of pathogen pressure and potential resistance or prevalence in hosts. researchers have recently investigated β-defensin genes in the wild, because their variability suggests that they may play an important role in innate host defense. this study investigated the variation occurring at 6 innate immune genes of the β-de ... | 2017 | 28186244 |
| strategic adjustment of parental care in tree swallows: life-history trade-offs and the role of glucocorticoids. | life-history theory predicts that optimal strategies of parental investment will depend on ecological and social factors, such as current brood value and offspring need. parental care strategies are also likely to be mediated in part by the hypothalamic-pituitary-adrenal axis and glucocorticoid hormones. here, we present an experiment in tree swallows (tachycineta bicolor), a biparental songbird with wide geographical distribution, asking whether parental care is strategically adjusted in respon ... | 2016 | 28083111 |
| evolutionary potential of morphological traits across different life-history stages. | despite accumulating examples of selection acting on heritable traits in the wild, predicted evolutionary responses are often different from observed phenotypic trends. various explanations have been suggested for these mismatches. these include within-individual changes across lifespan that can create important variation in genetic architecture of traits and selection acting on them, but also potential problems with the methodological approach used to predict evolutionary responses of traits. h ... | 2017 | 28000316 |
| temporal overlap and repeatability of feather corticosterone levels: practical considerations for use as a biomarker. | the measurement of corticosterone (cort) levels in feathers has recently become an appealing tool for the conservation toolbox, potentially providing a non-invasive, integrated measure of stress activity throughout the time of feather growth. however, because the mechanism of cort deposition, storage and stability in feathers is not fully understood, it is unclear how reliable this measure may be, especially when there is an extended interval between growth and feather collection. we compared co ... | 2016 | 27933163 |
| an assessment of the reliability of quantitative genetics estimates in study systems with high rate of extra-pair reproduction and low recruitment. | quantitative genetics approaches, and particularly animal models, are widely used to assess the genetic (co)variance of key fitness related traits and infer adaptive potential of wild populations. despite the importance of precision and accuracy of genetic variance estimates and their potential sensitivity to various ecological and population specific factors, their reliability is rarely tested explicitly. here, we used simulations and empirical data collected from an 11-year study on tree swall ... | 2017 | 27782118 |
| conservation implications of a lack of relationship between baseline glucocorticoids and fitness in a wild passerine. | the application of physiological measures to conservation monitoring has been gaining momentum and, while a suite of physiological traits are available to ascertain disturbance and condition in wildlife populations, glucocorticoids (i.e., gcs; cortisol and corticosterone) are the most heavily employed. the interpretation of gc levels as sensitive indicators of population change necessitates that gcs and metrics of population persistence are linked. however, the relationship between gcs and fitne ... | 2016 | 27763712 |
| within seasons and among years: when are corticosterone levels repeatable? | hormones play a central role in integrating internal and external cues to help mediate life-history decisions as well as changes in behavior and physiology of individuals. describing the consistency of endocrine traits within and among individuals is an important step for understanding whether hormonal traits are dependable predictors of phenotypes that selection could act upon. however, few long-term field studies have investigated the individual consistency of hormonal traits. glucocorticoid h ... | 2011 | 21872600 |
| do hormones, telomere lengths, and oxidative stress form an integrated phenotype? a case study in free-living tree swallows. | synopsis all organisms must anticipate and balance energetic demands and available resources in order to maximize fitness. as hormones coordinate many interactions between an organism's internal condition and the external environment, they may be key in mediating the allocation of resources to meet these demands. however, given that individuals differ considerably in how they react to changes in energetic demand, we asked whether variations in endocrine traits also correspond with life history v ... | 2016 | 27252220 |
| concentrations and spatial patterns of organic contaminants in tree swallow (tachycineta bicolor) eggs at united states and binational great lakes areas of concern, 2010-2015. | tree swallows, tachycineta bicolor, were sampled across the great lakes basin in 2010 through 2015 to provide a system-wide assessment of current exposure to organic contaminants. the results provide information identified as critical by regulators to assess the "bird or animal deformity or reproductive problems" beneficial use impairment. eggs were collected from 69 sites across all 5 great lakes, including 27 areas of concern (aocs), some with multiple sites, and 10 sites not listed as an aoc. ... | 2016 | 27187748 |
| a meta-analysis of relationships between polychlorinated biphenyl exposure and performance across studies of free-ranging tree swallows (tachycineta bicolor). | habitats worldwide are increasingly being degraded by human activities, with environmental pollution representing a significant threat to species and ecosystems. the presence of persistent organic chemicals, such as polychlorinated biphenyls (pcbs), has generated concern. captive experiments and field studies have reported some evidence for detrimental effects of pcb exposure, but also significant variation across studies and species. here, i use a meta-analytical approach to combine findings ac ... | 2016 | 27152205 |
| metals and metalloids in nestling tree swallows and their dietary items near oilsands mine operations in northern alberta. | tree swallows (tachycineta bicolor) nesting near oilsands development in northern alberta are potentially exposed to elevated levels of metals. the objective of this study was to determine whether levels of metals and metalloid elements in dietary items and tissues of nestling tree swallows inhabiting areas near oilsands mine operations were higher compared to those of reference sites. we hypothesized that if there was increased, industry-related exposure to metals, it would be via the diet. we ... | 2016 | 27110982 |
| experimental evidence that brighter males sire more extra-pair young in tree swallows. | across taxa, extra-pair mating is widespread among socially monogamous species, but few studies have identified male ornamental traits associated with extra-pair mating success, and even fewer studies have experimentally manipulated male traits to determine whether they are related directly to paternity. as a consequence, there is little experimental evidence to support the widespread hypothesis that females choose more ornamented males as extra-pair mates. here, we conducted an experimental stu ... | 2016 | 27105297 |
| multidimensional environmental influences on timing of breeding in a tree swallow population facing climate change. | most phenological traits are extremely sensitive to current climate change, and advances in the timing of important life-history events have been observed in many species. in birds, phenotypic plasticity in response to temperature is thought to be the main mechanism underlying yearly adjustment in the timing of breeding. however, other factors could be important and interact to affect the levels of plastic responses between and/or within-individuals. here, we use long-term individual-based data ... | 2015 | 26640519 |
| analysis of the optimal duration of behavioral observations based on an automated continuous monitoring system in tree swallows (tachycineta bicolor): is one hour good enough? | studies of animal behavior often rely on human observation, which introduces a number of limitations on sampling. recent developments in automated logging of behaviors make it possible to circumvent some of these problems. once verified for efficacy and accuracy, these automated systems can be used to determine optimal sampling regimes for behavioral studies. here, we used a radio-frequency identification (rfid) system to quantify parental effort in a bi-parental songbird species: the tree swall ... | 2015 | 26559407 |
| a hidden markov model for reconstructing animal paths from solar geolocation loggers using templates for light intensity. | solar archival tags (henceforth called geolocators) are tracking devices deployed on animals to reconstruct their long-distance movements on the basis of locations inferred post hoc with reference to the geographical and seasonal variations in the timing and speeds of sunrise and sunset. the increased use of geolocators has created a need for analytical tools to produce accurate and objective estimates of migration routes that are explicit in their uncertainty about the position estimates. | 2015 | 26473033 |
| weathering the storm: parental effort and experimental manipulation of stress hormones predict brood survival. | unpredictable and inclement weather is increasing in strength and frequency, challenging organisms to respond adaptively. one way in which animals respond to environmental challenges is through the secretion of glucocorticoid stress hormones. these hormones mobilize energy stores and suppress non-essential physiological and behavioral processes until the challenge passes. to investigate the effects of glucocorticoids on reproductive decisions, we experimentally increased corticosterone levels (t ... | 2015 | 26438064 |
| candidate gene-environment interactions and their relationships with timing of breeding in a wild bird population. | monitoring and predicting evolutionary changes underlying current environmental modifications are complex challenges. recent approaches to achieve these objectives include assessing the genetic variation and effects of candidate genes on traits indicating adaptive potential. in birds, for example, short tandem repeat polymorphism at four candidate genes (clock, npas2, adcyap1, and creb1) has been linked to variation in phenological traits such as laying date and timing of migration. however, our ... | 2015 | 26380692 |
| relationships among plumage coloration, blood selenium concentrations and immune responses of adult and nestling tree swallows. | in a number of taxa, males and females both display ornaments that may be associated with individual quality and could be reliable signals to potential mates or rivals. we examined the iridescent blue/green back and white breast of adult tree swallows (tachycineta bicolor) to determine whether plumage reflectance is related to adult or offspring immune responses. we simultaneously addressed the influence of blood selenium levels and the interaction between blood selenium and plumage coloration o ... | 2015 | 26347556 |
| tissue mercury concentrations and survival of tree swallow embryos, nestlings and young adult females on a contaminated site. | tree swallows nesting on mercury-contaminated sites along the south river in virginia, usa were monitored for reproductive success. the bodies of nestlings found deceased in their nest boxes were collected, along with blood and feather samples from the adult parents and surviving siblings. we also measured hatching and fledging success of the clutches and the annual recapture rate of adults. we found that the body feathers of deceased nestlings contained significantly higher concentrations of me ... | 2015 | 26318205 |
| low cost audiovisual playback and recording triggered by radio frequency identification using raspberry pi. | playbacks of visual or audio stimuli to wild animals is a widely used experimental tool in behavioral ecology. in many cases, however, playback experiments are constrained by observer limitations such as the time observers can be present, or the accuracy of observation. these problems are particularly apparent when playbacks are triggered by specific events, such as performing a specific behavior, or are targeted to specific individuals. we developed a low-cost automated playback/recording syste ... | 2015 | 25870771 |
| chromosomal damage and erod induction in tree swallows (tachycineta bicolor) along the upper mississippi river, minnesota, usa. | the health of tree swallows, tachycineta bicolor, on the upper mississippi river (umr) was assessed in 2010 and 2011 using biomarkers at six sites downriver of minneapolis/st. paul, mn metropolitan area, a tributary into the umr, and a nearby lake. chromosomal damage was evaluated in nestling blood by measuring the coefficient of variation of dna content (dna cv) using flow cytometry. cytochrome p450 1a activity in nestling liver was measured using the ethoxyresorufin-o-dealkylase (erod) assay, ... | 2015 | 25777616 |
| the effects of a remediated fly ash spill and weather conditions on reproductive success and offspring development in tree swallows. | animals are exposed to natural and anthropogenic stressors during reproduction that may individually or interactively influence reproductive success and offspring development. we examined the effects of weather conditions, exposure to element contamination from a recently remediated fly ash spill, and the interaction between these factors on reproductive success and growth of tree swallows (tachycineta bicolor) across nine colonies. females breeding in colonies impacted by the spill transferred ... | 2015 | 25690609 |
| importance of breeding season and maternal investment in studies of sex-ratio adjustment: a case study using tree swallows. | the control of primary sex-ratio by vertebrates has become a major focus in biology in recent years. evolutionary theory predicts that a differential effect of maternal characteristics on the fitness of sons and daughters is an important route, whereby selection is expected to favour a bias towards the production of one sex. however, despite experimental evidence for adaptive brood sex-ratio manipulation, support for this prediction remains a major challenge in vertebrates where inconsistencies ... | 2012 | 22130173 |
| effects of coal fly ash on tree swallow reproduction in watts bar reservoir, tennessee. | coal-fly ash was released in unprecedented amounts (4.1 × 10(6) m(3) ) into the emory river from the tennessee valley authority kingston fossil plant on watts bar reservoir in tennessee. tree swallows were exposed to ash-related constituents at the ash release via their diet of emergent aquatic insects, whose larval forms can accumulate constituents from submerged river sediments. reproduction of tree swallow colonies was assessed over a 2-year period by evaluating whether 1) ash constituent con ... | 2015 | 25345977 |
| detoxification, endocrine, and immune responses of tree swallow nestlings naturally exposed to air contaminants from the alberta oil sands. | changes in environmental and wildlife health from contaminants in tailings water on the canadian oil sands have been well-studied; however, effects of air contaminants on wildlife health have not. a field study was conducted to assess biological costs of natural exposure to oil sands-related air emissions on birds. nest boxes for tree swallows (tachycineta bicolor) were erected at two sites; within 5 km of active oil sands mining and extraction, and ≥ 60 km south, at one reference site. passive ... | 2015 | 25240100 |
| estimating dispersal among numerous sites using capture-recapture data. | dispersal affects processes as diverse as habitat selection, population growth, and gene flow. inference about dispersal and its variation is thus crucial for assessing population and evolutionary dynamics. two approaches are generally used to estimate dispersal in free-ranging animals. first, multisite capture-recapture models estimate movement rates among sites while accounting for survival and detection probabilities. this approach, however, is limited in the number of sites that can be consi ... | 2014 | 25230481 |
| variation in riparian consumer diet composition and differential bioaccumulation by prey influence the risk of exposure to elements from a recently remediated fly ash spill. | emerging aquatic insects play a key role in transporting aquatic nutrients and contaminants to riparian consumers. however, little is known about how within- and between-year variation in the diet or patterns of element bioaccumulation in emerging insect taxa may influence the risk of exposure to wildlife. during 2 breeding seasons, the composition of the diet of tree swallows (tachycineta bicolor) was examined at several colonies that were exposed to element contamination from a remediated coal ... | 2014 | 25113541 |
| employing individual measures of baseline glucocorticoids as population-level conservation biomarkers: considering within-individual variation in a breeding passerine. | labile physiological variables, such as stress hormones [i.e. glucocorticoids (gcs)], allow individuals to react to perturbations in their environment and may therefore reflect the effect of disturbances or positive conservation initiatives in advance of population-level demographic measures. although the application of gcs as conservation biomarkers has been of extensive interest, few studies have explicitly investigated whether baseline gc concentrations respond to disturbances consistently ac ... | 2016 | 27757239 |
| omega-3 long-chain polyunsaturated fatty acids support aerial insectivore performance more than food quantity. | once-abundant aerial insectivores, such as the tree swallow (tachycineta bicolor), have declined steadily in the past several decades, making it imperative to understand all aspects of their ecology. aerial insectivores forage on a mixture of aquatic and terrestrial insects that differ in fatty acid composition, specifically long-chain omega-3 polyunsaturated fatty acid (lcpufa) content. aquatic insects contain high levels of both lcpufa and their precursor omega-3 pufa, alpha-linolenic acid (al ... | 2016 | 27638210 |
| organic contamination in tree swallow (tachycineta bicolor) nestlings at united states and binational great lakes areas of concern. | contaminant exposure of tree swallows, tachycineta bicolor, nesting in 27 areas of concern (aocs) in the great lakes basin was assessed from 2010 to 2014 to assist managers and regulators in their assessments of great lakes aocs. contaminant concentrations in nestlings from aocs were compared with those in nestlings from nearby non-aoc sites. polychlorinated biphenyl (pcb) and polybrominated diphenyl ether concentrations in tree swallow nestling carcasses at 30% and 33% of aocs, respectively, we ... | 2017 | 27539913 |
| stable nitrogen isotopes of nestling tree swallows indicate exposure to different types of oil sands reclamation. | tree swallows (tachycineta bicolor) inhabiting reclaimed wetlands on the oil sands in northern alberta are potentially exposed to elevated levels of oil sands constituents such as polycyclic aromatic compounds (pac) through diet. while increased detoxification enzyme activity as measured using 7-ethoxyresorufin o-deethylase in nestlings is a generally accepted indicator of exposure to oil sands constituents, there is no apparent method to detect dietary exposure specific to oil sands processed m ... | 2014 | 24627996 |
| polybrominated diphenyl ethers and multiple stressors influence the reproduction of free-ranging tree swallows (tachycineta bicolor) nesting at wastewater treatment plants. | reproductive success of birds is influenced by maternal factors, ambient temperatures, predation, food supply, and/or exposure to environmental contaminants e.g., flame retardants (frs). reproduction of tree swallows (tachycineta bicolor) was compared among waste water treatment plants (wwtps) and a reference reservoir in ontario, canada (2007-2010), to determine the importance of exposure to polybrominated diphenyl ether (pbdes) frs within a complex contaminant cocktail, relative to natural and ... | 2014 | 24291556 |
| interspecific differences in egg production affect egg trace element concentrations after a coal fly ash spill. | in oviparous vertebrates, trace elements transfer from mother to offspring during egg production. for animals that produce eggs slowly, like turtles, the trace element concentration of each egg reflects an integration of dietary and stored accumulation over the duration of vitellogenesis. because turtles also produce eggs synchronously, all eggs within a clutch should exhibit uniform trace element concentrations. in contrast, for animals that produce eggs in sequence and primarily from current d ... | 2013 | 24180645 |
| phenotypic plasticity in response to breeding density in tree swallows: an adaptive maternal effect? | territorial animals breeding in high-density environments are more likely to engage in aggressive competition with conspecifics for resources necessary for reproduction. in many avian species, increased competition among breeding females results in increased testosterone concentrations in egg yolks. generally, elevated yolk testosterone increases nestling growth, competitive behaviors, and bold behavioral traits. however, few studies provide an environmental context with which to examine the pot ... | 2013 | 23994066 |
| day length, reproductive effort, and the avian latitudinal clutch size gradient. | explaining latitudinal patterns in life history traits remains a challenge for ecologists and evolutionary biologists. one such prominent pattern is the latitudinal gradient in clutch size in birds: the number of eggs laid in a reproductive bout increases with latitude in many species. one intuitive hypothesis proposes that the longer days at high latitudes during the breeding season allow parents to spend more time foraging each day, which results in greater total food delivery to the brood eac ... | 2013 | 23923496 |
| exposure and effects of perfluoroalkyl substances in tree swallows nesting in minnesota and wisconsin, usa. | the exposure and effects of perfluoroalkyl substances (pfass) were studied at eight locations in minnesota and wisconsin between 2007 and 2011 using tree swallows (tachycineta bicolor). concentrations of pfass were quantified as were reproductive success end points. the sample egg method was used wherein an egg sample is collected, and the hatching success of the remaining eggs in the nest is assessed. the association between pfas exposure and reproductive success was assessed by site comparison ... | 2014 | 23860575 |
| riparian swallows as integrators of landscape change in a multiuse river system: implications for aquatic-to-terrestrial transfers of contaminants. | recent research has highlighted the transfer of contaminants from aquatic to terrestrial ecosystems via predation of aquatic emergent insects by riparian consumers. the influence of adjacent land use and land cover (lulc) on aquatic-to-terrestrial contaminant transfer, however, has received limited attention. from 2010 to 2012, at 11 river reaches in the scioto river basin (oh, usa), we investigated the relationships between lulc and selenium (se) and mercury (hg) concentrations in four species ... | 2013 | 23792246 |
| dredging and contaminant exposure to tree swallows nesting on the upper mississippi river. | in 2008 and 2009, dredge material from the mississippi river in pool 8 south of brownsville, minnesota was used to construct nearby islands. chemical analysis of sediment in 2001 and 2002 in the area to be dredged indicated detectable concentrations of organic and inorganic contaminants. tree swallows (tachycineta bicolor), whose diet is mainly aquatic invertebrates, were used to evaluate contaminant exposure in both the dredged and newly created habitat. organic and inorganic contaminant data w ... | 2013 | 23666121 |
| ecological immunology in a fluctuating environment: an integrative analysis of tree swallow nestling immune defense. | evolutionary ecologists have long been interested by the link between different immune defenses and fitness. given the importance of a proper immune defense for survival, it is important to understand how its numerous components are affected by environmental heterogeneity. previous studies targeting this question have rarely considered more than two immune markers. in this study, we measured seven immune markers (response to phytohemagglutinin (pha), hemolysis capacity, hemagglutination capacity ... | 2013 | 23610646 |
| assessing costs of carrying geolocators using feather corticosterone in two species of aerial insectivore. | despite benefits of using light-sensitive geolocators to track animal movements and describe patterns of migratory connectivity, concerns have been raised about negative effects of these devices, particularly in small species of aerial insectivore. geolocators may act as handicaps that increase energetic expenditure, which could explain reported effects of geolocators on survival. we tested this 'energetic expenditure hypothesis' in 12 populations of tree swallows (tachycineta bicolor) and barn ... | 2015 | 26064659 |
| microsatellite evolution: mutations, sequence variation, and homoplasy in the hypervariable avian microsatellite locus hru10. | microsatellites are frequently used genetic markers in a wide range of applications, primarily due to their high length polymorphism levels that can easily be genotyped by fragment length analysis. however, the mode of microsatellite evolution is yet not fully understood, and the role of interrupting motifs for the stability of microsatellites remains to be explored in more detail. here we present a sequence analysis of mutation events and a description of the structure of repeated regions in th ... | 2008 | 18471288 |
| contaminant exposure of birds nesting in green bay, wisconsin, usa. | in earlier studies, elevated concentrations of polychlorinated biphenyl (pcb) and p,p'-dichlorodiphenyldichloroethylene (dde) were reported in double-crested cormorant (phalacrocorax auritus) eggs and tree swallow (tachycineta bicolor) eggs and nestlings collected from lower green bay (wi, usa) in 1994 and 1995 and black-crowned night-heron (nycticorax nycticorax) eggs collected in 1991. comparable samples collected in 2010 and 2011 indicated that concentrations of pcbs were 35%, 62%, 70%, and 8 ... | 2014 | 24733712 |
| the relationship between fitness and baseline glucocorticoids in a passerine bird. | glucocorticoid (cort) hormones are increasingly applied in studies of free-ranging animals, with elevated baseline cort levels generally assumed to indicate individuals or populations in worse condition and with lower fitness (the cort-fitness hypothesis). the relationship between cort and fitness is rarely validated and studies investigating the cort-fitness relationship often find results inconsistent with the cort-fitness hypothesis. the inconsistency of these studies may result in part from ... | 2009 | 19135999 |
| seasonal patterns in tree swallow prey (diptera) abundance are affected by agricultural intensification. | in many parts of the world, farmland bird species are declining at faster rates than other birds. for aerial insectivores, this decline has been related to a parallel reduction in the abundance of their invertebrate prey in agricultural landscapes. while the effects of agricultural intensification (ai) on arthropod communities at the landscape level have been substantially studied in recent years, seasonal variation in these impacts has not been investigated. to assess the contention that intens ... | 2013 | 23495641 |
| hydrogen isotope variability in prairie wetland systems: implications for studies of migratory connectivity. | hydrogen isotopes (delta2h) are often used to infer the origins of migratory animals based on the strong correlation between deuterium content of tissues and long-term patterns of precipitation. however, the extreme flood and drought dynamics of surface waters in prairie wetland systems could mask these expected correlations. we investigated h isotopic variability in an aquatic food web associated with tree swallows (tachycineta bicolor) that rely heavily on wetland-derived aerial insects for fo ... | 2013 | 23495640 |
| temperature effects on food supply and chick mortality in tree swallows (tachycineta bicolor). | tree swallow (tachycineta bicolor) breeding success in ithaca, ny, usa, over the past quarter century has shown generally healthy fledgling production punctuated by years of high nestling mortality. this study tested the potential effects that temperature may have on the food supply and breeding success of swallows. data from 17 years of daily insect samples were used to relate flying insect abundances to daily maximum temperatures and to define "cold snaps" as strings of consecutive days when t ... | 2013 | 23468236 |
| life history trade-offs and behavioral sensitivity to testosterone: an experimental test when female aggression and maternal care co-occur. | research on male animals suggests that the hormone testosterone plays a central role in mediating the trade-off between mating effort and parental effort. however, the direct links between testosterone, intrasexual aggression and parental care are remarkably mixed across species. previous attempts to reconcile these patterns suggest that selection favors behavioral insensitivity to testosterone when paternal care is essential to reproductive success and when breeding seasons are especially short ... | 2013 | 23342089 |
| adult tree swallow survival on the polychlorinated biphenyl-contaminated hudson river, new york, usa, between 2006 and 2010. | the upper hudson river basin in east central new york, usa, is highly contaminated, primarily with polychlorinated biphenyls (pcbs). reduced adult survival has been documented in tree swallows (tachycineta bicolor) at a similarly pcb-contaminated river system in western massachusetts. the purpose of the present study was to assess whether adult survival of tree swallows was likewise affected in the hudson river basin. between 2006 and 2010, a total of 521 female tree swallows were banded, of whi ... | 2012 | 22639085 |
| ambient noise increases missed detections in nestling birds. | ambient noise can mask acoustic cues, making their detection and discrimination difficult for receivers. this can result in two types of error: missed detections, when receivers fail to respond to the appropriate cues, and false alarms, when they respond to inappropriate cues. nestling birds are error-prone, sometimes failing to beg when parents arrive with food (committing missed detections) or begging in response to stimuli other than a parent's arrival (committing false alarms). here, we ask ... | 2012 | 22357939 |
| consequences of immune system aging in nature: a study of immunosenescence costs in free-living tree swallows. | immunosenescence, the aging of the immune system, is well documented in humans and laboratory models and is known to increase infection risk, morbidity, and mortality among the old. immunosenescence patterns have recently been unveiled in various free-living populations, but their consequences in the wild have not been explored. we investigated the consequences of immunosenescence in free-living tree swallows tachycineta bicolor through a field experiment simulating a bacterial infection (challe ... | 2011 | 21661557 |
| the stress of parenthood? increased glucocorticoids in birds with experimentally enlarged broods. | variation in baseline glucocorticoid (cort) levels can be attributed, at least in part, to differences in energetic demands confronting individuals. elevated baseline cort levels are routinely interpreted as indicating individuals in poor condition, with low relative fitness. however, when greater reproductive effort increases energetic demands, individuals with high cort might paradoxically be those with the highest fitness. here, we experimentally test the hypothesis that increased reproductiv ... | 2011 | 21632615 |