Vireo Griseus Research Articles

Phenotypic signatures of urbanization? Resident, but not migratory, songbird eye size varies with urban-associated light pollution levels.

Urbanization now exposes large portions of the earth to sources of anthropogenic disturbance, driving rapid environmental change and producing novel environments. Changes in selective pressures as a result of urbanization are often associated with phenotypic divergence; however, the generality of phenotypic change remains unclear. In this study, we examined whether morphological phenotypes in two residential species (Carolina Wren [Thryothorus ludovicianus] and Northern Cardinal [Cardinalis cardinalis]) and two migratory species (Painted Bunting [Passerina ciris], and White-eyed Vireo [Vireo griseus]), differed between urban core and edge habitats in San Antonio, Texas, USA. More specifically, we examined whether urbanization, associated sensory pollution (light and noise) and brightness (open, bright areas cause by anthropogenic land use) influenced measures of avian body (mass and frame size) and lateral eye size. We found no differences in body size between urban core and edge habitats for all species except the Painted Bunting, in which core-urban individuals were smaller. Rather than a direct effect of urbanization, this was due to differences in age structure between habitats, with urban-core areas consisting of higher proportions of younger buntings which are, on average, smaller than older birds. Residential birds inhabiting urban-core areas had smaller eyes compared to their urban-edge counterparts, resulting from a negative association between eye size and light pollution and brightness across study sites; notably, we found no such association in the two migratory species. Our findings demonstrate how urbanization may indirectly influence phenotypes by altering population demographics and highlight the importance of accounting for age when assessing factors driving phenotypic change. We also provide some of the first evidence that birds may adapt to urban environments through changes in their eye morphology, demonstrating the need for future research into relationships among eye size, ambient light microenvironment use, and disassembly of avian communities as a result of urbanization.

Local weather affects body condition of three North American songbird species on the Texas Coast.

Body condition is a frequently used physiological indicator of avian health and can be affected by an array of environmental variables. Although a number of studies have investigated the specific effects of individual weather variables on body condition in birds, few have analyzed the effects of both temperature and precipitation within the context of an extreme weather event such as hurricanes. In this study, we examined the relationship between breeding-season body condition and daily maximum temperature, daily minimum temperature, and monthly total precipitation for three passerine bird species at the Welder Wildlife Refuge near Rockport, Texas. We also evaluated yearly changes in body condition over a 12-year period for northern cardinals (Cardinalis cardinalis), painted buntings (Passerina ciris), and white-eyed vireos (Vireo griseus), focusing on the extreme precipitation event of Hurricane Harvey, which caused heavy localized flooding. We found that body condition declined with average daily minimum and maximum temperatures, while precipitation had varied, species-specific effects in the three species analyzed. Our results also suggest that northern cardinals experienced a notable reduction in average body condition in the 2 years following Hurricane Harvey. Taken together, we conclude that short-term precipitation and temperature drivers can be important correlates of body condition in songbirds and that severe weather events may reduce body condition in some bird species.

The relationships of breeding stage to daytime singing behaviour and song perch height in Bermuda white‐eyed vireos Vireo griseus bermudianus

Bird song is crucial for attracting mates and defending territories, but different types of song or different singing behaviours may be involved in acquiring or maintaining each resource. Furthermore, male songbirds may adjust when and where they sing throughout the breeding season, depending on their breeding stage. However, such relationships remain untested in several avian taxa. Here, we studied male Bermuda white‐eyed vireos Vireo griseus bermudianus, a passerine with two distinct song types (discrete and rambling), to test the mate attraction and territory defence hypotheses. We compare song production and song perch height among different stages of the breeding season and during the non‐breeding season. We show that male vireos produce both song types during the breeding and non‐breeding seasons, suggesting dual roles in mate choice and territorial defence. Song production did not differ significantly between the breeding and non‐breeding seasons, but, within the breeding season, males without nesting duties sang significantly more songs than males with nesting duties. Song perch height was higher during the breeding season versus non‐breeding season, among males without nesting duties compared to males with nesting duties, and when males produced discrete versus rambling songs. Our findings suggest that male vireos increase their conspicuousness to prospecting females by increasing song production and song perch height, and that they sing during the breeding and non‐breeding seasons to defend year‐round territories. Collectively, our study supports the mate attraction and territory defence hypotheses of bird song.

Territorial responses of male Bermuda White‐eyed Vireos (Vireo griseussubsp.bermudianus) reflect phylogenetic similarity of intruders and acoustic similarity of their songs

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Evidence for Suspension of Prebasic Molt in a White-eyed Vireo

Evidence for Suspension of Prebasic Molt in a White-eyed Vireo

Effects of pine-oak woodland restoration on breeding bird densities in the Ozark-Ouachita Interior Highlands

Restoration is underway to restore lost or degraded remnants of savanna and woodland in the Midwestern United States in the hopes of restoring floristic and wildlife diversity. Information is needed on the effects of pine savanna-woodland restoration on bird abundance to inform management decisions. We conducted point-count surveys for 19 bird species across the gradient of savanna, woodland, and forest in restored and non-restored areas throughout the Ozark-Ouachita Highlands in parts of Missouri, Arkansas, and Oklahoma during the 2013–2015 breeding seasons. We estimated densities of 16 species using distance sampling to account for detection probability, and we determined relationships of bird abundance with management and vegetation variables by evaluating support for a priori models. Densities of early-successional and generalist species were positively related, and interior-forest species negatively related, to restoration. Densities of Brown-headed Nuthatch (Sitta pusilla), Eastern Towhee (Pipilo erythrophthalmus), Eastern Wood-Pewee (Contopus virens), Pine Warbler (Setophaga pinus), Prairie Warbler (Setophaga discolor), Red-headed Woodpecker (Melanerpes erythrocephalus), White-eyed Vireo (Vireo griseus), and Yellow-breasted Chat (Icteria virens) were positively related to prescribed fire activity. Blue-winged Warbler (Vermivora cyanoptera), Kentucky Warbler (Geothlypis formosa), and Yellow-breasted Chat densities were positively related to tree thinning. Many species had higher densities in areas with less canopy cover, tree density, and forest cover. Acadian Flycatcher (Empidonax virescens), Black-and-white Warbler (Mniotilta varia), Ovenbird (Seiurus aurocapilla), Wood Thrush (Hylocichla mustelina), and Worm-eating Warbler (Helmitheros vermivorum) were negatively related to one or more aspects of restoration treatment and generally preferred areas with greater tree density and canopy cover. Summer Tanagers (Piranga rubra) were abundant but density was not strongly related to management or vegetation variables. Restoration provided breeding habitat for disturbance-dependent species and woodland generalists, many of which are species of conservation concern, but canopy cover generally remained too great for species that require more open savanna.

Brooding and provisioning of nestlings by male and female White-eyed Vireos (Vireo griseus)

Most species of songbirds exhibit biparental care, but, for many taxa and species, little is known about the relative contributions of males and females in brooding and provisioning nestlings. Additional studies of the contributions of males and females in brooding and feeding nestlings are needed to better understand the respective roles of males and females as well as the factors that might contribute to interspecific variation in those roles. We examined the roles of adult male and female White-eyed Vireos ( Vireo griseus) in brooding and provisioning nestlings in east-central Kentucky during the 1996 breeding season. Nests were located by monitoring adult behavior and checking likely nest sites. Once eggs hatched, nests were video-recorded to monitor the behavior of adults. Subsequent review of videos revealed that both male and female White-eyed Vireos brooded young and that males provisioned nestlings at higher rates than females. In contrast to males in many other species of songbirds, male White-eyed Vireos assisted in brooding young and provisioned nestlings at higher rates than their mates. One possible explanation for this is that low rates of extra-pair paternity might increase male confidence of their paternity status. Parental care provided by male White-eyed Vireos may also limit energy expenditure by their mates and increase the likelihood of females re-nesting if nests are predated or initiating second nesting attempts if initial attempts are successful.

Responses of early-successional songbirds to a two-stage shelterwood harvest for oak forest regeneration

BackgroundThe early stage of forest succession following disturbance is characterized by a shift in songbird composition as well as increased avian richness due to increased herbaceous growth in the forest understory. However, regeneration of woody species eventually outcompetes the herbaceous understory, subsequently shifting vegetation communities and decreasing availability of vital foraging and nesting cover for disturbance-dependent birds, ultimately resulting in their displacement. These early stages following forest disturbance, which are declining throughout the eastern United States, are ephemeral in nature and birds depend on such disturbances for nesting and other purposes throughout their lives.MethodsWe investigated the use of a two-stage shelterwood method to manage long-term persistence of seven early successional songbirds over a 13-year period in an upland hardwood forest within the southern end of the mid-Cumberland Plateau in the eastern United States.ResultsCanopy and midstory gaps created after initial harvest were quickly exploited by tree growth and canopy cover returned to these areas, accelerating the displacement of early-successional species. Woody stem densities increased substantially following stage two harvest as advanced tree regeneration combined with the re-opening of the overstory layer increased resource competition for early-successional plants in the understory. Carolina Wren (Thryothorus ludovicianus), Eastern Towhee (Pipilo erythrophthalmus), Indigo Bunting (Passerina cyanea), and Yellow-breasted Chat (Icteria virens) were characterized by immediate increases following initial harvest in 2001; while the American Goldfinch (Spinus tristis), Prairie Warbler (Setophaga discolor), and White-eyed Vireo (Vireo griseus) did not show an immediate response. Stage two harvest in 2011 rejuvenated vegetation which benefitted focal species, with six of seven species showing increases in densities between 2010 and 2012.ConclusionThe two-stage shelterwood method created conditions advantageous to early-successional birds by helping to re-establish understory vegetation through periodic disturbance to the canopy layer. This method provides evidence that early-successional species can be managed long-term (> 15 years) while using relatively small spatial disturbance through the two-stage shelterwood method.

Comparative reproductive ecology of co-occurring rare and common vireos in shrublands and woodlands

ABSTRACT Black-capped Vireos (Vireo atricapilla) and White-eyed Vireos (Vireo griseus) are closely related and ecologically similar. Despite these similarities, the White-eyed Vireo is widely distributed and common, whereas the Black-capped Vireo has a restricted breeding range and is currently federally endangered in the United States and Mexico. Here we address this apparent paradox with a comparative ecological study of co-occurring Black-capped and White-eyed vireos. We studied vireos in shrublands and woodlands in central Texas, USA, in 2013 and 2014. We used point count surveys (n = 256) and nest monitoring (n = 144) to determine arrival dates, settlement patterns, nest site selection, and nest survival relative to temporal and habitat factors. Additionally, we conducted reciprocal playback trials (n = 16) to test for the presence of interspecific aggression. White-eyed Vireos arrived first and established territories in both habitats with equal probability. Black-capped Vireos arrived after White-e...

Bird response to intercropping switchgrass within a loblolly pine plantation

ABSTRACTGlobal interest in alternative, renewable energy sources has led to the development of novel land‐use practices and techniques aimed at maximizing energy production while also minimizing environmental, economic, and societal costs. One such novel practice is intercropping switchgrass (Panicum virgatum) within loblolly pine (Pinus taeda) plantations. However, minimal knowledge currently exists regarding the influence of intercropping switchgrass on ecosystem functions and services and biological diversity of loblolly pine plantations. Therefore, we assessed the influence of intercropping switchgrass on breeding‐bird species density and community composition during 2014–2015 in Mississippi, USA. We had 3,619 detections encompassing 39 species, with 10 species used in density analysis. Breeding‐bird density estimates did not significantly differ for 8 out the 10 species modeled between control and intercrop treatments. However, white‐eyed vireo (Vireo griseus) and indigo bunting (Passerina cyanea) densities differed between intercrop and control, with white‐eyed vireos having a greater density on control and indigo buntings having a greater density on intercrop. Treatment influenced breeding‐bird community composition, with monocultures supporting an atypical species composition within a loblolly pine plantation, but species composition did not differ between control and intercrop treatments. © 2017 The Wildlife Society.

Abundance and Distribution of Mangrove Landbirds in Florida

Abstract Florida's mangroves provide habitat for an eclectic mix of bird species, including five taxa rarely found elsewhere in North America. Little is known of the natural history of any of these birds, which poses an obstacle to effective conservation. To help fill some of the basic gaps in our understanding of this avifauna, we conducted extensive surveys in Florida's mangroves during 2008–2011, with the goals of quantifying distribution and estimating breeding-season abundance of mangrove landbirds. We detected 80 species in the mangroves during the breeding season; most were species in Passeriformes (n = 29), but other important taxa included Ciconiiformes (n = 13) and Charadriiformes (n = 12). We focused our analysis on the 18 landbird species (including members of Falconiformes, Columbiformes, Cuculiformes, Piciformes, and Passeriformes) that had >90 detections and that were detected at >5% of the survey points. The landbird avifauna of Florida's mangroves is lower in both species richness and total number of individuals than other vegetation types of southern Florida. The breeding assemblage of mangrove landbirds was dominated numerically by four species that accounted for 58% of all detections of landbirds (this same group accounted for 52% of detections of all species encountered): red-bellied woodpecker Melanerpes carolinus, northern cardinal Cardinalis cardinalis, Florida prairie warbler Setophaga discolor paludicola, and white-eyed vireo Vireo griseus. Only Florida prairie warbler is restricted to mangroves; the other three species are common throughout much of eastern North America. Each of these species was also widely distributed in the mangroves. Of the other species unique to the mangroves of Florida, black-whiskered vireo Vireo altiloquus was widespread but was less abundant than Florida prairie warbler. White-crowned pigeon Patagioenas leucocephala, gray kingbird Tyrannus dominicensis, and Cuban yellow warbler Setophaga petechia gundlachi were detected only in the Florida Keys and on the islands of Florida Bay, but were found in high densities where present. Mangrove cuckoo Coccyzus minor was found throughout the mangroves but occurred at very low density and at only a small percentage of survey points. Overall, mangrove landbirds reflect the biogeographic condition common throughout southern Florida, in which largely temperate faunas coexist with largely tropical floras. The predominance of temperate species in Florida's mangroves has produced an avifauna apparently more species-rich than that found in the mangroves of West Indian islands, which include additional tropical species but no species of temperate origin.

Understanding nest success and brood parasitism in the endangered Black-capped Vireo: comparisons with two sympatric songbirds

Abstract Nest predation and brood parasitism likely cause declines in many songbird species, yet the rate of these declines varies among species. Simultaneously studying co-occurring species with overlapping territories provides an opportunity to identify differences among the species that may explain differential reproductive success. We monitored nests of three co-occurring songbird species to determine whether the federally endangered Black-capped Vireo (Vireo atricapilla) experienced lower reproductive success than Northern Cardinals (Cardinalis cardinalis) and White-eyed Vireos (V. griseus) on private lands with and without trapping of brood parasites. We assessed if habitat metrics and nesting phenology were associated with nest success and frequency of brood parasitism by Brown-headed Cowbirds (Molothrus ater) to determine if these characteristics explain poor reproductive success. We monitored 188 nests in shrubland and ecotones with woodlands in central Texas from 2006–2008. We found species-spec...

Breeding bird response to habitat and landscape factors across a gradient of savanna, woodland, and forest in the Missouri Ozarks

Savanna and woodland were once common in the Midwest, but land use changes have led to increasing scarcity of these communities. These transitional habitats are being restored across the Midwest, but few studies have evaluated the response of wildlife to restoration or the vegetative gradient created by management. We conducted point counts for 25 songbirds at sites undergoing savanna or woodland restoration and nearby non-managed forest sites across the Ozark Highlands of Missouri during the 2009–2011 breeding seasons; these sites represented a gradient of canopy cover and tree density from savanna to woodland to forest. We estimated density of 17 species with ⩾50 detections using distance-based models, which adjust estimates by the detection probability. Bird densities were more strongly related to habitat structure, fire history, and landscape composition than simply whether a site was managed or non-managed. Mature forest species such as Acadian Flycatcher (Empidonax virescens), Northen Parula (Setophaga americana), Red-eyed Vireo (Vireo olivaceous), and Worm-eating Warbler (Helmitheros vermivorum) were generally more abundant at points with more trees, higher canopy cover, lower shrub density, and less frequent or no fire in the 20years prior to surveys. Woodland generalists such as Blue-gray Gnatcatcher (Polioptila caerulea), Eastern Wood-Pewee (Contopus virens), Great Crested Flycatcher (Myiarchus crinitus), Summer Tanager (Piranga rubra), and Yellow-billed Cuckoo (Coccyzus americanus) were generally more abundant at points with less landscape forest cover (10-km scale), more large and fewer small trees, intermediate to high canopy cover, lower shrub density, and recent or frequent fire. Early-successional species such as Eastern Towhee (Pipilo erythrophthalmus), Field Sparrow (Spizella pusilla), Indigo Bunting (Passerina cyanea), Kentucky Warbler (Geothlypis formosa), Prairie Warbler (Setophaga discolor), White-eyed Vireo (Vireo griseus) and Yellow-breasted Chat (Icteria virens) were generally more abundant at points with lower canopy cover, recent or frequent fire, and higher shrub density. Brown-headed Cowbirds (Molothrus ater) were more abundant at points with intermediate landscape forest cover and lower canopy cover. Restored sites provided breeding habitat for woodland generalists and early-successional species of conservation concern; however, managed landscapes with more open canopy and herbaceous ground cover may be required for species more indicative of open savannas.

Results of 20 years of experimental forest management on breeding birds in Ozark forests of Missouri, USA

Understanding the relationship between forest management and bird populations requires understanding the effects of silvicultural practices on avian demography at large spatio-temporal scales. The Missouri Ozark Forest Ecosystem Project (MOFEP) is a long-term, large-scale manipulative experiment testing the effects of even-aged (3–13ha cuts over 10–15% of the site; n=3), uneven-aged (0.03–3.14ha cuts over 57% of the site; n=3), and no harvest forest management on ecosystem level responses. We report on the effects of these management systems on the density and reproductive success of 11 songbird species from 5years of pre-harvest (1991–1995) to 14years of post-harvest (1997–2010). Density of four of the five mature forest species were lower after harvest in all management types and did not return to pre-harvest density, even in no harvest sites. Ovenbird (Seiurus aurocapilla) and Wood Thrush (Hylocichla mustelina) responded most negatively to even-aged management in the early post-harvest period (1997–2003) where density was significantly lower than in no harvest sites. Kentucky Warbler (Geothlypis formosa) density increased on uneven-aged and even-aged sites during early post-harvest, but returned to pre-harvest density on both management types by 14years post-harvest. Acadian Flycatcher (Empidonax virescens) and Worm-eating Warbler (Helmitheros vermivorus) had lower density in all treatments post-harvest. Among the six early-successional species, density of Blue-winged Warbler (Vermivora cyanoptera), Hooded Warbler (Setophaga citrina), Indigo Bunting (Passerina cyanea) White-eyed Vireo (Vireo griseus) and Yellow-breasted Chat (Icteria virens) were significantly higher in even-aged and uneven-aged sites than in no harvest sites after harvest. Density of Prairie Warbler (Setophaga discolor) were significantly higher only in even-aged management after harvest. Prairie Warbler, Hooded Warbler, and White-eyed vireo appeared on the study sites following harvest while Indigo Bunting, Prairie Warbler, and Yellow-breasted Chat were absent from the study area 14years post-harvest. Nest survival of mature forest and early-successional species did not change significantly from the pre- to the late post-harvest period or with forest management. Brood parasitism rates remained low from pre-harvest to late post-harvest, but parasitism rates were higher for early-successional species (4%) than mature forest species (1%). Although forest management had variable effects on species, we suggest a modified version of even-aged management could maximize benefits to early-successional species while minimizing decreases in mature forest bird species in central hardwood forests. Rather than the current prescription to harvest 10–15% of the mature stands every 15years, we recommend harvesting approximately half the number of mature stands with a shorter re-entry period of 8–10years.

Birds and Land Classes in Young Forested Landscapes

In the Mississippi Coastal Plain of the southeastern United States, we explored relationships among bird species and vegetation types and landscape characteristics at four different scales. We modeled abundance of priority avian species from Breeding Bird Surveys using land class metrics at 0.24, 1, 3, and 5-km extents. Our modeling method was logistic regression and model selection was based on Akaike’s Information Criteria and validation with reserved data. Northern bobwhite (Colinus virginianus), red-headed woodpecker (Melanerpes erythrocephalus), northern parula (Parula americana), Swainson’s warbler (Limnothlypis swainsonii), prairie warbler (Dendroica discolor), hooded warbler (Wilsonia citrina), and brown-headed cowbird (Molothrus ater) had models containing positive area or core area variables. White-eyed vireo (Vireo griseus) and gray catbird (Dumetella carolinensis) had models with a combination of area and edge associations at different scales. Acadian flycatcher (Empidonax virescens), red-bellied woodpecker (Melanerpes carolinus), wood thrush (Hylocichla mustelina), and yellow-breasted chat (Icteria virens) had positive edge density models. Modeling at different scales produced more complete habitat associations for most species and landscape variables were more influential at larger extents than the smallest extent. Although Mississippi is heavily forested, the landscape is unexpectedly fragmented, with small areal extents of vegetation types. Managers should seek to provide large extents of a variety of habitats, including historically representative vegetation types such as low density pine, to support persistence of a complete suite of avian species.

Effect of Sampling Blood of Nestlings on Success of Fledging in White-eyed Vireos (Vireo griseus)

Abstract Because the white-eyed vireo (Vireo griseus) is a less sensitive species than the endangered black-capped vireo (V. atricapilla), it served as a proxy to quantify potentially adverse effects of sampling blood. Success of fledging was quantified using split-sampled broods with non-bled nestlings serving as a control. Sex ratio of broods was determined, and sampling and storage methods for blood were assessed. Obtaining blood from nestlings did not affect success of fledging. The male:female ratio of nestlings was 65:35.

Opposite but analogous effects of road density on songbirds with contrasting habitat preferences

AbstractRoads are a widespread and growing form of habitat alteration, making their effects on wildlife a major conservation concern. We investigated effects of roads on occupancy patterns and stress physiology of the golden‐cheeked warbler Setophaga chrysoparia, an endangered songbird that depends on large tracts of old‐growth forest for breeding. We compared those effects in the white‐eyed vireo Vireo griseus, a common songbird that prefers to breed in scrubby habitat that is common along forest roads. In warblers, older, socially dominant males were more likely to occupy territories, but had higher baseline plasma concentrations of corticosterone, in less‐roaded habitats. In vireos, older males were equally likely to occupy territories, but, opposite to warblers, had lower baseline corticosterone concentrations, in less‐roaded habitats. In both species, the corticosterone response to acute stress was unrelated to road density, and body condition and fat stores either increased or were sustained across road density groups during the breeding season, suggesting that breeding near roads did not cause chronic stress. Our results suggest that roads can cause increased male–male competition for territories in nearby roadless habitat, and may result in higher corticosterone concentrations in dominant individuals defending preferred sites near or far from edge, depending on species habitat preferences. Increased competition and chronically elevated corticosterone levels may be of concern if they alter parental care or immunity of individuals breeding in the best habitat.

Win-stay, lose-switch and public information strategies for patch fidelity of songbirds with rare extra-pair paternity

Determining where organisms breed and understanding why they breed in particular locations are fundamental biological questions with conservation implications. Breeding-site fidelity is common in migratory, territorial songbirds and is typically thought to occur following reproductive success with a social mate and success of nearby conspecifics. It is currently unknown if frequency of extra-pair paternity in a population influences use of information about reproductive success of nearby conspecifics for site fidelity decisions. We investigated patch fidelity of white-eyed vireos (Vireo griseus) based on reproductive success and quantified frequency of extra-pair paternity. We found support only for females making patch fidelity decisions following reproductive success with a social mate. Patch fidelity of males was not associated with reproductive success of nearby conspecifics, suggesting males may not use this information when extra-pair paternity is infrequent or the association is non-existent in this species.

Habitat Use by Coastal Birds Inferred from Stable Carbon and Nitrogen Isotopes

Conservationists need to know the degree of habitat fidelity for species of conservation concern. Stable Isotope Analysis in R quantified the contribution of terrestrial vs. saltmarsh primary production sources to terrestrial passerine food webs from four habitats of Sapelo Island, Georgia (USA), saltmarsh, maritime scrub–shrub, maritime broadleaf (oak), and maritime narrowleaf (pine) forests, using δ 13C and δ 15N. Models suggested Northern Parula (Parula americana) in oak forests, White-eyed Vireos (Vireo griseus) in shrub, and Brown-headed Nuthatches (Sitta pusilla) in pine forests derived most of their food from habitats they occupied (53–100%). Saltmarsh provided 47–94% of Painted Bunting (Passerina ciris) food sources, supporting previous findings by Springborn and Meyers (2005). Thus, Painted Bunting conservation in the Southeastern USA should focus on Springborn and Meyers’ suggestion of maritime scrub–shrub habitat and forests with 50% ground cover, and patches of shrubs that are within 700 m of saltmarsh.

Energetic response to human disturbance in an endangered songbird

Physiological changes in response to environmental stressors can reveal cryptic effects of disturbance that can potentially lead to species decline. However, such responses may vary with life history. We used heart rate telemetry to continuously and instantaneously measure energy expenditure in response to human-mediated disturbance in a free-living breeding population of the endangered [International Union for Conservation of Nature, vulnerable] black-capped vireo Vireo atricapilla (n=10). Heart rate predicted 84% of energy expenditure as determined by respirometry (n=3). Each bird mounted with a 0.5 g heart rate transmitter were subjected to standardized disturbance trials for 1 or 4 h during the day, and for 1 h at night. Only 1-h daytime disturbances elicited an increase in heart rate but this was not significant when compared with control no-disturbance periods. Our findings suggest that black-capped vireos quickly acclimate to a limited amount of human disturbance during the breeding season, which may be an adaptive response for any ‘fast-living’ species with a short life span and a short and synchronized breeding season. Because similar results were reported for another fast-living species, the common white-eyed vireo Vireo griseus, we suggest that life-history traits are stronger predictors of short-term physiological responses to disturbances than population status.