Ecostudies Institute

Mount Vernon, WA, United States

Ecostudies Institute

Mount Vernon, WA, United States
Time filter
Source Type

Frieze R.D.,Ecostudies Institute | Lloyd J.D.,Ecostudies Institute | Lloyd J.D.,Vermont Center for Ecostudies
Wilson Journal of Ornithology | Year: 2017

Soft-part coloration can be a useful method for determining the age of a bird. For example, hatch-year and early second-year Mangrove Cuckoos (Coccyzus minor) are supposedly distinguishable from older birds based on the presence of a dusky gray eye-ring; individuals gain a vivid yellow eye-ring in their second year of life that they retain for the rest of adulthood. However, observational data collected on banded Mangrove Cuckoos throughout the year indicate that eye-ring coloration varies seasonally rather than with age. We captured and banded two individuals in early spring, each with a yellow eye-ring. Re-sightings of these individuals later in the spring and early summer revealed that the eye-ring had changed to a dusky gray color. Subsequent re-sightings of these individuals again in the fall and winter revealed that both once again had a yellow eye ring. In reviewing photographs and notes taken during observation of marked and unmarked individuals, we determined that this pattern-a yellow eye-ring during late summer, fall, and winter (nonbreeding) and a dusky-gray eye-ring during spring and early summer (breeding)-was consistent across individuals in the population in Florida that we studied.

Murphy S.P.,U.S. Geological Survey | Virzi T.,Ecostudies Institute | Sanders F.,South Carolina Department of Natural Resources
Waterbirds | Year: 2017

The conservation of a species is reliant on identifying threats to critical vital rates such as survival and dispersal. Accurate estimates of these vital rates and the factors that affect them can be used to better manage populations. The USA Atlantic Coast population of American Oystercatchers (Haematopus palliatus) benefits from a large-scale conservation effort, but this long-lived species remains especially sensitive to fluctuations in adult survival. The model used here and 8 years of mark-resight data from three breeding populations with varying migration strategies from the United States (migratory: Massachusetts and New Jersey; non-migratory: South Carolina) were used to estimate adult survival and site fidelity. Results indicated a resident population in South Carolina with 100% of the breeding population wintering in that State, a migratory population in Massachusetts with the majority of individuals wintering in Florida (42%), and a partially migratory population in New Jersey with a portion of the breeding population overwintering in that State (33%). Annual adult survival did not vary among populations. Although the average estimate of adult survival was high (0.89), there was an apparent decline in adult survival (from 0.94 to 0.83) over the study period. Given strong site fidelity (0.91), adult mortality is a critical factor for the viability of local populations.

Lloyd J.D.,Vermont Center for Ecostudies | Lloyd J.D.,Ecostudies Institute
PeerJ | Year: 2017

I used radio-telemetry to track the movements of Mangrove Cuckoos (Coccyzus minor)captured in southwest Florida. Relatively little is known about the natural history ofMangrove Cuckoos, andmygoal was to provide an initial description of how individualsuse space, with a focus on the size and placement of home ranges. I captured andaffixed VHF radio-transmitters to 32 individuals between 2012 and 2015, and obtaineda sufficient number of relocations from 16 of them to estimate home-range boundariesand describe patterns of movement. Home-range area varied widely among individuals,but in general was roughly four times larger than expected based on the body sizeof Mangrove Cuckoos. The median core area (50% isopleth) of a home range was42 ha (range: 9-91 ha), and the median overall home range (90% isopleth) was 128ha (range: 28-319 ha). The median distance between estimated locations recordedon subsequent days was 298 m (95% CI [187 m-409 m]), but variation within andamong individuals was substantial, and it was not uncommon to relocate individuals>1 km from their location on the previous day. Site fidelity by individual birds waslow; although Mangrove Cuckoos were present year-round within the study area, Idid not observe any individuals that remained on a single home range throughout theyear. Although individual birds showed no evidence of avoiding anthropogenic edges,they did not incorporate developed areas into their daily movements and home rangesconsisted almost entirely of mangrove forest. The persistence of the species in the studyarea depended on a network of conserved lands-mostly public, but some privatelyconserved land as well-because large patches of mangrove forest did not occur on tractsleft unprotected from development. © 2017 Lloyd.

Hobson K.A.,Environment Canada | Slater G.L.,Ecostudies Institute | Lank D.B.,Simon Fraser University | Milner R.L.,P.O. Box 1100 | Gardiner R.,Simon Fraser University
Condor | Year: 2013

On the western coast of North America, several estuaries provide shorebirds with important winter and stopover habitat. These habitats include not only aquatic estuarine resources but also adjacent upland agricultural lands. The extent to which shorebirds use estuarine vs. upland habitats at these stopover sites is difficult to quantify but crucial to designing strategies for their conservation. We measured stable isotopes (δ13C, δ15N) in whole blood of Dunlins (Calidris alpina) and their prey from two major estuaries in north Puget Sound, Washington, USA, to estimate their relative use of estuarine vs. upland agricultural zones. We identified four isotopically distinct dietary inputs (agriculture high in 15N, other agriculture, marsh/marine, and freshwater plume). Isotopic sampling and modeling was informed by movements and habitat use derived from radiotelemetry. This isotopic structure allowed us to conclude that these Dunlins obtained about 62% of the protein in their diet from agricultural lands and 38% from the estuary. Our results underline the urgent need to combine management of estuaries and upland agricultural areas in strategies for shorebird conservation. © The Cooper Ornithological Society 2013.

Lloyd J.D.,Ecostudies Institute | Doyle T.,U.S. Fish and Wildlife Service
Journal of Field Ornithology | Year: 2011

The avifauna of south Florida's mangrove forests is unique and relatively unstudied. The population status of landbirds that breed in these forests is currently unknown, and this lack of information is especially problematic for species that have North American ranges limited almost exclusively to Florida's mangroves. To address this information gap, we estimated trends in abundance using data generated during bird surveys conducted from 2000 to 2008 at 101 points in mangrove forests in southwestern Florida. We found that populations of two of three mangrove-dependent species that breed in these forests, Black-whiskered Vireos (Vireo altiloquus) and Mangrove Cuckoos (Coccyzus minor), declined significantly during our study. In contrast, only one of seven species with a broader North American range (Red-bellied Woodpecker, Melanerpes carolinensis) declined in abundance. No species increased in abundance. The Mangrove Cuckoo population exhibited the greatest decline, with numbers declining 87.1% from 2000 to 2008. Numbers of Black-whiskered Vireos declined 63.9%. These declines coincided with the outbreak of West Nile virus that has been linked to population declines of other North American birds, but we could not rule out other potential causes, including changes in the quality or extent of breeding or wintering habitat. ©2011 The Authors. Journal of Field Ornithology ©2011 Association of Field Ornithologists.

Slater G.L.,Ecostudies Institute | Altman B.,American Bird Conservancy
Northwest Science | Year: 2011

Avian reintroductions are an important conservation tool, but landbird reintroductions are substantially underrepresented compared to other avian taxa, which hinders progress in improving the value and efficacy of landbird reintroductions. We document an ongoing reintroduction of Western bluebirds (Sialis mexicana) to their historic range in the prairie-oak ecosystem on San Juan Island, Washington. Further, we assess the success of preliminary reintroductions and discuss the feasibility of further landbird reintroductions in this threatened ecosystem in the Pacific Northwest. We released 80 adults and 26 juveniles from 2007 to 2010 using a variety of soft-release techniques, and we collected demographic data on the reintroduced population. The program achieved preliminary criteria of success: individuals were safely translocated to the release site, and released individuals established breeding territories; both translocated individuals and their offspring reproduced successfully; and the reintroduced population grew each year. Results reinforced the use of large aviaries and two to three week holding periods for reintroductions of the genus Sialia, and also showed, for the first time, that the reintroduction of a migratory landbird can be effective. Besides contributing to bird conservation, the reintroduction generated tangible accomplishments towards conservation of prairie-oak habitats through education and habitat protection. Reintroductions of Western bluebirds to former parts of their range and of slender-billed white-breasted nuthatch to south Puget Sound should be considered practical options for future avian conservation efforts in the prairie-oak ecosystem. © 2011 by the Northwest Scientific Association.

Lloyd J.D.,Ecostudies Institute | Slater G.L.,Ecostudies Institute | Snyder J.R.,U.S. Geological Survey
Fire Ecology | Year: 2012

Standing dead trees, or snags, are an important habitat element for many animal species. In many ecosystems, fire is a primary driver of snag population dynamics because it can both create and consume snags. The objective of this study was to examine how variation in two key components of the fire regime-fire-return interval and season of burn-affected population dynamics of snags. Using a factorial design, we exposed 1 ha plots, located within larger burn units in a south Florida slash pine (Pinus elliottii var. densa Little and Dorman) forest, to prescribed fire applied at two intervals (approximately 3-year intervals vs. approximately 6-year intervals) and during two seasons (wet season vs. dry season) over a 12-to 13-year period. We found no consistent effect of fire season or frequency on the density of lightly to moderately decayed or heavily decayed snags, suggesting that variation in these elements of the fire regime at the scale we considered is relatively unimportant in the dynamics of snag populations. However, our confidence in these findings is limited by small sample sizes, potentially confounding effects of unmeasured variation in fire behavior and effects (e.g., intensity, severity, synergy with drought cycles) and wide variation in responses within a treatment level. The generalizing of our findings is also limited by the narrow range of treatment levels considered. Future experiments incorporating a wider range of fire regimes and directly quantifying fire intensity would prove useful in identifying more clearly the role of fire in shaping the dynamics of snag populations.

Lloyd J.D.,Vermont Centerfor Ecostudies | Lloyd J.D.,Ecostudies Institute
PLoS ONE | Year: 2016

Mangrove Cuckoo (Coccyzus minor) exhibits substantial phenotypic variation across its geographic range, but the significance of this variation for taxonomy remains unresolved. Using measurements of bill size and ventral color recorded from 274 museum specimens, I found that variation in these traits was clinal. No named subspecies was reciprocally diagnosable from all others, and none was distinguishable from the nominate form, such that previously recognized subspecific distinctions are invalid. Greatest differences in phenotype occurred between populations in Florida, the Bahamas, and the Greater Antilles-characteristically small-billed- and those in the Lesser Antilles, which had larger bills. Phenotypically intermediate individuals on the geographically intermediate islands of Barbuda and Antigua linked these two extremes. Individuals intermediate in bill size and color also characterized populations from throughout the remainder of the range in northern South America and Middle America. Mechanisms maintaining the fairly pronounced phenotypic differences between nearby populations of Greater and Lesser Antillean birds are unknown, yet the geographic proximity of these populations suggests that they probably persist despite occasional gene flow, and may be adaptive. Copyright: © 2016 John D. Lloyd. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Lloyd J.D.,Ecostudies Institute | Slater G.L.,Ecostudies Institute
Natural Areas Journal | Year: 2012

Managers of natural areas often employ controlled disturbances as a tool to manage plant and animal populations. This approach assumes that disturbances are responsible for the structure of biological communities and that appropriate application of the disturbance will ensure the persistence of native plants and animals. If species in a community do not respond predictably to variation in disturbance regime, then management strategies based on emulating disturbance may fail to ensure the persistence of all species. In this study, we examined the efficacy of using prescribed fire as a tool for managing populations of breeding and wintering birds in the pine rocklands of southern Florida. We found that variation in fire history had little effect on vegetation structure and no effect on bird abundance. Instead, vegetation structure was more closely associated with water-table elevation and soil type, whereas most of the observed variation in the structure of bird assemblages appeared to be a function of degree of urbanization in the landscape. That the structure and composition of bird assemblages was independent of variation in fire history suggests that manipulating the fire regime, at least within the range of variability observed in this study, is unlikely to prove effective as a means to manage bird populations. In general, our results argue for caution in assuming that a single process can be used to control the structure of biological communities, especially in systems where landscapes have been substantially altered by human activity.

Lloyd J.D.,Ecostudies Institute | Slater G.L.,Ecostudies Institute
Natural Areas Journal | Year: 2011

At the broadest spatial scales, the distribution of south Florida slash pine (Pinus elliottii var. densa Little and Dorman) is limited by variation in fire and hydrological regimes, occurring only in relatively dry areas and succeeding to hardwood hammocks when fire is absent. These same forces also appear important in driving smaller-scale variation in the structure and composition of slash-pine forests. Important gaps remain, however, in our understanding of how plants and animals in slash-pine ecosystems respond to variation in fire and hydrological regimes. We addressed this issue for one taxon - landbirds - by estimating density at 285 locations in southwest Florida that differed in fire history and water-table elevation. Bird densities during the breeding season and during the winter did not vary appreciably as a function of either fire history or water-table elevation, and neither did vegetation structure at our survey locations. Birds and plants in this fire-climax forest are both resilient and resistant to changes brought about by frequent, low-intensity fire, and we suspect that significant effects of variation in fire history are only observable under extreme conditions (e.g., complete fire suppression) outside of the range of variation that we sampled. Water-table elevation had a stronger, albeit still small, effect on bird densities and vegetation structure, but the effects were difficult to generalize. Sampling across a broader range of hydrological conditions may yield valuable insight into the structure of pineland bird assemblages, especially given the likelihood that ecosystem restoration efforts in south Florida will produce substantial changes in water-table elevation.

Loading Ecostudies Institute collaborators
Loading Ecostudies Institute collaborators