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 |
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.
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.
Faccio S.D.,Vermont Center for Ecostudies |
Amaral M.,U.S. Fish and Wildlife Service |
Amaral M.,Warner University |
Martin C.J.,Audubon Society of New Hampshire |
And 2 more authors.
Journal of Raptor Research | Year: 2013
Knowledge of dispersal patterns and survival rates is essential to understand population dynamics and demography, and to develop effective long-term management strategies for species of conservation concern. In New England, Peregrine Falcons (Falco peregrinus) were extirpated as a breeding species in the 1960s. Following a captive breeding and release program, the population subsequently underwent a rapid, dispersal-based expansion into its former range, particularly during the last two decades. Use of buildings, bridges, and other human-made structures for nesting has become widespread in urban areas, where the species only infrequently nested prior to reintroduction. We analyzed encounters of Peregrine Falcons banded as nestlings in the six New England states between May 1990 and June 2009 to determine: (a) differences in dispersal patterns (distance and direction) by sex; (b) differences in movement and natal dispersal among birds from cliff and artificial nest sites; (c) causes of mortality; and (d) effects of sex, age, and natal habitat type on survivorship. Of 986 Peregrine Falcons banded, 24% were encountered again at least once by December 2009. Although most encounters (76%) occurred within the study area, 24% were outside New England in eight other eastern states, three Canadian provinces, Cuba, and Nicaragua. Five percent of the marked population was later confirmed at breeding territories in the eastern U.S.A., primarily in New England. Females dispersed greater distances (natal dispersal = 152.6 km; range = 70.2-853.5 km; n = 28) than males (88.0 km; range = 0.03-1009.7 km; n = 22). New England peregrines showed a strong tendency to settle at nest types similar to those on which they were raised (rural cliff vs. urban structures); however, we documented movement from urban to rural habitats and vice versa in equal proportions. The causes of mortality for 122 recovered birds included unknown (61%), collisions with aircraft (11%), collisions with stationary objects (8%), falling from nest site (8%), collisions with vehicles or trains (7%), gunshot wounds (2%), entanglement in fishing gear (1%), and poisoning (1%). Most deaths occurred among first-year (68%) and second-year (11%) birds, with first-year peregrines experiencing significantly higher mortality than other age classes. The estimated annual survival rate for second-year and adult falcons combined was 81%, whereas our estimate for first-year birds was only 9%; however, the latter rate likely is a significant underestimate. We found no effect of natal habitat or sex on survival. © 2013 The Raptor Research Foundation, Inc.
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.