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Harrington B.A.,Manomet Center for Conservation science | Hill N.P.,4380 North Main Street
Waterbirds | Year: 2010

A review of numbers and distribution of Red Knots (Calidris canutus) on the Massachusetts coast during southward migration indicates major declines beginning in the early 1970s. Overall numbers increased during the third quarter of the 20th Century, largely at mainland versus Cape Cod locations, and then declined early in the fourth quarter at the mainland-but not the Cape Cod-locations. Evidence suggests that both the mainland and the Cape Cod areas were historically used by knots having Patagonian destinations, but that recently the Cape Cod locations have increasingly been used by knots with wintering destinations in the southeastern United States, thus balancing out the declining numbers of knots with Patagonian destinations. Source

Keeton W.S.,University of Vermont | Whitman A.A.,Manomet Center for Conservation science | McGee G.C.,New York University | Goodale C.L.,Cornell University
Forest Science | Year: 2011

Managing the contribution of forest ecosystems to global carbon cycles requires accurate predictions of biomass dynamics in relation to stand development. Our study evaluated competing hypotheses regarding late-successional biomass dynamics in northern hardwood-conifer forests using a data set spanning the northeastern United States, including 48 mature and 46 old-growth stands. Continuous data on dominant tree ages were available for 29 of these and were used as an indicator of stand development. Aboveground live biomass was significantly (P < 0.001) different between mature (195 Mg/ha) and old-growth (266 Mg/ha) sites. Aboveground biomass was positively (P < 0.001) and logarithmically correlated with dominant tree age; this held for live trees (r2 = 0.52), standing dead trees (r2 = 0.36), total trees (r2 = 0.63), and downed woody debris (r2 = 0.24). In a Classification and Regression Tree analysis, stand age class was the strongest predictor of biomass, but ecoregion and percent conifer accounted for ~25-33% of intraregional variability. Biomass approached maximum values in stands with dominant tree ages of ~350-400 years. Our results support the hypothesis that aboveground biomass can accumulate very late into succession in northern hardwood-conifer forests, recognizing that early declines are also possible in secondary forests as reported previously. Empirical studies suggest a high degree of variability in biomass development pathways and these may differ from theoretical predictions. Primary forest systems, especially those prone to partial disturbances, may have different biomass dynamics compared with those of secondary forests. These differences have important implications for both the quantity and temporal dynamics of carbon storage in old-growth and recovering secondary forests. © 2011 by the Society of American Foresters. Source

Harrington B.A.,Manomet Center for Conservation science | Koch S.,U.S. Fish and Wildlife Service | Niles L.K.,Conserve Wildlife Foundation of New Jersey | Kalasz K.,The Landing
Waterbirds | Year: 2010

Southward migrating Red Knots (Calidris canutus) were surveyed on Cape Cod, Massachusetts. Unique markers, including ones applied to birds in wintering areas in North and South America, were found. Northern and southern-marked knots had different migration chronologies, plumage characteristics and flight feather molt. Knots from the two groups were found to have different foods and foraging habitats. Numbers of knots more than one year old were found to increase from mid-July to mid-August, decline during late August and then increase in SeptemberOctober. As numbers declined in August, the proportion of knots from South America decreased and, by 1 September, all remaining marked birds had been tagged in North America. Average minimum stopover durations were found to vary according to original banding locations, e.g. 8.5 (±2.6) days for South America, 14.2 (±3.2) days for Delaware Bay, 16.1 (±3.5) days for the U.S. mid-Atlantic coast and 49.5 (±24.6) days for Florida. The proportion of knots with alternate plumage was higher in JulyAugust than in September and by mid-October almost all had basic plumage. Also, low numbers (tens) of basic-plumaged knots-probably one-year-old subadults were found during JulyAugust; most had active flight feather molt. First-arriving juvenile knots were seen beginning in the third week of August and their numbers peaked in mid-September. Differential uses of foraging and roosting habitats were found to be related to migration destinations. Vital habitats that should be managed for protection of threatened Red Knots at this key southward migration stopover area were identified. Source

Andres B.A.,U.S. Fish and Wildlife Service | Johnson J.A.,U.S. Fish and Wildlife Service | Brown S.C.,Manomet Center for Conservation science | Lanctot R.B.,U.S. Fish and Wildlife Service
Arctic | Year: 2012

On the Arctic Coastal Plain of the National Petroleum Reserve-Alaska (NPR-A), the Teshekpuk Lake Special Area (TLSA) was recognized to protect outstanding wildlife values. Although information has accumulated on the TLSA's value to caribou and waterfowl, its importance to breeding shorebirds remains largely unquantified. Therefore, we undertook a broad-scale ground study to estimate the population size and density of shorebirds breeding in the TLSA. From a series of plot surveys conducted from 2006 to 2008, we estimated a detection-adjusted total breeding population of more than 573 000 shorebirds and an overall density of 126 shorebirds/km2. Most shorebird species had their greatest densities on the Outer Coastal Plain or had approximately equal densities on Outer and Inner Coastal Plains; only two species had their greatest densities on the Inner Coastal Plain. The greatest densities of breeding shorebirds occurred immediately around Teshekpuk Lake. The TLSA supported more than 10% of the biogeographic populations of black-bellied plover (Pluvialis squatarola), semipalmated sandpiper (Calidris pusilla), and dunlin (C. alpina). Breeding shorebird density in the TLSA is one of the highest in the NPR-A, on Alaska's North Slope, and throughout the circumpolar Arctic. Our results, coupled with previous information on waterfowl and caribou, indicate that the area around Teshekpuk Lake and the recognized goose molting area northeast of the lake should be protected from oil and gas development. © The Arctic Institute of North America. Source

Saalfeld S.T.,Manomet Center for Conservation science | Saalfeld S.T.,U.S. Fish and Wildlife Service | Lanctot R.B.,U.S. Fish and Wildlife Service
Auk | Year: 2015

Shorebirds seem to have evolved a number of strategies for adapting to and exploiting the unpredictable and inhospitable Arctic environment. Two such strategies put forth by Holmes and Pitelka suggest that species either conservatively or opportunistically select breeding locations based on local environmental conditions. "Conservative" species were characterized by strong site fidelity and territoriality, consistent population densities, relatively even spacing of individuals, and monogamous mating systems, while "opportunistic" species exhibited opposite traits and were polygamous. Here, we assessed whether 10 shorebird species consistently exhibited these settlement strategies over a 10-year period (2003-2012) near Barrow, Alaska, by comparing annual estimates of site fidelity, territoriality, and population density. Additionally, we determined the relative importance of past and current environmental and social conditions in predicting annual breeding densities of these same species. Data from 1,413 captured adults and 1,946 shorebird nests indicated that most species conformed to 1 of the 2 settlement strategies, while others exhibited traits of both strategies, and a few had settlement patterns inconsistent with that predicted for their mating system. We suggest that deviations from these strategies may occur depending on a species' location within its breeding range. For some species, however, described settlement patterns may be too simplistic. Species with the same settlement strategy seem to respond similarly to environmental cues but differently than species with the alternative strategy. However, we were unable to determine a common environmental cue for species with the same settlement strategy, although lemming abundance, overall nest survival rate, and presence of conspecifics or heterospecifics did seem to influence settlement decisions in some species. Results from this study indicate that understanding how species settle may have important consequences for implementing monitoring or conservation actions. © 2015 American Ornithologists' Union. Source

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