Spatial ecology of long-tailed ducks and white-winged scoters wintering on Nantucket Shoals, Massachusetts
Item
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Title
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Spatial ecology of long-tailed ducks and white-winged scoters wintering on Nantucket Shoals, Massachusetts
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Identifier
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d_2009_2013:1abf5b525b14:11858
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identifier
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12480
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Creator
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White, Timothy Paul,
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Contributor
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Timothy P. White
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Date
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2013
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Language
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English
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Publisher
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City University of New York.
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Subject
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Ecology | Behavioral sciences | Evolution & development | Gammarid amphipods | hotspots | hydrographic fronts | Long-tailed Ducks | Nantucket Shoals | White-winged Scoters
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Abstract
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A substantial proportion, perhaps 30%, of the North American breeding population of Long-tailed Ducks (Clangula hyemalis) winter in the vicinity of Nantucket Island, Massachusetts. These birds spend the night on Nantucket Sound and commute during daylight hours to the Nantucket Shoals, which extend about 65 km offshore from the southeastern corner of Nantucket. Strip transects done from a single-engine plane in 1997 and 1998 indicated that Long-tailed Ducks foraged over the shallower (~ 20 m depth) portions of the Nantucket Shoals, up to 70 km offshore. Diet analyses of ten birds collected in February 1999 and five in December 2006 showed that they fed principally (106.6 +/- 42.0 individuals per crop) on Gammarus annulatus, a pelagic amphipod that often forms large aggregations, and is consumed by several species of fish and marine mammals.;I conducted high-intensity aerial surveys to map the distribution and abundance of foraging sea ducks on Nantucket Shoals, MA in February 2008 - Spring 2011. For these surveys, west/east transect orientation ran perpendicular to bathymetric gradients, and covered a greater extent of Nantucket Shoals than did our preliminary surveys in 1997 and 1998. Core foraging areas of Long-tailed Ducks and White-winged Scoters (Melanitta fusca) overlapped along southwest Nantucket Shoals (mean foraging depth (m) +/- SD: Long-tailed Ducks = 27.20 +/- 8.25; White-winged Scoters = 29.8 +/- 7.23), a zone where clams and pelagic amphipods are historically abundant. I mapped the spatial dispersion of Long-tailed Ducks and White-winged Scoters to determine if and where foraging aggregations persisted through space and time in relation to prey hotspots. Spatial dispersion of both species was strikingly concordant. Since previous studies have found very little dietary overlap between Long-tailed Ducks and White-winged Scoters, I sought to explain this high degree of spatial concordance. I also examined the potential physical and biological mechanisms (e.g., structural fronts, primary productivity) that may influence the spatial organization of Long-tailed Ducks, White-winged Scoters and their prey on Nantucket Shoals.
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Type
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dissertation
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Source
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2009_2013.csv
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degree
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Ph.D.
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Program
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Biology
