Spring migration patterns of red knots in the Southeast United States disentangled using automated telemetry.

Red Knots use the Southeast United States as a stopover during north and southbound migration and during the winter. We examined northbound red knot migration routes and timing using an automated telemetry network. Our primary goal was to evaluate the relative use of an Atlantic migratory route through Delaware Bay versus an inland route through the Great Lakes en route to Arctic breeding grounds and to identify areas of apparent stopovers. Secondarily, we explored the association of red knot routes and ground speeds with prevailing atmospheric conditions. Most Red Knots migrating north from the Southeast United States skipped or likely skipped Delaware Bay (73%) while 27% of the knots stopped in Delaware Bay for at least 1 day. A few knots used an Atlantic Coast strategy that did not include Delaware Bay, relying instead on the areas around Chesapeake Bay or New York Bay for stopovers. Nearly 80% of migratory trajectories were associated with tailwinds at departure. Most knots tracked in our study traveled north through the eastern Great Lake Basin, without stopping, thus making the Southeast United States the last terminal stopover for some knots before reaching boreal or Arctic stopover sites.

Circulating Fat-Soluble Vitamin Concentrations and Nutrient Composition of Aquatic Prey Eaten by American Oystercatchers (Haematopus palliatus palliatus) in the Southeastern United States.

The American oystercatcher (Haematopus palliatus palliatus) is currently listed as a species of high concern by the United States Shorebird Conservation Plan. Because nutritional status directly impacts overall health and reproduction of individuals and populations, adequate management of a wildlife population requires intimate knowledge of a species' diet and nutrient requirements. Fat-soluble vitamin concentrations in blood plasma obtained from American oystercatchers and proximate, vitamin, and mineral composition of various oystercatcher prey species were determined as baseline data to assess nutritional status and nutrient supply. Bird and prey species samples were collected from the Cape Romain region, South Carolina, USA, and the Altamaha River delta islands, Georgia, USA, where breeding populations appear relatively stable in recent years. Vitamin A levels in blood samples were higher than ranges reported as normal for domestic avian species, and vitamin D concentrations were lower than anticipated based on values observed in poultry. Vitamin E levels were within ranges previously reported for avian groups with broadly similar feeding niches such as herons, gulls, and terns (eg, aquatic/estuarine/marine). Prey species (oysters, mussels, clams, blood arks [Anadara ovalis], whelks [ Busycon carica ], false angel wings [ Petricola pholadiformis ]) were similar in water content to vertebrate prey, moderate to high in protein, and moderate to low in crude fat. Ash and macronutrient concentrations in prey species were high compared with requirements of carnivores or avian species. Prey items analyzed appear to meet nutritional requirements for oystercatchers, as estimated by extrapolation from domestic carnivores and poultry species; excesses, imbalances, and toxicities-particularly of minerals and fat-soluble vitamins-may warrant further investigation.

Health assessment of American Oystercatchers (Haematopus palliatus palliatus) in Georgia and South Carolina.

The American Oystercatcher (Haematopus palliatus palliatus) is the only species of oystercatcher native to the Atlantic coast of North America and is restricted in distribution to intertidal shellfish beds in coastal areas. Currently, the American Oystercatcher population in South Carolina and Georgia is threatened by widespread habitat loss, resulting in low reproductive success and small population size. Oystercatchers could be an important indicator of ecosystem health because they depend on quality coastal breeding habitat and prey on bivalves, which can accumulate toxins and pathogens from the local environment. Data were collected from American Oystercatchers (n=171) captured at five sites in South Carolina and Georgia between 2001 and 2006. Iridial depigmentation was frequently noted during physical examination and was more prevalent in female birds. Female birds were larger than males on average, but ranges for weight and morphometric measurements had considerable overlap. Mean values were calculated for hematology, plasma biochemistry, and hormone levels, and prevalence of exposure to select pathogens was determined. Mercury was the only trace metal detected in blood samples. These data provide baseline health information needed for longitudinal monitoring and conservation efforts for American Oystercatchers. In addition, this study illustrates the potential use of this species as an indicator for the health of the southeastern US coastal nearshore ecosystem.