Abstracts

Presented by Cory Overton - Email: coverton@usgs.gov

Migration, both spring and fall, are arguably the most crucial periods during the annual cycle of waterfowl. Migration results in the redistribution of most waterfowl across the continent and conditions along migration routes may incur carry-over effects to other life history stages due to the increased energy expenditure and energy gain at staging areas. Staging areas are considered particularly influential to waterfowl due to the high number of individuals concentrated at them combined with their irreplaceability within the landscape and have therefore been the focus of much research. Many waterfowl, however, migrate along coastal routes or over the open ocean. Until recently it has been impractical to accurately monitor at-sea migration strategies. We use a database containing 950 individuals of 10 species with 218 individual migration tracks to describe a variety of oceanic and coastal migration patterns. At-sea migration varied with Rosss and Snow Geese (except the Wrangel Island population), Wigeon, and Mallards demonstrating few to no flights over the ocean. Moderate numbers of Pintail, Blue-winged Teal, and Shoveler flew coastal or oceanic routes. All Tule and Greater White Fronted Geese flew over the ocean with stoppage at sea common among both species. A single Wrangle Snow goose stopped twice on the water during a 41+ hour fall crossing of the Gulf of Alaska during gale-force winds and 20-foot waves. Total time spent floating in the ocean for all geese ranged from 4 to 48 hours with 1 to 7 individual stops on the water during a single migration. At-sea stoppage by pintail was likely but could not be confirmed due to a longer GPS interval and occurrence closer to the coastline. The prevalence, and consequence, of at-sea migration behaviors for some species/populations may be substantial and warrant additional investigation.