Habitat Use of Surf Scoters Wintering in The Mesohaline Region of the Mainstem Chesapeake Bay, Maryland
Thesis submitted to the Faculty of the Graduate School of the University of Maryland, College Park,
Abstract
Thesis submitted to the Faculty of the Graduate School of the University of Maryland, College Park,
Abstract
Cooke, Wells. 1906. Distribution and Migration of North American Ducks, Geese and Swans. United States Department of Agriculture Bulletin. No. 26. 46 pp.
This study is a large scale, multi-year, collaborative project that will use satellite telemetry to document annual migration patterns and habitat use. Driven by a lack of knowledge on sea duck distribution, migration patterns, and seasonal habitats used, the Sea Duck Joint Venture (SDJV) partnership has launched a large-scale satellite telemetry study of sea ducks in the Atlantic Flyway. From 2009 to 2013, about 300 transmitters will be deployed in four species: Black Scoter, Surf Scoter, White-winged Scoter, and Long-tailed Duck - all species of high conservation concern.
Diving ducks wintering in Chesapeake Bay during the last 50 years have accounted for 23% of Atlantic Flyway and 9% of North American populations based on aerial surveys. Continental and local factors have affected these population changes. Loss of submerged aquatic vegetation (SAV) due to degradation of water quality, has been a contributing factor, although, many other factors related to human population increases have been implicated in the changes in the distribution and abundance of diving ducks.
Introduction: Historically, the Chesapeake Bay has been a major wintering area for seaducks. Based on aerial surveys, three species of seaducks, surf scoters (Melanitta perspicillata), black scoters (Melanitta nigra), and long-tailed ducks (Clangula hyemalis), have shown major declines in recent years. One possible explanation for this decline is a reduction of available food items.Data indicates that surf and black scoters likely feed at depths ranging from 10 to 30 feet in the mesohaline region of the Chesapeake Bay.
Numbers of scoters (black, surf, and white-winged) and long-tailed ducks wintering in the Maritime provinces of Canada and the Chesapeake Bay (MD and VA, USA) have noticeably declined in recent years. Common goldeneye populations have also declined, but bufflehead populations have increased in numbers.
North American populations of breeding surf scoters and long-tailed ducks appear to be decreasing. Along the Atlantic coast, wintering populations of surf scoters are suspected to be decreasing, while the status of wintering populations of long-tailed ducks remains unknown. These trends have led conservation organizations to assign a "high" relative conservation priority to both species.
The purpose of the study was to gain a greater understanding of locations and behaviors of wintering sea ducks when they return each evening. The goal of the study was to identify the nighttime roosting location and behavior of the Long Tailed Duck. In particular any commuting movements in the sound and if so the height of flight. While focusing on Long-Tailed Ducks, night time observations of Eiders and Scoters were also to be included in this study.
More than half of North American sea duck populations have apparently declined over the past 2-3 decades, although reasons for declines are unknown. Population delineation (i.e., the links among breeding, molting, wintering, and staging areas) is critical information needed to design and interpret monitoring surveys, to better understand population ecology and population dynamics, and determine limiting factors and potential strategies to improve conservation status of sea ducks.