WINTER ECOLOGY OF THE LONG-TAILED DUCK
(Clangula hyemalis) IN THE CHESAPEAKE BAY.
Little is known about the ecology and population status of the long-tailed duck (Clangula hyemalis) in the Chesapeake Bay area and the Atlantic Coast. By improving our knowledge about the ecology of this species, we will have a better understanding about the management needs for this species. Breeding population surveys conducted in Alaska suggest a declining population. We have no good information on the population status for the sub-population that winter along the Atlantic Coast and in the Great Lakes. Surveys of seaducks wintering on the Atlantic coast (1991-99) have shown major declines for the long-tailed duck. Surveys are continuing in hopes to better understand and delineate the size and location of Atlantic coast seaduck populations.
In the Chesapeake Bay area, long-tailed ducks are scattered in the mesohaline areas of the Bay where mollusks appear to be their preferred food item. Long-tailed ducks on the Bay have received more attention in recent years as hunters have increased hunting pressure on these species, mostly due to closed seasons on Canada geese. The distribution and abundance of long-tailed ducks could be influenced by hunting pressure. Hunting and other disturbance factors (commercial and private boats) could become a more serious problem in the future for long-tailed ducks in combination with the habitat problems in the Bay.
The Chesapeake Bay has undergone major changes in the food sources it offers wintering waterfowl due to the degradation of water quality. There is a need for research on the availability and nutritional quality of these food sources for wintering seaducks as a possible explanation for the decline in the wintering populations. The availability of food resources is especially important in areas of the Chesapeake Bay at depths of 20-40 feet where seaducks typically feed. These areas may be the first to be impacted by anoxic conditions if poor water conditions occur during the summer months.
Methods: Locations of
long-tailed ducks on the Chesapeake Bay will be determined
throughout the winters with the aid of existing aerial surveys.
Information from surveys will be used to identify important
wintering areas for long-tailed ducks in the Bay so that more
intensive ground observations from boats can be conducted. Boats
will be used to determine more specific feeding areas of the
ducks on both sides of the Bay. Boats will travel at high speeds along shoal areas of
approximately 20-40 feet in a sinuous pattern. When ducks are observed coming to the
surface after feeding a GPS location will be recorded along with
the approximate size of the population in the general area of
Samples will be frozen until analyses are conducted. Contents will be removed and analyzed in white lab trays and macroscopes. Organisms will be separated by species, and dry weights and volumes will be determined for each sample. Frequencies of occurrence, average weight, and average volume of the food items will be determined for each duck species. Grit content will be determined and calculated separately from food items. Historic food habits data for long-tailed ducks on the Chesapeake Bay will be reexamined and compared to present food habits.
Benthic Sampling: The habitat used by long-tailed ducks for feeding and loafing will be evaluated to determine its value to the ducks in comparison to apparently similar areas not used for feeding and loafing. Benthic samples will be taken from boats to determine invertebrates from bottom sediments in areas where seaducks are observed. Surveys at night will also be conducted from boats especially equipped with night-lighting equipment to determine night-time distribution. Habitat surveys will be local in perspective and no attempt will be made to survey large areas of seaduck habitat.