DABBLING DUCK BEHAVIOR AND AIRCRAFT ACTIVITY IN COASTAL NORTH-CAROLINA

Requests to increase military aircraft activity in some training facil ities in the United States have prompted the need to determine if wate rfowl and other wildlife are adversely affected by aircraft disturbanc e. We quantified behavioral responses of wintering American black duck s (Anas rubripes), American wigeon (A. americana), gadwall (A, strepte ra), and American green-winged teal (A. crecca carolinensis) exposed t o low-level flying military aircrafts; at Piney and Cedar islands, Nor th Carolina, in 1991 and 1992. Waterfowl spent less than or equal to 1 .4% of their time responding to aircraft, which included flying, swimm ing, and alert behaviors. Mean duration of responses by species ranged from 10 to 40 sec. Costs to each species were deemed low because disr uptions represented a low percentage of their time-activity budgets, o nly a small proportion of birds reacted to disturbance (13/672; 2%), a nd the likelihood of resuming the activity disrupted by an aircraft di sturbance event was high (64%). Recorded levels of aircraft disturbanc e (i.e., (x) over bar = 85.1 dBA) were not adversely affecting the tim e-activity budgets of selected waterfowl species wintering at Piney an d Cedar islands.