DO BLACK DUCKS AND WOOD DUCKS HABITUATE TO AIRCRAFT DISTURBANCE

Requests to increase military aircraft activity in some training facil ities in the United States have raised the need to determine if waterf owl and other wildlife are adversely affected by aircraft disturbance. We hypothesized that habituation was a possible proximate factor infl uencing the low proportion of free-ranging ducks reacting to military aircraft activities in a training range in coastal North Carolina duri ng winters 1991 and 1992. To test this hypothesis, we subjected captiv e, wild-strain American black ducks (Anas rubripes) and wood ducks (Ai x sponsa) to actual and simulated activities of jet aircraft. In the f irst experiment, we placed black ducks in an enclosure near the center of aircraft activities on Piney Island, a military aircraft target ra nge in coastal North Carolina. The proportion of times black ducks rea cted (e.g., alert posture, fleeing response) to visual and auditory ai rcraft activity decreased from 38 to 6% during the first 17 days of co nfinement. Response rates remained stable at 5.8% thereafter. In the s econd experiment, black ducks and wood ducks were exposed to 6 differe nt recordings of jet noise. The proportion of times black ducks reacte d to noise decreased (P < 0.05) from first day of exposure (25%) to la st (i.e., day 4. 8%). Except for a 2% difference in comfort, we detect ed no differences (P > 0.05) in time-activity budgets of black ducks b etween pre-exposure to noise and 24 hr after first exposure. Unlike bl ack ducks, wood duck responses to jet noise did not decrease uniformly among experimental groups following initial exposure to noise (P = 0. 01). We conclude that initial exposure to aircraft noise elicits behav ioral responses from black ducks and wood ducks. With continued exposu re of aircraft noise, black ducks may become habituated. However, wood ducks did not exhibit the same pattern of response, suggesting that t he ability of waterfowl to habituate to aircraft noise may be species specific.