Interpreting short-term behavioural responses to disturbance within a longitudinal perspective
Author(s):
LARS BEJDERa*, AMY SAMUELSb, HAL WHITEHEADa & NICK GALESc
aBiology Department, Dalhousie University, Canada
bBiology Department, Woods Hole Oceanographic Institution, MA, USA
cAustralian Antarctic Division, Tasmania, Australia
We conducted experimental vessel approaches to bottlenose dolphins in Shark Bay, Western Australia, to understand effects of vessel traffic on dolphin behaviour. We found that when the vessel was nearby, the dolphins’ swimming patterns became more erratic, their groups became more compact, and group membership was more changeable. We observed these responses in regions of both high and low vessel traffic, but dolphins living with low vessel traffic had responses that were stronger and longer lasting. The less dramatic responses of dolphins in a region of high vessel traffic would typically be taken to mean that they had become accustomed to vessel activity. However, another study – showing that dolphin-watching tourism in Shark Bay contributed to declining dolphin numbers in the region of high vessel traffic (Bejder et al. in press,
Conservation Biology) – led us to conclude that we documented moderated responses to vessels because the dolphins sensitive to vessel disturbance had left the region of high vessel traffic before our study began. From this, we concluded that behavioural responses may not be reliable indicators of the effects of human disturbance on wildlife.
DOI (Digital Object Identifier, will open in another window)::
doi:10.1016/j.anbehav.2006.04.003
