Noisy ecotourists get wild birds in a flap
Bob Holmes, New Scientist 28 May 09;
Ecotourists who "ooh" and "aah" over the marvels of nature may be doing more harm than if they appreciated the animals silently. Some species, it turns out, become significantly more stressed by even quiet conversation.
Daniel Karp, of Stanford University in California, studied three colonies of hoatzins, a large primitive bird popular with tourists, near several ecotourism lodges in the Peruvian Amazon.
Karp and his colleagues approached individual hoatzins by canoe either silently or while playing recordings of tourist conversation at different levels.
These started at a volume of 50 decibels, which is just a little louder than the hushed conversation of a library and typical of ecotourists' "don't scare them" chat; and rose to 60 and 70 dB, which equal and exceed the loudest conversations of actual tourists. On each approach, the researchers recorded the distance at which the bird became visibly agitated, and the distance at which it took flight.
The sound of even a quiet conversation caused the birds to begin clucking and defecating – a common defence response – at longer approach distances than for quiet approaches. The noisiest approaches also caused the birds to fly off more readily. Previous studies have shown that stressed hoatzins are less likely to rear chicks successfully.
'Zipped lips'
As time passed during Karp's month-long study, the hoatzins gradually allowed silent people to approach more closely before becoming agitated, indicating that the birds were becoming accustomed to the people. In contrast, the hoatzins showed no such adaptation to approaches that included playback of conversation.
Karp's results show that ecotourism is not as benign as many people think, says Dan Blumstein, a behavioural ecologist and conservation biologist at the University of California at Los Angeles. "We all want to pat ourselves on the back and say ecotourism is good for the environment, but we ignore the fact that there may be deleterious consequences."
Karp takes a more sanguine view. If tourists learn to keep their lips zipped and maintain a safe distance, they can get closer to the birds without agitating them, he says.
Journal reference: Biodiversity and Conservation (DOI: 10.1007/s10531-009-9675-6)
