The exotic wildlife that ecotourists flock to see may be getting stressed out from all the attention, according to new research. A study of Magellanic penguins in Argentina reveals that newly hatched chicks in tourist areas ramp up their fight-or-flight response much more strongly than do chicks in undisturbed areas.
Every year, over 70,000 people come to Punta Tombo, Argentina, to see the world's largest colony of Magellanic penguins. The birds don't appear to mind the tourists and don't budge when approached. But researchers from the University of Washington in Seattle, led by ecological physiologist Brian Walker, wondered whether the penguins felt any anxiety compared to birds in areas without tourists.
To find out, the team studied the most vulnerable members of the colony: newly hatched chicks. The researchers captured chicks from both areas and took blood samples within 3 minutes, before levels of glucocorticosteroid--a stress hormone involved in the fight-or-flight response--had time to rise. Initial levels of the hormone did not differ between touristed and untouristed chicks. But after 30 minutes, touristed chicks displayed an increase in hormone levels 3 times as large as that seen in untouristed chicks, the authors report in the October issue of Conservation Biology.
Chronically raised levels of stress hormones are associated with reduced growth and a dampened immune system, so the researchers were concerned to see such a strong stress response in animals so young. But by the time the chicks were 40 to 50 days old, they all reacted the same way to being captured and held: both groups showed raised glucocorticosteroid levels. So why worry? Walker, now at Gonzaga University in Spokane, Washington, says that an elevated early reaction to stress could open the door to negative health effects in the future.
Still, stress physiologist Michael Romero of Tufts University in Boston, Massachusetts, doesn't see cause for alarm. Sometimes a little bit of stress is good, he says. It could give chicks a boost of energy should a real predator appear.
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