It wasn't until chicks with limited human exposure reached 40 to 50 days old that they showed a stress response like the newly hatched chicks in areas frequented by humans, said researcher Brian Walker, who led the work as part of his doctoral thesis at the UW. He is now an assistant professor of biology at Gonzaga University in Spokane.

Magellanic penguin chicks are hatched in a very immature and helpless condition. Walker's group found that by the time they reached 70 days old, nearly the time of fledging, chicks in human-visited areas had become far more accustomed to the presence of people than those in non-visited areas.

"In the tourist areas, you can walk among them and they put up with you. But when you walk over the hill to the places where tourists don't go, they're much more skittish. They run away or dive into their nests," he said.

The research was conducted at a penguin reserve at Punta Tombo, Argentina, with three separate sampling periods in November and December 2001 and January 2002. Chicks aged 6 to 7 days were captured and blood was drawn to measure the level of a hormone called corticosterone. The first sample was obtained within three minutes of capture to establish a baseline because, unlike a hormone such as adrenaline, it takes several minutes for corticosterone to build up in the bloodstream after a stressful event, such as being captured. Additional blood samples were drawn after 30 and 60 minutes. The same procedures were followed when the chicks were 40 to 50 days old and again two weeks before fledging, which occurs when the chick is about 75 days old.

None of the chicks demonstrated an elevated baseline corticosterone level. But 30 minutes
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Contact: Vince Stricherz
vinces@u.washington.edu
206-543-2580
University of Washington
27-Sep-2005