Visitors trigger stress in penguin chicks
If people regularly get too close to Magellanic penguin chicks (Spheniscus magellanicus), they react with significantly increased release of stress hormones compared to undisturbed offspring.
Blood tests by Brian Walker and his colleagues at the University of Washington in Seattle have taken forty to fifty days to acclimate the animals to the point where their corticosterone levels approach those of largely unaffected birds: While it increased three- to five-fold in the first week of life, it now falls to lower values that are roughly equivalent to those of the comparison group. Shortly before fledging after seventy days, the value then levels off at a slightly higher level for both.
The researchers cannot yet judge whether these initial hormone surges have long-term negative consequences. In any case, they observed no differences in growth or weight between the different populations; the human-contact chicks also developed normally.
The penguins observed in the Punta Tombo reserve in Argentina, however, get used to the tourists without their stress factor being noticeably reduced. But compared to their fellow species, who are not regularly visited, they soon no longer flee from humans, so that visitors can approach them to within a few steps. In contrast, the birds that are rarely or never visited maintain a minimum flight distance of nine meters.