When a penguin chick begs for food, it makes its siblings’ hearts flutter.
Begging calls encourage a chick’s parents to regurgitate freshly collected food.
But by recognising its siblings’ calls, a wandering chick can home in on its
parents to get its share of the spoils, say Shinichi Nakagawa and Joe Waas of
the University of Waikato in Hamilton, New Zealand.
They measured the heart rates of penguin chicks while playing back calls from
siblings, unknown chicks and neighbours (Behavioral Ecology and
Sociobiology, vol 50, p 180). The chicks’ heart rates shot up an average of
10 beats per…
