A windy day can be an unpleasant one for a bird — even a bird that doesn’t fly. The world’s smallest species of penguin, the little penguin, appears to have trouble when winds blow strong, a new study finds.
On Phillip Island in Australia, south of Melbourne, some 30,000 adult little penguins (or fairy penguins, as they are also called) nest on the shoreline. The birds, only 33 centimeters tall, spend their days foraging out at sea and return home at night to rest and feed their chicks. This regular pattern of behavior has provided a great opportunity for tourists, who watch the “penguin parade” from a boardwalk where they can’t get in the way of the birds (to protect the penguins, photography isn’t even allowed).
This daily journey also lets scientists study the penguins without interfering with the animals. At one of the entrances to the main colony, researchers set up an automated penguin monitoring system that weighs birds as they come and go and records the weights of birds that had been marked with transponders when they were young. From the bird weights, scientists can determine how much food they and their chicks are eating.
In a study that will appear in Ecology, Claire Saraux of the French Research Institute for Exploitation of the Sea in Sète and colleagues used data on more than 17,000 foraging trips recorded by the monitoring system to see how foraging, chick feeding and adult body reserves in breeding adults were affected by wind speed. They looked at 11 breeding seasons, from 2002 to 2012, and focused on three stages of penguin procreation: egg incubation, chick-guard (when chicks were young and constantly guarded by one parent) and post-guard (when chicks were older and left on their own but still fed by mom and dad).
During incubation and chick-guard, adult penguins spent the same amount of time at sea as calm days but were less efficient at fishing, the monitoring system data showed. When the chicks got older, and parents left them alone all day, the adult penguins compensated for windy days by foraging for longer times. But in both chick-guard and post-guard phases, high winds resulted in smaller meals for the chicks.
Why windy days affect the penguins isn’t quite clear, but the scientists do have a couple of ideas. First, strong winds may mix up the water, driving fish that usually live in the shallowest ocean layer into deeper waters and making them harder for little penguins to find. Alternatively, the winds could be whipping up waves that are more difficult for the penguins to swim through.
Either way, the result is less food for the littlest little penguins.
The smaller meals did appear to have a small effect on chick survival, the team found, but it wasn’t enough to affect the colony as a whole.