When it’s time to procreate, northwestern song sparrows don’t let a little sickness get them down.
When breeding is in full swing in summer, the birds will ignore bacterial infections and continue to fend off territorial invaders as well as keeping up a constant weight. In winter, however, sick sparrows eat less and burn fat reserves to fight off the disease, while paying less attention to defending their territory. It’s the first time that animals have shown seasonal “sickness behaviour” in the wild.
Noah Owen-Ashley and John Wingfield of the University of Washington, Seattle, injected the song sparrows (Melospiza melodia…
