After losing flockmates, sparrows move on

When golden-crowned sparrows lose a longtime flock member, they move on from their overwintering spots to stake out new terrain.

Sparrows that winter in San Diego, California, typically return to within yards of where they spent the previous winter. But researchers found they drift away when their flockmates fail to return.

“The fact that they come back to this winter site and then hang out with the same individuals—and it’s important for them to be with the same individuals—is kind of a crazy thing that we’re still wrapping our heads around,” said Annie Madsen, lead author of the study published recently in the Proceedings of the National Academy of Sciences. 

In the 10-year study, researchers tried to tease apart what brought golden-crowned sparrows (Zonotrichia atricapilla) back to the same place year after year. Was it the resources they found there? Or did social bonding play a role? By banding the birds and determining their social network over a decade, researchers concluded that the presence of longtime flockmates played a key role.

“There’s something to having familiar flockmates that is important,” said Madsen, a postdoctoral researcher at the University of California, San Diego, who conducted the research for her doctorate at the University of Nebraska.

Read more from the University of Nebraska.