Natural History Wanderings

Small Bay Area birds have gotten larger almost every year for three decades.

A recently published  article in the journal of Global Change Biology reported wingspans and body weight have increased in  finches, robins, swallows hummingbirds, and other birds.   Seventy-three birds  have been studied and the increase occurs in both resident and migrating birds of the Bay Area. It is believed the cause is climate change. Scientists theorized that warmer temperatures would result in animals becoming thinner and smaller to stay cool.  An alternate theory proposes lush wet conditions on the West Coast increasing the plants, insects and other food sources for birds, which may account for the growth in bird size.

Another study in Pennsylvania had found that  songbirds decreased in size, which is more typical of what scientists had expected from climate change. Read more at the Bay Citizen Bay Area Songbirds Growing Bigger as Climate Changes.