Did you know that SFBBO runs one of the few year-round bird banding stations in the US? We band about 2,500 birds per year with unique ID tags that identify individuals when we recapture them. We can use this data to look at population trends and life history patterns of resident and migratory species over time. Some of our tagged birds have lived 11 years!

SFBBO uses banding data from the Coyote Creek Field Station to track population trends over time. For a 20-year period between 1999 and 2018, bird populations on average have been declining.

This graph (below) shows two population groups: resident species like the Song Sparrow and Common Yellowthroat, and neotropical migrant species like the Yellow Warbler and Wilson’s Warbler.

​Both populations groups are declining at similar rates, despite one group (residents) staying in the Bay Area year-round, and the other group (neotropical migrants) traveling hundreds of miles to winter in Central and South America.