Migratory Bird Habitat Shrinking In California

The Sacramento Valley is a globally important resting and refueling stop for birds migrating along the Pacific Flyway. The valley provides habitat for more than 400,000 birds making their way from Alaska to Argentina and back.

A new study shows the amount of flooded habitat available during peak migration for the birds has decreased every year for the last 30 years.

“We estimate on average that we’ve lost an area of about four times the size of Central Park in each year,” says Danica Schaffer-Smith, a doctoral student with Duke University who conducted the study. 

After peak migration, the study also found that the amount of water on the landscape increases five-fold.

"A lot of that we think has to do with just the management practices on agricultural lands," says Schaffer-Smith.

She says rice farmers can help provide more bird habitat by changing the time of year they flood fields.  A few years ago, during the peak of the drought, conservation groups launched a program called Bird Returns that compensates farmers for doing so.

Rice farmers typically flood their fields to decompose stubble left over from harvest. Bird Returns goes a step further by paying farmers to keep their fields flooded at certain levels to attract certain kinds of birds.

"One thing we hope to gain from this type of research is to look more deeply at this question of how can we be very strategic about where and when we're putting additional habitat on the landscape through those types of programs," says Schaffer-Smith.

Schaffer-Smith used NASA satellite data to look at the long-term changes in land use. The study was published in the journal Remote Sensing of Environment.

Land use and land cover in the Sacramento Valley, within California's Central Valley. (Herbaceous wetlands and agriculture: National Land Cover Database (Homer et al., 2015); flood-irrigated rice: (USDA-NASS, 2014.))