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Birds & Elephant Trees

April 25, 2014

Migratory gray vireos help elephant trees disperse their seeds in Baja, California.



Of birds and elephant trees. I’m Bob Hirshon and this is Science Update.

A gray vireo eats the seed of an elephant tree in Baja, California. (Alan Harper/Flickr)

A gray vireo eats the fruit of an elephant tree in Baja, California. (Alan Harper/Flickr)

Small birds called gray vireos breed in southern California, but their population has declined during the past hundred years. Avian ecologist Lori Hargrove and her colleagues at the San Diego Natural History Museum found that nest predation by larger birds may play a role. But on a recent expedition to Mexico, they discovered the birds spending the winter in a little-studied region of southern Baja.

LORI HARGROVE (San Diego Natural History Museum):

So we were excited to go down to the Sierra Cacahilas find that there were good numbers of gray vireos wintering there.


She says the birds may be thriving there because of their mutually beneficial relationship with rare elephant trees. The birds’ large beaks make them especially good at dispersing the seeds of the ancient-looking, thick-trunked trees. She says to better protect the birds, it’s important to understand how they’re doing on both their breeding grounds and their winter range. I’m Bob Hirshon, for AAAS, the science society.