Bell’s Vireo Returns to the Central Valley

Endangered Songbird Reappears After 60 Years at River Restoration Site

by River Partners Staff

One of the greatest affirmations that the restoration work done at River Partners is having an impact came in the form of a distinctive “cheetle, jeew” call, heard at the San Joaquin River National Wildlife Refuge, a call that hasn’t been heard anywhere in the Central Valley for more than 60 years. The call came from a pair of nesting least Bell’s vireo (Vireo bellii pusillus), who are raising their young in a three-year-old restoration site at the Refuge, designed and implemented by River Partners. The birds were first discovered by Point Reyes Bird Observatory (PRBO) bird monitor Lynette Lina in the Refuge in early June.

The least Bell’s vireo is a state and federally-listed endangered species that was once common throughout California’s Central Valley. They had disappeared from the area due to a 90% decline in the riparian habitat used by the birds. The restoration site is in a former, non-productive farm field that was planted by River Partners to match the original valley riparian habitat of willows, blackberry, wild rose thickets and mugwort. After three years, the plantings have grown together to form these thick brambles, which is where the vireo nest was found.
“Hearing the least Bell’s vireo again demonstrates that a good recovery plan, committed partners and resources to carry it out, can bring many species back to life in areas where they seemed lost forever,” said Steve Thompson, manager of the U.S. Fish and Wildlife Service’s California-Nevada Operations Office.

Geoffrey Geupel, Terrestrial Ecology Division Director of PRBO Conservation Science, which conducts bird monitoring throughout California, called it a “superb success story” and an example of how the restoration project, which included patch work design and planting herbaceous under story, supports native bird species.
Says River Partners Senior Restoration Ecologist, Tom Griggs, “The recent news of the least Bell’s Vireo nesting and successfully fledging two young in our restoration project at the San Joaquin River NWR is a very significant milestone in the evolution of riparian restoration planting .”

The project has been funded by CALFED, which provided key funds to purchase an 800-acre farm on flood-prone land, which was transferred to the U.S. Fish and Wildlife Service (USFWS). Other agencies also contributed, including the Natural Resources Conservation Service, USFWS, the California Resources Agency, the Army Corps of Engineers, and the Audubon Society. The restoration was conducted by River Partners, with input, consultation and monitoring by PRBO conservation Science, the USFWS and the Endangered Species Restoration Program at CSU-Stanislaus.

Although the area immediately around the vireo nest has been temporarily closed to the public, check the River Partners and Refuge websites for updates on the status of the birds and additional sightings, at www.riverpartners.org and www.fws.gov/pacific/sanluis.

This article originally appeared in Summer/Fall 2005 Environmental News.