Other Endangered Species:

Southwestern Willow Flycatcher
                               

The Southwestern Willow Flycatcher is a small, insect-eating migratory songbird that comes to the riparian areas of southern California between late April and late August to breed in willows and other vegetation along the rivers and creeks. About 50 years ago it was considered common in southern California. Now it is extremely endangered because of the loss of habitat and parasitism by the brown-headed cowbird. This bird is one of five subspecies of the willow flycatcher but it is the only one that breeds in Southern California. The Southwestern Willow Flycatcher was listed as endangered by the California Depatrment of Fish and Game in 1992 and by the U.S. Fish and Wildlife Service in 1995. The loss of habitat and parasitism are thought to be the major reasons for the declining numbers of Southwestern Willow Flycatchers (Pike et al, 1996). Over 90 percent of California’s riparian habitat has been destroyed by human land use practices such as grazing, agriculture, and the modification of rivers and streams for flood control projects, including channelization to allow for urban development. This habitat destruction is taking place in a naturally fragmented landscape. It is a wonder that even a few birds can find their way to the fragmented habitats that remain. Brood parasitism by the brown-headed cowbird is another cause for the decline of the flycatcher. The brown-headed cowbird does not build its own nest but lays its eggs in the nests of other birds. The flycatcher may abandon its nest when its nest is parasitized or it does not recognize that the cowbird egg is not its own and feeds the cowbird nestling when it hatches. The cowbird nestling is bigger so it gets most of the food even if the host bird’s eggs hatch. Rarely does a native bird as small as a Willow Flycatcher fledge from a nest that also has fledged a cowbird; most of the small native nestlings die. Some habitat restoration is occurring in Southern California. The Santa Ana Watershed Association (SAWA) has removed thousands of acres of Arundo donax from the Santa Ana River Watershed. Once removed, willows and cottonwoods and other riparian vegetation can flourish and habitat for native wildlife can be reestablished. SAWA biologists manage brood parasitism by trapping cowbirds so that they cannot lay their eggs in the nests of native birds, and by locating nests of native birds and removing the cowbird eggs. Trapping and nest monitoring is known to have helped another endangered bird, the least Bell’s vireo, but it has not helped the Southwestern Willow Flycatcher as much. More research is needed to identify further problems that affect this bird. For more information, go to www.sawatershed.org.