| Comments: Least Bell’s Vireo,
found in California and Baja Mexico was Red-listed in 1986. It’s preferred
habitat is dense willow forests in riparian areas with lush under-story
vegetation. The least Bell’s vireo is predominately an insect eater. The
birds will forage in high and low shrubs and along riparian areas. During
nesting season, most of the foraging occurs in the vicinity of the nest
site which is predominately in willow trees. A dense shrub layer is
considered essential for nesting. Nests are constructed about three feet
off the ground and are usually made from willows. The most common plant
species used for foraging and nesting are the California wild rose and the
coastal live oak. Most nest sites are located near the edges of thickets
and males often reuse the nest in succeeding years.
There was an estimated 385 pairs in 1992 and it is threatened because
it’s critical riparian habitat is quickly vanishing to make way for
off-road recreation (vegetation destruction/disturbed areas) and golf
courses (herbicides/pesticides/loss of natural vegetation). In addition,
periodic flooding of riparian areas are essential to the health of these
areas. Water control projects hamper and halt this natural cycle. Cowbirds
(see Southwestern Willow Flycatcher) are also threats to the nesting
cycle. |