Photos by (c) Merlin D. Tuttle, Bat Conservation International

 

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Literature Review

Southern yellow bat

Lasiurus ega (xanthinus)

USFWS: No status
CDFG: Species of Special Concern

Background

Distribution, Abundance and Trends. The southern yellow bat occurs in extreme southeastern California, the southwest to Texas and the northwestern portion of Mexico, including Baja (Burt and Grossenheider 1976). Its range appears to be expanding due to the use of palm trees for landscaping. While very few surveys have been conducted for the species in the Plan area, and it is known to occur only at the Coachella Valley Preserve, Dos Palmas Preserve/ACEC, and on the Applegarth Ranch in the Thermal area, the yellow bat is believed to occur throughout the Coachella Valley in the palm oases and in residential areas with untrimmed palm trees. The Coachella Valley is probably very important to this species, as it has a significant number of the native palm oases in southeastern California. There is no estimate of the population size of this species in the Plan area.

Threats and Limiting Factors. The most serious threat to this species would be loss of dead palm fronds. This can result from fire or pruning when trees are used for landscape purposes. If loss of fronds occurs in the spring before the young can fly, it could result in the loss of a year's reproduction. Fires may be naturally occurring from lightning or may be the result of vandalism. Small colonies may be lost in residential areas or resorts and golf courses where the fronds from the trees are trimmed. Pesticides may impact food availability for this species, particularly where agricultural areas occur adjacent to roosting habitat.

Special Considerations. This species roosts in trees, primarily palm trees. It appears to prefer the dead fronds of palm trees. It feeds on flying insects such as beetles and true bugs, and forages over water and among trees. This species is thought to be non-colonial, although aggregations of up to 15 have been found in the same roost site. Yellow bats probably do not hibernate; activity has been observed year-round in both the southern and northern portions of the range. This species probably forms small maternity groups in trees and palms. Pregnancy occurs from April to June, with lactation occurring in June and July. Females carry from one to four embryos. In Texas, bat pups have been found on fronds that have been trimmed from trees (Mirowsky 1997). There is very little information available on the life history of this species.

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