Background: As the Lower Colorado River’s (LCR) riparian habitat has been degraded due to human development, Arizona Game and Fish working in conjunction with the U.S. Bureau of Reclamation on the Multi Species Conservation Program which looks to mitigate and reduce the effects of dam operations on wildlife at the LCR. Our part in the plan is to study four species of bats: the Western red bat (Lasiurus blossevillii), Western yellow bat (Lasiurus xanthinus), California leaf-nosed bat (Macrotus californicus), and the Townsend’s big-eared bat (Corynorhinus townsendii pallescens). The purpose of our study is to determining their specific habitat requirements, so that we can then create/restore habitat areas for these species. Among the conservation actions proposed are measures to create 765 acres of western red and western yellow bat habitat.

Location: As seen in the map bellow, our area of study extends from Davis Dam to Laguna Dam near Yuma Arizona. We have divided the study area into 3 reaches. In each reach we are surveying four distinct vegetation types: marsh, mesquite, salt cedar, and cottonwood/willow.

Approach: In order to survey the bats in the study area, LCR Reaches 3, 4, 5 and small area of Reach 6 (see map fig.) will be sampled each of the four seasons using Anabats, acoustic devices that record bat echolocating calls. This is a monitoring method allows researchers to be less invasive. Yet detection and identification of individual species can at times be difficult, therefore mist-netting will be used to confirm bat distribution. To provide information on bat migratory movement along the river we have placed 4 permanent bat detector stations (picture to the left), which allows us to evaluate variability of bat activity as well as migration patterns. This permanent stations are equipped with temperature, wind speed and humidity sensors that can aid researchers to find a correlation between such environmental variables and bat activity.

Important finding patterns:  Thus far we have found positive correlations between high temperatures and bat activity, meaning that in warm nights we can expect many bats flying in the skies.

Benefits: The primary purpose of this study is to determine the distribution and habitat use of the bats mentioned within the study area during all seasoned of the year; and to evaluate their migration patters. This data can then be used to make recommendations as to the management activities in the area, as far as to in which areas to concentrate restoration efforts.

For more information contact:

Beatriz Vizcarra, Wildlife Specialist I
Arizona Game & Fish Department
5000 W. Carefree Highway, Phoenix, AZ 85086
E-mail: Bvizcarra@azgfd.gov

Vince Frary, Wildlife Specialist III
Arizona Game & Fish Department
5000 W. Carefree Highway, Phoenix, AZ 85086
E-mail: Vfrary@azgfd.gov

Michael Ingraldi, Ph.D.
Arizona Game & Fish Department
5000 W. Carefree Highway, Phoenix, AZ 85086
E-mail: mingraldi@cybertrails.com