Effects of disturbance on shrub steppe habitats and raptor prey in the Snake River Birds of Prey National Conservation Area, Idaho

Publication Type:

Conference Paper

Authors:

Knick, Steven T.; Rotenberry, John T.; Van Horne, Beatrice

Source:

USDI Bureau of Land Management, Idaho State Office, Boise, Boise State University, Boise, ID, p.98-99 (2000)

Call Number:

U00KNI01IDUS

Keywords:

Black-tailed Jackrabbit, Lepus californicus, Paiute ground squirrel, Spermophilus mollis

Abstract:

The authors examined the effects of military training and wildfires on shrub steppe habitats and two primary raptor prey, Paiute ground squirrels (Spermophilus mollis; formerly called Townsend’s ground squirrels, Spermophilus townsendii) and black-tailed jackrabbits (Lepus californicus) in the Snake River Birds of Prey Natural Conservation Area (NCA) in southwestern Idaho. Habitat change is a significant management concern because big sagebrush (Artemisia tridentata), winterfat (Krascheninnikovia lanata), and shadscale (Atriplex confertifolia) communities are rapidly being converted to large expanses dominated by cheatgrass (Bromus tectorum), an exotic annual grass. This change has led to decreased intervals between fires in the NCA. The authors have found that combined disturbances from wildfires, military training, and livestock grazing had an additive or synergistic effect on the landscape. Conversion from shrubland and perennial vegetation to habitat dominated by annual vegetation primarily influence ground squirrel populations through an increased susceptibility to environmental fluctuations. Grasslands dominated by exotic annual species supported high population densities of ground squirrels during nondrought years, but populations were less viable there than in habitats with a perennial shrub component because of great population fluctuations. Densities of black-tailed jackrabbits have declined over 3 successive population peaks. Night surveys found that they were primarily associated with large shrubland patches and absent from highly fragmented landscapes or those dominated by grasslands. Distribution and abundance of jackrabbits will be related to the restoration or loss of shrublands in the NCA.

Notes:

ELECTRONIC FILE - Zoology

Citation: Knick S, Rotenberry JT, Van Horne B. 2000. In: Entwistle PG, DeBolt AM, Kaltenecker JH, Steenhof K, compilers. 2000. Proceedings: Sagebrush Steppe Ecosystems Symposium; 23-25 June 1999; Boise, ID. Boise: USDI Bureau of Land Management, Idaho State Office. Publication No. BLM/ID/PT-001001+1150. p. 98-99.