Mammal Inventory of City of Rocks National Reserve 2003: Upper Columbia Basin Network

Rodhouse, Tom; Madison, Erica; Oelrich, Katie; Garrett, Lisa

Results from the 2003 City of Rocks National Reserve mammal inventory included species lists and additional information on mammals in the City of Rocks and Castle Rocks area in southeast Idaho. The University of Idaho Department of Fish and Wildlife Resources conducted the 2003 inventory under a cooperative agreement with the National Park Service Northern Semi-Arid Network (now the Upper Columbia Basin Network—UCBN). Inventory fieldwork was conducted from June 9-13 and July 2 –September 30, 2003. The primary goal of the inventory was to confirm 90% of the species expected to occur within the Reserve. Additional goals included the development of baseline data for monitoring as well as providing the National Park Service and the research community-at-large with new and important information on the biodiversity of the region. Expected species lists used for the inventory were developed from published literature, historic reports, and expert opinion. A set of four criteria was used to determine the likelihood of detection in the Reserve. Range, elevation, habitat, and species detectability were considered and developed into a criteria set that was used to place species into “expected” or “possible but not expected” categories. Fieldwork in 2003 utilized a variety of methods to achieve the primary objective and maximize the chance of detecting species in the study area, including visual encounter surveys and trapping. Species documentation included the collection of voucher photographs, specimens, digital bat call recordings, and field observation records. The 2003 mammal inventory was productive and brought species confirmation totals to 75%. Thirty-five species of mammals were confirmed in the Reserve during 2003. The cliff chipmunk (Tamias dorsalis), a “peripheral species” in Idaho, was found to be common in the area and the Reserve appears to support a relatively large population of this species. The spotted bat (Euderma maculatum) was confirmed in the Reserve in 2003. This species is listed as a species of special concern by the state of Idaho and is poorly known in the state. The hoary bat (Lasiurus cinereus), silver-haired bat (Lasionycteris noctivagans), and pallid bat (Antrozous pallidus) were also confirmed in the Reserve for the first time during the 2003 inventory. The deer mouse (Peromyscus maniculatus) and the great basin pocket mouse (Perognathus parvus) were the two most abundant mammals represented in trapping results. The piñon mouse (Peromyscus truei) was reconfirmed in the Reserve for the first time since an unvouchered report was made in 1967. City of Rocks is at the northern limit of the range for this unique species and the voucher specimen for this species collected in 2003 may represent a significant range extension for Idaho. In March of 2003, a ringtail (Bassariscus astutus) was found dead in the Castle Rocks area of the Reserve by Idaho Department of Fish and Game personnel. This was the first record of the species in Idaho and also represents a significant northward range extension. The status of this unique and secretive species in the Reserve should be further evaluated in the future. Data from the 2003 inventory will be incorporated into a long term monitoring program that will focus on selected “vital-signs”, including mammals. Future monitoring activities will also provide opportunities to add additional species to the inventory list as they are encountered.

Mammal Inventory of City of Rocks National Reserve 2003: Upper Columbia Basin Network

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