Executive Summary 



The Montana Natural Heritage Program, in 

 partnership with Red Rock Lakes National 

 Wildlife Refuge and the Bureau of Land 

 Management — Dillon Field Office, has completed 

 a terrestrial faunal survey of the Centennial Valley 

 Sandhills of southeastem Beaverhead County. No 

 previous comprehensive animal survey has been 

 conducted in these Sandhills, the second largest 

 sandhills complex in Montana. This work 

 compliments previous studies of the plants and 

 vegetation dynamics in the Centennial Sandhills by 

 associating a number of animal species to specific 

 physical features and successional stages at this 

 site. Maintaining the current diversity of animals 

 will depend upon the controlled introduction of 

 disturbance processes such as fire and grazing to 

 create a mosaic of vegetation in various stages of 

 succession. Disturbances should be conducted at 

 scales appropriate for the entire Centennial Valley 

 as well as the Sandhills specifically. 



The Sandhills support a diverse array of 

 vertebrates and invertebrates with affinities to 

 shrub-steppe habitats more representative of the 

 entire Centennial Valley. Eighteen mammal 

 species, 29 bird species, 3 amphibian and reptile 

 species, 4 tiger beetle species, and 14 butterfly 

 and skipper species were documented in the 

 Sandhills during the 1 999 survey. 



Three state mammal species of special concem 

 were documented: Preble's Shrew (Sorex 

 preblei). Black-tailed Jackrabbit {Lepus 

 californicus), and Great Basin Pocket Mouse 

 {Perognathus parvus). Preble's Shrew is 

 collectively the twentieth state record and the first 

 for Beaverhead County, Black-tailed Jackrabbit is 

 the fourteenth state record, and Great Basin 

 Pocket Mouse is the first record for the Centennial 

 Valley and the first record for Montana since 

 1 96 1 . The shrew appeared to be widespread at 

 low density, the jackrabbit was observed in 

 stabilized sandflats with scattered sagebrush cover, 



and the pocket mouse was associated with 

 scattered sagebrush in stabilized low-dune habitat. 

 A fourth species of special concem, Pygmy Rabbit 

 (Brachylagus idahoensis) was not seen in 1 999 

 but has been reported recently in the Sandhills in 

 stands of dense big sagebrush. 



Three Montana Partners In Flight (PIF) Priority 11 

 bird species (Sage Thrasher, Brewer's Sparrow 

 and Grashopper Sparrow) were present daily. 

 The thrasher was associated only with tall and 

 mature big sagebrush, the Brewer's Sparrow also 

 was associated with sagebrush, but in a variety of 

 size classes. Grasshopper Sparrow, a rare 

 transient species in the Centennial Valley, was 

 present in a localized site of grassy habitat with 

 little shrub cover. Defensive behavior by a pair of 

 Long-billed Curlews, and discovery of an old nest 

 of Ferruginous Hawk, both PIF Priority II species, 

 indicated these species bred in the Sandhills. 



Two tiger beetle species, Cicindelaformosa and 

 C. decemnotata, were common in sandy 

 blowouts or other early-seral sites, but in different 

 parts of the Sandhills. C. tranquebarica, was 

 localized on or near sites where sandy or pebbly 

 soil was somewhat moist. C. longilabris, was 

 encountered only twice in sandy sites with 

 moderate shrub and grass cover. The rare Idaho 

 Dunes Tiger Beetle (C arenicold), endemic to 

 Idaho and present 64 km (40 miles) south in the 

 St. Anthony Dunes (Fremont County), was not 

 encountered but may occur. 



As opportunities present themselves, additional 

 surveys of selected groups/species with specific 

 habitat or food needs (small mammals, songbirds, 

 ground beetles, butterflies) may be warranted. In 

 addition, surveys of all animal groups should be 

 conducted throughout the Centennial Valley to 

 identify the significance of the sandhill-associated 

 fauna to the entire valley system. 



