Population survey of the southern Idaho ground squirrel

Publication Type:

Report

Authors:

Yensen, Eric; Haak, Bruce

Source:

p.16 (2000)

Call Number:

U00YEN01IDUS

Keywords:

Southern Idaho Ground Squirrel, Spermophilus brunneus, Urocitellus endemicus

Abstract:

Southern Idaho ground squirrel (Spermophilus endemicus [Urocitellus endemicus]) populations have declined abruptly throughout the species' very limited range in Gem, Payette, Washington, and extreme southern Adams counties, southwestern Idaho. This survey was undertaken to determine the location and sizes of populations on Bureau of Land Management (BLM) lands in the known range in southwestern Idaho. Because some BLM parcels are being considered for land exchange in the near future, priority was given to surveys of those sites during the 2000 field season. Between 14 March and 4 June 2000, 93 exchange parcels were surveyed. In addition, 21 sites previously surveyed in 1999 were revisited to evaluate population trends. At the end of the field season, time was available to search some additional BLM land for southern Idaho ground squirrel (SIGS) populations. The authors found SIGSs at 8 exchange sites (#1021,1038, 1049, 1052, 1055, 1124-1, 1128, and 1129). All of these sites had very small SIGS populations, but most had at least some potential for restoration. Resurvey of 1999 sites indicated little change from the low population densities encountered last year. Eighteen new sites were located on BLM non-exchange parcels and 5 on adjacent private property. Most of these were located from systematic searching in Gem County where there was good potential for new sites, but some were discovered incidental to other field work. All inhabited sites were occupied by small populations, but unfortunately these at the moment are all we have for future restoration efforts. Poor range condition was noted at most sites. Observations of a negative correlation between medusahead (Taeniatherium asperum) cover and ground squirrel presence noted in earlier studies appears to be corroborated, and such range condition might explain the decrease in ground squirrel populations.