Effectiveness of forest restoration and plague treatments on demography of a federally listed ground squirrel

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Abstract:

The authors’ efforts to evaluate the effectiveness of forest restoration treatments on the demography of the federally threatened northern Idaho ground squirrel (Urocitellus brunneus brunneus) continued and expanded in 2014. They and field assistants captured 107 adult and 75 juvenile northern Idaho ground squirrels (NIDGS) at 9 Restoration study sites. Return rates for all age groups of NIDGS ranged from 0.0% at Huckleberry and Slaughter Gulch to 42.1% at Fawn Creek. Reproductive rates (# of juveniles to adult female) in 2013 ranged from 0.0 at Huckleberry and Slaughter Gulch to 1.9 at Rocky Top. Annual return rates of adult NIDGS (≥ 1 years old) were 0.22 (± 0.21 SE) for males and 0.29 (± 0.22 SE) for females. Reproductive rates in 2014 ranged from 0.8 at Tamarack East and Rocky top to 2.1 at Steve’s Creek. Size of each active colony mapped ranged from 0.7 ha at Huckleberry to16.2 ha at Slaughter Gulch. After one season of surveying grazed and ungrazed plots, the authors found the number of seed heads and total percent herbaceous cover was higher on ungrazed plots. Fallen seed biomass was higher on grazed plots. Twenty-two VHF collars were placed on adult NIDGS at 4 study sites, including a high-elevation study site (Lick Creek Lookout) where collars had not been deployed in previous years. The average date that NIDGS entered their hibernacula in 2013 ranged from 24 July at Big Mud 1 to 31 August at Bear OX. In 2014, the average date that NIDGS entered their hibernacula ranged from 26 July at Fawn Creek to 3 September at Lick Creek Lookout. NIDGS hibernacula tended to be located at forest edges, within the forest when there was forest adjacent to the active colony, or hillsides. An additional 238 adults and 160 juvenile squirrels were captured at five Plague study sites. The percent of NIDGS, Columbian ground squirrels, and chipmunks that harbored fleas in 2014 ranged from 0.0 to 100.0%. The percent of NIDGS that harbored fleas on dusted sites ranged from 10.0 to 13.3%, while on undusted sites the range was 39.1 to 51.9%. The percent of Columbian ground squirrels that harbored fleas on dusted sites ranged from 0.0 to 5.9% and on undusted sites ranged from 80.0 to 91.5%. Six species of fleas were identified from 2 sites collected during the 2013 field season. Thrassis pandorae was the most common flea species found on both NIDGS and Columbian ground squirrels, while Eumolpianus eumolpi was the most common on yellow-pine chipmunks. These experiments will allow the authors to test an alternative hypothesis regarding the potential factors responsible for the current rarity and past population declines of NIDGS.

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ELECTRONIC FILE - Zoology

"The habitat restoration project was funded by the USFS (Payette National Forest) and the Plague project is funded by USFWS and USGS."

Possible contract no.: Threatened and Endangered Species Projects TE-94776A-0