Graduate Thesis Or Dissertation
 

Oregon spotted frog (Rana pretiosa) habitat use and herbage (or biomass) removal from grazing at Jack Creek, Klamath County, Oregon

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https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/gh93h2324

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  • We evaluated the effects of herbage removal from livestock grazing on Oregon spotted frog (Rana pretiosa) habitat use by monitoring frog locations in grazed and matched ungrazed treatments across a range of grazing intensities at Jack Creek, Fremont-Winema National Forest, Oregon. Thirteen cattle exclosures were deployed along Jack Creek in the summer of 2003. Movements were monitored using radio telemetry on adult frogs (N = 24 frogs) within treatments sites from July through October 2004. Individual frogs were located 1 to 28 times ([mean]=11.7) and were tracked from 1 to 74 days [mean]=35.8 days). A 10-pinpoint intercept frame was used to estimate relative differences in removed vegetation cover. This difference between ungrazed treatments and paired grazed controls was used as a measure of grazing pressure at treatment sites, and examined in relation to frog habitat preference. Pin measurements ranged from an average monthly difference of -1.2 to 2.97 pin hits between an exclosure and its control. As pin differences increased by one unit, the odds of finding a frog in the exclosure increased by a factor of 1.62 (F1,4 = 3.90, p = 0.05) with an approximate 95% confidence interval of 1.00 to 2.74. Based on the proportion of time frogs spent inside exclosures, there was evidence that as grazing pressure increased, frogs preferred ungrazed livestock exclosures. Secondary objectives of this study were to describe migration routes and identify overwintering sites of the R. pretiosa population on Jack Creek. From August to mid-December 2003, frogs (N = 36) were tracked from 5 to 92 days ([mean] = 49.5 days) and located 2 to 39 times ([mean] = 23.2 times). In mid-October, individuals were located in sheltered areas along the creek such as willow root complexes and abandoned beaver runs. Frogs also were found in deep (130 cm) pools associated with active springs and individuals in these areas were active within the pools under 5 cm of ice. Using mark-recapture techniques and deployment of cattle exclosures, we examined 1) frog migration and 2) grazing effects on frog habitat use for the Jack Creek R. pretiosa population in 2003-2004. Ultimately, a more complete understanding of the natural history of this species and how anthropogenic activities affect amphibians such as R. pretiosa will aid managers in mitigating potential adverse affects, especially in riparian systems, and contribute to recovery and restoration strategies.
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Déclaration de droits
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file details Shovlain_Amie_M._2006.pdf 2017-08-14 Public Télécharger