a multi-level, field-based study to document potential ecological interactions between mountain goats and American pikas: two mammalian herbivores that are specialists in alpine habitats. Understanding these interactions will have important implications for the conservation of each species. Such data will be particularly useful for both pika conservation and agencies tasked with managing the land that introduced mountain goat herds inhabit.
The Specific Aims of my research this summer was to:
1) Evaluate mountain goat use of pika-occupied talus habitat using GPS telemetry data from multiple subpopulations for habitat selection function analysis.
2) Compare forage utilization between goats and pikas. Test for evidence of competition or facilitation using a replicated three-plot semipermeable exclosure design. Additionally, test for ecosystem-level feedback loops in herbivore-plant interactions that might influence forage quality for both species around pika-inhabited talus slopes.
3) Assess risk-sensitive foraging by pikas by testing whether pika giving up distance varies with (a) mountain goat pellet density, (b) vegetation coverage of soil, and (c) mountain goat visitation based on GPS data.
4) Review the ecological interactions between pikas and mountain goats, and the management options for both, in the context of conserving the biodiversity of alpine habitats of the Colorado Plateau.
Great progress was made this summer toward completing these aims. I worked with two field research technicians to finish installing grazing exclosures. We now have a total of 10 exclosure sites each with two exclosure plots and one reference plot installed. At the end of the growing season in September, I went back into the field with one technician and several volunteers to clip the vegetation in all of our experimental plots and sample two soil samples at each site (one near the talus edge and one in an alpine meadow far from the talus edge).
This fall I will dry, weigh, and compare the clipped vegetation from each site. This will serve as a baseline measurement of above-ground biomass for the final analysis. The soil samples will soon be sent to the Soil Lab at USU to be tested for soil nutrients such as nitrogen, phosphorous, sodium, and ph using funds from the Discovery Pool grant. To monitor visitation rates to our experimental plots by pikas and goats, we deployed two camera traps at each site and are in the beginning stages of processing them. Additionally, we collected over 400 observations for pika giving up distance and conducted four vegetation/goat sign transects at each of our exclosure sites (Specific Aim 3). Currently, I am preparing mountain goat GPS and GIS data to run a preliminary habitat selection analysis (Specific Aim 1).