Distance and temperature effects on pika forage

Abstract

The American pika, Ochotona princeps, has been referred to as a 'canary in the coal mine' when it comes to climate change. This small rabbit relative inhabits cool alpine and subalpine mountain areas and has been shown to be sensitive to higher temperatures from both physiological experiments (Smith 1974) and from past climate transitions in the late Quaternary (Grayson 2005). Two studies in the Sierra Nevada and Great Basin showed recently abandoned pika habitats possibly due to global warming and associated heat stress (Beever et al. 2010, Millar et al. 2010). A more indirect influence on long term pika success at individual sites could be through their forage base. Researchers in Colorado have shown that most pika foraging is within four meters of safe sites in talus with late summer haying occurring slightly further away (Roach et al. 2001, Huntley et al. 1986). Naturalists as far back as 1917 have noted that pika feed on "low vegetation" such as grass near talus slopes and are distributionally restricted to "rock-pile" habitats (Grinnel 1917). Changing climate conditions in temperatures and precipitation may alter the composition, extent, production and phenology of vegetation in their alpine habitat. Most pika studies have focused on behavior such as foraging distance from talus and response to avian predators or alternatively, changes in plant biomass or plant functional group (graminoid, cushion plant, forb, and woody) abundance changes with distance from talus (e.g. Roach et al. 2001, Smith and Weston 1990, Huntley et al. 1986). Few studies have attempted to measure plant species composition within the pika foraging zone or compared it with species composition outside of this zone (10+ m). Categorized as Tier III species in Utah's Wildlife Conservation Strategy, the Division of Wildlife has established studies to monitor pika occupancy across the state. Data from these studies on the La Sal Mountains in 2008 and 2011 found pika in all suitable habitat sampled, and no changes in occupancy between years. DWR personnel will redo the survey in 2014.

Citation

Fowler, Jim F.; Smith, Barbara; Overby, Steve. 2014. Distance and temperature effects on pika forage. Final report. Moab, UT: Canyonlands Natural History Association. 18 p.