Presentation on theme: "Additional Key Results Pika abundance in talus patches was negatively correlated with the minimum temperature recorded beneath the talus surface during."— Presentation transcript:
Additional Key Results Pika abundance in talus patches was negatively correlated with the minimum temperature recorded beneath the talus surface during surveys (Figure 1), suggesting as sub-surface temperatures increased, pika abundance decreased. Total pika abundance in 1-km 2 survey areas was positively correlated with elevation (Figure 2) and an interaction between elevation and the proportion of vegetation cover in patches, suggesting higher elevation survey areas and those with more cover supported more pikas compared to lower elevations. This finding may be indicative of higher quality vegetation at higher elevations. The population growth rate in 1-km 2 survey areas between 2009 and 2010 was negatively correlated with elevation, which is likely the result of a combination of winter and spring conditions resulting in later snowmelt that varied with elevation. The growth rate was also positively correlated with the estimated average minimum daily temperature during December 2009 through February 2010, which may be attributed to cold stress on pika over-winter survival. Because pika populations in the North Cascades National Park Service Complex during 2009 and 2010 were influenced by multiple climate and habitat factorsnotably temperature, elevation, and resource availabilitythe potential exists for pikas to be adversely affected by climate change in future years. While many of these effects could take many decades to manifest themselves, especially for pika populations at higher elevations, changes may become apparent in lower elevation populations on shorter time scales. Jason E. Bruggeman 1, Roger Christophersen 2, Regina Rochefort 2, Robert Kuntz 2, and Rachel Richardson 1 Pika Research in the North Cascades National Park Service Complex in 2009 and 2010 The Pika in the North Cascades The American pika (Photo 1) is a small mammal that lives only in talus patches located in habitats ranging from low elevation forests up to high elevation alpine meadows in the North Cascades National Park Service Complex. Pikas are considered to be a climate change indicator species because of their sensitivity to high temperatures and obligation to talus habitat. Climate change may affect pikas through changes in foraging behavior owing to summer temperature increases, alterations in vegetation across elevations that may affect forage availability, and changes in winter snowpack and temperature patterns that may negatively influence survival. Field Methods and Results In summer 2009, surveyors gathered data on pika abundance, habitat attributes, and temperature in 115 talus patches contained within 30 1-km 2 survey areas throughout the North Cascades National Park Service Complex. Surveyors found pikas in 74% of talus patches and 90% of 1-km 2 survey areas, with abundance per survey area ranging from 0 to 101 pikas. In summer 2010, surveyors revisited 58 of the 115 patches included in 13 of the 30 1-km 2 survey areas, and found pikas in 76% of patches and all 13 survey areas, with abundance per area ranging from 4 to 106 pikas. During 2009 and 2010, surveyors found pikas in patches ranging in elevation from 351 to 2,130 m, which spanned the entire range of elevations for patches surveyed. Surveyors recorded vegetation cover types within talus patches in a total of 1,932 1-m 2 plots in 2009 and 2010. The frequency of occurrence of vegetation cover types varied with elevation. Bryophytes and lichens occurred most frequently in plots at low and middle elevations, while cushion plants, forbs, graminoids, and shrubs occurred more often at high elevations (Photos 2, 3 & 4). 1--Beartooth Wildlife Research, LLC, Farmington, MN; 2--National Park Service, North Cascades National Park Service Complex, Sedro-Woolley, WA. Funding for the study was provided by Seattle City Lights Wildlife Research Program. Photos 2, 3 & 4. From left to right, examples of talus patches at low (472 m), middle (1,464 m), and high (2,118 m) elevations in the North Cascades National Park Service Complex. Photo 1. A pika in a low elevation talus patch in the North Cascades National Park Service Complex Figure 1. The negative correlation between pika abundance in talus patches and the minimum recorded sub-surface temperature (ºF). Figure 2. The positive correlation between total pika abundance in 1-km 2 survey areas and elevation (meters).