Factors Affecting Pika Populations in the North Cascades NPS Complex

1. Factors Affecting Pika Populations in the North Cascades NPS Complex Jason E. Bruggeman1, Roger Christophersen2, Regina Rochefort2, Robert Kuntz2 , and Rachel Richardson1 1--Beartooth Wildlife Research, LLC, Farmington, Minnesota2--National Park Service, North Cascades National Park Service Complex, Sedro-Woolley, Washington

2. Background on Pika Ecology • Habitat specialist -- live in talus patches • Sensitive to higher temperatures • Exposure to >77ºF for several hours may be lethal (Smith 1974) • Climate change indicator species (Beever et al. 2003, Smith et al. 2004)

3. Climate Change and Pikas • Climate change may affect pikas through: • Affecting time spent haying • Haying behavior begins in early summer • Time spent haying: • increases throughout summer • is negatively correlated with maximum snow cover from previous winter • is positively correlated with elevation (Richardson 2010; Richardson in prep.)

4. Climate Change and Pikas • Climate change may affect pikas through: • Behavioral changes owing to thermoregulation needs • Pikas spend less time grazing as temperature increases (Richardson 2010) and may adjust foraging and haying behavior accordingly • Impacts on vegetation communities • Vegetation presence/absence may change across elevations, affecting pika foraging

5. Pikas in the North Cascades • Initiation of collaborative study between Beartooth Wildlife Research and North Cascades NPS Complex in 2009 • Pilot study funded by Seattle City Light’s Wildlife Research Program • Goals: • Establish baseline count for pika populations in NOCA • Collect habitat attribute data from talus patches • Analyze data to examine biotic and abiotic factors affecting pika populations

6. Pikas in the North Cascades 30 1-km2 areas surveyed in 2009 27 areas with pikas Abundance: 0 to 101 pikas (mean = 23.6; SE = 4.6)

7. Pikas in the North Cascades 13 1-km2 areas resurveyed in 2010 13 areas with pikas Abundance: 4 to 101 pikas (mean = 30.6; SE = 9.0)

8. Methods • Pika Surveys • Record abundance in talus patches • Habitat Attribute Data Collection • Vegetation cover • Talus temperature profiles • Data Analyses • Assorted regression techniques and model selection

9. Key Results • Elevation Effects • Area Abundance: Positively correlated with elevation • Significance to Pikas in NOCA? • Lower elevation populations are relatively small and may be most susceptible to extirpation with continued climate change and elevation shifts in vegetation

10. Key Results • Elevation Effects • Growth Rates: Negatively correlated with elevation • Significance to Pikas in NOCA? • Low elevation populations may benefit from milder winter conditions. The trend in 2009-2010 growth rates likely owes to a mild winter, but lingering snowpack at mid to high elevations likely kept those populations relatively stable. This trend may change with more data.

11. Key Results • Large-Scale Temperature Effects • Growth Rates: Positively correlated with estimated average minimum daily winter temperature • Significance to Pikas in NOCA? • Warmer winter temperatures, occurring at lower elevations, reduce thermal stress on pikas and likely increase overwinter survival, resulting in population growth.

12. Key Results • Small-Scale Temperature Effects • Patch Abundance: Negatively correlated with average minimum summer temperature beneath the talus surface • Significance to Pikas in NOCA? • Areas beneath the talus provide a cool microclimate and refuge for pikas from warmer temperatures at the surface. As sub-surface temperatures increase, pikas lose this cool refuge and are more susceptible to thermal stress, possibly reducing survival.

13. Key Results • Negatively correlated with elevation • Temperature beneath the talus surface • Significance to Pikas in NOCA? • Higher elevation talus patches may have more hospitable sub-surface temperatures than lower elevations.

14. Key Results • Negatively correlated with talus depth • Temperature beneath the talus surface • Significance to Pikas in NOCA? • Talus patches with more depth and rock structure may provide more favorable habitat than those with minimal depth.

15. What does this mean for Pikas in NOCA? • Lower elevation populations will likely be the indicators for continued climate change • Extirpations will likely occur first at low elevations • Summer temperatures and sub-surface talus temperatures are warmer at low elevations • They may experience large fluctuations in population size in response to winter climate

16. What does this mean for Pikas in NOCA? • Mid to high elevation populations • Larger population sizes less prone to extirpation • Experience trade-offs between cooler summer temperatures and harsher winter conditions with later spring snow melt • All pika populations are susceptible to climate variability, especially winter conditions, and may experience large fluctuations as a response (Morrison and Hik 2008)

17. Ongoing and Future Work • Temperature Data Loggers • Deployed in fall 2010 in 30 talus patches • Collecting temp. data every 10 min. • Data to be gathered in fall 2011 • Used to gain insights into temperature extremes pikas experience and how temperature is related to abundance and growth rates

18. Acknowledgements • Seattle City Light’s Wildlife Research Program • Washington’s National Park Fund • North Cascades NPS Complex • Field Data Collection Crews