Big Pine Creek. Low. 2414. Green Lake. High. 3385. Piute Lake. High. 3381. Bishop Creek. Low. 2506. Tamarack Lakes. High. 3568. Rock Creek. Low. 2637.
CAN PIKAS ADAPT TO RISING TEMPERATURES? Comparisons of Behavior between High and Low Elevation Pikas in the Sierra Nevada
C o d y P. M a s s i n g USGS Bishop Field Station California Polytec hnic University
ALPINE SPECIES AT RISK • Climate change may have large consequences for alpine organisms+ • American pikas, small alpine mammals • Proposed for listing as endangered or threatened in California and federally, but proposals were denied + • Many groups are studying pikas to determine population status
+
Blackfoot-Jackson Glacier in Glacier National Park, http://www.nrmsc.usgs.gov/research/
Beniston 2003, Naftz et al. 2002, Lenoir et al. 2008, Walther et al. 2005, Wilson et al. 2005, Gustafson and Logsdon 2007.
AMERICAN PIKA, Ochotona princeps • Small lagomorph (rabbit relative) • Montane obligate, above ~1500 m • Generalist herbivores
AMERICAN PIKA ECOLOGY Talus habitat
AMERICAN PIKA ECOLOGY Adapted to cold alpine winters • Do not hibernate • Collect haypiles • High body temperature
AMERICAN PIKA ECOLOGY • Poorly adapted to heat • Die when confined above ground, 25.5˚- 29.4˚ C+ • Cannot regulate body temperature to heat physiologically • Remain under rocks when warm
+
Smith 1974
ARE PIKAS IN PERIL? • Much emphasis on thermal stress, but… • Evidence that pikas may be able to withstand the heat • Select particular microclimates • Remain under talus where temperatures are more moderate • Smith (1974), low elevation pikas more crepusuclar (active at dawn and dusk) • Behavioral plasticity?
MY RESEARCH 1. How much individual variation do pikas have? • Potential for behavioral plasticity
2. Are pikas less active at warmer temperatures? 3. Are activity schedules different between warmer and cooler sites? • Are specific behaviors different?
4. Can alarm calls be used to measure activity rate?
METHODS: STUDY SITE • 6 high and 6 low elevation sites • 3-6 plots within each site • 1-2 unique pikas in each plot Site
Category
Elevation (m)
Onion Valley
Low
2641
Kearsarge Pass
High
3471
Big Pine Creek
Low
2414
Green Lake
High
3385
Piute Lake
High
3381
Bishop Creek
Low
2506
Tamarack Lakes
High
3568
Rock Creek
Low
2637
North Peak
High
3168
Lundy Lake
Low
2384
Virginia Lakes
High
3394
Barney Lake
Low
2543
METHODS: STUDY SITE • High sites: 3162 - 3569 m (mean = 3376 m)
• Alpine meadow vegetation (e.g. sedges, (Carex spp.) and columbine (Aquilegia spp.))
• Low sites: 2376 - 2680 m (mean = 2526 m)
• Shrubby vegetation (e.g. sagebrush (Artemisia tridentata), fernbush (Chamaebatiaria millefolium))
METHODS: OBSERVATIONS Time Blocks 1 – 4: Start: 10 min before sunrise 10:00-12:00 14:00-16:00 Finish: 10 min after sunset
• Shade surface temperature recorded • Each plot observed once in each time block • 20 minute observation sessions • Scan samples • Recorded specific behavior every 30 seconds
RECORDED BEHAVIORS Activity Perch Forage
Definition Sitting Consuming vegetation Carrying plant or other material and returning to rocks with the Hay material Run Moving from place to place (includes walking and hopping) Groom Cleaning self Alarm calls Any alarm calls by focal pika Inactive Pika not in view (presumed under rocks) for at least 30 seconds Out of view Pika is believed to be active, but is out of sight
METHODS: ANALYSIS • Aboveground activity rate • Any aboveground activity occurring in one 30-second time slot = 1 • Sum all activities during observation session • Divide by number of pikas in plot • Divide by number of visible observation minutes • One pika visible in every time slot for 20 minutes: 40 ÷1 ÷ 40 = 1 • Range = 0 - 1
• Specific activity rates • Same as above, except using only each specific activity type (foraging, haying, etc.)
METHODS: ANALYSIS • General linear mixed models • Sites are random effects • Compared activity rates (both overall and specific activities) at different time blocks and elevation classes and temperatures • Explored additive and interaction effects for example:
activity rate ~ sites (random effect) + elevation class * time block
RESULTS: TEMPERATURE • Temperatures were higher in the low elevations (P =
Time Block Temperature Averages 30 25 Temp (C)
20
0.0022)
15
Low
10
High
5 0
1
2
3 Time Block
4
• Temperatures varied throughout the day in both elevations (P < 0.0001)
RESULTS: TEMPERATURE
Activity Rate
• Pikas were less active at warmer temperatures • BUT, when the time block was accounted for, temperature was not significant in predicting activity (P = 0.3947).
Temperature and Activity
Temperature (C)
RESULTS: SITES • Activity rates were different between different sites (P < 0.0001)
• And between different plots, when sites were accounted for (P = 0.0108) Average Activity Rates in High and Low Sites
Activity Rate
0.20 0.15
High Low
0.10 0.05 0.00 Elevation Class
• High and low elevations were not significantly different in activity rates when sites were accounted for (P = 0.1979)
RESULTS: TIME 0.35
Daily Activity Rates High
0.30
Low
Activity
0.25 0.20
0.15 0.10 0.05 0.00 1
2
3
Time Block
4
Activity was greatest at dawn and dusk (P < 0.0001) • Even when temperature was accounted for • Elevation classes did not have different activity schedules (P = 0.6578)
RESULTS: SPECIFIC ACTIVITIES Specific Activities 0.14
0.12
Activity Rate
0.10
High 0.08
Low
0.06 0.04 0.02
0.00 Perch
Run
Forage
Hay
Groom
• Less foraging in the low sites (P = 0.0122) • More haying in the high sites later in September • Little haying in the low sites throughout the summer
ALARM CALLS • Alarm calls were not related to activity • Most calls occurred under the talus
• Unfortunately, this is not a valid method for determining activity rate Photo: http://seattletimes.nwsource.com/html/localnews/2009 702923_pika21m.html?syndication=rss
INDIVIDUALITY • Pikas very individualistic • Some hayed or foraged all day, some never, some only in the morning…
• How can such different survival tactics be maintained in a population? • Alpine environment is very unpredictable • No one tactic is best from year to year
ACTIVITY RATE • High variation between sites, so not representative of all pikas, but…
• Activity rates were more dependent on time of day than temperature and other weather conditions • Activity schedules were not different between elevation classes • Pikas had a set activity schedule, most active at dawn and dusk
FORAGING • Less diurnal foraging occurred in the low site • Could they be foraging at night? • Smith (1974) heard more
alarm calling at night in his low elevation site
• Afghan pikas exhibit nocturnal behavior , maybe American pikas do too +
• Would allow them to escape higher daytime temperatures +
Kosaka et al. 1988
CONSEQUENCES • Reduced activity during warmer temperatures could impact pika health • Less foraging and lower haypile size could increase pika mortality by reducing a pika’s preparedness for winter • Undernourished pikas could be more susceptible to disease and parasites and less reproductively successful
CONCLUSION • Pikas foraged less in lower elevation--more research needed • Are they stressed, or adapting?
• Individual variation high • Behavioral plasticity • Environmental changes caused by climate change may occur too fast for pikas to adapt
• Focus on pikas, but may have implications for other species
THANKS TO… USGS-BRD-WERC NCCWSC California Polytechnic University
QUESTIONS?
Rob Klinger John Perrine Laurel Triatik Bridget Benedict Steve Anderson
