Factors Influencing Pika Foraging Behavior in North Cascades National Park, Washington Rachel Richardson 1,2 and Jason Bruggeman 1 1--Beartooth Wildlife.

Factors Influencing Pika Foraging Behavior in North

Cascades National Park, Washington

Rachel Richardson1,2 and Jason Bruggeman11--Beartooth Wildlife Research, LLC; 2--University of Montana

• Rising temperatures

• Changing precipitation patterns

• Increased frequency of extreme weather events

• Shifting species distributions

• Upslope range contractions in alpine species

Global Climate Change

Alpine species are vulnerable!

American pika (Ochotona princeps)

Pika Ecology

• Small herbivorous lagomorphs

• Restricted to talus slopes (i.e., rock piles)

• Well adapted to moist, cool climates

• Behaviorally thermoregulate

• Resting body temperature near lethal maximum

• Sensitive to higher temperatures

• Retreat under rocks to avoid stressful daytime temps (Smith 1974)

Climate Change Indicator Species

Pika Foraging Behavior

• Grazing behavior - immediately consume plants

• Haying behavior - collect, transport, and store plants for

winter use - cache vegetation in “hay piles”

Why are these hay piles important?

• Provide adequate forage for overwinter survival (Dearing 1997)

• Seasonal fluctuation in food availability • Enable pikas to manage resources during

winter

• Preferred plants contain beneficial compounds (Dearing 1997)

• Hay piles may insulate nesting sites from extreme temps (Krear 1965)

• Provide predator protection (Ivins 1984)

However …

• Short summer growing season (early July – August)

• Time available to build hay piles restricted (Huntly et al. 1986)

• Increased foraging during peak vegetation biomass (Morrison et al. 2009)

• Thermal stress may constrain time available for foraging

North Cascades National Park

Encompasses 275,684 ha in north centralWashington

Elevations ranging between 300 and 2,800 m

Study Area

High Priority Species

Primary Research Question:

How will a changing climate affect pika foraging behavior?

Research Plan

• Collect data on pika behavioral time budgets

• Calculate proportion of time spent grazing and haying

• Evaluate relationships between foraging behaviors and temperature, elevation, date, climate and vegetation covariates

Data Collection Methods

• Pika Surveys- Direct observations- Audible vocalizations- Active hay piles with

fresh vegetation

• Focal Animal Sampling- 5 minute individual

observations on up to 5 pikas in a patch

Data Collection Methods

• Habitat Attributes- 25 m vegetation

transects (classification, % cover)- Recorded surface temperature- GIS elevation layer

• Covariate Estimation- Data from 8 NRCS SNOTEL sites (estimate SWE, melt date)

2009 Surveys

30 1-km2 areas surveyed in 2009

27 areas with pikas

Behavioral observations in

15 of the selected sites

2010 Surveys

13 1-km2 areas resurveyed in

2010

13 areas with pikas

Behavioral observations in 8 of the selected

sites

Analysis Methods

• 8 predictor variables: TEMP, ELEV, DATE, MELT, SWEMAX,

VEGCOVER, FORAGECOVER, YEAR

• Logistic regression modeling• Evaluated 71 models with additive combinations of covariates• R 2.6.2 to fit models and estimate parameter coefficients

• AICc and wi for each model

• ΔAICc to rank and select top models

HypothesesCovariates Proportion of

time grazingProportion of time haying

Temperature - -

Elevation + +

Date - +

Date of spring snowmelt + -

Maximum snowpack snow water equivalent (SWEMAX)

+ -

Proportion of vegetation cover

+ +

Proportion of forage cover

+ +

Results

• 95 foraging observations• 15 unique 1-km2 survey areas and 37 unique patches• ELEV: 889 – 2,173m (mean = 1,552; SE = 34) • TEMP: 42.9°F – 83.5°F (mean = 61.5; SE = 1.0)• DATE: June 25 - September 27 (mean = August 14; SE = 2)• SWEMAX: 0.5 - 1.1 m (mean = 0.72; SE = 0.02 )• MELT: May 12 - August 9 (mean = June 14; SE = 2)• VEGCOVER: 0.07 - 0.66 (mean = 0.29; SE = 0.01)• FORAGECOVER: 0.0 - 0.3 (mean = 0.09; SE = 0.01)

Results -- Grazing Models

Model ΔAICc wi

47 0.00 0.808 46 2.93 0.187

Model ΔAICc wi

47 0.00 0.808 46 2.93 0.187

Model #47 Coefficient SignTEMP -ELEV -DATE -MELT +VEGCOVER -YEAR (2010) +

Results -- Grazing Models

Allsignifican

tat P =

0.05

Results -- Haying Models

Model ΔAICc wi

46 0.00 0.999 47 13.96 0.001

Results -- Haying Models

Model ΔAICc wi

46 0.00 0.999 47 13.96 0.001

Model #46 Coefficient SignTEMP +ELEV +DATE +SWEMAX -VEGCOVER +YEAR (2010) -

Allsignifican

tat P =

0.05

Some answers …Covariates Proportion

of time grazing

TEMP -

DATE -

MELTDATE +

Covariates Proportion of time haying

DATE +

ELEV +

VEGCOVER

+

SWEMAX -• TEMP : Behavioral thermoregulation• DATE : Time/energetic considerations• MELTDATE : Time constraint • ELEV : Availability of higher quality forage, lower temperatures• VEGCOVER : Increased availability of vegetation in a talus patch • SWEMAX : Greater snowpack accumulation may delay melt and influence new vegetative growth

More questions …

Covariates Proportion of time grazing

ELEV -

VEGCOVER

-

Covariates

Proportion of time haying

TEMP +

• ELEV : Differences in plant abundance/quality among elevations?• VEGCOVER : Influence of preferred forage types?• TEMP : Data limitation? Not enough observations at higher temps?

Conclusions -- Pikas and Climate Change

• Multiple interacting factors influencing

pika foraging behavior• Increasing temps, shifting precip patterns may negatively impact forage availability - Less forage = smaller hay piles - Smaller hay piles = lower winter survival (reduction in food and nest insulation)

Conclusions -- Pikas and Climate Change

• Increasing temps may also limit time available for foraging - Less daytime activity = shift to night activity?• Low elevation populations may experience effects of climate warming first - Unsuitable habitat = low elevation extirpations = upslope range contractions

Management Recommendations

• Compare environmental variables across elevations

• Observations throughout the day to better understand temp variability

• Evaluate changes in plant communities across elevations

• Annual surveys!

• North Cascades NPS Complex

• Seattle City Light’s Wildlife Research Program

• Field crews during 2009 and 2010

Acknowledgements

Questions?