the American
pika
Chris Ray, CU
pikas are...
...and...
related to rabbits
as big as your fist
non-hibernating
highly vocal
habitat specialists
herbivorous
highly territorial
hay-stackers
Ochotona
princeps
chris.ray@colorado.edu
Outline
Motivation for an
individual-based
study of climatic
stressors
Preliminary
results from a
long-term study
in Montana
Preliminary
results from a
comparative study
of MT & CO pikas
chris.ray@colorado.edu
shanaweber@mac.com
Summer heat-stress
Grinnell 1917
MacArthur & Wang 1973, 1974
Smith 1974
Hafner 1993, 1994
Hafner & Sullivan 1995
Verts & Carraway 1998
Li et al. 2001
Simpson 2001
Beever et al. 2003, 2010
Winter cold-stress
Tapper 1973
Smith 1978
Morrison and Hik 2007
Beever et al. 2010 & in prep.
chris.ray@colorado.edu
Shrinking
distribution
of the American pika
chris.ray@colorado.edu
25 historical populations
recorded 1898-1990
(average date = 1933)
6 extinct by 1999 (►)
10 by 2008 (◄)
Extinction rate is rising
chris.ray@colorado.edu
Rising mean minimum elevation
of 25 historical pika populations
in the Great Basin
2008: 2,566 m
1999: 2,474 m
>10 m/yr
>1 m/yr
1933: 2,374 m
Similar patterns in the Sierra Nevada
(Moritz 2007)
chris.ray@colorado.edu
What predicts extinction?
Habitat size/structure
Human impacts
Species interactions
Thermal stress
Beever et al. in press:
Habitat area
Accessibility
Livestock grazing
Acute heat-stress
Chronic heat-stress
Acute cold-stress
Climatic refugium
chris.ray@colorado.edu
Defining local extinction
Persisting
N = 11
3 km
N = 10
Extinct
200 m
N=4
Transitional but persisting
chris.ray@colorado.edu
Candidate predictors of extinction:
“Habitat area” – amount within 0.8 km, or entire mtn range
3 km
“Refuge” – elevation of highest habitat within 3 km
chris.ray@colorado.edu
Candidate predictors of extinction (continued):
“Accessibility” – distance to nearest non-4WD road
“Grazing” – long-term use of the site by livestock
“Acute heat stress” – number of days above 28°C/82°F
“Chronic heat stress” – average summer temperature
“Acute cold stress” – number of days below -10°C/14°F
chris.ray@colorado.edu
Hourly haypile temperatures
40
Niwot Ridge, CO
Gallatin Range, MT
30
Temperature
temp (C) (C)
20
10
Joyce
Gellhorn
0
-10
-20
-30
A-04 S-04 O-04 N-04 D-04
J-05
F-05 M-05 A-05 M-05 J-05
date
Date (Month-Year)
J-05
A-05
Hindcasting metrics of stress
Study site T (°C)
3 data sets: Σ = long-term, Δ = climate change, τ = recent
1945
1955
1965
3 stress metrics
Acute heat-stress
Chronic heat-stress
Acute cold-stress
1975
1985
Data used
# days > 28 °C
Summer mean T
# days < -10* °C
1995
2005
Hindcasts
Σ >28 , Δ>28 , τ>28
Σ μS , ΔμS , τμS
Σ <-10 , Δ<-10 , τ<-10
What predicts extinction?
Given the many factors
that may be responsible
for pika extinctions,
perhaps the only reason
our list of predictors looks
like this is because we
haven’t yet had the
opportunity to consider
other (perhaps better)
predictors, and data from
other regions.
Cold days
(last 60 yrs)
Refuge
(upslope habitat)
Habitat area
(w/in 0.8 km)
Hot summer
(recent mean)
Habitat area
(w/in range)
Grazing
chris.ray@colorado.edu
Erb, Ray & Guralnick study, in prep.
Of 69 historically occupied sites
in the southern Rockies,
only 4 are no longer occupied
The 4 local extinctions are explained
by moisture issues: pikas are
missing only from the driest sites
How might climate cause
extinction?
chris.ray@colorado.edu
Outline
Motivation for an
individual-based
study of climatic
stressors
Preliminary
results from a
long-term study
in Montana
Preliminary
results from a
comparative study
of MT & CO pikas
chris.ray@colorado.edu
Gallatin Range
Demographic Study
Montana
Ray 1989-2009
chris.ray@colorado.edu
Gallatin Range
Demographic Study
Montana
Ray 1989-2009
Proportion of temperatures
0.4
2005-2009 pika fate vs. microsite temperature
0.35
Pika survived (n = 30)
0.3
Pika died (n = 37)
0.25
0.2
0.15
0.1
0.05
0
-14 -10 -6
-2
2
6 10 14 18
Temperature (C)
chris.ray@colorado.edu
22
26
30
Gallatin Range
Demographic Study
Montana
Ray 1989-2009
Proportion of temperatures
0.5
2008-2009 pika fate vs. microsite temperatures
Pika survived (n = 5)
Pika died (n = 4)
0.4
0.3
0.2
0.1
0
-14 -10
-6
-2
2
6
10
14
Temperature (C)
chris.ray@colorado.edu
18
22
26
0.9
0.8
0.7
0.6
0.5
0.4
Proportion adults in population
1.0
Gallatin Range
Demographic Study
Montana
Ray 1989-2009
1990
1995
chris.ray@colorado.edu
2000
Year
2005
2010
0
-1
-2
-3
Adults
Juveniles
-4
Cache size, Aug 31
1
2
Gallatin Range
Demographic Study
Montana
Ray 1989-2009
2000
2002
2004
2006
Year
chris.ray@colorado.edu
2008
Outline
Motivation for an
individual-based
study of climatic
stressors
Preliminary
results from a
long-term study
in Montana
Preliminary
results from a
comparative study
of MT & CO pikas
chris.ray@colorado.edu
Stress and survival study
Gallatin Range, MT
& Niwot Ridge, CO
Ray et al., 2008-2009
Bob Rapp
0.8
Stress and survival study
Gallatin Range, MT
& Niwot Ridge, CO
Ray et al., 2008-2009
Main site, MT
LTER site, CO
0.4
0.2
0.0
Survival rate
0.6
(c)
MT
CO
Site
Southern Northern
CO slope aspect
Stress and survival study
Gallatin Range, MT
& Niwot Ridge, CO
Ray et al., 2008-2009
Plasma glucose (mg/dl) X 100
14
12
(d)
10
8
6
4
2
0
CO
MT
Site
0.4
MT
CO
0.1
0.2
0.3
(a)
0.0
Proportion of temperatures recorded
Stress and survival study
Gallatin Range, MT
& Niwot Ridge, CO
Ray et al., 2008-2009
-20
10
0
-10
Temperature (C)
20
0.4
S aspect
N aspect
0.1
0.2
0.3
(b)
0.0
Proportion of temperatures in CO
Stress and survival study
Gallatin Range, MT
& Niwot Ridge, CO
Ray et al., 2008-2009
-20
-10
0
10
Temperature (C)
20
How might climate cause
extinction?
?
?
?
?
?
?
chris.ray@colorado.edu
How might climate cause
extinction?
Summer heat-stress
Heat avoidance behavior
Reduced foraging activity
Smaller or inferior haypiles
Winter cold-stress
chris.ray@colorado.edu
How might climate cause
extinction?
Summer heat-stress
Heat avoidance behavior
Reduced foraging activity
Smaller or inferior haypiles
Winter cold-stress
chris.ray@colorado.edu
Haypile
Pika
chris.ray@colorado.edu
How might climate cause
extinction?
Community
interactions
chris.ray@colorado.edu
shana.weber@mac.com
Automated camera
at a marmot den
Morning
Late morning
Noon
Afternoon
How might climate cause
extinction?
Predation
chris.ray@colorado.edu
chris.ray@colorado.edu
How might climate cause
extinction?
Disease
chris.ray@colorado.edu
What does the future hold?
Manuscript in review, by Scott Loarie et al.*
models local extinction probability according to climate
for 97 resurveyed pika sites
Mean annual temperature
IV. Rocky Mtns
III. Great Basin
II. Cascade
I. Sierra
Decade (20th century)
*S. Loarie, C. Field, C. Ray, E. Beever, P. Duffy, K. Hayhoe, J. Wilkening and J. Clark
chris.ray@colorado.edu
What does the future hold?
Mean annual temperature
Manuscript in review, by Scott Loarie et al.*
models local extinction probability according to climate
for 97 resurveyed pika sites
IV. Rocky Mtns
Mean annual
temperature
III. Great
Moderate
emission
Basin
scenarios
Mid-high
emission
scenarios
Projected
II. Cascade
I. Sierra
Observed
Lower
emission
scenarios
Decade (20th century)
*S. Loarie, C. Field, C. Ray, E. Beever, P. Duffy, K. Hayhoe, J. Wilkening and J. Clark
chris.ray@colorado.edu
Probability of local extinction
Over 50% extinct by 2100?
Predictions were
conservative
for the Great Basin
*S. Loarie, C. Field, C. Ray, E. Beever, P. Duffy, K. Hayhoe, J. Wilkening and J. Clark
chris.ray@colorado.edu
The End
chris.ray@colorado.edu