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[email protected] Signs of demographic change and physiological stress in Rocky Mountain pikas Chris Ray, CU-Boulder Nifer Wilkening, CU-Boulder Karen Sweazea, ASU-Tempe
Signs of demographic change and physiological stress
in Rocky Mountain pikas
Chris Ray, CU-Boulder
Nifer Wilkening, CU-Boulder
Karen Sweazea, ASU-Tempe
Outline
Rationale 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
Contextual [email protected]
[email protected] heat-stressGrinnell 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-stressTapper 1973
Smith 1978
Morrison and Hik 2007
Beever et al. 2010 & in [email protected]
-30
-20
-10
0
10
20
30
40
A-04 S-04 O-04 N-04 D-04 J-05 F-05 M-05 A-05 M-05 J-05 J-05 A-05
date
tem
p (
C)
Niwot Ridge, CO
Gallatin Range, MT
Hourly haypile temperatures
Joyce
Gellhorn
Tem
pera
ture
(C
)
Date (Month-Year)
2005-2009 pika fate vs. microsite temperature
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
-14 -10 -6 -2 2 6 10 14 18 22 26 30
Temperature (C)
Pro
po
rtio
n o
f te
mp
era
ture
s Pika survived (n = 30)
Pika died (n = 37)
Gallatin Range
Demographic Study
Montana
Ray 1989-2009
Gallatin Range
Demographic Study
Montana
Ray 1989-2009
2008-2009 pika fate vs. microsite temperatures
0
0.1
0.2
0.3
0.4
0.5
-14 -10 -6 -2 2 6 10 14 18 22 26
Temperature (C)
Pro
po
rtio
n o
f te
mp
era
ture
s
Pika survived (n = 5)
Pika died (n = 4)
Gallatin Range
Demographic Study
Montana
Ray 1989-2009
1990 1995 2000 2005 2010
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Year
Pro
port
ion a
dults in p
opula
tion
Gallatin Range
Demographic Study
Montana
Ray 1989-2009
2000 2002 2004 2006 2008
-4-3
-2-1
01
2
Year
Cache s
ize,
Aug 3
1
AdultsJuveniles
Bob Rapp
Stress and survival study
Gallatin Range, MT
& Niwot Ridge, CO
Ray et al., 2008-2009
Stress and survival study
Gallatin Range, MT
& Niwot Ridge, CO
Ray et al., 2008-2009
0.0
0.2
0.4
0.6
0.8
Surv
ival ra
te
MT CO Southern Northern
Main site, MTLTER site, CO
Site CO slope aspect
(c)
0
2
4
6
8
10
12
14
Site
Pla
sm
a g
lucose (
mg/d
l) X
100
MT CO
(d)
Stress and survival study
Gallatin Range, MT
& Niwot Ridge, CO
Ray et al., 2008-2009
-20 -10 0 10 20
0.0
0.1
0.2
0.3
0.4
Temperature (C)
Pro
port
ion o
f te
mpera
ture
s r
ecord
ed
MTCO(a)
Stress and survival study
Gallatin Range, MT
& Niwot Ridge, CO
Ray et al., 2008-2009
-20 -10 0 10 20
0.0
0.1
0.2
0.3
0.4
Temperature (C)
Pro
port
ion o
f te
mpera
ture
s in C
O S aspectN aspect(b)
Stress and survival study
Gallatin Range, MT
& Niwot Ridge, CO
Ray et al., 2008-2009
How might climate cause
extinction?
Summer heat-stress
Heat avoidance behavior
Reduced foraging activity
Smaller or inferior haypiles
Winter cold-stress
How might climate cause
extinction?
Summer heat-stress
Heat avoidance behavior
Reduced foraging activity
Smaller or inferior haypiles
Winter cold-stress
Smaller or inferior haypiles
Habitat size/structure
Human impacts
Species interactions
Thermal stress
What predicts extinction?
Beever et al. in prep.:
Habitat area
Accessibility
Livestock grazing
Acute heat-stress
Chronic heat-stress
Acute cold-stress
Climatic refugium
What predicts extinction?
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
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.
