chris.ray@colorado.edu

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 reviewchris.ray@colorado.edu

shanaweber@mac.comSummer 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 prep.chris.ray@colorado.edu

How might climate cause

extinction?

chris.ray@colorado.edu

-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)

Gallatin Range

Demographic Study

Montana

Ray 1989-2009

chris.ray@colorado.edu

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

chris.ray@colorado.edu

Gallatin Range

Demographic Study

Montana

Ray 1989-2009

chris.ray@colorado.edu

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

chris.ray@colorado.edu

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

chris.ray@colorado.edu

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?

chris.ray@colorado.edu

?

?

?

?

?

?

How might climate cause

extinction?

chris.ray@colorado.edu

Summer heat-stress

Heat avoidance behavior

Reduced foraging activity

Smaller or inferior haypiles

Winter cold-stress

How might climate cause

extinction?

chris.ray@colorado.edu

Summer heat-stress

Heat avoidance behavior

Reduced foraging activity

Smaller or inferior haypiles

Winter cold-stress

Smaller or inferior haypiles

Pika

chris.ray@colorado.edu

Haypile

The End

chris.ray@colorado.edu

Habitat size/structure

Human impacts

Species interactions

Thermal stress

chris.ray@colorado.edu

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?

chris.ray@colorado.edu

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.