Changes in dates of emergence from hibernation by chipmunks, ground squirrels, and marmots at high altitude in the Colorado Rocky
Mountains: An effect of climate change?
David W. InouyeUniversity of Maryland and RMBL
billy barrRocky Mountain Biological Laboratory
Crested Butte, CO
Metadata: www.rmbl.orgFunding: NSF LTREB
The Rocky Mountain Biological Laboratory
Winter Snowfall in Gothic
1975 1980 1985 1990 1995 2000 2005
Snow
fall
(cm
)
0
200
400
600
800
1000
1200
1400
1600
1800
Chipmunk (Tamius minimus)
Golden-mantled ground squirrels (Spermophilus lateralis)
Yellow-bellied marmots (Marmota flaviventris)
1975 1980 1985 1990 1995 2000 2005
Day
of y
ear o
f firs
t chi
pmun
k si
ghtin
g
90
100
110
120
130
1975 1980 1985 1990 1995 2000 2005
Day
of y
ear o
f firs
t chi
pmun
k si
ghtin
g
90
100
110
120
130
The North Pacific Oscillation (also known as PDO) Typical wintertime Sea Surface Temperature (colors),
Sea Level Pressure (contours) and surface windstress (arrows) anomaly patterns during warm and cool phases
warm phase cool phase
http://tao.atmos.washington.edu/pdo/
Annual means for North Pacific Oscillation index-10 -5 0 5
Win
ter s
now
fall
in G
othi
c (c
alcu
late
d fr
om s
trea
mflo
w)
400
600
800
1000
1200
1400
1600
1800
1937
1938
1939
19421943
194419451946
1947
1948
19491951
1952
1953
1954
1957
1958
195919601961
1962
1963
1964
1965
1966
1967
1968
1969
1970
19711972
1973
19741975
1976
1977
19781979
1980
19821985
1988
1989
1990
1991
1994
1995
19961998
20002001
2002
2004
r2 = .059p = .0485
1975 1980 1985 1990 1995 2000 2005
Tota
l sno
wfa
ll in
Got
hic
(cm
)
400
600
800
1000
1200
1400
1600
1800r2 = .159p = .060
1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 2025
Tota
l sno
wfa
ll in
Got
hic
(cm
)
400
600
800
1000
1200
1400
1600
1800r2 = .159p = .060
?
??
?
1975 1980 1985 1990 1995 2000 2005
Day
of y
ear o
f firs
t chi
pmun
k si
ghtin
g
90
100
110
120
130
Calendar day of first date of bare ground in Gothic100 110 120 130
Cal
enda
r day
of f
irst c
hipm
unk
sigh
ting
100
110
120
130
140
150
160
170
r2 = .117p = .05
10 April 10 May
19 June
Heating degree days in April800 900 1000 1100
Cal
enda
r day
of f
irst c
hipm
unk
sigh
ting
90
100
110
120
130
140
r2 = .237, p = .007
Conclusions
• Chipmunks – No trend over 33 years– Some trend before/after 1998– Date of snowmelt and April temperatures
important
1975 1980 1985 1990 1995 2000 2005Day
of y
ear o
f firs
t gro
und
squi
rrel
sig
htin
g
90
100
110
120
130
140
1975 1980 1985 1990 1995 2000 2005Day
of y
ear o
f firs
t gro
und
squi
rrel
sig
htin
g
90
100
110
120
130
140
r2 = .622p = .01
r2 = .371p = .002
Day of year of first bare ground110 120 130 140 150 160 170Day
of y
ear o
f firs
t gro
und
squi
rrel
sig
htin
g
90
100
110
120
130
140
r2 = .109, p = .066
April Heating Degree Days750 800 850 900 950 1000 1050 1100 1150
Cal
enda
r day
of f
irst g
roun
d sq
uirr
el s
ight
ing
80
90
100
110
120
130
140
1974
1976
1979
1981 19821983
1984
1985
1986
1987
1988
1989
1990
1991
1992
19931994
1995
19961997
1998
1999
2000
20012002
2003
2004
2005
2006
r2 = .153p = .036
Conclusions
• Ground squirrels– No trend over 33 years– Significant trends before/after 1998– Snowmelt dates and April HDD important
1975 1980 1985 1990 1995 2000 2005
Dat
e of
firs
t mar
mot
sig
htin
g in
Got
hic
25 March
1 April
10 April
20 April
1 May
10 May
20 May
30 May
r2 = .399p = .0002
April mean temperature (F)26 28 30 32 34 36 38 40
Cal
enda
r day
of f
irst m
arm
ot s
ight
ing
90
100
110
120
130
140
150
1976
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003 20042005
2006
r2 = .458, p < .0001
1980 1990 2000
Snow
pack
on
date
of f
irst s
ight
ing
(cm
)
0
50
100
150
200
250
r2 = .322p = .009
Conclusions• Marmots
– Are emerging significantly earlier– April temperature increases may be
responsible
First ground squirrel sighting (calendar day)100 110 120 130
Firs
t chi
pmun
k si
ghtin
g (c
alen
dar d
ay)
90
100
110
120
130
140
1974
19761977
1978
19791980
198119821983
1984
1985
1986
1987
1988
1989
1990
1991
1992
19931994
1995
19961997
1998
1999
2000
20012002
2003
2004
2006
2007
r2 = .405p = .0001
Calendar day of first marmot sighting90 100 110 120 130 140
Cal
enda
r day
of f
irst g
roun
d sq
uirr
el s
ight
ing
80
90
100
110
120
130
140
Historical snowfall predictions based on peak spring runoff in the East River at Almont, using snow data 1975-2000
1940 1960 1980 2000
Pred
icte
d w
inte
r sno
wfa
ll fo
r Got
hic,
CO
(cm
)
0
500
1000
1500
2000
1975 1980 1985 1990 1995 2000 2005Day
s be
twee
n fir
st S
. lat
eral
is s
ight
ing
and
first
Mer
tens
ia fl
ower
10
20
30
40
50
60
70 r2 = .145p = .05
More conclusions
• Chipmunks and ground squirrels are responding differently than marmots
• Phenology of animals and plants is diverging
• Regional climate change (affecting snowpack) may be important as well as global climate change
Global climate
Regional climateNPO ENSO
Local climateSnowpackSnowmelt
FloweringPhenologyAbundance
Hibernation
Migration
Frost Effects
Plant Demography
Species Interactions
Adaptation?
• Phenotypic plasticity• Evolutionary responses
National Phenology Network• http://www.usanpn.org/
Special Feature on PhenologyEcology, February 2008
Inouye, D. W. Consequences of climate change for phenology, frost damage, and floral abundance of sub-alpine wildflowers.
Kudo, G., et al. Effects of phenology and carbon assimilation on plant reproduction: Implications for climatic changes.
Rich, P., et al. Phenology of mixed woody-herbaceous ecosystems following extreme events: Net changes from differential responses
Post, E., et al. Phenological sequences reveal aggregate life history response to climatic warming
Miller-Rushing et al. Global warming and flowering times in Thoreau’s Concord: A community perspective
