Plumas-Lassen Administrative Study
Small Mammal Module
Douglas A. Kelt1, Dirk H. VanVuren1, Michael L. Johnson2
1University
of California Davis
Department of Wildlife, Fish, & Conservation Biology
2University
of California Davis
John Muir Institute of the Environment
Small Mammals and Forest Ecosystems

Dispersers and consumers of seeds, fruits, and fungi


Constitute a substantial portion of the prey biomass
consumed by predators such as the spotted owl,
northern goshawk, fisher, and marten.


Forest regeneration
Trophic cascades, elements of keystone complexes
Valuable feedback
2
Mammal Module Mission
To evaluate small mammal responses to
different forest management practices,
and to model these responses in terms
of demography, spatial distribution,
and habitat associations at local and
landscape scales
3
Module Objectives




Determine habitat associations of small
mammals.
Develop demographic profiles of small
mammal populations in selected habitats.
Assess ecology of focal species – key prey for
spotted owls and mesocarnivores.
Develop predictive models of small mammal
habitat preferences to forecast responses to
forest management.
4
Productivity to date

3 students completed MS theses



Stephanie Coppeto – small mammal
habitat associations. Currently with
USFS Lake Tahoe.
Robin Innes – spatial ecology & habitat
associations of dusky-footed woodrats.
Currently with USFS Montana.
Jaya Smith – spatial ecology & habitat
associations of northern flying squirrels.
Currently with USGS Idaho.
5
8 publications in peer-reviewed literature
2 in review
currently 3 in progress
6
2010 Field Season – our 8th & Final



An abbreviated season – June-September.
Complete sampling of 21 long-term trapping
grids to characterize temporal patterns in small
mammal numbers.
Quantify productivity by conifer species to
allow prediction of 2011 small mammal
numbers.
Collaborate with PLAS Vegetation module to
quantify habitat structure for assessment of
responses to forest treatments.
7
Outline


Module objectives
Methods and results


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Long-term grids
Landscape transects
Focal species biology
Dusky-footed woodrat
 Northern flying squirrel

8
Methods: Long-term Grids

21 grids in 4 forest types, 12 placed in experimental plots

3 groups of 4 plots - white fir

Control
Group selection
Light thin (50% canopy cover)
Heavy thin (30% canopy cover)

Trapping array
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100 Sherman traps, 10-m spacing
72 Tomahawk traps, 30-m spacing
2.25 ha (≈5½ acre)
4 nights / session
9
Long-term Grids

2010 marked 8th year of data collection,
4th year of post-treatment data

14,448 trap-nights effort

673 individuals of 1,399 captures of 10 species

Deer mice and chipmunks most common
10
Long-term Grids
No. Individuals
¾ shadow chipmunk (T. senex)
¼ long-eared chipmunk (T. quadrimaculatus)
Chipmunks
Deer mice
Red-backed voles
Northern flying squirrels
Douglas Squirrels
Ground squirrels
11
Trends in Abundance
Yearly Trends
30
Woodrats
Deer mice
Flying Squirrels
Chipmunks
Mean Abundance
25
20
15
10
5
0
2003
2004
2005
2006
2007
Year
2008
2009
2010
12
Long-Term Grids
Habitat Types
Northern flying squirrels
Woodrats
10
5
Doug-fir
Pine-cedar
Red-fir
White-fir
4
Mean Abundance
Mean Abundance
8
6
4
3
2
2
1
0
0
2003
2004
Doug-fir
Pine-cedar
Red-fir
White-fir
2005
2006
2007
Year
2008
2009
2010
2003
2004
2005
2006
2007
Year
2008
2009
2010
Long-Term Grids
Habitat Types
Chipmunks
Deer mice
50
70
Doug-fir
Pine-cedar
Red-fir
White-fir
50
Doug-fir
Pine-cedar
Red-fir
White-fir
40
Mean Abundance
Mean Abundance
60
40
30
20
30
20
10
10
0
0
2003
2004
2005
2006
2007
Year
2008
2009
2010
2003
2004
2005
2006
2007
Year
2008
2009
2010
Long-Term Grids
Treatments
Northern flying squirrels
Woodrats
0.7
Control
Group-select
Heavy-thin
Light-thin
Treatment
Mean Abundance
Mean Abundance
2.0
1.5
1.0
Control
Group-select
Heavy-thin
Light-thin
0.6
0.5
0.4
0.3
0.2
0.5
0.1
0.0
0.0
2005
2006
2007
2008
Year
2009
2010
2003
2004
2005
2006
2007
Year
2008
2009
2010
Long-Term Grids
Treatments
Deer mice
Chipmunks
Treatment
Control
Group-select
Heavy-thin
Light-thin
15
Control
Light-thin
Heavy-thin
Group-select
30
Mean Abundance
Mean Abundance
20
35
10
5
25
20
15
10
5
0
0
2003
2004
2005
2006
2007
Year
2008
2009
2010
2003
2004
2005
2006
2007
Year
2008
2009
2010
Long-Term
Grids
Mice over Time
120
100
Mean Cone Abundance
Mean Mouse Abundacne
Annual Snow Fall
Mean Chipmunk Abundance
80
60
40
20
0
2003
2004
2005
2006
2007
2008
2009
2010
Year
• Copetto et al. 2006 documented that forest type and year explained 93% of
yearly variation in deer mice on the same study grids (n = 18).
•
Year is a surrogate measure that reflects:
-Temporal variations in resource abundance (i.e., conifer cones).
&
-Environmental factors such as precipitation.
Long-Term Grids
More on mice
A single-variable model (snow) explained 43% of variation!
Predictive Model - Peromyscus
6
Observed
Model Predicted
Mean Abundance
5
R2 = 0.62
4
3
2
1
0
Abund. = 5.00 + 0.85*Ppt (Current season)
+ 0.15*White pines
+ 0.09*True firs
- 0.68*Snow (Preceding winter)
2004
2005
2006
2007
Year
2008
2009
2010
Long-Term Grids
. . . and chipmunks
A single-variable model (white pines) explained 57% of variation!
Preditive Model - Tamias
5
Observed
Model Predicted
Mean Abundance
4
R2 = 0.48
3
2
1
Abund. = -3.54 + 0.55*Snow (Preceding winter)
+ 0.54*White pines
+ 0.34*True firs
0
2004
2005
2006
2007
Year
2008
2009
2010
Focal Species:
Northern Flying Squirrel
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Home Range
Habitat Associations
Den Trees
© Sean Bogle
Flying Squirrel Methods
… and Radiotracking
Trapping
Collaring
Home Range
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Helps forest managers make
decisions:
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How much area is needed?
What habitat types are in the
home range?
Home Range Area (Fixed Kernel)
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Results
Wilson et al. – 72.33 acres (7♂♂, 4 ♀♀)
Smith et al. – 21.16 acres (5♂♂, 17 ♀♀)
In both studies, ♂♂ = ♀♀
Substantial variation in area!
Flying Squirrels
Habitat Analysis
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Wildlife Habitat Relations
(WHR) layer with 7 categories:
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Riparian
Sierra mixed conifer (Sm, Med, Lg)
Monocultures
Wet meadows
Barren areas
Chaparral
Bodies of water
Flying Squirrels
Habitat Analysis
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Compare Used habitat with
Available habitat
Assessed on two scales:
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Broad scale – Across the
forest
Narrow scale – Within the
home range itself
Flying Squirrels
Habitat Analysis
Results
Broad scale
Placement of home range
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
-Large Sierra mixed conifer
-Medium Sierra mixed conifer
Narrow scale
Activity within home range
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-Large Sierra mixed conifer
-Medium Sierra mixed conifer
Den Trees
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Methods
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Telemetry/Homing
Use vs. Availability
Den
Tree
Available
Trees
Den Trees Used
92 Flying
Squirrel
Dens
Measured
White Fir
Black Oak
Douglas
Fir
Ponderosa Pine
Lodgepole Pine
Jeffrey Pine
Red
Fir
Bigleaf Maple
Incense Cedar
Den Trees:
Used vs. Available
0.4
Available
Used
0.3
0.2
0.1
Den Tree Species
0.0
White Fir
Douglas Fir
Black Oak
Red Fir
70
60
Available
Used
Percent
50
Den Tree Size
40
30
20
10
0
g
plin
Sa
er
ber
ber
ood
ood
mb
tim
tim
rdw
rdw
w
w
leti
a
a
a
a
o
h
h
s
s
P
all
ge
all
ge
Sm
Lar
Sm
Lar
Focal Species:
Dusky-footed woodrats
Neotoma fuscipes
Habitat Associations and Home
Range
31
Natural History
 Semi arboreal, nocturnal
 Solitary, territorial
 Size of black rat
(although much nicer!)
 Varied habitats
 Oak specialist
 Build “houses”
32
Woodrat Stick Houses
 Houses important for




all life stages
 Adults, subadults
 Males, females
Food storage
Nurseries
Protection
Social communication
33
Objectives
To determine habitat associations

Forest type

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Relationship with California black oak
Microhabitat

Tree and ground house site selection and use
To determine spatial organization
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Home range
Overlap
34
Results: Habitat Associations of
Woodrats
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↑ oak density = ↑ woodrat density
Ground house sites:
↑ large logs, ↑ large stumps, and ↑ slope
Tree house sites:
large oaks, large snags
House use:
↑ use of tree houses in the fall
35
Results: Macrohabitat Associations
Woodrat density (ha-1)
3
2
R2=0.68
P=0.09
1
R2 = 0.68
P=0.08
0
0
5
10
15
20
25
Large oak density (ha-1)
36
Results: Woodrat Home Range
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Home range size was 3.0-9.4 acres
Lack of overlap indicates territoriality
Relative to other populations:
↑ home ranges, ↓ woodrat density
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Forage availability?
Suggests home ranges likely to be ↑ in winter
when resources are scarce
37
Woodrats and Flying Squirrels:
Common Ground?
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Mature black oak very important
to multiple species
Large conifers preferred by NFS
provide large logs and large
stumps preferred by DFW
Thank You!
Questions?