Transcript Pre-Project Seminar - Wildlife and Roads

Landscape dynamics of bird and small
mammal communities in sagebrushdominated mountain meadows
Tammy L. Wilson
MS candidate
USGS Utah Cooperative Fish and Wildlife Research Unit
Department of Forest, Range, and Wildlife Sciences
Utah State University
Committee:
John A. Bissonette
Thomas C. Edwards Jr.
James A. MacMahon
Overview
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Status of sagebrush-steppe ecosystems
Species that use sagebrush habitats
Project goals and organization
Methodology
L+1 level analysis
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Pattern and process
What is a landscape?
Thinking outside of the box
Choosing the right scale
Vector analysis
• Brief summary
Status of Sagebrush-steppe ecosystems in the
Western United States
excluding Arizona and New Mexico
Knick et al. 2003. Teetering on the edge or too late? Conservation and research issues for avifauna of
sagebrush habitats. The Condor. 105:611-634
Sagebrush Obligates of
Management Concern (SO)
• Species that require sagebrush for some portion of their
life history
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Sage Sparrow
Brewer’s Sparrow*
Sage Thrasher
Greater Sage-grouse
Pygmy Rabbit
Sagebrush Vole *
Least Chipmunk*
* Species Observed
Greater Sage-grouse
USFWS- Mountain and Prairie Region
http://mountain-prairie.fws.gov/species/birds/sagegrouse/
Sagebrush Near-Obligates (SNO)
• Species that commonly use sagebrush but
do not require it
– 33 species of birds
– 19 species of small mammals
Project Goal
• Determine the contribution of high elevation sagebrush
steppe to bird and small mammal species diversity
patterns
• Determine whether or not high elevation sagebrush
provides a refuge for sagebrush obligate species
Tammy Wilson Jason Robinson, and
Joel Ulmer cleaning mammal traps
Beth Johnson, Ruth Kikkert, and Ron
Daigle trapping small mammals
Hierarchy Theory
Two Masters Thesis projects will be divided using a
conceptual hierarchy based on the triadic approach
The conceptual hierarchy
– L Project focal level is the animal community
within a sagebrush meadow
– L+1 Tammy Wilson is focusing on the
influence of meadow arrangement on bird and
small mammal diversity and density
– L-1 Beth Johnson is examining the
relationship between meadow characteristics
and bird and small mammal diversity and
density
Objectives
• Assess the influence of meadow arrangement on
bird and small mammal diversity and density of
selected species (supplementation and complementation processes)
Tammy Wilson collecting Vegetation
data
Study Area
Wasatch-Cache National Forest in Northern Utah
Methods
First Tier Randomization
• Designed to reduce
pseudoreplication at both
levels of observation
• 50 Random points
generated within the study
area using a dispersion
interval of 2500m
Methods
• Meadows in an area around the points were digitized
using DOQQs
• The meadow closest to the randomly selected point was
chosen as the focal meadow of interest
Methods
• Meadows were sampled if they met the following
criteria
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on public land
contain at least some sagebrush
within 5km for birds or 1km for mammals of a road
contained within a forested matrix (evaluated using a
6 km2 buffer)
– mostly less than 50% slope
• 36 Meadows were sampled for birds and 11 for
mammals in the summers of 2003 and 2004
• Each meadow was sampled only once
Methods
Second Tier Randomization
• 2-10 sub-sample points were placed in each
focal meadow
– 100 or so Sub-sample points were randomly placed
within the meadow
– Points were evaluated in order until no more points fit
in the meadow or 10 points were selected
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250m apart
occur on a slope less than 50%
not in water
not in a group of trees
excess points were deleted
Methods
• Birds and Vegetation were measured at
each sub-sample point
• Mammals and soil characteristics were
measured at the first 2 sub-sample points
in selected meadows
• The bird and mammal data became the
response variable for both L+1 and L-1
level analyses
Mammals
• Mammals were trapped using a 50m radius trap web
with 8 arms
• Sherman live traps and Victor snap traps were placed at
the center, 5m, 10m, 20m, 30m, 40m, and 50m points
along each arm of the web
common
Deer Mouse
Least Chipmunk
Uinta Chipmunk
Great Basin pocket mouse
Red-Backed Vole
Montane Vole
Long-Tailed Vole
Snowshoe Hare
Unknown Vole
Golden-Mantled Ground Squirrel
Uinta Ground Squirrel
Western Jumping Mouse
Unknown Mouse
Unknown
Northern Pocket Gopher
Short-Tailed Weasel
Unknown Pocket Gopher
Northern Flying Squirrel
Rock Squirrel
Long-tailed Weasel
Mammals Trapped
1128 Total observations
16 Species observed
1 SO observed
4 SNOs observed
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36
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Birds
• Fixed-radius point counts conducted for 8
minutes at each sub-sample point
• The double observer method was used for
each point count
• All birds seen or heard were recorded
• Distance and bearing was measured to
each bird
10 Most common species
Less common SNOs
Common Name
Green-tailed Towhee
Unknown Bird
American Robin
Brewer's Sparrow
Chipping Sparrow
Ruby-crowned Kinglet
Dark-eyed Junco
Mountain Chickadee
Hermit Thrush
Dusky Flycatcher
White-crowned Sparrow
Vesper Sparrow
MacGillivray's Warbler
Yellow Warbler
Orange-crowned Warbler
Brewer's Blackbird
Western Meadowlark
Song Sparrow
Wilson's Warbler
Swainson's Thrush
Grasshopper Sparrow
Gray Flycatcher
Birds Observed
3615 Total observations
82 Species Observed
1 SO observed
14 SNOs observed
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Objectives
• Assess the influence of meadow arrangement
on bird and small mammal diversity and density
of selected species
Tammy Wilson collecting bird data
Linking Pattern and Process
• Our study area contains sagebrush
patches within a forested matrix
• Habitat obligates can exist in patchy
landscapes through complementation
and/or supplementation of resources
(Dunning et al. 1992)
Dunning, J. B., B. J. Danielson, and H. R. Pulliam. 1992. Ecological processes
that affect populations in complex landscapes. Oikos. 65:169-175
• Complementation
– If non-substitutable resources
are located in different patches,
“the presence of resources in
one patch is complemented by
the close proximity of the
resources in a second patch.”
A
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• Supplementation
– If habitat patches are too small
to support a population or
individual, then necessary
resources can be supplemented
by using adjacent patches.
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Figures adapted from
Dunning et al. 1992
Elements of complementation and
supplementation
• Proximity of adjacent meadows
– Supplementary or complementary resources
will have to be near enough for use by the
individual or population
• Size of focal meadow and adjacent
meadows
– The amount of resources contained within
adjacent patches will be a function of their
size
What is a Landscape?
• Landscape metrics are typically calculated on a
classified satellite imagery with a fixed grain,
using an arbitrary extent
• Organisms scale allometrically to their
surroundings, so choice of right scale resolution
and extent is important
• We intend do detect many organisms, making it
difficult to use any one species life history to
define scale parameters
• Without modification, these problems may limit
our ability to detect important ecological
phenomena
Effects of decreasing landscape extent
• Large patches are
truncated and edge
effects are magnified
• Rare classes are
reduced or lost
• Landscape metrics will
change making them
difficult to interpret
Thinking outside of the box
• By eliminating the ‘landscape’ with a fixed grain
and extent, we tend to eliminate the problems
associated with the box and the image
simultaneously
– We already have a vector coverage of our digitized
meadows
– Patch size and distance to nearest, next, 3rd, 4th, 5th…
nearest meadows can be measured directly with a
vector analysis
– Results are much easier to interpret, because scalerelated problems are reduced
Vector analysis
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• Create centroids in each
adjacent polygon
• Measure distance to the
adjacent polygons of
interest
• Create logistic
regression relating
presence/absence of
selected SO or SNO
species to distance and
size of adjacent
meadows
• Extract amazing story
about patch
arrangement and
ecological processes of
supplementation and/or
complementation
Thinking outside of the box
Part 2
• But we don’t get to ignore scale effects
altogether because we still need to know how
close a meadow needs to be in order to affect
ecological process
– J. Bowman related territory size and dispersal
distance of birds and small mammals
– Others, including C. S. Holling, related body size and
territory size
– C. S. Holling also noticed that body sizes tended to
be clumped
– Maybe there is a way to use this to get at the proper
scale (extent) to use for our analysis
Choosing the right scale
• Published data on our most commonly observed
species can be analyzed using Bowman’s
equations
• The accuracy of these equations can be
checked where we have both home range and
dispersal data
• The robustness of these equations can be tested
by adding our species and re-running Bowman’s
analysis
• These relationships can be used to guide scale
extent choices if there is a reasonable amount of
overlap amongst species.
Summary
• Preliminary observations
– Only 2 or maybe 3 of 7 SOs and 18 of 52 SNOs were
observed
– Preliminary results suggest that small mammal
diversity is lower (16 observed vs. 22 SO/SNO), and
bird diversity higher (82 observed vs. 37 SO/SNO) in
montane sagebrush patches than in contiguous lowelevation sagebrush
• Future analyses
– Linking patch arrangement to species diversity and
habitat-specialist presence/absence
– Analysis of published body mass, home range, and
dispersal data to determine the scale important to
detected species
Acknowledgements
• Beth Johnson
• Committee
– John Bissonette
– Tom Edwards
– Jim MacMahon
• Technicians
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Ron Daigle
Ruth Kikkert
Jason Robinson
Joel Ulmer
Mark Johnson
Dave Johnson
Robert lloyd Morris
• Funding
– United States Forest
Service
– USGS Utah Cooperative
Fish and Wildlife
Research Unit
Questions…