Transcript Scale Matters - University of Washington

Resource Use and Selection
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Habitat (resource) Selection
Levels of Selection
Multiple Scale Studies
Methodological Issues
Behavioral Mechanisms of
Resource (Habitat) Selection
• The Problem:
– We look at distributions of animals among
habitats and try to infer what habitats are
most important to our species of interest
– This allows us to compare use of habitat to
availability of habitat (which is often defined
as selection, but does not allow us to say
ANYTHING about preference of habitat
Problem Results Because
Distributional Pattern  Choice
• Predators may promote habitat specificity
without selection by the prey
– pepper moths
• Sessile organisms may have distribution
affected by dispersal agents
– plankton, barnacles---wave action
• Competitive exclusion may force animals
to settle in suboptimal habitat
The Solution?
• Detailed behavioral study
– Understand the mechanism that produces
distributional pattern
– If all else is equal is a certain habitat selected
over another?
– Usually takes lab and field approach
Habitat Selection by Tits (Partridge
1978)
Wild
Birds
Handreared
• Wild and hand-reared
birds show
preferences when
given equal access to
oak and pine in lab
– Coal tits prefer pine
– Blue tits prefer oak
• Genetic component to
selection indicated by
hand-reared birds
Choices Made by Tits Are
Adaptive
• Coal tits better at
foraging skills needed
Skills Appropriate for:
in pines
Pine
Oak
• Blue tits better at
foraging skills needed
in oak
Detecting
Cammo
Prey
Ability to
Tear and
Hack
As With Tits, Most Studies Indicate
Choices are Innate, but Modified by
Experience
Squares
C
C
RL
Stripes
RL
Raised on square
background
Raised on striped
background
• Red-legged and
Cascade Frog
Tadpoles (Wiens 1972)
– RL--live in naturally striped
backgrounds (sticks,
cattails, etc)
– C--live in square
backgrounds (gravel)
• Preference for squares
by cascade reduced by
raising on stripes--visa
versa for red-legged
Features Important in Habitat Selection
(Verner 1975, Hilden 1965, Klopfer and Hailman 1965)
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Food
Nest Sites
Song Posts, Hunting Perches, Shelter
Terrain
Vegetation
Previous Experience
Other Animals
– Social stimulation
• Colonial Animals--young often settle in established
colonies (Herring Gulls, Drost 1958)
How Are Multiple Cues Integrated?
• Summation (Hilden 1965)
– each cue is added or subtracted to form a total score
for a habitat
– if score exceeds some threshold, animal settles
• Niche Gestalt (James 1971)
– habitat is responded to as a whole
• Hierarchical Selection (Wiens and Rotenberry
1981)
– large scale vs. fine scale selection
Natural Ordering of Selection
Process (Johnson 1980)
• First order
– Selection of the physical or geographical range of a a
species
• Second order
– Placement of the home range of an individual or
social group within the species’ range
• Third order
– Use of various habitat components within the home
range
• Fourth order
– Selection of resources from within areas within the
home range (food selection at a foraging site, for
example)
Scale Matters
Need to
understand
differences in each
animal’s grain and
extent
Habitat relationships
of wildlife include
multiple hierarchical
levels and spatial
scales
•Capercaillie (Black Grouse)
•Forest stand
•Moderate canopy cover
•Large stands
•Home range
•Old forest
•Contiguous forest
•Management is needed at
landscape scale
•European political structure
does not allow
•Hunters manage at
stand scale for habitat
structure
(Storch 1997)
•American Martin (Bissonette et al.
1997)
•Substand
•Mature forest with CWD,
local variation
•Stand
•Old contiguous forest,
except in Maine where even
young forests and clearings
are used because prey is
abundant
•Home range
Effect of fragmentation was not
evident until landscape scale was
used, happens over smaller spatial
extent outside of Maine where loss of
forest results in patches of unsuitable
habitat interspersed with suitable
habitat
•Uniformly prefer mature
forest
•No selection in uniform
old forest environments
•Landscape
•Consistent selection for
areas with ~75% forest
Managing for Goshawks at Multiple Scales
(Finn et al. 2002, 2003)
•Biologically-relevant scales need to be
investigated
•Managers must provide different
resources at some scales
•Strategies to statistically sort among
the myriad of inter-related variables
•Only include variables of
biological and management
relevancy
•Weed out redundant variables
•Conduct single scale analysis and
later combine best predictors at each
scale to determine important scales
Methodological
Issues
• How to sample across
multiple scales (Brennen et
al. 2002)
• Too much data
– Overpowering?
– What is experimental
unit?
• Landscape, not the pixel
• Spatial Autocorrelation
Relating Wildlife Populations to
Landscape Variables
• We selected 4
variables that were
minimally correlated
– Number of Patches
– Contrast-weighted
Edge Density
– Juxtaposition
– Mean Shape Index
(Marzluff et al. 2003)
High
Low
Create UD
Utilization distribution
Relate UD
to various
resource
metrics
Quantify Resources
Within UD
Distribution of vegetation
at each pixel in UD
Surface depicting meters
of high contrast edge within
200m of each pixel in UD
Points Matter More
Than Smoothing
Factor
(Kertson and Marzluff 2010, Environmental Conservation)
Multiple Regression Produces a
Resource Utilization Function
• Relative Use = 1.32
Use is a
CONTINUOUS
MEASURE
- 0.14 (Mature Forest)
- 0.29 (Clear cut)
+ 0.09 (Number of Patches)
+ 0.005 (Contrast-weighted Edge)
- 0.002 (Patch Juxtaposition)
+ 0.14 (Patch Shape)
Relative Importance of Resources at
the Population Level (n = 25)
Resource Attribute
Mean
Standardize
d

95%
Confidence
Interval
P
( =
0)
# of jays with use
significantly
associated with
attribute
+
-
Number of Patches
+0.11*
-0.57 – 0.28
0.19
14*
9
Contrast-weighted Edge
+0.06*
-0.13 – 0.26
0.50
10*
9
Mature Forest
-0.05
-0.18 – 0.08
0.45
12
8
Clear cut
-0.04
-0.17 – 0.09
0.51
6
9
Interspersion –
Juxtaposition
-0.01*
-0.14 – 0.16
0.87
11
8*
Patch Shape Index
+0.01*
-0.11 – 0.14
0.84
9*
12
* Use in direction predicted if jays select for edgy, fragmented areas within their home range
Relative Importance of Resources at
the Population Level
(n = 25)
Pattern more
Resource Attribute
Mean
Standardize
d

important
than
95%
P
type
of
Confidence
( =
Interval
0)
vegetation
# of jays with use
significantly
associated with
attribute
+
-
+0.11*
-0.57 – 0.28
+0.06*
-0.13 – 0.26
Mature Forest
-0.05
-0.18 – 0.08
Clear cut
-0.04
-0.17 – 0.09
Interspersion –
Juxtaposition
-0.01*
-0.14 – 0.16
0.87
11
8*
Patch Shape Index
+0.01*
-0.11 – 0.14
0.84
9*
12
Number of Patches
Contrast-weighted Edge
0.19
14*
Greater use of
0.50
10*
areas with
0.45 patches
12
many
and
edge6as
0.51
expected
9
9
8
9
* Use in direction predicted if jays select for edgy, fragmented areas within their home range
Relative Importance of Resources at
the Population Level (n = 25)
Resource Attribute
Mean
Standardize
d

95%
Confidence
Interval
P
( =
0)
# of jays with use
significantly
associated with
attribute
+
-
Number of Patches
+0.11*
-0.57 – 0.28
0.19
14*
9
Contrast-weighted Edge
+0.06*
-0.13 – 0.26
0.50
10*
9
Mature Forest
-0.05
-0.18 – 0.08
0.45
12
8
Clear cut
-0.04
-0.17 – 0.09
0.51
6
9
Interspersion –
Juxtaposition
-0.01*
-0.14 – 0.16
0.87
11
8*
Patch Shape Index
+0.01*
0.84
9*
12
Population Not Consistent in Use of Resources
-0.11 – 0.14
* Use in direction predicted if jays select for edgy, fragmented areas within their home range
Relative Use () of Edge
Correlates of s Can Indicate
Why Effects Are Not Greater
0.25
0.20
0.15
0.10
N=15
0.05
0.00
N=10
-0.05
-0.10
<1Km
>5Km
Proximity to Humans
• Use of contrastweighted edges is
related to
landscape shape
index (P=0.03) and
proximity to human
activity (P=0.04)
– >50% of variation
unaccounted for
• Behaviorally-specific
use areas?
Mapping Expected Use
Post-fledging Habitat
Use by Songbirds
(Whittaker and Marzluff 2007)
Another way to Relate Use to
Habitat
• Map the similarity between habitat at point
Z and habitat used
• Vector of habitat attributes measured at
used sites and all points in landscape
• Calculate the similarity between point in
landscape and average vector of used
habitat
– Mahalanobis distance
Mahalanobis Distance
d = ( x  u ) ( x  u )
1
x is a vector of habitat characteri stics
associated with each cell
u is a mean vecto r of habitat characteri stics
at all used locations
Measure of dissimilarity between sample habitat
characters (x) and ideal habitat represented by u.
Example of Mahalanobis
Distance Probabilities
• Clark et al. 1993
• Black Bears in
Arkansas
• Yellow depicts areas
where habitat
characters approach
the ideal mean habitat
vector
Scale and Our Perception of
Availability
• Your insights and conclusions about
resource selection are dependent upon
your definition of resource availability
– Availability in one sense defines the level in
the ordered selection hierarchy
• You define available as habitat within the home
range or within the western US, etc.
• But the point is—the investigator defines
availability
New Sensors are Available to
Better Define Availability
• Animal-borne Video and Environmental
Data Collection Systems
•Sound, vibration
•Pressure, depth
•Acceleration
•Travel speed rhythm, activity
•Imagery
•Blood flow / pressure, heart rate
•Body orientation
•Light
•Temperature (internal, external)
•Body fluid chemistry
•Biopotentials
Cooke et al. 2004 TREE
Moll et al. 2007 TREE
Integrating Location and Behavior
New Goal is to:
Integrate multiple
sensors to better
understand the
behavioral
context of a
location
Rutz et al. 2007 Science
But Still We Define Available
• My suggestion is to
focus on use rather
than use:availability.
• GPS transmitters
are constantly
improving our view
of what is used.
References
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