A multi-scale approach to assess sage-grouse nesting habitat
Comparing nest site selection and nest success
Dan GibsonErik BlombergMichael AtamianJim Sedinger
Overview: Sage-grouse
• Habitat degradation is the primary mechanism driving sage-grouse population declines
• Habitat will continue to be degraded
• We need to establish what habitat is important (during various life history stages) for species persistence at multiple scales and manage it appropriately
Why is knowledge regarding habitat use important?
So, what is “important” habitat?
• Is it being used?
• Are individuals successful?
• In theory, the relationship between habitat selection and success compares what habitat features improved fitness along an organism’s evolved life history, and what improves fitness in its current environment
Research Objectives
• Investigate which habitat characteristics sage-grouse are being selecting for as nesting habitat and how they influence nest success
• Use this information to develop tools to make more informed management decisions
• Monitored female sage-grouse from 2003-2012 in Eureka Co. Nevada
• Ground level vegetation data was collected at nest and random sites
• ~410 nests
Analyses• Nest Site Selection (RSF models)
– Binomial generalized linear mixed models (GLMM) in R (lme4 package)
• Random effects: year and individual
– Two independent analyses performed (two scales: “spatial” and “local”
• Nest Survival– Nest survival module in Program
MARK• Predictor variables
– Ground-scale vegetation– Spatial-scale habitat structure– Temporal – Disturbance – Individual heterogeneity
Results • Nest Survival
– Estimates of overall nest survival were low (17%)• Note: It is very difficult to achieve a lambda >1.0 at this level of
success
• Selection• Local: selection pressures were the greatest for various forms of
cover and forb availability• Spatial: provided a mechanism to delineate nesting from available
habitat using relatively coarse spatial metrics
• Very few habitat features were supported to influence both nest selection and nest success
Covariate Beta Survival SE Beta Selection SESeason -0.21 0.06 N/A N/AClutch Size 0.21 0.06 N/A N/ANon-Sagebrush Shrub Cover 0.30 0.09 0.69 0.19 2
Forb Cover 0.25 0.08 0.42 0.19 2
Interaction 0.32 0.12 -0.10 0.28 2
Wildfire 2000m -0.12 0.07 0.41 0.23 1
Wildfire 2000m2 -0.04 0.04 -0.14 0.10 1
Pinyon-Juniper 2000m 0.12 0.11 0.41 0.23 1
Pinyon-Juniper 2000m2-0.02 0.04 -0.27 0.14 1
Distance from lek 0.07 0.07 -0.64 0.09 1
Habitat classified as sagebrush within 1000m 0.01 0.09 1.43 0.12 1
Interaction 0.01 0.06 -0.62 0.08 1
Slope -0.05 0.09 0.51 0.10 1
Elevation 0.09 0.09 0.60 0.08 1
Interaction -0.05 0.07 -0.33 0.07 1
Shrub Height 0.12 0.06 -0.46 0.19 2
Forb Richness 0.05 0.06 0.25 0.12 2
Average Forb Height 0.05 0.07 0.21 0.12 2
Residual Grass Height 0.03 0.07 0.38 0.14 2
Grass Cover -0.02 0.07 0.37 0.14 2
Interaction -0.05 0.06 0.34 0.14 2
Non-Sagebrush Shrub Cover 0.28 0.11 1.00 0.22 2
Non-Sagebrush Shrub Cover2 -0.02 0.03 -0.10 0.05 2
Sagebrush Shrub Cover 0.10 0.07 0.98 0.15 2
Sagebrush Shrub Cover2-0.02 0.04 -0.13 0.08 2
1 denotes spatial selection model
2 denotes local selection model
Bold values significant
Selection versus Survival
Proportion non-sagebrush shrub cover
0.0 0.2 0.4 0.6 0.8 1.0
Re
lati
ve p
rob
ab
ilit
y o
f u
se
0.0
0.2
0.4
0.6
0.8
1.0
Relative Probability of SelectionNestsAvailable
0.0
0.2
0.4
0.6
0.8
1.0
0
10
20
3040
5060
70
0.00.2
0.40.6
0.8
Ove
rall
pro
bab
ilit
y o
f n
est
su
rviv
al (
un
til
37
day
s)
Perc
ent f
orb
cove
r
Proportion non-sagebrush shrub cover
Successful NestsFailed Nests
Non-sagebrush shrub cover & Forb cover
Percent Forb Cover
0 10 20 30 40 50 60
Rel
ati
ve p
rob
abil
ity
of
use
0.0
0.2
0.4
0.6
0.8
1.0
Relative Probability of SelectionNestsAvailable
Sagebrush canopy cover
Proportion sagebrush shrub cover
0.0 0.2 0.4 0.6 0.8 1.0
Pro
bab
ilit
y o
f n
est
site
sel
ecti
on
or
nes
t su
cces
s
0.0
0.2
0.4
0.6
0.8
1.0
Relative Probability of UseOverall Probability of Nest SuccessNests
* Guidelines to manage sage grouse populations and their habitats Connelly et al. 2000
Grass cover * Residual grass height
0.5
0.6
0.7
0.8
0.9
1.0
0
20
40
60
80
020
4060
Rel
ativ
e p
rob
abili
ty o
f u
se
Perc
ent G
rass
Cov
erResidual Grass Height (cm)
Available Used
0.0
0.1
0.2
0.3
0.4
0
20
40
60
80
020
4060O
vera
ll p
rob
abili
ty o
f n
est
surv
ival
Perc
ent g
rass
cov
er
Residual grass height (cm)
Nests0.0 0.1 0.2 0.3
* Guidelines to manage sage grouse populations and their habitats Connelly et al. 2000
Proportion of habitat classified as Pinyon-Juniper
0.0 0.2 0.4 0.6 0.8
Pro
babi
lity
of u
se/s
ucce
ss
0.0
0.2
0.4
0.6
0.8
1.0
Weighted probability of useProbability of nest survival (until 37 days)
Pinyon-Juniper encroachment
Proportion of habitat converted to exotic grasslands due to wildfire
0.0 0.2 0.4 0.6 0.8
Pro
babi
lity
of u
se/n
est s
urvi
val
0.0
0.2
0.4
0.6
0.8
1.0
Weighted probability of useProbability of nest survival (until 37 days)
Exotic Grasslands
• Very few habitat features exhibited a selective pressure and influenced nest success
• Current management decisions geared to improve sage-grouse populations through modifying nesting conditions may ultimately not be successful
• Current guidelines for management of sage-grouse nesting habitat do not appear to be appropriate for central Nevada
• So, can we develop tools to assist management?
Summary so far…
Elevation * Slope + Distance from lek * Amount of habitat classified as sagebrush (1000m)
Developing a nesting habitat use model
0.0
0.2
0.4
0.6
0.8
1.0
0
5
10
1520
2530
35
16001800
20002200
24002600
28003000
Rel
ativ
e P
rob
abili
ty o
f U
se
Slop
e (d
egre
es)
Elevation (m)
Nests
0.0
0.2
0.4
0.6
0.8
1.0
0
20
40
60
80
100
02000
40006000
800010000
1200014000
Rel
ativ
e P
rob
abili
ty o
f U
se
Perc
ent o
f Sur
roun
ding
Hab
itat
Cla
ssifi
ed a
s Sa
gebr
ush
Distance from Lek (m)
Nests
Delineation of nesting habitat
• ~18% of surrounding habitat was classified as suitable which encompassed 75% of nest points
• Estimate of concordance = 0.72
• Independently collected nest locations fit the model well … for the most part
• Additionally, statewide spring telemetry locations fell within “suitable habitat” at a high rate
Suitability Threshold
0.0 0.2 0.4 0.6 0.8 1.0
Pro
po
rtio
n o
f ne
sts
cla
ssifi
ed
to b
e in
su
itab
le h
ab
itat
0.0
0.2
0.4
0.6
0.8
1.0 Central/Northeast NevadaEureka CountyNorthwest NevadaVirginia Mountains
Demographiccontinuity NestingEarly Brood RearingLate Brood Rearing
*Atamian et al. 2010
• Establish what habitats are required during “important” life history stages
• Protect the commonalities
• Allow for connectivity between stages
Probability of Use
• Thanks to: – Jim Sedinger, Erik Blomberg, and
Mike Atamian
– Shawn Espinosa, Chet Van Dellan (NDOW) and Peter Coates (USGS)
– All previous graduate students, technicians, and volunteers that have worked on this project
– All funding sources:
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