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: