Population-level implications from climate change for a montane songbird, Bicknell's Thrush

Population-level implications for climate change for a montane forest songbird
Sarah J K Frey Allan M Strong Kent P McFarland
AOU 2009 Philadelphia

Mountains & Climate Change

Focal Species: Bicknell’s Thrush
High conservation concern
Vulnerable to climate change
Available data

How will local- and landscape-scale habitat change with climate warming?
How might Bicknell’s Thrush respond to these changes?
Research Questions

Fewer & smaller patches = HABITAT LOSS (Rodenhouse et al. 2008 Mitig Adapt Strateg Glob Change)
Remaining habitat will likely change in quality (Beckage et al. 2008 PNAS)
alteration of successional processes
Predictions – Hypotheses

If this is happening, then BITH populations will have to respond in one of 3 ways

Change their behavior (adapt to the new conditions)

2. Move to a new location (latitude or elevation)

3. Decline/go extinct

Multi-season Occupancy Model (MacKenzie et al. 2003 Ecology)
Population Parameters
Occupancy  Colonization
Detection  Extinction
Methods - Model
Between seasons
Colonization or extinction
1,2,3
1,2,3
1,2,3
1,2,3
Surveys
Seasons 1 2 3 4
Occupancy & detection
Within seasons

Habitat Covariates
Local = boreal basal area (BBA) (Beckage et al. 2008 PNAS)
Landscape = patch size (Lambert et al. 2005 Wilson Bull)
Methods - Model

Climcalc(http://www.pnet.sr.unh.edu/climcalc/)
Mean July Temp (MJT) calculated - lat, long, elv, slp, asp
Current MJT envelope for BITH habitat
Methods – Landscape Climate Data

Landscape: + 1° C to MJT envelope
Local (BBA): MJT inc. over time (amnt. of time for 1° C inc. = 7 yrs.)
Northeast Climate Data (www.northeastclimatedata.org)
A1 Scenario
Methods – Warming Predictions

Current & future (+1°C) maps of predicted habitat amount (landscape) & suitability (patch)
Compared amount and quality of habitat
Estimated occupancy, colonization, and extinction now and with 1°C of warming
Methods – Population Predictions

Occupancy (Boreal Basal Area * Patch Size)
Colonization (Boreal Basal Area)
Extinction (Boreal Basal Area + Patch Size)
Detection (Survey + Patch Size)
Methods - Model

No time lag – once pixel moves out of MJT envelope, it is no longer available as habitat
Boreal basal area is a good indicator of local habitat quality
Beckage et al. 2008 model realistically represents changes in the composition of local habitat over time
Lambert et al. 2005 model is a realistic representation of current potential habitat availability at the landscape scale
Model Assumptions

Results - Landscape
# of patches decreased from 128 to 29
Total amount of habitat reduced by 67%

Results - Local
Avg. patch size increased 44.6% (90.5 to 130.8 ha)
Remaining patches = higher quality
BBA 29.1 - 60.6 m2/ha
Total BBA decreased 31.3%

Results - Local
Avg. patch size increased 44.6% (90.5 to 130.8 ha)
Remaining patches = higher quality
BBA 29.1 - 60.6 m2/ha
Total BBA/patch decreased 31.3%

Results - Population parameters
occupancy
colonization

Results - Occupancy
Current

Results - Occupancy
+1OC

Results - Colonization
Current

Results - Colonization
+1OC

Colonization least influenced by changes in landscape scale features, although total area available for colonization decreased by 66.8%
Results - Population parameters

Results - Extinction
Current

Results - Extinction
+1OC

Population implications are primarily related to the total amount of habitat lost
Composition of montane patches altered – less so than overall amount of habitat
Loss of lower elevation sites likely has less of an impact - represent marginal habitat (?)
Conclusions

Under small amounts of warming, Bicknell’s Thrush may be able to persist in the remaining high quality patches
> 1°C of warming may call into question the long term persistence of this species in Vermont
Conclusions

Landscape - Increased Warming

Hope for Bicknell’s
?

70+ year dataset on Mt. Washington (NH) shows that warming at high elevations may be occurring at a slower rate than at lower elevations (Seidel et al. 2009 Arctic, Antarctic, and Alpine Research)
Hope for Bicknell’s?

UVM
Strong Lab
Terry Donovan
Sara Helms-Cahan
Carolyn Goodwin-Knueffer
Funding: McIntire-Stennis
VCE
Chris Rimmer
Dan Lambert
Julie Hart
MBW volunteers
Thanks
Field Assistants
Juliette Juillerat
HéctorSlongo
Katie Pindell
Oregon State University
Bett’s Landscape Ecology Lab

Population-level implications from climate change for a montane songbird, Bicknell's Thrush

by Vermont Center for Ecostudies on Sep 01, 2009

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Population-level implications from climate change for a montane songbird, Bicknell’s Thrush — Presentation Transcript

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