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COLONY GIS: A NEW APPROACH TO MAPPING AND ANALYZING POPULATION PRODUCTIVITY
Cortney Pylant and Falk Huettmann
EWHALE Lab
Inst. of Arctic Biology
Dept. of Biology & Wildlife
University of Alaska Fairbanks
Presentation Outline
• Conventional Monitoring• Description of Study Area and Species• Colony GIS Method• Methods• Analysis• Results• Application• Future of Colony GIS Method
Conventional Monitoring
• Track individual nests throughout season
• Limitations:– Weather– Vantage points– Number of birds
monitored– Effort– Etc. Ram Papish
Study Area
• St. George Island– Second largest of
Pribilof Island group– Eroding basalt cliffs
create dynamic habitat
CP
Study Species
• Red-Legged Kittiwake (Rissa brevirostris)– Endemic to Bering Sea
region– Four known breeding
colonies• St. George Island
• Annual monitoring by AMNWR
CP
Colony GIS Method
• Integrate small-scale GIS and habitat mapping
• Incorporate monitoring data and predictive modeling
• Identify “hotspots” for productivity across entire colony
Habitat Mapping
Few Monitoring Data
Small-scale GIS
Predictive Modeling
Identify “hotspots” across entire colony
=> More efficient
Methods
• Current photographs with marked nests
Methods
• Current photographs with marked nests
• Map habitat features
Methods
• Current photographs with marked nests
• Map habitat features• Determine distances
from features in GIS
Methods
• Current photographs with marked nests
• Map habitat features• Determine distances
from features in GIS• Create grid of regularly
occurring points
Analysis
• Create statistical model (TreeNet Salford Ltd.) using monitoring data, training data, and regularly occurring points
• Generate predictions from model characterizing probability of success/failure at each point
• Compare predictions to actual monitoring data
Results
Variable Importance (n = 92)
0.00ROCK
||||||||||||||||||||||||||||||||76.22DIST
||||||||||||||||||||||||||||||||||||86.01VEGE
||||||||||||||||||||||||||||||||||||||||||99.40Y (VERT)
||||||||||||||||||||||||||||||||||||||||||100.00EDGE
ScoreVariable • Position of nest with respect to distance from edge and vertical height most important variables
Predicting a Successful Nest
Results
• Importance of Edge– Increased distance from edge
yields greater probability of success
• Importance of Height (Y)– Probability of success favors
some mid-value with respect to vertical position
Success
Failure
Success
Failure
Results
• Importance of Neighbors– Increased distance between
nearest neighbor yielded greater probability of success (to a point)
• Importance of Vegetation– Greater distance from
vegetation seems to increase probability of success
Success
Success
Failure
Failure
ResultsPredicting to Colony
Plot 70
Real Data [Failed; Success]
ResultsPredicting to Colony
Plot 67Ram Papish
Real Data [Failed; Success]
ResultsPredicting to Colony
Plot 69
Real Data [Failed; Success]
CP
Application
• Does the colony GIS method work?
Application
CP
Plot 68
ApplicationPredicting to Colony
Plot 68
Application
Plot 68
Predicting to Colony Real Data [Failed; Success]
Application
Overall Model AccuracyReal Data
1520Success1674Failed
SuccessFailed
Pre
dict
ed
79% of failed nests correctly predicted
52% of successful nests correctly predicted
Overall, 71% model accuracy
Future of Colony GIS Method
• Goal: Use small-scale GIS, habitat mapping, and monitoring data to predict productivity “hotspots” across entire colony, cliffs, and islands
• Future considerations:– More habitat features– Time photographs taken– Species competition for nest sites– Oceanic parameters– Etc.
Future of Colony GIS Method
9CP
A Word of Caution:
“Today's scientists have substituted mathematics for experiments, and they wander off through equation after equation, and
eventually build a structure which has no relation to reality.”-Nikola Tesla Modern Mechanics and Inventions, July, 1934
• When working with models:– Check for biological realism
– Compare with actual data
– Constantly revise models to reflect patterns and processes
Acknowledgements
• Alaska Maritime National Wildlife Refuge– Art Sowls
• 2006 St. George Field Technicians – Jade Cash, Karin Holser, Rachel Holser, Ryan
Kingsbery, Ram Papish
• Dean Kildaw (St. George Island photographs)
Questions?