colony gis: a new approach to mapping and analyzing population productivity cortney pylant and falk...

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

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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]

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Application

• Does the colony GIS method work?

Application

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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?