Estimating the relative abundance of emperor penguins at inaccessible colonies using satellite imagery
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Emperor penguin (Aptenodytes forsteri) populations are useful environmental indicators due to the bird’s extreme reliance on sea ice. We used remote sensing technology to estimate relative adult bird abundance at two inaccessible emperor penguin colonies in the Ross Sea, Antarctica. We performed supervised classification of 12 panchromatic satellite images of the seven known Ross Sea colonies. We used regression to predict adult bird counts at the inaccessible colonies by relating the number of pixels classified as “penguin” in the satellite images of the accessible colonies to corresponding known adult bird counts from aerial photographs or ground counts. While our analysis was hampered by excessive guano and shadows, we used satellite imagery to differentiate between relatively small (<3,000 adult birds) and larger colonies (>5,000 adult birds). Remote sensing technology is logistically less intense and less costly than aerial or ground censuses when the objective is to document penguin presence and/or large emperor penguin population changes (e.g., catastrophic changes). Improvements expected soon in the resolution of the satellite images should allow for more accurate abundance estimates.
KeywordsAbundance Antarctica Aptenodytes forsteri Emperor penguin Inaccessible colonies Remote sensing Ross Sea Satellite imagery
This project was supported by a Tinker Foundation Inc. grant for 2006–2007 to GK and NSF grants to PP (OPP 02-29638, OPP 02-24957, and OPP 05-38594). We thank all those at NSF that helped make this work possible, those at Raytheon Antarctic Support Services for all the field support and Kenn Borek Air and Petroleum Helicopters International for air support. We are grateful for the access to geographic information systems (GIS) software and a computer workstation at the IGPP Munk Lab, Scripps Institution of Oceanography, La Jolla, CA, USA. Satellite photos are DigitalGlobe. Mention of trade names does not indicate product endorsement. We are grateful for Christophe Barbraud’s helpful suggestions on an earlier draft.
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