 San Diego Zoo, Natural Research and Magadan Zapovednik (State Nature Reserve) teamed back in 2006 to track young Steller’s sea eagles via satellite, and continue long-term surveys and monitoring of eagles on the breeding grounds. Since then Los Angeles Zoo, Denver Zoo and Hogle Zoo have joined the effort. Very little is known about the period of time prior to breeding for any eagle species, and this undermines conservation. (See this: http://www.sandiegozoo.org/news/stellers_sea_eagle_tracking.html).
During 2006-2008 we fitted 15 nestling Steller’s sea eagles with satellite-received transmitters. Apparently, only two of these birds survived past their first year, and humans were implicated in the deaths of a large proportion of the 13 others. Some birds died of natural causes with at least two of them apparently getting trapped by by the progress of winter when they did not move far enough south early enough.
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Recoverd tag whose harness had been cut. |
Of the two birds that did survive, one that was tagged in 2006 spent its first two winters on the east coast of Hokkaido and on the southernmost Kuril Islands. It spent the summers of 2007 and 2008 on Sakhalin Island, mostly near the main oil and gas development areas of the east central seaboard. Visit this site to learn more about the part of Sakhalin where our eagle spent its summers: http://www.sakhalin.ru/Engl/Region/cities.htm.
Of the five birds fitted with satellite tags in 2008, only one has apparently survived its first year. After making its first southward migration, around New Year it settled into its wintering area near the town of Terney on the Russian coast of the Sea of Japan. It started its northward migration on 8 April and on 27 May it reached its apparent summering area on the Russian mainland near Ayan (Ayan has a Wikipedia entry…have a look! http://en.wikipedia.org/wiki/Ayan).
We remain surprised that such a large proportion of the birds we tagged have apparently died, and that in most cases the culprits in those deaths are humans! Steller’s sea eagles face many threats. There was the lead poisoning threat of the 1990’s, and there is the constant pressure (as yet unmeasured) of purported overfishing. The fossil fuel energy developments of Sakhalin and the windfarms of Hokkaido are a worry. On top of this, eagles have a naturally high mortality in their first year. We always knew that there would be some direct human persecution. Although few people live in these areas, most have guns and many are very bored. Because of this and despite the fact that not everyone out there shoots eagles, if our sample is representative, we should be worried!
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Steller's sea eagle ID 65632 on Shiretoko Peninsula, Japan, 8 March 2008. Copyright G. Tozuka |
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Movement of a juvenile Steller's sea eagle during its first year 2008-2009. |
We will be updating this page periodically as we recieve more data, so visit again. With the continuing help of San Diego Zoo, LA Zoo, Denver Zoo and the Hogle zoo we are mounting our 2009. You can keep up to date with that effort by visiting our blog http://stellerseaeagle.blogspot.com/
For more information please contact info@natural-research.org
Photos copyright M. McGrady
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