Tracking Steller’s Sea-eagles, Part 2
Posted at 1:51 pm March 28, 2008 by Mike McGrady
Read Mike’s previous blog, Tracking Steller’s Sea-eagles, Part 1…
In late July 2007, I was back in the field on the breeding grounds, surveying breeding pairs on the rivers and the coast near Magadan with my team. This time Dave Rimlinger, San Diego Zoo curator of birds, joined us as we tagged another group of Steller’s sea-eagle chicks as part of a study of this species in the Magadan State Reserve in Russia.
We surveyed stretches of the Kava and Chelomdza Rivers that are within the Magadan Zapovednik, the Tauy River, and the coast west of the village of Balagonoe, including Motykley Bay and Talan Island. Of the 30-some territories on the rivers, although all were occupied, only one had produced a chick. We think this lack of productivity in this year was due to heavy rains that may have affected survival of eggs and hatchlings or influenced the hunting of the adults. In contrast, the great majority of the 20 or so territories that we surveyed on the coast had large chicks. We fitted five nestlings with GPS satellite transmitters and left them to grow up, fledge, and start their first migration south.
So, summer passed and migration time came. Four of the five birds we fitted with tags in 2007 left their nest sites. One bird apparently died or lost its tag near the nest. We should find out when the weather clears and we can visit the site this summer. One bird died at the Arman River and one died on the coastal slope of the Sheltinga Bay. We do not know whether humans were involved in these losses, but this part of the Arman River is where caviar-harvesting operations occur. At these places there are lots of discarded fish carcasses, meaning plenty of food, so we cannot imagine them dying of hunger!
Two birds started on a “normal” migration. Well, one did; the other (#42678) made a big victory lap around various rivers to the north and east of its natal range before setting off on proper migration around the end of October. By late November, this bird was near the village of Fedorovskoe where, the evidence from the tag’s transmissions suggests, it was apparently killed in the vicinity of the village. This village and the nearby area of sea is under the nominal protection of the Dzugdzhur Strict State Nature Reserve, and this incident may serve to illustrate how difficult it is to police these places.
So, at year’s end we were left with a single, live bird from 2007 that was transmitting, and that bird’s situation at that time was not bright because it was sitting on the Okhota River, some distance inland. Winter was closing in and food was likely getting scarce. In mid-January, after a big storm, this bird made a “hopeful hop” back to the coast on Cape Shestakov, only about 15 miles (25 kilometers) from its natal site. We were hopeful that some miracle would allow this bird to overwinter (the winter had been relatively mild and satellite images showed some open water near its last location), but alas, this bird apparently perished soon thereafter. (In 1997 we also tracked some eagles, and one bird behaved in exactly the same manner. Sadly, it apparently perished when it found itself without food and too far from ice-free water where it might hunt. Back then one could almost feel winter closing in on it as time passed. It survived until the end of January.).
For most of 2008, we have been tracking the only bird that appears to be alive and with a working transmitter, #65332. It spent its winter (early July to mid-February) on the second-most southerly Kuril Island, Iturup. It has just made a move to the southerly most Kuril island, so we may be seeing the start of the migration. Fingers crossed!
We will be heading out to Magadan again and supporting the work of the Magadan Zapovednik in 2008. We will also be running a pilot effort in Kamchatka. We will also make a start on some DNA work that might reveal information important to the conservation of Steller’s sea-eagles and other eagles. We are currently running a similar project on golden and white-tailed eagles. Have a look: golden eagles and white-tailed eagles.
Note: Although other eagles seem to have either perished or lost their tags, we continue to hear them broadcasting. Theoretically, we can use these locations to find the tag, but this is one of the remotest areas of the world, so this is sometimes not easy. However, it seems that at least one of our contacts may have located a tag because it suddenly moved in early January. Hopefully, we will hear soon! That said, we are still very concerned (and a little surprised) at the number of eagles that were apparently lost to human persecution.
Dr. Mike McGrady is a researcher with Natural Research Limited, partnered with the San Diego Zoo.
Here’s more information about the Steller’s sea-eagle project…
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March 29th, 2008 at 6:13 pm
Hi! Just read this article about the Steller’s sea eagles and the huge problems that they are having just surviving one year! WOW!!! I’m glad that you had transmitters on some of them so that you can track them on their migrations, but it looks like you have very serious problems with people in those areas that these eagles choose to migrate thru. My suggestion would be to start getting a large team of Stellar sea eagle experts together to start going to every village and town along the bird’s migration routes and where they nest/live at, and start a huge ongoing education program about these birds’ importance to the environment to all of the people in those areas. There has to be some way to get the people to understand that by killing these birds, they are taking away a natural population control that these eagles do so well, namely keeping rodent populations at reasonable levels as well as other small animal populations. These eagles are a natural part of the order of the food chain with them being one of the top predators in that region. We have certainly learned that here in the USA when the bald eagle was in danger of being extinct and government/wildlife agencies finally put them on the endangered species list and also have them federally protected in all 50 states. Now, the bald eagle has recovered very well since the 1970s, are still federally protected, and are now off the endangered species list as of 2007. But, the bald eagles are still being watched very carefully for any signs of unusual population losses that could put them back on the endangered list. I am hoping that the ICN has the Stellar sea eagles listed as endangered as well. They need to be on that list, and the Russian government must step up to protect these birds 100% now! Hopefully, you all can help them achieve that and get this education program about the eagles going to everyone that lives in the eagle’s range. Please let us know what is happening with these birds, and if there will be any progress in their protection. Good luck in your efforts!
Chari Mercier
St. Pete, FL