04-07-16 Raptor Research Update

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04-07-16 Raptor Research Update

April 7, 2016

Raptor View Research shares an update on raptor migration counts, and satellite tracking of ospreys and eagles.

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On March 10, we finished our 2016 winter eagle trapping on the MPG Ranch. We captured 16 Golden Eagles and three Bald Eagles this year, all but one of which tested high for bloodlead levels. We outfitted six of the Golden Eagles with GPS transmitters and look forward to learning where they spend the summer.

Three of the adult Golden Eagles captured this winter appear to be Montana residents, while two are well on their way to summer territories further north. The young Golden Eagle (dark blue), who fledged last summer from a nest near Nome, Alaska, has spent the last few weeks just north of the Idaho-British Columbia border.

We are also still tracking seven adult Golden Eagles captured in earlier winters. One male (dark blue) is a resident of the Skalkaho drainage of the Bitterroot Valley. Four of the six migrants have already reached their summer territories, while the other two should reach theirs in the next few days. The two eagles who summer in southern Canada started north extremely early, and reached their summer territories before the others had even started their journeys.

All seven of the Ospreys we are tracking are still on their wintering grounds. We expect the earliest of them to start moving next week.

On March 15 we began our sixth consecutive season of monitoring the spring hawk migration over the MPG Ranch. MPG biologist Kerr Rasmussen, and RVRI’s Sarah Norton, Mary Scofield, and Jessica Taylor are conducting this year’s counts. So far we have counted a total of 341 raptors. As in previous years, Red-tailed Hawks, Rough-legged Hawks, and Golden Eagles dominate the first weeks of migration. Our total of 32 Bald Eagles is the most we have counted in the first two weeks of any spring count.

After a warm and sunny first half of March, the weather has been chilly for most of the count.

Previous Research Update

04-06-15 RVRI Research Update