04-06-15 RVRI Research Update

04-06-15 RVRI Research Update

April 6, 2015

Raptor View Research shares a research update on winter eagle trapping, spring migration raptor counts, and satelite telemetry tracking efforts.

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Raptor View Research Institute Research Update MPG Ranch 4/3/15

We concluded our fourth winter of eagle research in the second week of March. We captured a total of 20 eagles this season, 11 Golden and nine Bald. We outfitted four adult Golden Eagles with satellite transmitters and marked six younger Golden Eagles with wing tags.

We also collected parasites from 13 eagles, which will be identified by colleagues at Oklahoma State University. We spend the same amount of time on each region of feathers to standardize the amount of effort between individuals. Currently, we know very little about the type and amount of parasites Golden and Bald Eagles carry.

Earlier this winter, we shared the story of an adult female Golden Eagle originally captured on January 7, 2013 and outfitted with a satellite transmitter. After spending the summer in Alaska’s Arctic National Wildlife Refuge, the eagle returned to the MPG Ranch in the winter of 2014. We recaptured it on December 27.

On March 1, 2015, the transmitter on a male Golden Eagle stopped moving near Dillon, MT.

Though the GPS units provide locations accurate within 25 meters, their small size can make them a challenge to find. The sparse vegetation at the location of the downed transmitter made searching fairly easily. We found the transmitter in view of McCartney Mountain, an area the eagle frequented. Upon inspection, we saw that the break-away harness had functioned just as it was designed. Our goal is to have the birds drop the transmitters after one to three years of wear, before the units stop functioning. Then we can recover and refurbish the transmitters for future use, and the eagle isn’t saddled with the device for it’s entire lifetime, which could be upwards of 30 years!

On March 15, we began our fifth consecutive season of monitoring the spring hawk migration over the MPG Ranch.

We have already seen diverse weather conditions this season, from warm and sunny, to cold with rain showers.

We frequently see large flocks of Snow Geese, especially early in the season.

Spring migration is an exciting time to monitor our satellite tracked birds. To date we have instrumented 18 Golden Eagles and 16 Ospreys with GPS units.

Golden Eagle migration is well under way. After spending the winter near Craig, Colorado, this adult male Golden Eagle started heading north on March 8. So far, he has completed approximately 2/3 the journey to where he spent last summer.

This adult female Golden Eagle is currently further north than any other tracked individual. She left the Bitterroot Valley on February 15, and reached the her summer range on March 24. She used the same summer range last year.

This adult male Golden Eagle has remained on a territory in southern Canada for over a year. It is unlikely he will leave this area during the coming months.

This adult male Golden Eagle seemed to be migrating since his capture on January 7, 2015. Currently, he is near McBride, British Columbia, where he has been since February 26. We do not expect him to travel any further north.

Previous Research Update

Satellite Telemetry Update

Next Research Update

04-07-16 Raptor Research Update

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