Category Archives: migration

Golden eagle!

Here are some photos from yesterday’s big golden eagle adventure; click through to see larger sizes (or click here to view them as a slideshow). As readers of Marcia’s Game News column will have just learned, the golden eagle migration last year only really got underway in late November. This year, it’s almost a month earlier. (By contrast, the autumn foliage has only now reached its peak — a good two weeks late.)

show-and-tell golden eagle 1This bird was hatched this spring, probably somewhere in northern Quebec or Labrador. It was one of at least ten goldens that soared down along our ridge on the afternoon of November 3, chased and harried by a resident redtail. It came along just before dusk, dove for the bait, and was caught in a bow trap by Trish Miller of the Powermill Avian Research Center, who was staffing a blind on an almost inaccessible part of the Plummer’s Hollow property. The eagle had to spend the night in a pen in our basement, until all the scientists could assemble and get it fitted with a radio transmitter.

show-and-tell golden eagle 2 (Todd Katzner)Todd Katzner, a scientist with the National Aviary in Pittsburgh who has extensive experience with wild eagles, was kind enough to do a short show-and-tell for us and our friends. Apparently, the white on the underside of the wings is one of the things that distinguishes a juvenile golden eagle from an adult. The talons are also a brighter yellow.

eagle talons
Typical golden eagle prey consists of hare-sized animals, Todd said. They can kill animals as large as a fox or a fawn, but they eat a lot of birds, too. They have no natural predators of their own.

touching the eagleMouth-breathing is a sign of stress, Todd said. Fortunately, it was a crisp morning — they don’t take heat very well.

measuring the beakMeasurements of wings, bill, etc. were taken not only for record-keeping purposes, but also to try and determine the sex of the bird. They compared their measurements to a list and determined that it was a female, as Todd had already surmised. Not having handled as many female as male golden eagles, they were surprised by how much thicker its down seemed to be. But that, in addition to its larger size, may be of adaptive benefit since the female does most of the incubating of the chicks in the first two weeks, until they become better at thermoregulating on their own.

weighing the eagle (Trish Miller and Todd Katzner)Weighing the eagle. It took several hours to complete the measurements and fit the radio transmitter. The eagle was hooded with a knit cap for most of that time to reduce stress, though the superficial resemblance to the infamous images of Abu Ghraib inmates was a little unsettling at first. They also bound her talons with surgical gauze after Todd cut his finger on them.

kids with eagleTrish did much of the work, since the golden eagle study is going to be the topic of her PhD dissertation. Here, her daughter Phoebe interacts with the bird.

fitting the transmitter 2A soft teflon harness was sewn together on the spot and carefully worked under the feathers. They used cotton thread, with the expectation that it will rot off in a couple of years.

fitting the transmitterThe radio transmitter is much lighter than it looks. If all works correctly, it will transmit the bird’s GPS coordinates to a satellite twice every minute.

eagle with transmitterThis shot reminded me of a pow-wow dancer, almost. I wonder if the Indians ever captured eagles along this ridge? The eastern golden eagle is nowhere near as easy to trap as its western counterpart, and when this project got started two years ago, they had a hard time getting funding because few people thought they’d be successful. This is the first female to be fitted with a transmitter in Pennsylvania.

golden eagle over Bald Eagle ValleyWe all trooped back up to the capture site to release the bird. My mother was given the honor of actually tossing the bird into the air, in part perhaps because she was one of the few people present without a camera! Unfortunately, however, my reactions are slow — I didn’t get a good picture of her with the bird. Here’s the eagle seconds after release, with Bald Eagle Valley and the Allegheny Front beyond.

eagle in pineShe flapped over into a white pine at the edge of the talus slope to groom herself. At one point, she reached around and lifted the transmitter in her beak, but then released it. It was a tense moment.

taking off from pine

She spent four or five minutes trying to straighten her ruffled feathers and get used to the feeling of the harness against her skin and the strange new backpack. Finally, she launched herself into the air, circled low over our heads once, twice, then headed off to the south along the ridge. We were awed and humbled by the experience, and still have a bit of a hard time believing that our far-from-wild ridge twice a year becomes a highway for these archetypal denizens of the northern wilderness.

–Dave

UPDATE: Unfortunately, the transmitter failed after just a few days. But Trish told me they got some great data from the bird before that happened.

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Monarchs on the move

foggy monarch The monarch butterfly migration is well underway, with higher numbers than we’ve seen in many, many years. With close to fifty acres of goldenrod and asters in our First and Far Fields, we get a lot of monarchs coming in to nectar and spend the night. And with nighttime temperatures falling into the 40s and 50s (5-15 C), the monarchs tend to seek each other out in late afternoon so they can spend the night in small clumps in the trees. The next morning, the fields are aflutter with hundreds of monarchs, especially bordering Sapsucker Ridge where the sun strikes first.

Anecdotal evidence suggests a robust monarch migration throughout the east. My Uncle Hal drove up from Beckley, West Virginia the other day, and said he was dodging monarchs all the way. And a post to the Pennsylvania Birding listserve on Thursday reported a staggering 7,000 monarchs in one morning at a hawk watch in Northampton County. The poster, Michael Schall, says, “It was non-stop on the clicker trying to get a decent count with my total of nearly 7000 by the time I had to leave at 1300pm conservative at best. Most were counted between 0900 and 1030 as numbers were light when I left for work.” This jibes with our impression of the greatest movement occuring in the morning.

To see what our main field looks like when the goldenrod is in bloom, click on the newly illustrated “Where and What is Plummer’s Hollow?” page and scroll down to the bottom.

–Dave