Eaglets eleven weeks old

As our regular cam watchers can testify, our two eaglets — Chesapeake and Choptank — are spending less time at the nest now that they’ve become more skilled at flying. Next in line for our eaglets is developing their hunting and fishing skills, which will be the hardest abilities to master but will determine if they survive their first winter.

In the fall of this year, our eaglets will eventually become fully independent and will break off from their parents for good. At that time the eaglets will have to provide their own meals and will truly be on their own. Many young eagles do not make it through their first winter because they have difficulty catching or finding regular meals, so the preparation that our eaglets are doing now — developing these important food-finding skills — are crucial for their long-term survival.

Wildlife research has taught us that young bald eagles that are searching for easy food (and not bound by a mate or nest) will travel long distances, often showing up in areas that might surprise us. Solar-powered satellite transmitters are the devices that allow researchers to follow the movements of birds (and other animals) to discover just where they go and when. In the Chesapeake Bay area, bald eagles have been tracked in the past by different organizations (educational, nonprofit, and government) using satellite transmitters, which incorporate technology that is becoming more sophisticated every year. Although many eagles in the Bay area have been tracked, most of the birds studied have been from the Upper Chesapeake Bay rather than from the Lower Chesapeake Bay, which is where Blackwater NWR is located (see map).

Earlier this week, I had mentioned on our cam page and on our Twitter account that folks from the Center for Conservation Biology (CCB) at the College of William and Mary went to the Norfolk Eagle Cam on May 20 and fitted the cam’s biggest eaglet (a female named Azalea) with a satellite transmitter. This was exciting not only because we got to watch the event on their live cam but also because this is one of the somewhat rare instances of an eaglet from the Lower Chesapeake Bay being fitted with a solar-powered transmitter that could potentially tell us a great deal about where these eaglets go when they leave home for good but before they reach breeding age (about 4-5 years of age).

The CCB folks did say that the transmitter should last about a minimum of 3 years, but eventually the eaglet could pull it off, so the transmitter does have a limited life. They also mentioned that eagle research using satellite transmitters has revealed that Bay eaglets sometimes travel north to areas like Labrador, Canada and south down to North Carolina, so even though our adult bald eagles in the Bay area don’t migrate much, their offspring can explore a wide area before settling down.

And since we’re talking about satellite tracking, I should mention that there is some controversy about putting satellite transmitters on birds — especially young birds that have not fledged yet. While the transmitter pack is often fitted using soft teflon ribbons (a more bird-friendly fastener), there is some concern that it could offer an unnecessary impediment to a young bird that is trying to learn to fly. On the Norfolk Eagle Cam blog, they did report the following:

The largest of the chicks will be selected to ensure the best fit. Choosing the largest of the eaglets will also reduce the ratio of the weight of the transmitter relative to the eagle. As a general rule of thumb the weight of a transmitter shouldn’t exceed 3% of a bird’s body weight. The transmitter being used weighs 70 grams (equivalent to about 14 U.S. nickels). At the time of the banding the largest eaglet was #2 (readable band HH) at 2973 grams. By the time the bird fledges the transmitter will only be about 1.5% (or less) of its body weight. The eaglet will be weighed and measured again while on the ground being fitted with the transmitter.

So it does appear that the CCB folks are being cautious in not burdening the eaglet with something that will interfere with its ability to fledge in a normal way, just like its siblings.

Be sure to visit the Norfolk Eagle Cam home page where they have links to a slide show and video showing Azalea being fitted with her transmitter. Also visit the websites EagleTrak and WildlifeTracking.org to learn more about the tracking of Chesapeake Bay bald eagles.

Note that Azalea is still a nest-bound eaglet at this time, so her tracking information will not get terribly exciting until she has fledged and begun exploring her home area. We wish her the best of luck for a long life that will hopefully further our knowledge of the movement patterns of young bald eagles.

As for our two youngsters — Chesapeake and Choptank — we have what will probably be our final round of video clips to post, and we’ll do that in the coming week, so stay tuned to our site. Even though the eaglets are around less, we’re still not done with the season.

Until next time,
Lisa – webmaster
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Tags:
eagles, wildlife refuge, eagle cam, Blackwater Refuge, Maryland

This entry was posted on Thursday, May 21st, 2009 at 7:20 pm and is filed under Blackwater NWR, Eagle Cam, Eaglets, Fledging. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.