Sunday, April 09, 2006

April 9 notes: precious eggs near hatching?



We are all eager to detect hatching at the nest this coming week. The adult eagles have faithfully tended their egg(s) for nearly 5 weeks. The incubation period for bald eagles is "about 35 days!" Very young nestlings may not be visible initially from our camera angle so watch eagle behaviors closely. There is a subtle difference between the prone posture of an eagle incubating eggs and the slightly raised (but very low) position of one brooding an eaglet. If there is more than 1 egg, hatching dates are days apart identical to the interval between egg-laying dates. In other words, an adult in the nest has to perform both tasks in this challenging time frame!

The first clear evidence of a successful hatch will either be a glimpse of the young eaglet or observations of feeding motions to an unseen, tiny hatchling. Look for food morsels being passed "beak to beak" from the adult to an eaglet.

We have discussed the impacts of disturbance and inclement weather on nesting eagles, but there are many other risks. One that once jeopardized bald eagles across most of their range in the continental U.S. was chronic breeding failures from environmental contaminants. DDE (a by-product of the insecticide DDT) once caused widespread eggshell thinning and breakage before hatching. In the 1960s and 1970s, only 30% of eagle nesting attempts in Maine yielded eaglets. At the time, levels of DDE were higher than any other findings in wildlife tissue sampled in the U.S.

The photo above shows the 1974 transplant of eggs not impaired by DDE into a nest in midocast Maine. Frank Gramlich and Paul Nickerson (both now retired from the U.S. Fish and Wildlife Service) were attempting to bolster the supply of eaglets where eggs failed to hatch at all local nests in the Kennebec River estuary during a 16-year period. It helped hold eagles in areas where the species was nearly extirpated. A limited supply of "precious eggs" was brought in a thermal suitcase from a captive breeding program in Maryland or healthy donor populations in Minnesota and Wisconsin.

Paul Nickerson, former endangered species coordinator in the Northeast, recalls egg transplants during 1974-76. Paul brought 3 eggs from Minnesota's Chippewa National Forest in 1974. Only one of 3 attempts succeeded that year. Addled eggs taken from each nest revealed high levels of contaminants. Egg transplants were about 40% successful. In later years, eaglets were fostered into nests with contaminated eggs. This technique was 90% successful. Desparate circumstances required extreme measures as the decline of Maine eagles continued well into the 1970s.

Our "eagle cam" was placed at this Hancock County nest partly because this location has the best nesting record of any nest in Maine since it was first used in 1995: 100% of ALL nest attempts here have been successful. Eighteen eagles have taken first flight here over the last 11 years: nearly double the average nesting productivity among Maine eagles.

Other nests are less fortunate, and some have continuing problems with environmental contaminants like PCBs and mercury. Another pair of eagles nesting only 30 miles away from the "eagle cam" represents the other extreme. Eagles nesting there have NEVER raised eaglets during 12 years of breeding at a remote location free from disturbances.

Most nests in Maine have nesting statistics somewhere between these two extremes. Since 1996, 60% of all eagle nesting attempts in Maine yielded eaglets that survived to fledging. Some of the 40% failures in the population are due to environmental contaminants. We hope that this problem does not arise at our "eagle cam" nest, and toxics never again threaten the population.

Management comments: Bald eagles are a top-level predator and therefore exposed to concentrated doses of environmental contaminants passed through food webs. Beginning in the mid-1940s, several raptors and fish-eating birds like bald eagles experienced dramatic declines for nearly 3 decades during the height of the DDT era. Banned in 1972, there are still residues in most eagle tissues in Maine, but the impact of DDE has diminished.

Mercury and PCBs still harm some Maine eagles. These contaminants can transport through the atmosphere exposing other regions. Maine is downwind from prevailing westerly winds in North America. Most people value bald eagles as our national symbol or a magnificent part of our wildlife heritage, but their role as an indicator of environmental quality cannot be understated. -- Charlie Todd, Maine Dept. of Inland Fisheries and Wildlife

20 Comments:

Anonymous Rose and Bill from CT said...

My husband and I have caught two nest exchanges over the past week. Last evening, at dusk, I checked the webcam site for signs of new life and I feel pretty certain that I heard some peeps and a peeking and at the same time, the eagle looked behind at the source. The egg(s) was rotated immediately following. I hope it wasn't my hopeful imagination! This is all so very exciting. Thank you so much.

12:52 PM  
Blogger Anne M said...

Thank you for this unique opportunity! I have just witnessed a guardian changeover at the nest (at a little past 3am GMT + 8 hours) & I feel privileged!
Anne M

3:40 PM  
Anonymous Anonymous said...

I think what your doing is stupedous and your a great bunch of people for doing this and i hope you can keep it up for as long as it takes to get them back the way they used to be.
(THANK YOU VERY MUCH FROM KINGBELLYMAN@YAHOO.COM) AKA LADD BALDWIN AND GOD BLESS YOU ALL.

7:07 AM  
Anonymous jane edwards said...

I think one has hatched. This morning heard and then saw the male come in at 6:14 to relieve the female, and she wasn't having it!! He sat within view of the camera for several minutes, then eventually flew off.

It seems to me she is sitting a little higher today, too.
But maybe I'm just over anxious!!

Thanks for posting the blog telling us what to watch for.

Jane Edwards

7:24 AM  
Anonymous Anonymous said...

As a watcher from Vermont, saw a fuzzy white head reach up for some food this afternoon! We also watch a nesting pair of BaE's on the CT river. Wish we had a cam for our nest, but pretty sure we've also had a hatch. 041206 @1640 HRS.

4:49 PM  
Anonymous Anonymous said...

I think the first eaglet hatched on Tuesday, April 11th and the second today. I watched one of the eagles bring a duck back to the nest and feed the eaglets at about 5:15 today. I'm positive I saw a tiny white head appear above the rim of the nest. I have really enjoyed watching this live cam. Can't wait to really get a good look at the eaglets and watch them grow.

5:54 PM  
Blogger Laurie said...

Saw a tiny white head above the rim of the nest today, just before one of the eagles brought a sea duck back to the nest and fed the eaglets. I think the first one hatched on Tuesday and the second last night or this morning, based on the eagles behavior.

6:09 PM  
Blogger Laurie said...

Watched the eagles feed their eaglets this afternoon (duck). I'm not an expert, but based on the eagles behavior, I think the first one hatched on Tuesday, April 11th and the second today or last night. Can't wait to watch the eaglets grow. Thanks.

6:15 PM  
Blogger Cheryl Oakes said...

The students at WELLS Elementary School in Wells Maine would like to thank you for this great eagle cam.
We want to know how you tell the male from the female?
Thanks

10:08 AM  
Anonymous Wifeymac said...

3:55 PM Thursday-
Noted adult eagle tearing bits from carcass after backing to edge of nest then proceeding to lean forward to feed baby. Could see a little movement between sticks of nest. Very exciting!
Wifeymac

4:01 PM  
Anonymous Anonymous said...

It seems the eggs have hatched! I have noticed feeding behavior since Tuesday, April 11. This is very exciting to watch! Can't wait to see the chicks.

10:19 AM  
Anonymous Anonymous said...

What animal are the eagles feeding off on now? I can see it's head in the nest.
dana

11:44 AM  
Anonymous Anonymous said...

It is amazing watching the eagles. I never thought I'd see anything like this up close. How old are the babies when they start to fly. Thank you for the oppitunity to see the eagles.

1:29 PM  
Blogger Brenda said...

I have not seen the parents of the baby eagles since Thursday, has anyone seen them lately? If the baby eagles are abandoned, will they be rescued?

7:02 PM  
Blogger JOJO said...

I wonder what effects do chemtrails do to the Eagles.
My Grandkids love the eagles,and watching them grow is amazing ,
Keep up the fantastic job

9:23 PM  
Blogger JOJO said...

This is so amazing and wonder.I let the grandkids watch also.Keep up the fantastic job
I wanted to know what the chemtrails effect the eagles in a negative way

9:25 PM  
Anonymous Cheryl S. said...

5/30
Brenda said she had not seen the adult eagles since Thursday. I don't know what Thursday (date,) but I have seen the adults each day, usually early in the morning, and sometimes when I check again at night just before dark one of the adults is there. They eaglets sure seem to be trying their wings out more and more. The one day the bigger eaglet was standing tall, flapping his/her wings and it was very windy, and it almost lifted off the ground. I could see it grab the nest with its one talons!! Boy that was quite a site!! CS

8:34 PM  
Anonymous Anonymous said...

Is there something wrong with the smaller eagle's wing? It seems to flop down away from the body.

3:20 PM  
Anonymous Anonymous said...

The smaller one does not appear to be getting much food, is that why it is so small or have I missed it being fed. Seems weak and doesn't move around much.

4:20 PM  
Blogger Kitty said...

Is the smaller one getting enough food or have I missed it being fed. It appears weak and doesn't move around much.

4:22 PM  

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