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Observations from the Blind: Bald Eagles in Alabama

Over the next few weeks we hope to share with you the events that occur as an adult pair of Bald Eagles hatch and fledge a new addition to Alabama’s growing population of wild Bald Eagles. ADCNR video producer Ron Jolly will report from the nest site and Alabama Division of Conservation and Natural Resources Wildlife Biologist Keith Hudson will add biological insight to each post.
 

 

 
"An Empty Nest"
March 11, 2011
This is the final post from the eagle nest in Wilcox County for the year. The adult eagles had little or no interest in the nest over the last two weeks. There was obviously something wrong. A fly over by ADCNR Pilot Ray Stroud and photographer Billy Pope proved what I feared was true, an empty nest.
 
Projects like this are always difficult, but rewarding if successful. This project would not have been possible without support from friends and colleagues. A special thank you goes to Bruce Henderson with the Auburn Extension Service and James "Big Daddy" Lawler. Hopefully next year the results will be different.
 
-Ron Jolly, ADCNR video producer
 
 
As mentioned in earlier posts, not all eagle nests are successful.  It appears the one being followed by our cameras this year was one of the approximately 28 percent of eagle nests each year that are not successful.  Without the remains of eggs or young eaglets we will likely never know what caused this unsuccessful nesting attempt.  It might have been weather related, poor parenting, predation, or perhaps the lingering effects of the insecticide DDT.  In some cases, a renesting is attempted by the adult pair, though this usually only happens when eggs are lost early in the nesting cycle.
 
Fortunately, we were able to confirm an unsuccessful nesting by surveying the site from light airplane and removing all doubt that juveniles are not in the nest.  Without an aerial flyover, it may have been many days or weeks (or perhaps never) before ground observers would have known the outcome of this nest.
 
However, most of the other eagle nests being surveyed in Alabama this year appear to be doing fine with no unusual level of nesting failures.  Such is the way of nature.  Some survive; others do not, even our national symbol.
 
-Keith Hudson, Alabama Division of Wildlife and Freshwater Fisheries wildlife biologist

 

"Where are the Eagles?"
March 1, 2011
Something is very different at the nest. When I came to the blind yesterday the mature pair was near the nest, but not in it, and they were not agitated by my approach to the blind. After nine hours, the pair of eagles did not come to the nest, and spent most of the day soaring in the distance, then landed in a snag and spent the afternoon there. Has something happened to the chick? 
 
-Ron Jolly, ADCNR video producer
 
Inactivity at the nest
Observations from the ground at this stage are sometimes inconclusive. When eaglets begin to get their flight feathers and are old enough to thermoregulate, the adults begin to visit the nest less often. Though there may be eaglets in the nest, at this point they are sometimes difficult to see. When the chicks are larger they are more easily seen.
 
Success rate of nesting pairs
It is possible the eaglet(s) has died and this is the reason no activity is being observed. A study of Alabama nesting data shows that of the 493 nesting attempts between 1985 and 2006, 355 were successful, a 72% success rate. Success is defined as at least one eaglet fledged the nest. The mortality rate of fledged juveniles varies, but many studies show that less than 50 percent survive the first year. If juveniles can survive the first year, mortality rates drop significantly to between 20-25 percent a year.
 
We can't be sure of what is happening in this nest unless a survey by airplane is attempted, or until the young are large enough to be more easily seen. Life and death is the way of nature - even for our magnificent Alabama bald eagles.
 
-Keith Hudson, Alabama Division of Wildlife and Freshwater Fisheries wildlife biologist


 

“Hatched!”
February 16, 2011 
There is an eagle chick (or chicks) in the nest. Both mature birds were extra alert until I was concealed in the blind. One adult is sitting higher in the nest than before and focuses its attention on “something” else. The adult was also pulling morsels from a carcass and turning as if to offer it to a chick. The clincher came through my headset. I could hear the pleading of a hatchling (listen closely at :26 in the video). The angle of the blind obscures the view, but I am positive there is a newly hatched eagle in the nest!
 
-Ron Jolly, ADCNR video producer
 
Young adult bald eagles generally have one juvenile per year.  Older adults have two young per year, and there is rarely three young per year. When only a few days old, adults will feed the young several times a day, picking small pieces from prey items and directly feeding the chicks.  After a few weeks, food items are left in the nest a few times a day and the young begin to feed themselves. In about three weeks, the young become large enough to be obvious in the nest.  Their down feathers are soon replaced by flight feathers and the juveniles begin flapping and preening.  They are capable of flight in about eight weeks, but only rarely fledge the nests at this time.  Usually, it is 12 to 14 weeks before fledgling is complete.
 
-Keith Hudson, Alabama Division of Wildlife and Freshwater Fisheries wildlife biologist

 

“The Waiting Game”
February 10, 2011 
If correct, the eagles began incubation on January 10. Today is the 29th day. I had hoped to be there for the hatch, but it is still a waiting game. One eagle is always on the nest and the other is never far away. The vigil continues.
 
-Ron Jolly, ADCNR video producer
 
Did you know?
Eaglets are relatively small at hatching and require nearly three months of development before leaving the nest. Bald Eagles can live an estimated 25 years.
 
Nest Facts
Large nests are most often built in the crowns of tall trees, usually near water. Breeding pairs usually return to the same nest year after year, sprucing up the nest by adding new nesting material. Some nests may reach 10 feet across and weigh 2,000 pounds.
 
- Keith Hudson, Wildlife Biologist, Alabama Division of Wildlife and Freshwater Fisheries
 


 

"Incubation"
February 2, 2011 
I have no doubt the eagles are incubating. We first observed this behavior on January 10. They are so focused that entering the blind does not cause them to leave the nest. When I arrived yesterday afternoon one of the adult eagles was barely visible in the nest. She did not leave the nest yesterday and has not left today. Incubation is definitely on!
 
- Ron Jolly, ADCNR video producer
 
Some bald eagles in Alabama begin nesting as early as December, though most begin in January. Young adults usually lay one egg, older adults two, and rarely three eggs are laid.  Incubation is 30-32 days, but this can vary slightly according to how many eggs are laid, the weather and the time between the laying of individual eggs.  Both adults build the nest, co-parent the young and brood the hatchlings until they can thermoregulate. As the juveniles begin to grow the adults spend less time at the nest, sometimes only flying in to bring food.  When the hatchlings are small they are susceptible to predation by other predatory birds. Adults will remain nearby often within sight of the nest.  As the young grow larger they are not as susceptible to predation and within a few weeks are larger than many other adult birds of prey.
 
- Keith Hudson, Wildlife Biologist, Alabama Division of Wildlife and Freshwater Fisheries
 

 


"It's On!"

January 4, 2011
Not so long ago the fledging of a wild Bald Eagle in Alabama was a rare event. Today, due to the efforts of the Alabama Department of Conservation and Natural Resources (ADCNR) and other interested groups the Bald Eagle has made a tremendous come back.  After unsuccessful attempts to document a mating pair of eagles last year, I have found a nest in Wilcox County, Alabama that offers a perfect view.
 
In December 2010, the eagles added new nest materials at the site. This January it is apparent the eagles are committed to the nest based on their defensive posturing as I entered the blind. During the 17 hours I spent in the blind over two days, one of the eagles never ate, drank or left the nest site. I am now convinced there is an egg in the nest.
 
- Ron Jolly, ADCNR video producer
 
In the early 1980's, a recovery project to restore Alabama's nesting eagles was initiated by ADCNR's Nongame Wildlife Program.  The strategy was to force juvenile eagles to take their first flight in Alabama and become imprinted on a geographical area in the state.  Then, after reaching sexual maturity in about five years, these eagles would return to Alabama and establish nesting territories.  The process is called "hacking."  From 1985-1991, 91 juvenile eagles were released from six separate sites across the state. 
 
Each year Alabama's wildlife biologists survey for bald eagle nests.  The first confirmed successful nest in the post-DDT era occurred in 1991.  Surveys have shown nest numbers and nesting success have gradually increased since 2001.  By 2006, when comprehensive statewide nesting surveys were discontinued, nest numbers had reached 77.  Today, bald eagle nests number well over 100.

- Keith Hudson, Wildlife Biologist, Alabama Divison of Wildlife and Freshwater Fisheries


 


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