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Friday, December 9, 2016

Chilkat Bald Eagle Preserve


An immature eagle above the Chilkat River.

Last week, I was lucky enough to visit the Chilkat Bald Eagle Preserve which is just north of Haines, Alaska. The preserve is one of the most unique places on the planet. If you follow the highlighted link you will see a map of the Chilkat River and the surrounding alluvial fan. The fan accumulates water and warmth during spring, summer and fall.



The Alaskan Department of Natural Resources explains that in early winter this store of warm water percolates into the river and slows the freezing process. 


Each year the free flowing river enables one of the latest salmon runs in the state. In turn the late runs of salmon attract the largest congregation of bald eagles in the world


The 'warm' water also attracts trumpeter swans and common mergansers, while the potential for salmon scraps attracts ravens, gulls and black-billed magpies. On Saturday and Sunday, when the temperature fell sharply, ice began to accumulate in the river.

Earlier in the week, the temperature and the weather around the Chilkat varied with highs usually around freezing. I found photography in the snow a bit of a challenge. Lucky for me, I was invited, on my first trip to Alaska, by Laurence Norton, my photographic mentor. During this trip Laurence and my new friend Elliot Solomon both gave me many tips to help improve my photography. I am looking forward to practicing and assimilating the information.

This photo is one of Laurence's. I found it especially interesting because of the startling symmetry and the way it shows off the eagle's alula. The alula are the short feathers sticking up from the top of the wing. They are most similar to our thumbs, while the individual primary feathers at the ends of the wings are similar to our fingers. Both types of feathers assist birds in making slow and controlled landings. 

You can see more of Laurence's photos on Facebook by Clicking Here.

Elliot caught me relaxing on Saturday - when the eagles calmed down just before sunset - around 2:30 in the afternoon. The photo even shows some of the ice starting to form in the river.

You can see Elliot's eagle photos on Flickr by Clicking Here.

If you look closely at the first five primary feathers on this eagle's right wing you can see the distal or last half of each feather is narrower than the proximal or upper half. In addition to helping them land I suspect the outer primaries also reduce drag and make soaring more efficient. When eagles are gliding you can often see their wing tips are upturned - somewhat similar to the wing tips on a modern jetliner. They first photo in this post provides a good example.

The most captivating bald eagle behaviors related to their competition for food. The eagle in the middle was momentarily in possession of a fish which attracted competition from all sides and from above.

These aerial attacks can even happen when an eagle is already airborne. In either case it appears the safest way for an eagle to face an aerial attack is to roll over and fight talons with talons.

I never did see an eagle do the classic fly-over method of fishing, like we see on television, when an eagle grasps a fish from the surface of the water and continues flying. I suspect these salmon were simply too large. This drenched eagle most likely just lost a fish-fight with another eagle while trying to pull a salmon to shore. While drying, the eagle carefully watched the water.

When the eagle saw a new opportunity it glided down and pulled another salmon on to the shore. Surprisingly, instead of quietly eating the fish, the eagle called out loudly. This 'boasting' behavior was repeated over and over along the river. I never did understand why. It always seemed to attract the competition.

Within sixty seconds the first eagle was chased away from its catch.

The behavior was repeated by at least four different eagles before this particular fish was finally incapacitated. Magpies were also attracted to the possibility of scraps.

This capture appeared to be a variation on the theme.

The eagle quietly dragged the salmon away from the shore...

...before calling loudly.

After which, a second smaller eagle was allowed to share in the catch. Since males are about one third smaller than females I suspect the first eagle was a female and the second was its mate.

Sadly, even having a two to one advantage did not stop an aerial attack.

Momentarily, all three birds were intertwined.

It became hard to follow the action.

However, I think the male successfully defended the food, at least for a while.

A third method of 'fishing' is a bit more indirect. This gull apparently grabbed and swallowed a piece of fish and then tried to fly away. 

As Laurence pointed out, the eagle's pursuit is telling the gull, 'Your food or your life!'

The gull makes a wise decision.

It loses its lunch, improves its agility and saves its own life.

As the gull flew away the eagle settled down for a quick easy bite. This was the first time I had seen this behavior. It was however precisely like the description of a parasitic jaeger's feeding strategy which was explained by Dennis Paulson during our Master Birder Class a few weeks earlier.

A fourth feeding behavior was demonstrated whenever a portion of a fish became small enough to carry. The eagles would then cross over the river, to get away from the heavy competition...

 ...and feed in the relative safety of a tree.

This bird found a frozen fish tail, apparently left behind during a prior food fight.

The other eagles did not follow but one of the corvids... 

...became very attentive.

One of the locals told me the black corvids were raven's. I was surprised to see their tails looked fan-shaped more like an American Crow. Their calls were deep like ravens and their bills were heavy. Yesterday, when I saw a raven on Snoqualmie Pass it clearly had a diamond-shaped tail. It makes me wonder if there is variation in the tails of ravens in Alaska compared to the tails of ravens in Washington.

Regardless of the corvid's angle of approach...

... the bald eagle was not willing to share.

I certainly hope the folks in Alaska are able to maintain the salmon runs along the Chilkat River. I understand there is an effort underway to open a copper mine upstream. Certainly, the mine would provide important jobs. I just hope the mining company, the State of Alaska and the local people are able to safeguard the salmon. It would be sad to see Alaskan salmon share a fate similar to the salmon in the Pacific Northwest.

Happy Holidays!

Larry

6 comments:

  1. Extraordinary photography as always, Larry, and you really illustrate how tough it is for these apex predators to eat a meal in peace. Now that I know where you were, remind me not to complain about the cold.

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  2. Beautiful as always Larry. An extraordinary place. Just superb storytelling.

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  3. Oh, how I am captivated and educated by your photos and information. You do wonders for my soul and my passion for birds and wildlife. I stand in your shadow. Thank you, Larry and Co.

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    1. Judy,
      Thank you for your kind words and for following along. Visiting the Chilkat River and all the Bald Eagles was truly the experience of a lifetime.
      Larry

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