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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

Saturday, November 26, 2016

Flamingo Fantasy

Yesterday morning, Union Bay was filled with sunshine. The common mergansers seemed to enjoy it almost as much as I did.

There was bathing and wing-flapping by the male...

...and the female mergansers. Not only are the heads and backs of the females different colors than the males, the females apparently get their hair done at a stylish salon instead of the buzz-cut barber shop which the males frequent.

Although the males do have their moments. When a male sits in the sunshine and curves his neck into an elegant 'S' shape, I must admit he cuts a fairly fine looking figure.

Earlier in the week, when the sun was hiding behind clouds of grey, I spent some time watching the mergansers and fantasizing I was someplace sunny with sandy beaches and pink flamingos. While mergansers are obviously not flamingos, they do have at least one thing in common, besides being birds. Both species have feathers which may be in part colored pink by the food they eat.


Oddly, not all of the merganser's white or whitish feathers have this pink or salmon coloring. 

It made me wonder if the wing feathers grew when the merganser was not eating the color-enhancing food or if their bodies simply produce both white and salmon colored feathers at the same time.

In spite of the color differences between the genders, their shapes are almost identical, especially when the females lay down their stylish head feathers. In our Master Birder Class we were taught that ignoring a bird's colors and focusing on their shape can sometimes actually make identification easier.

In addition to color differences on the head and back, the female common mergansers also seem to have less of the salmon coloring. Their undersides are much more white. I doubt that this has to do with dietary differences because the males and females are usually close together and they appear to be feeding on the same schools of fish.

In this photo, the foremost female does show a hint of a salmon tinge but it is clearly less extensive than in the males. In case you were wondering, my answer is no, I do not think the females eat less salmon. Plus, nothing I have read links the color of salmon meat to the salmon colored feathers on the mergansers, but it did make me wonder.

I ended up reading somewhere that a blue-green algae can induce flamingos to have a richer pink color. If that is true, then I suspect that the color of the food which the mergansers eat does not directly correlate with the coloring in their feathers. In fact, I suppose the differences in the head feathers of the male and female mergansers may actually prove that point. I wonder how the genetics in their bodies, and ours too, allow us to eat the same foods and yet produce different colored feathers, hair or skin.

In the case of the mergansers their gender genetics and body color genes must be very closely associated. Obviously, it is not the same with humans, but it does make me wonder would our society be better or worse if our color differences were gender based. My conclusion is that it is not how we look, but rather how we think and act which will determine whether our society improves or not.

Regardless of how the process works, there is no doubt that the mergansers love fish. Whenever a bird surfaces with food, its colleagues watch very closely. If the fish is large or awkwardly held, the others begin to close in. They obviously hope the fish will be dropped and they can pickup a free meal. Usually, within a second or two the first bird tips its head up and the fish disappears.

Whenever one merganser dives...

 ...the others quickly follow suit. It seems a bit like the old saying, 'Monkey see, Monkey do'. It may actually be very logical, if one bird spots a fish there may be more passing by. Plus, with multiple mergansers underwater they can surround a school of fish and cut off their escape routes.

I suspect as soon as their heads dip below the surface they are focused on food.

Their webbed feet give the initial dive a powerful boost and also propel them underwater.

It is easy to imagine how human divers came up with the idea for flippers.

One moment there can be a dozen mergansers floating offshore and seconds later there are only ripples fading across the surface.

I often think of the pattern of a bird's colors as being perfectly symmetrical. A closer look shows subtle differences, just like a human face. I wonder if these patterns help them to recognize their mates during breeding season.

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By the way, common mergansers are cavity nesters. Since they cannot create their own holes in trees they must search for those created by others. They are one of the dozens of creatures who depend primarily on pileated woodpeckers for dry, spacious nesting sites. In turn woodpeckers depend on us to leave dead, standing nature trees which they can easily excavate to find food and create the cavities which they ultimately leave behind for others. 

A squirrel taking shelter in an abandoned flicker nest in a dead cottonwood on Foster Island.

The preferred trees for woodpeckers, at least around Union Bay, are alder, cottonwood and willow. From a human perspective these are softwood trees which are not highly valued. However, every one of these dead trees which we leave standing - especially near water - makes life around Union Bay richer by increasing the reproduction of birds and other wildlife.

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The larger splash on the left may indicate that the merganser is making a steering adjustment to chase after a fish.

If we had the time, equipment and inclination we could analyze the diving splashes of mergansers. I suspect the angle and size of the splash may indicate the direction and speed of the diving bird.

All of these photos were taken at the east end of Montlake Cut.

I counted more the two dozen mergansers in the area. It seems to me that they settle in around the entrance to Union Bay every winter. I suspect that Montlake Cut provides a bottle neck which increases the density of fish and makes their feeding more efficient. 

Since I cannot supply you with flamingo photos from Union Bay, I will end this Thanksgiving weekend post with a final pinkish merganser photo.


I hope you had a Happy Thanksgiving! 

Larry