Aging Eagles

Yesterday, this bald eagle sat in a cottonwood just north of the Waterfront Activity Center (WAC). Its beak is turning yellow, its irises have lightened up, there is white showing on its head. This set of colors does not mean the eagle is over-the-hill and in need of an aerial, skywalker.

In fact, this is a relatively immature bird - in its third year. It is making progress, however it still has many feathers to replace before it reaches maturity. This combination of feather colors and especially its dark 'eye stripe', indicates the bird's age. Bald eagles can live into their thirties, so a three year old is quite young.

The eagle silently took notice of a raccoon crossing the dock below, before it refocused on the coots, wigeons and gadwalls feeding just offshore. The raccoon was favoring its right hind foot. Since it was only using three legs, Tripod, seemed like an appropriate name. Its appearance was only superior to the eagle in one area - its well defined eyestripe. (In the case of raccoons I do not think the eyestripe is much of an indication of age.)

Tripod swam to the little island directly offshore. After a brief foray Tripod swam to the next island to the north and then the next one after that. Given that Tripod is easily identifiable it should be easy for us to track him-or-her as s/he wanders around Union Bay. In particular, we may want to report Tripod to an animal shelter if s/he begins to look thin and in need of help.

The only vocalization from the bald eagle was when another eagle approached. The loud, angry sounding call, seemed to say, 'This is my spot. Don't even think about slowing down!' The second eagle's steady wingbeats took it directly overhead and then north in the direction of the cormorants, which are almost always stationed above the UW baseball field. 

While I was distracted by the raccoon the first eagle silently took flight. When I looked up a moment later it was no where to be found.

This older photo, from Hood Canal, shows a bald eagle in its fourth year - almost mature. The eyestripe is basically gone the white feathers on the body have been mostly replaced. Notice the variation in the brown body feathers. The darker feathers have spent less time exposed to sunshine, weather and rain, while the light brown feathers have slowly faded from exposure and age. On the head and tail the inverse is true. The older, darker feathers are being replaced by the white feathers which will ultimately indicate the bird's maturity.

On Tuesday, I saw five young bald eagles sitting around Union Bay. This third year eagle, and another very much like it, were watching from the cottonwoods above the totem pole on the southeast corner of Montlake Cut.

Another young eagle bird was stationed in the tree on the north end of Foster Island, apparently, unconcerned by the construction work.

North of the WAC this first year bird was 'sharing' the cottonwood trees with a second year bird. It was sharing in the sense that it had a great view of the empty asphalt roadway between the Dempsy Center and the cottonwood trees. First year eagles have mostly dark beaks, dark eyes and mostly dark feathers. If you would like to see more in-depth coverage of a first year eagle - Click Here!

The second year bird had the more favorable shoreside seating.

It would occasionally take off from its prime waterfront location and inspect the ducks who were feeding below.

Curiously, just after it took off it seemed to slow up and turn vertically in the air. The only time I remember seeing eagles do this type of maneuver is when they are interacting with another bird, which usually is trying to attack them.

In this case there were no other birds nearby. My best guess is the eagle was watching another bald eagle far in the distance and maybe 'over-reacting' to some threatening behavior.

In any case, the young bird soon resumed normal flight. In addition to the multitude of white body and wing feathers this eagle also displayed some additional characteristics which are unique to a second year bird. Do you see the clues?

Whatever was bothering the eagle was momentarily forgotten as it passed over the ducks. It appeared to refocus on the concept of lunch.

Not seeing any opportunities to its liking the eagle began to return to the cottonwoods.

This close up of the eagle's right wing shows a number of interesting features. For instance if you look at the last half-a-dozen primary feathers, e.g. the feathers at the tip of the wing, you can see that they are notched. The bottom half of each feather is wider while the extended portion of each feather seems to suddenly shrink. This creates a finger-like look and provides the eagles with the means to fine tune their control of lift and airspeed.

The feathers which indicate the bird's age are related to the length of some of the other wing feathers. Eagles are so large and have so many feathers it takes them a couple of years to replace all of them. Curiously, their first year feathers are the longest set of feathers they ever own. Possibly, the extra length helps when they are first learning to fly.

In this case, you can see two light brown feathers and five white speckled wing feathers which are visibly longer than the newer, darker feathers. By the end of the eagle's second year all of the longer first year feathers will be gone. For this reason the uneven trailing edge of its wing's is indicative of an eagle in its second year.

Both wings have a similar look although the number of older feathers on each wing does not appear to be consistent.

The young eagle returned to its prime real estate and continued to be highly observant.  My best guess is it was worried about a mature eagle showing up and sending it on its way,

Perhaps this idea was inspired by one of the adult bald eagles which chased the young eagle out of the Foster Island cottonwood tree. The young eagle is just below the tree line about half between the tree and the crane on the left side of the photo.

Once a bald eagle reaches maturity, around age 5, there is no longer any visual means to determine their age. This November photo from Foster Island is most likely Eva or Albert from the Broadmoor nest or possibly one of the adult eagles from the nest just north of Yesler Swamp.

Update:   (1/30/2017)

Yesterday, while birding on Vashon Island, a member of our class pointed out an interesting immature bald eagle. Thank you, Lynne! The bald eagle was not a precise fit for any of the examples I have given in the post. Like the eagle at the beginning of this post it had light colored irises, however unlike my first example the bald eagle which we encountered had a completely mature looking yellow bill and a head which was nearly perfectly white - except for an eyestripe. The eyestripe was getting lighter at both ends and Master Birder Penny Rose stated that this particular bird was most likely a fourth-year eagle. Penny went on to explain that there can be individual variations in the manner in which eagle's mature.

Clearly, to some degree, bald eagles can mature at different speeds and in their own individual way - just like humans. Please use the examples given in this post as a rule of thumb. Don't forget to examine each individual eagle carefully, be aware that variations are possible and always be open to seeing something you have never seen before. Thank you, Penny!

Have great day on Union Bay...where the eagles are aging right before our eyes.

Larry

Going Native:

Without a functional Environmental Protection Agency, each of us will need to be even more vigilant in protecting our local environments. Native plants and trees encourage the largest diversity of lifeforms because of their long intertwined history with local creatures. I have been told that even the microbes in the soil are native to each local landscape. My hope is that we can inspire ourselves, our neighbors and local businesses to plant native at every opportunity. (Does anyone know who we should contact to inspire the use native shrubs and plants at the next Light Rail Station?)

My intention is to include at least one photo each week and visually challenge us to know the difference between native and non-native lifeforms. Here is a simple start:

What trees do these cones come from and which are native to the Pacific Northwest?

One of the most useful documents I have found is:

Native Plants for the Lively Garden in Puget Sound Country

Following the link will bring you to a printable, online copy of the information. This wonderful document was written by Russell Link and is provided via the Seattle Audubon Society (SAS). Thank you to both Russell and SAS. 

The Answers:

The clump of cones on the left are from a native Red Alder. These trees take nitrogen from the air and convert it so it can be used in the soil. They make the soil healthier for a wide variety of plants. 

Also, the only trees I have seen our local pileated woodpeckers nesting in have been Red Alder. Large old alders decompose nicely and provide the perfect fit for these wonderful birds. In turn the pileated woodpeckers provide holes, homes and nests, for dozens of native creatures who are unable to excavate their own sites. Each year we need a new set of alders planted somewhere around Union Bay to insure future pileated woodpecker nesting sites.

The cone in the center is from a native Douglas Fir tree. The Douglas Fir is the most common tree in the Pacific Northwest. It is hard to spend much time under a mature Douglas Fir without seeing multiple native birds and creatures searching the tree for food.

The cone on the right is from a Giant Sequoia. The trees are wonderful and the wood is very durable - however they are native to California where they fit very nicely with the local flora and fauna.

A Full Circle

The eyelid and the nictitating membrane both partially close just prior to the bill impacting the tree.

While rereading last week's post, I began to question whether the male pileated woodpecker was really the young male, Squall, or his father, Chip. I was also curious where the woodpecker was roosting, e.g. spending his night's. 

On Sunday afternoon, I returned to Foster Island in hopes of finding the woodpecker and possibly his roost. Luckily, he was there. The first photo (from last Sunday) made me confident I was looking at the same bird, especially when compared with the next photo which was from the preceding Friday. 

In both photos we can see a faint supercilium, the thin white line starting above and in front of the eye. It gets thicker behind the eye and then recedes toward the back of the head. Also, consistent in both photos is the dark little notch, which hangs down from the back portion of the black eyestripe, just below the far end of the supercilium. Clearly, we are looking at the same bird in both photos, but I was still uncertain whether it was Chip or Squall.

Hoping to see the bird return to its roost for the night I follow it around the north end of the island for a couple of hours. At 4:20 p.m., just before sunset, the bird flew to a nearby tree. The tree was taller than the one where he had been feeding. He purposefully climbed the tree and immediately took off from the top. Evidently climbing requires less energy than flying to the same height. He headed off in a straight line, flying south and slightly west and apparently leaving Foster Island. Last Winter, I observed a male pileated flying a similar trajectory. At the time I was further south, along the shore of Duck Bay and it was also just before sunset. In both cases the male birds appeared to be heading towards the nest site where Chip, and his mate Storm, would raise Squall and his two sisters in the Spring of 2016. 

Early on Monday, I returned to the north end of Foster Island and found the same bird again. During this visit he worked his way down and searched for food below these two conks. The location on the tree was low enough that I realized I could determine the bird's length, if I returned with a tape measure.

On Tuesday, I photographed the site and compared the results. I estimated the size of the bird at fourteen inches. I have read from multiple sources that male pileated woodpeckers can reach up to nineteen inches in length, however individual sizes can vary significantly. The small size seemed to reinforce the idea that this might be the younger of the two males. 

Sadly, at this time I did not spot any pileated woodpeckers in the area. I searched most of Foster Island and when the rain began in ernest, I packed up the camera and headed for home.

Just as I neared the walking bridge on the southwest side of Foster Island I heard a pileated call. Much to my surprise I found what was clearly the same male pileated woodpecker. He was hanging on the stump of the dead tree which held Storm's 2016 winter roost.

In November of 2015 Storm, who I ultimately learned was Chip's mate, excavated a northern flicker's nest. I had watched the flicker build the initial nest earlier in the year. Storm  made the abandoned nest large enough that she could spend her nights there. This roost worked fine until February 2016 when a windstorm broke the top off of the tree. The break happened right where Storm had weakened the tree by enlarging the hole. The tree top landed in the canal below. I call this area Cottonwood Downs since the surrounding cottonwoods, usually killed by local beavers, often fall and end up in the canal.

In November of 2015, long before his son Squall was hatched or conceived, Chip came and inspected Storm's winter roosting spot. Imagine my surprise when I pulled up this old photo. I immediately compared Chip's features with the male bird I have been watching for the last few days. The supercilium and the eyestripe notch were consistent. At this point it became obvious that the little fourteen inch bird must be Chip, not Squall.

All of the above photos of Chip have been from the left side. I included this photo from the right side (also from November 2015) to show that the distinctive features are similar on both sides.

Having started on this adventure of researching and comparing pileated features in old photos I decided to continue through 2016. This would help me to be sure that Squall's features are different from his father's.

In February 2016, Chip and Storm feed on a fallen cottonwood southeast of Foster Island.

This close up of Storm, from March of 2016, shows a faint supercilium, which starts and ends behind her eyes. It also displays the red color of one of her irises. Storm's 'black' forehead and malar stripe are common distinctive features for female pileated woodpeckers. In mature males both of these areas are bright red.

This photo shows Chip and Storm mating in early April of 2016. This took place to the west of Duck Bay. This photo shows that Storm is smaller than Chip, which is normal among pileated woodpeckers. Given that Chip is only fourteen inches long, I suspect Storm may be just twelve inches in length.

In early May, this photo shows Storm feeding one of her young in the nest. The young bird's grey malar stripe, which will ultimately turn black like Storm's, denotes that she is a female. 

Here Storm is regurgitating food for her young nestlings. I suspect the young birds are about a week and half old at this point and that the eggs were initially laid in mid-April.

Chip provides a later feeding on the same day. Here we see that there are three young birds. Their faint but obvious coloring shows them to be two females and a male. The male was so noisy and insistent that I decided to call him, Squall.

Five days later, around mid-May, the colors of the young birds have visibly darkened. Their young feathers are short but obvious. Even at this early point Squall's supercilium is shaped differently from Chip's. Squall has a small white arc which is positioned behind his eye.

This photo and the following were taken on May 31st, just after Squall fledged. For pileated woodpeckers learning to fly and leaving the nest seems to happen all at once. Once they escape the nesting tree they seem to have no problem with living outside the box. 

Although, I do remember laughing when I watched Squall trying to land on this paved surface. I suspect it was his first landing on a manmade surface which he could not grip with his claws. He landed on his belly and then struggled to get up on his feet.

Squall's supercilium is not precisely the same on both sides, but in both cases it stays behind the eye, unlike Chip's. The irises of the young bird are actually a grey-blue color but it can be hard to see them clearly in shaded photos. While studying Squall's unique features I began to wonder whether they might change as he matured.

This link to the post called, Family Time, shows more photos of the young birds and contains links to other related historical posts about Storm.

In early June, I found Squall working on a telephone pole in Montlake. At the same time, Chip was working on a second pole a block and a half to the south.

In these photos Squall's supercilium remains consistent and distinctive. Did you notice his tongue searching inside the telephone pole?

Later in the same day, Chip posed for photos from both the left and... 

...the right. The dark descending little bump on the lower back portion of his eyestripe is obvious in both photos. Also, at this point his bright yellow irises are still quite different from Chip's. These photos were taken near Elderberry Island just to the west of Duck Bay.

Towards the end of the month, on June 26th, Chip is still supplementing Squall's food supply. At this point, the young bird's 'red' coloring is still slightly orange and not as brilliant as his father's crest.

On July 8th, one of Squall's sisters still has dark eyes and her crown has also not yet reached its full flaming potential.

 On July 13th, one of the sisters displays her ability to help the forest recycle itself.

She is looking more and more like Storm.

However, when we see Storm with the sister in the background there is a noticeable difference in the color of their crests.

This August 9th photo of Squall is one of the last set of photos I have of him. His iris is starting to turn yellow, like Chip's, but if you zoom in close you can see that the outside of the iris is still dark in color. Also, you can see his supercilium is clearly behind his eye.

In November, I saw Chip, and Storm, high in the top of a dead snag. They were just to the northeast of the Wilcox Bridge in the Arboretum. 

Based on what I have just read in Birds of North America (see Citation below) it is logical to assume that the young birds had already moved on. The scientists say that starting in the Fall the young leave their parents and begin wandering. By Spring, they will be looking for their own territories and mates.

On Tuesday afternoon, I watched Chip leave the remains of Storm's old roost and fly east above the Cottonwood Down canal. He called repeatedly as he moved from tree to tree. 

Finally, from out of the rain, came an answering call and Storm flew in from the direction of the Beaver Lodge Sanctuary. After feeding nearby the two birds turned and headed west.

They returned to the old half-a-snag which was Storm's primary roost last winter. Storm was much more active and moved around from one tree to the next, feeding voraciously. Chip sat calmly, watching from the top of the broken snag. Due to the poor light and I was unable to see Storm's red eyes, but her other features and her behavior, along with what I read on Bird's of North America, ultimately made me positive this must be Storm.

These last two photos show her 'shivering' in the rain. I suspect this behavior is actually an attempt to get more air between her feathers to help her stay warm.

Having skimmed through the last fifteen months of Chip and Storm's lives and having ended up back at the tree where we started does make me feel like the story has come full circle. I still do not know where Chip and Storm are roosting - which provides a mystery I hope to solve in a future post.

Have a great day on Union Bay...where pileated woodpeckers live in the city!

Larry

Recommended Citation

Bull, Evelyn L. and Jerome A. Jackson. (2011). Pileated Woodpecker (Dryocopus pileatus), The Birds of North America (P. G. Rodewald, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America: https://birdsna.org/Species-Account/bna/species/pilwoo

DOI: 10.2173/bna.148