All About Tsulos, The Small White Eaglet

Here is a recent post from the Union Bay Watch Blog published by Larry Hubbell, long-time local photographer and birder.

Out On A Limb

This July 9th, 2020 photo proves Tsuloss has begun branching.

It is hard to believe this small white eaglet, photographed on April 26th, is the same bird. She has probably replaced every feather on her body, gained close to ten pounds, increased her wingspan by close to six feet, and done it all in less than three months.

On July 3rd, Tsuloss was focused on feather cleaning and alignment. Her eaglet down appeared to be gone but her new feathers still needed to be aligned to maximize lift as she begins preparations for her first flight. 

Sadly, I am not certain of Tsuloss' gender. However, female Bald Eagles are usually larger than their mates. (This distinction is primarily useful when you see two adult birds side by side.) Nonetheless, Tsuloss' size is impressive. I am guessing, she is a female.

Possibly because of the weight difference, juvenile females are slower to develop than males. If we estimate Tsuloss was ten days old when first photographed, that would make her 92 days old as of July 17th. All About Birds estimates the nestling period is 56 to 98 days. This implies that Tsuloss should learn to fly within the next week. If you are planning a visit to see her in the nest - the sooner the better! 

The nest is located on the southeast corner of Montlake Cut. You do not need to worry about disturbing her. I suspect the nearby sewer replacement, highway construction, and the constant flow of boats through Montlake Cut has thoroughly acclimated her to humans and noise.

However, when it comes to taking her first flight she does seem to be behind schedule. Which might be another reason to assume she is female. Larger birds need extra time to reach their full size and potential. In this July 6th photo, she apparently just walked out on the easily accessed northern limb, attached at the same height as the nest.

On July 8th, she walked a bit further. When Monty returned to the nest, possibly with food, she did not fly (or even walk) over to investigate.

The parents no longer need to be constantly near the nest to protect her. Tsuloss' new feathers can handle the elements just fine.

Plus, with her fully-grown talons and bill, she could probably handle most predators as well. I suspect any predators capable of reaching the nest, will wish they hadn't.

I am often asked how to tell the difference between a young Bald Eagle and a Golden Eagle. One easy difference is that Golden Eagles have feathers covering their complete tarsus. In this photo, we can see the feathering near the lower portion of a Tsuloss' tarsus looks a lot like 'high-water' pants revealing an exposed ankle.

Also, as far as I know, Golden Eagles don't reside in cities.

On July 9th, as in our initial photo, we see Tsuloss spreading her wings. However, this appeared to be mostly a response to the wind and not a part of a consistent exercise regime.

As impressive as her wingspan and feather development is, she needs to be regularly working the wings to develop muscle strength. While I have not been at the nest around the clock, I still have not seen her flapping her wings with the expected consistency required to develop flight strength.

This July 11th photo, shows her still walking on the northern 'easy-access' branch.

On the positive side, when she reached the end of the flat portion of the branch she flew-hopped approximately two feet up onto the outer portion of the branch, where she could watch the boats passing through Montlake Cut.

This week, Tsuloss has finally taken the next step in the process. She has moved out to a westward pointing branch. I have watched her fly-hop from the branch back to the nest. She kind of scrambles into the nest, which may tend to pull it apart. Hopefully, her flight skills improve rapidly.

Earlier this week, after she returned to the nest she hurried out onto the northern branch. She was apparently trying to get a better look at Monty, who flew in and landed in a tree at the east end of the nesting grove. She was probably hoping for food delivery.

Now is an important time for all of us to be watching out for Tsuloss. At this point, if she leaves the nest I suspect at best she might glide to the ground. Even if she lands safely, I doubt she would have the strength to return to the nest. It is also possible she could easily be injured coming down. From what I have read, leaving the nest may be the most dangerous moment in an eagles life.

I would rather see her spend the next few weeks constantly flapping her wings and learning to move about in the nesting tree. 

Exploring the upper branches would give her multiple opportunities to practice short flights, precise landings, and functional takeoffs. Even though the branch to the west requires a small flight-hop, it is still at almost exactly the same height as the nest, and not enough of a challenge. I believe, she needs to work her way higher in the tree to properly develop her skills.

It also would not be surprising for her to remove some small branches and leaves, so she has room to extend her wings and practice. Over many more years, the Bald Eagles in Broadmoor have nearly denuded the tree above their nest.