Friday, June 19, 2020

All About Owlets

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

Here also is an in-depth article about Larry and his work.

Owlets and the Art of Feather Maintenance

There are very few birds as confident (and competent) as a Barred Owl. 

A Bald Eagle is far larger and stronger but they will seldom sit and look you in the eye. (The post, Tsuloss, from two weeks ago provides an excellent example of how quickly a Bald Eagle retires from close proximity.)

I have no doubt that Barred Owls know humans cannot fly. They must also know humans can be dangerous, otherwise, they would just completely ignore us. To be honest, for the most part, this owl did ignore me. It flew my direction, landed, and checked me out, watched some smaller birds, and then headed back towards the family unit.

By the way, I do not believe its raised right 'eyebrow' is a look of curiosity. I have yet to see a Barred Owl photo where the right upper portion of the facial disk was not higher than the left. I suspect the lack of symmetry is correlated to their offset ear holes and a species-wide attribute. Hearing sounds from different heights enables them to pinpoint prey positions by sound as well as sight.

If I had not seen the owl's return flight, I might never have noticed its mate and one of their young in the top of a Big Leaf Maple tree. 

During the first month or two after a young owl leaves the nest, their primary occupation appears to be feather maintenance. This young owl still has bushy tufts of down around its tail and a partial covering on its back and head. Over time, one way or another, the down must go - whether it is pulled, plucked, or pushed out by more durable feathers.

These first few photos were taken last month in Interlaken Park.

When we think of feathers this is the first shape that comes to mind. In this case, this is a flight feather from an American Coot. Flight feathers (and tail feathers) are the largest and most easily recognized feathers on a bird's body. However, they are not the most common way in which we encounter feathersWe are far more likely to sleep with our heads on a pillow filled with down while warming ourselves with a down comforter. 

While this owl feather resembles down near the base, overall it is more similar to a contour feather e.g. the feathers we see covering a bird's body. The ends of contour feathers are exposed to the elements while the 'downy', insulating portion is covered by the tip of another contour feather. I spotted this feather near a young Barred Owl which explains why even the outer portion does not bind tightly together. A young owl's initial feathers are more about growing in quickly and providing warmth, e.g. loose and downy, rather than maximum protection from the elements.

By the way, in addition to legal requirements, Why should we leave feathers where we find them?  Because every feather left outdoors may become the critical lining in another bird's nest. On a cold stormy day, a single feather could be the difference between a young nestling expiring due to exposure or retaining adequate heat to survive. 

When a young Barred Owl leaves the nest they are still covered with downy feathers, their flight feathers are only partially developed and from what I have seen they are unable to fly.

I suspect this young owl, spotted last week in the Arboretum, has been out of the nest for a few weeks. One hint to its age is the length of its tail. (Another hint was watching it take flight.)

This photo from 2018 shows an upside-down owlet on the day it left the nest. I realize it is difficult to make out, it is clinging to a branch with one talon and grasping wildly with the closer one, while its fuzzy little 'tail' is pointed to the left. At this point, it has no normal-looking brown and white striped tail feathers.

When this young Barred Owl stretched, it exposed significant tail feather growth. You can also see it still has a clump of downy feathers on the leading edge of each wing. 

When we zoom in you can see some skinny almost 'wet-looking' feathers just below the downy clumps. These are new feathers that have only partially emerged from their sheaths. I suspect these will become coverts. Coverts are feathers that cover the attaching base portion of other, generally-larger feathers. If so, in this case, they will cover the base of the flight feathers and help create smooth, aerodynamic wings.

I never grow tired of watching an owlet stretch. The display of symmetrical feathering is always impressive even if not yet fully developed 

I do not understand is why the doors on cars, that open in an upward direction, are called gull-wing doors. I am sure gulls can raise their wings in a similar fashion, however, their wings are long and thin and do not resemble automobile doors. I guess from a marketing perspective the phrase 'owl-wing doors' does not have the right ring to it.

This young owl may not yet be able to catch its own prey but its predatory heritage is not in doubt. This close up also provides an interesting view of the downy-looking feathers.

The owl is stretching its leg while preening, which shows off its talon development.

When the young owl leaves the nest, even though it cannot fly, it can climb trees using its strong talons and its bill to hitch its way up. This is critical because if they were stuck on the ground raccoons, coyotes, and even family dogs could be threats.

Here, if you look closely, you can see a feather sliding through its bill. Even though I saw the owl preening and pulling at its feathers I did not see clouds of small feathers drifting to the ground. It would certainly be interesting to have a non-stop video of an owlet's first few months just to determine at what point(s) they lose these downy feathers.

The only thing cuter than a young Barred Owl is...

...two of them.

Once the tail feathers have begun to fill in the young owls start to look more mature, at least from the backside. Here the bird on the right is facing away from the camera while straightening some of its new tail feathers.

When the feather slides out of its bill the tail 'pops' back into position.

When I first saw these two owls they were not sitting side by side. One was facing me and the other was overhead with its tail feathers hanging down below the branch. Based on just the tail feathers, I initially thought the second owlet was an adult. However, when viewed side by side and facing me it was obvious they were both quite young.

Allopreening is when one bird cleans or preens the feathers of another. It is typically done around the head or neck - in areas the other bird cannot easily reach. Online information suggests allopreening may help strengthen the bond between mated pairs, reinforce the dominance of one bird over another, reduce stress between two birds, and of course improve cleanliness. 

Since Barred Owls are known to reuse the same nest site for multiple years infestations of feather lice, etc could potentially be an issue. Allopreening may be an evolutionary technique for removing parasites and helping to maintain their good health.

Pileated Woodpeckers take an opposite approach. They appear to never reuse a nest and never do allopreening. Bald Eagles, on the other hand, use nest sites for multiple years. However, they annually add a significant amount of material which may have a positive impact.

I have seen siblings doing this before and I have also watched adults preening their offspring. Barred Owls seem surprisingly social and caring within their family structures. 

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