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Thursday, April 16, 2015

Masters of Deception

This photo provides a profile view of the master of deception, as well as, its shadow.

When guiding a twig down the entry to its nesting site, our little master blends into the bark of the big-leaf maple. To be fair, the bird is likely a mistress of deception, since females do the majority of the nest building, according to All About Birds.

Here, the bird is entering the nest, while clouds are casting shadows on the maple. 
When vulnerable to unseen attacks, its camouflage helps hide it from predators.

In the crisp morning light, an extended wing makes our bird only slightly more discernible. If you easily found our "master of deception" in these first fours photos, try backing away. The real, naked-eye experience is similar to leaving five or six feet between you and your screen.  

Surprisingly, in the right light and at the right angle, our little bird is much easier to see.

Although where it hid its tail in this photo mystifies me.

Normally, our little bird uses its tail like the third leg of a tripod. The additional support and stabilization is vital when climbing a tree and searching the cracks and crevices for food.  

The tail is also helpful when bringing back brittle and dry douglas fir twigs to construct the base of its nest.

With larger twigs, sometimes the wings provide a power-assist. The burnt-orange of its rump offers an unexpected flash of color.

Guiding large twigs down the entry chute can be challenging.

 Bringing back two short twigs instead, might seem easier.

However feeding them both into the nest at once requires focus and attention as well.

Here, our little bird procures a scrap from the scaly bark of a pacific madrona tree.

It is interesting how the same piece of bark appears lightly colored in direct sunlight while…

…looking very dark when the shaded, underside is exposed.

This reminds me of our bird's two-tone coloring. I suspect its white tummy serves a similar purpose as the pale white on the underside of a fish. When either creature is back-lit by the sun, e.g. when prey looks up at it, the light-white color is difficult to perceive. The two-tone coloring means our bird is a master of deception as both predator and prey.

Once the framework for the nest is in place, the bird brings back progressively softer material.

This looks like a load of soft shredded bark, pulled from the exposed cambium layer of a living tree or shrub.

The light-colored lichen on the tip of the bird's beak is only faintly visible while...

…this slightly more apparent load looks like spider-silk to help hold the nest together.

All About Birds provided this eloquent description of our Master of Deception, written by W. M. Tyler,

"The Brown Creeper, as he hitches along the bole of a tree, looks like a fragment of detached bark that is defying the law of gravitation by moving upward over the trunk, and as he flies off to another tree he resembles a little dry leaf blown about by the wind."

The creeper always flies from the top of one tree to a lower point on the next tree. Then, upon arrival it climbs back up, searching for food as it ascends. The same climbing approach is used every time the bird approachs the nest as well.

Creeper nests are normally built between the bark and the heartwood of a tree. When a tree or a branch dies the living cambium layer dries out. In our forests, it is usually the dead big-leaf maple trees that end up with the largest separation between the bark and the tree. 

Even though the creeper can be difficult to see, they are common in forested areas from Alaska to Mexico and from the Pacific to the Atlantic. These photos were all taken in the Arboretum, during the last two weeks.

Have a great day near Union Bay…where masters of deception live in the city!


Pygmy Owl Update:

By the way this humorous photo from last week was given the following "Most Unique" award by birdfeeder.com.

Cooper's Hawk Update:

Last week Martin Muller, a local cooper's hawk expert, sent the following email to correct a couple of the assumptions I made in the late-March post titled, The Mating Game. I found Mr. Muller's comments highly instructive and with his approval I am sharing his thoughts and photos so that we can all learn together. Thank you to Martin Muller!


I really enjoy your excellent photos and stories!

The Coop images are fantastic. Nice Work!

However (and you knew this was coming, right?), there are a few statements in captions that are not quite accurate. I didn't want to start "lecturing" on your blog, the issues aren't that important. It's just that as a teacher (at least trained as one) I can't pass up the opportunity to share some knowledge….

In one caption in the copulation series you write: "The orange-coloring on the male's chest shows he is older and more mature. In this case, maybe because the females younger, the size difference is not obvious."

I think the size difference between the male and the female is not very obvious in the picture because of the angle and the different postures. Because these birds are pretty much full-grown a month or so after leaving the nest, at this time of year (spring), the immature should be pretty much the same size as the adult (of the same sex). However, there is one difference in measurements between immature-plumaged and adult-plumaged birds. The tail of the immatures is greater than that of adults. According to The Birds of North America account juvenile male tails =190 mm (n = 194) while adult male tails = 181 mm (n = 128). For juvenile female the tail measures 214 mm (n=286) and adult females 209 mm (n=285). So after the juvenile tail feather is dropped a slightly shorter adult feather replaces it.
Wings are almost identical in adult and juvenile of the same sex.
Because the tail is very important for maneuverability in flight the slightly bigger tail for the juvenile may give an advantage here. But that's just speculation on my part.

In Bald Eagles you have seen this phenomenon, that immature birds get longer feathers than the adults of the same sex. You've posted great shots of immature eagles and you can tell that they are less than a year old when you look at the trailing edge of their wings. In immature plumage, before their first (partial) molt, the feathers are all the same length, and the trailing edge is smooth. However, birds that have undergone molt (and these large birds may not replace all wing feathers each year) will show shorter replacement feathers, giving the wing a jagged trailing edge. They "shrink" as they get older!

In Coops this doesn't apply to the wing, but it does hold true for the tail, but because all the flight feathers are replaced each year you don't get to see that "jagged edge" effect.

Second point. You wrote: "He must grasp some of her feathers, hopefully nothing more, to maintain his position." Actually, that is not correct. He will not grasp her feathers (a good thing too, those feathers are her livelihood for a year!) He will actively close his talons, only towards the "jumping off" will he open his talons. Here are two still frames from video I've taken of copulation from a different angle that shows this:

This is during the "height" of copulation. He is maintaining his balance with wing flaps while he actually rests on his heel keeping the feet and toes "up". Note the carefully clasped talons to make sure he will not damage the female's plumage or body. All of courtship is geared towards establishing the bond of trust that is needed to have one predator sit on top of another predator….

This is just before he departs. He slightly opens his talons but will not "grab" which makes his push-off awkward and explains while his feet will often "slip" and make the whole departure clumsy. I think this is similar to thte situation in your shot, where one of his talons shows over her shoulder.

Think about it; these feathers have to last a year. This also explains the endless preening that all birds devote many hours each day to. Preening will keep the feathers in good condition and will remove some of the parasites that may attack the feathers. The running of the feathers through the bill will "zip them back up" after they start showing some gaps after the bird has hit a branch or otherwise has deranged a feather (this goes back to a previous post where you made a statement about eagle feathers with some "gaps" in them, which you thought might be the result of a crow pulling the feather; something I think is a little too far fetched and certainly wouldn't explain why the crow has similar gaps in its feathers).

Okay, I'll get off my soapbox now. Please don't be offended by my late-night "lecture." Again, I have the greatest admiration for your images and blog. Keep up the good work!

Martin Muller

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