Boldly Invisible

A continuation of the discussion in the last post of why black accent or coloration is so widespread, especially in small birds…there are still more questions to answer.

For example, you would think that a boldly striped, black and white animal would be an easy target to spot against the homogeneous green or gold African savanna.

But how many zebra do you actually see here?

Disruptive patterns of black and white break up the outline of an animal’s body, making it difficult to detect them in a complex background.  Maybe this is why a herd of zebra can be referred to as a “dazzle”?

Looking at a single chickadee against a plain white or tan or gray background makes them standout because of their bold black and white markings.

But finding them in their more typical, complex background of myriad tree branchlets and leaves is much more difficult.

How many chickadees hiding in the bushes?  They blend in well with highlights of snow on branches or in the background, deep shade on unlit branches, and the tan of leaves and bark.

Here they are!  Highlighted with a little illumination in Lightroom photo editor.

Birds that live in complex environments like the dappled shade of a forest, or the complex vegetation of a wetland or grassland, often have complex feather patterns (especially dark and light) that more or less blend with their background, or at the least, make them difficult to detect until they move.  Some of the boldest black and white patterns, like the stripes on a Kildeer’s breast, actually distract one’s eye from the outline of the bird’s body.

Until she moves, mama Kildeer isn’t obvious in this marshy wetland. I didn’t even notice her chick standing silently on her right until I was editing the photo for a blog post.

Some birds emphasize camouflage even more by combining spots of white or bands of dark and light on their feathers.

A sleeping Barred Owl has pretty good camouflage in this leafless Amur Maple forest.

Stripes down its breast and spots on the wings and back of the Barred Owl help break up the solid outline of its body.

The blotchy brown and white plumage of Brown Creepers lets them hide in plain sight on the rough bark of mature trees where they forage in crevices for prey.

So, one of the answers to why so many birds, especially those residents that live in the northern temperate forests all year, adopt splotchy patterns of black or brown and white plumage is that they maximize their ability to hide in plain sight by being boldly invisible.

Old friends in new places

Cave Creek ranch in the Chiricahua mountains near the New Mexico border is an idyllic haven for birders and hikers.  The scenery is pretty incredible too.

The view from my porch looks out over the creek and up into the rocks.

We’re set for an early morning hike up Cave Creek, to see if we can find some new birds we haven’t seen before.

Like the creek in Madera Canyon, sycamores line the banks of Cave Creek, stretching their limbs far and wide to create wonderful shade.

Sycamores can grow to be giants, but occasionally a limb snaps off, and we find animals taking advantage of the nook created by the amputated limb.

This Great Horned Owl created a nest cavity in one of the huge clefts left after a limb dropped.  We also found a western Screech Owl seeking refuge during the daytime in a similar cavity in another sycamore.

Desert animals are often pale in comparison to others of their kind in other climates, as this Great Horned Owl is.  But there is more to the story than just differences in color.

Animals in this part of the U.S. seem to be entirely different geographic races of their parent species, and the extent of differences in their DNA, their color, their song, and their behavior have led scientists to begin splitting the southwestern desert species off from their representatives in other parts of the U.S. and Mexico.  That’s great for birders that like adding species to their life lists!

The white-tailed deer are much smaller than their relatives in my backyard in MN. In fact, they are technically known as Coue’s white-tailed deer, a dwarfed race, or is it a different species?

Here’s a familiar bird, a male Hairy Woodpecker, but it looks quite different from the MN variety, as it lacks the spots on the wings, and has a broad white stripe down its back.  Would a MN female Hairy Woodpecker refuse to mate with this bird?  If so, then they would be considered separate species.

Brown Creepers have been divided into four groups now, one in Mexico, and three others in the U.S. divided into eastern, Rocky Mt, and Pacific races.  Differences in song and plumage have been known for some time, but recent DNA analysis has confirmed the separations.

We met some new friends along the Cave Creek trail, but apparently our “old friends” may be new as well.

Crypsis

Recently, I wrote a post about hiding in plain sight, but today I saw a much better example of this type of camouflage when a little Brown Creeper visited the Buckeye tree outside my sun porch window.

The Brown Creeper’s white breast feathers resemble the snow that still clings to some of the branches of the tree, and its mottled back feathers blend in perfectly with the bark.

Only slightly more obvious lower down on the tree, the bird spiraled its way up from the base of the tree, while poking into crevices along the way.  I can’t imagine what it could find on a day like this when the temperature was  -12 F (-24 C)

This tiny little bird weighs only half as much as a Chickadee. It’s hard to imagine how they survive the bitter cold winters of the northern Great Plains.  I assume they do find some little critters in the cracks and crevices of the trees they explore. Eating just one tiny spider will sustain them for another few hours of foraging.

One naturalist wrote about them:  “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.”  Which is exactly what I saw today.

A little creeper

A rarely seen bird (for me) was hunting insects or spiders on a live oak, and I stopped to watch while it foraged.

Brown Creepers (Certhia americana) are cryptically colored small bits of fluff that spiral up and around the trunk ad branches of a tree, continuously moving, in and out of shade and sun, stopping only for a fraction of a second to explore tiny crevices for their hidden prey.

The Cornell Lab of Ornithology website has a great quote that summarizes the peculiarities of this tiny bird wonderfully:

“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.”

Part Woodpecker, part Nuthatch in behavior, they have their own unique style and anatomy.

Their stiff tail feathers prop them up on the tree bark, and their very elongated big toe (hallux) opposes the other three toes to help stabilize them vertically.  The slightly decurved bill is useful for probing into miniscule cracks in the bark of the trees.

Brown Creepers are actually fairly common and year-round residents over much of the U.S. (except the Great Plains) and western Canada, but are rarely seen because they are so cryptic and so quiet.  Spotting what looks like a piece of bark moving in a jerky spurts upward around a tree trunk might lead to sighting one of these cute little brown jobs.

Blending into the bark on which it forages is a good survival strategy.

Note:  I’m back in the deep freeze of Minnesota now, where the temperature was -21 F (-30 C, not counting whatever windchill factor decreased the temperature even more) the night I arrived, an 85 degree difference from the sunny California weather a few hours before.   The Minneapolis paper headline read:  “Brrrrrutal” the next day.