[CT Birds] A question on cryptic plumage.

kmueller at ntplx.net kmueller at ntplx.net
Wed Feb 27 11:39:39 EST 2013


That's a good topic Paul. This is better answered by an Ornithologist,  
but let me add a short narrative based only on my experiences and  
thoughts. Although a Downy Woodpecker is clearly a bird with what we  
perceive as a strikingly obvious plumage pattern. But maybe in some  
instances though, it is very camouflaged. If you see this bird walking  
up a tree trunk or on your bird feeder in the open or at eye level,  
the pied plumage does stand out to us, but what about a predatory  
bird? Even in the open, the random pied patterns of the Woodpecker  
does create a certain amount of confusion, probably enough to offer a  
window of escape. If you look at this bird in a different location and  
angle, say looking up into the tree branches. The black barring and  
white spotting will replicate the interplay of light and branch  
patterns making the bird virtually disappear.

This sighting Jen and I experienced many years ago, opened my eyes to  
how a seemingly striking and brightly colored bird can escape  
detection from a predator. We were in Costa Rica floating down the Rio  
Sarapiqui on the Caribbean slope. I was studying Keel-billed Toucans  
and this area was a good location for them. The boat ride gave us a  
very private and intimate platform to study the birds in areas where  
the birds were undisturbed. Everyone knows the bright colors and  
plumage of a Keel-billed Toucan: bright green and yellow/green bill  
with an orange patch on the sides of the upper mandible and bright red  
tip. The plumage is basically black with magenta highlights on the  
head, bright yellow cheeks and chest (bib), white upper tail coverts  
and a scarlet red crissum.

We located a few small flocks of the birds (approx 30 birds total)  
along the river. They were roosting in the open branches cluttered  
with epiphytes hanging over the river. Some were enjoying the morning  
sun, others were partially in the shade. Their bright colors stood out  
like a neon light in the sun.

When we got closer, they all scattered into the deeper branches and  
foliage of the trees, but still at eye level. We pulled the boat  
closer to the overhanging trees, and although we could here then  
calling, we couldn't see one of them! The guide kept telling me that  
they were right in front of us at a few meters, but we still couldn't  
see them. At one point the guide (who was smiling a bit) stood behind  
me and ran his outstretched arm right in front of me pointing to a  
small cluster of birds. We still couldn't see them. We could hear them  
and they sounded like they were a few feet in front of us, but no  
luck. Finally one bird moved an it came into focus for us. It was  
amazing how such a brightly colored bird can be so difficult to find  
just because of a little shade.

In the rainforest, there is all kind of shapes and colors being  
augmented by the dabbled light that is allowed to squeeze through the  
canopy. Seemingly brightly colored Green leaves, yellow leaves, red  
flowers and bromileads, etc, can range in colors from their enhanced  
bright shades of color to the severely diffused and darkened values of  
the colors being altered by the shade. To add to the "confusion" if  
you look up, spots of white light peek through the open areas of the  
canopy adding more details to the already confused array of colors,  
shades, shapes and illusion. To evaluate the Toucan as it sits in the  
shadows. The colors of the plumage and bill are also diffused by the  
shade of the recesses of the trees. The bright bills look exactly like  
the dark green shades (and shapes) of the darker leaves. The dark  
yellow bib matches the dying and dead leaf colors and patterns that  
are mixed in with the values of green leaf and vegetation colors. The  
darkened red crissum and bill colors appear brown matching the colors  
of the branches and bark of the tree, and the the white spot of the  
upper tail coverts...just another light spot poking through the canopy.

So if a brightly colored Keel-billed Toucan can vurtually disappear in  
the lush and color intense rainforest, the Downy Woodpecker has a much  
easier job. Our lessons continued on the river with Orange-chinned  
Parakeets. When these large flocks retreated into the shadows,  
honestly, I am still looking for them! This will take some time!

Mother nature is so talented!!


Keith Mueller



Quoting Carrier Graphics <carriergraphics at sbcglobal.net>:

> A question on cryptic plumage.
>
> While looking out at the feeder birds this morning, I saw a neat and  
> trim male
> Downy woodpecker. Then a question came to mind.
>
> Why has evolution given this bird such a contrasting coloration? There is no
> better coloration to be noticed than Black against white. A downey  
> is certainly
> not the best cryptic colored bird out there to deter predation by hawks, and
> certainly not the best in flight to avoid predator attacks, (slow, undulating
> flight) so whats up with that?
>
>
> Hawks it is know have less color vision with the added benefit of better
> perception in movement and contrast – so one would think the Downey  
> is a prime
> prey species for any hawk. Contrasting B&W plumage, with a not so elusive
> flight. So why are their so many Downeys about? Logic would tell us  
> they should
> have been eliminated a long time ago... Any thoughts out there?
>
> Paul Carrier - Harwinton
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