Color me green, or gray, or brown…

Gray Treefrog, Hyla versicolor

The ever-changeable, Gray Treefrog.  How does it do it?

Green is a popular color for frogs, and birds too, but that lovely green color doesn’t come from a green pigment as you might expect, but from the interaction of multiple layers of specialized color and light-reflecting cells in the upper layers of their skin.

Frogs have three layers of chromatophores (color-producing cells) in their skin. The deepest layer are melanophores that produce melanin pigment giving skin a brown to black color. The middle layer are iridiphores which contain no pigment but instead have mirror like plates capable of producing iridescence, or when viewed from a certain angle, reflect blue light. The most superficial layer of chromatophores are xanthophores that contain a yellow pigment.  When the middle layer of iridophores interact with the top layer of yellow-pigment containing xanthophores, you get what elementary school students have learned:  yellow paint + blue paint = green color.

gray treefrog color

A closeup look at the skin of Gray Treefrogs reveals a mottled pattern of color — the result of different stimuli to those color producing cells in the skin.

Animals that change their skin color (like some frogs and reptiles) not only can change the shape and size of the chromatophore but the dispersion of the pigment within the cells.  Thus, tightly contracted chromatophores with no dispersion of pigment might appear white, and the opposite pattern would look black. Moderate dispersion of melanin pigment in the deepest layer of chromatophores looks gray. Dispersion of pigment in the xanthophores coupled with dispersion of light-reflecting particles in the iridophores produces variation of yellow, blue, and green colors in the skin.  Combination of all of the above produces the mottled pattern of coloration the animal uses to blend in with its background — a protective camouflage.

gray treefrog color-closeup

An even closer, close-up look at the skin of the Gray Treefrog.

Color change seems to be temperature dependent:  warmer frogs are lighter in color to reflect incident light; darker frogs are generally cooler and the darker skin helps them absorb heat.  Skin color becomes lighter when these frogs are placed on a brighter background, and darker when placed on a dark background.  This color matching is part of the effective camouflage protection.  And lastly color change may reflect the mood of the animal — e.g., sexual display, territorial display, etc.  The stimulus for all of this change begins in the brain, is transmitted by hormones, and carried out by the actions of the chromatophores — all in a matter of seconds to minutes.

A really detailed and fascinating discussion of how color change is achieved in animals (in this case a Chameleon) is shown below.

Hiding in plain sight

The weather at this time of year, with its gray overcast and monotonous gray, brown, and white color scheme, is perfect for hiding wildlife in plain sight — at least from my eyes.  Animals that would stand out against a green summer background disappear into the landscape, and I’ll use that as an excuse for why my posts have been so infrequent of late. A few examples:


There is an owl shown roosting in the middle of this photo — but it might go completely unnoticed by the casual passerby.

barred-owl-sleeping in the daytime

With the telephoto, you can see this Barred Owl much better.  Its mottled plumage on wings and back and stripes on its breast helps it blend into the background until you get right up close to it.  An example of disruptive camouflage that is so effective in hiding in plain sight.

ruffed grouse female

A female Ruffed Grouse foraging along the roadside in the spring is highly obvious.

A male Ruffed Grouse drumming to attract attention in the fall stays hidden (left center) in the fall leaf litter and twigs.  Photo by Laura.

A male Ruffed Grouse drumming to attract attention in the fall stays hidden (left center) in the fall leaf litter and twigs. Photo by Laura.


Standing like statues when they hear or see you coming, the gray-brown winter fur of White-tailed deer camouflages them well in the woods.  Unless they wave their white flag tails at me, I might never notice they were there.

deer camouflage

Even in the summer and fall, deer can remain hidden in plain sight in tall prairie grass. I copied the image on the left into the original photo to illustrate how well the rusty brown summer fur coat blends into the background.

It isn’t just the prey species that utilize camouflage effectively — predators do too.

great horned owl camouflage

Sitting close to the branches of an oak, Great Horned Owl plumage blends in not only with the bark but the color of the fall leaves as well.  Sitting quietly, they might hope to avoid the harassment from a wandering pack of crows.

great horned owlet camouflage

The little owlet, however, is vulnerable to predation and its plumage matches the branches it sits on extremely well.

coyote in winter

The mottled coloration of Coyote fur stands out against snow, but blends in well when the animal is stalking prey through the yellow-brown vegetation in the winter.


Letting that snow accumulate on top of its dense fur, however, is a great way to hide in plain sight during the winter.

If camouflage is such a great way to remain hidden, then how do some animals get away with flagrantly advertising their presence?  But that’s the subject of a different post.