A Pacific Tree Frog showing reddish temporary colors

Another post showed a Pacific Tree Frog (Pseudacris regilla) that had changed color, in 6 hours or so, from chocolate brown to tan. Today, in the same location—on our porch between the wall and a cardboard sixpack beer carrier—we found another (or maybe the same, who knows?) Pacific Tree Frog with distinct reddish color markings.

Frog, red markings IMG_7326.jpg

Here he is, shy fellow, looking out at me.

Frog, looking, red markings IMG_7326.jpg

This is the most common frog in our area, found from British Columbia to Northern California, and up to 11,000 feet in elevation. And they’re noted for color changing, “ranging from unicolor to mottled with greens, tans, reds, grays, browns, or blacks. They have the ability to change from light to dark”.

They’re in the “chorus frog” group.

During breeding season, males will call to attract females. A number of calling males is known as a chorus. A dominant male, or chorus master, leads off the calling which is then followed by subordinate males. If an intruding male comes instead, the Pacific Treefrog changes its usual two-part “ribbet” to a one-part encounter call. An observer trying to locate the Pacific Treefrog can mimic their calls and take over as chorus master, enticing the other frogs to begin calling as well. If this is done, be prepared to take on the responsibilities that come with being the chorus master!

I suppose they are the frog we hear so much in the spring, though I haven’t gone out to check; approaching calling frogs seems to make them be quiet, a very sensible move, so I haven’t pursued the matter. Great sound!

And their color changing is really intriguing.

There’s a rare blue morph,

Pacific Tree Frog, blue morph.jpg


and the more usual brown and green appearances,

Pacific Tree Frog, Wikimedia.jpg


Pacific Tree Frog, green.jpg

Source for both, Wikimedia Commons.

But the color-changing, apparently back and forth among all the colors except blue, is really intriguing. Wikipedia says, “Previously, it was thought that there were two different fixed colors that an adult tree frog could be. Now it has been found that some of them are able to change between the two.” The closer we look, the more complex things become. Wonderful!

Frog changes color with changed surroundings

I really wish I’d taken a photo of this frog when I found her this noon, sheltering on the porch next to the wall. There were some beer 6-pack carriers there waiting return to the store and when I picked one up there was this big dark frog clinging to the side. She (well, she just seems like a “she”) was a very dark brown tinged with green all over, with some darker mottling on her back, and sparkling gold stripes above her eyes. I caught her up and put her in our 100-gallon pond, on the lotus and water hyacinth leaves.

This afternoon, here she is, transformed in color.


The dark splotches on her rear are about the color that her entire body was, about six hours ago.

It was only recently that I learned frogs could do this, so now having seen it in action I had to talk about it. Apparently it’s an ability found in many species, and the frogs can change as a result of light, humidity, surroundings, or “mood”. Whatever that means. The frog changed and the researcher cannot see any objective alteration in environment so it’s put down to “mood”.

Fear or excitement makes many frogs and toads turn pale, but others, like the African clawed frog, darken when disturbed. Another African frog is normally green, but turns white in the heat of the day to reflect heat and keep cool. The tiny African arum frog is ivory white and lives in the white blossoms of the arum swamp lily. When the blossoms die, the frogs turn brown to match. from exploratorium.edu.

We think she’s probably a Pacific Tree Frog (Pseudacris regilla).

[Etymological note: Pseudacris from the Greek pseudes (false) + akris (locust) — alluding to the frogs’ song?; regilla from the Latin regilla (regal, splendid) — probably referring to the markings.]