You’ve probably guessed that I have a penchant for mimicy and “crypsis” (camouflage); I suppose it’s because the phenomena demonstrate the remarkable results that can be achieved by natural selection. For mimicry and crypsis are two of the few adaptations for which we know what the “target” is—complete resemblance or camouflage—and therefore we can judge how much natural selection can be impeded by things like evolutionary constraints or the lack of available mutations.
In the case of these two tawny frogmouths (Podargus strigoides) from Australia, they’re pretty damn cryptic. [Note: several readers seem to have missed the “two”in the preceding sentence. Note that there’s a parent and an offspring in the first picture.]
I know of few birds for which selection for camouflage is so obvious (photo from Parks Australia). Do note, as well, that there was probably selection for behavior as well: the behavior to sit on appropriate trees and hunker down motionless.
Here’s a frogmouth that not’s so camouflaged: an albino (and its normally-colored conspecific) (from Environmental Graffiti [more great photos there],image by Alicia Carter). All tawny frogmouths are born pure white, but turn brown and mottled with age. This one, judging from the lack of pigment in the eyes, seems to be a genuine albino rather than a leucistic variant.
h/t: SGM
The first is very good! I had to look at the picture for a few seconds, before I could see the bird.
There are two birds in that picture.
Your F* right! I didn’t see it at first.
The second photo also has two birds, I observe. The white one seems to be saying “I’m really cute, so why don’t you bring your finger closer!”
Holy crap you’re right! I had no idea!
Its baby is in the photo too.
I looked at the first photo for quite a while before I noticed the chick. It was quite a while later, when I looked at the enlargement, that I spotted the adult. Amazing.
There’s a neotropical species, the Common Potoo(Nyctibius griseus), that shows convergent evolution. Here’s a picture of one with it’s chick hiding in plain sight.
http://www.faunaparaguay.com/images/Nyctibius%20griseus%20at%20nest%20Pedro%20proc.jpg
Wow. If that’s the Common Potoo, the Uncommon Potoo must be fabulous.
Might not be convergent evolution though, I just read that they are related to the frogmouths.
These potoos don’t sit like that all the time. When they see a person (or presumably another creature) near them, they slowly go into that extreme upright position and close their eyes tight (their normal resting position is a little more relaxed).
We have tawny frogmouths where I live in northern NSW.
A lot of people mistake them for owls.
They have often scared the shit out of me when I have walked up to an avocado tree to pick some avos and they have flown off.
I never see them before they move.
I think this is an overstatement. The resemblance doesn’t have to be complete; it just has to be good enough to fool the target of the deception at minimal cost. Optimal crypsis or mimicry is a balancing act, and there’s no requirement that the ideal balance be convincing to our eyes, since we’re not the ones who are meant to be fooled.
In general we don’t know what that optimal balance point is, and are therefore not in a position to judge whether a case of less-than-complete resemblance (from our perspective) indicates any sort of evolutionary constraint or dearth of variation. The resemblance may be already be good enough that selective pressure to perfect it has largely vanished.
At least in tropical forests, there are visual predators with eyes much like our own. Most potential prey there is very very well camouflaged for our eyes. However, the camouflage does have a serious imperfection due to metamerism of pigments: the appearance of pigments varies with the spectral qualities of the incident light. A pigment can evolve to match another color in sunlight, but the same pigment might not match the target in light with a higher or lower color temperature. So if you go out with a flashlight (with a very low color temperature) at night, bugs and herps don’t match their substrates as well as they do during the day under the sun’s bluer light.
Evolution makes things “good enough” rather than perfect.
Ha — count me among those that had to look again to see the offspring.
Am I the only one who thinks they look like Jim Henson characters?
In that second photo their heads appear to be about 60% of their bodies, and their mouths look so large it looks like they could probably swallow themselves whole.
The trick with birds is to look for their eyes.
That doesn’t work too well with insects. :-/
I saw the eye, the tail, and the beak but, the adult in the first photo still looked too woody to be a bird.
Not only are they pretty much the same color as the tree, but they appear to orient or align their bodies parallel to the trunk, limb, branch on which they perch. They also close their eyes which, were they otherwise open, might likely be noticed. Makes me wonder if they “think” about such considerations, or if such alignment is purely instinctual.
I always wondered what would happen if my cat managed to get in my RES turtle’s environment!!
http://24.media.tumblr.com/f5b3f840fc954c3387fd5106ead03a69/tumblr_mnt946Wo0I1qb5gkjo2_400.gif
Reblogged this on Mark Solock Blog.