July 27, 2010 • 5:36 pm

The “Dracula morph” of the famous morphing owl might represent the bird’s attempt to hide by resembling part of a tree.  This is the strategy adopted by two other groups of birds, the New World potoos and the Old World frogmouths.

An alert reader, Geoff Beikoff, spotted and photographed two tawny frogmouths (Podargus strigoides) resting in a gray box eucalyptus tree (Eucalyptus microcarpa) in North Queensland, Australia (click to enlarge).  Are these cryptic or what?

Tawny frogmouths live in Australia, New Guinea, and Tasmania. Their resemblance to owls is an evolutionary convergence, since they’re only distantly related. But, like owls, they’re nocturnal hunters (eating insects and small rodents) and sit immobile in trees during the day. According to Geoff, “They remain perfectly still and slit their eyes so that the eyes are not readily discernible.” (Note that the morphing owl also slits its eyes during the Dracula display.)

Here, courtesy of the London Zoo website, is a tawny frogmouth and her chick. You can see how the birds got their name:

Here’s a group of captive frogmouths awaiting repatriation to the wild:

Finally, just to show you another weird nocturnal and cryptic bird, here’s a common potoo (Nyctibius griseus) from South America:

Here’s my prediction as an evolutionary biologist who knows little about frogmouth biology:  there exists—or did exist in the recent past—a diurnal, visually hunting predator that kills frogmouths.

h/t: Geoff Beikoff

16 thoughts on “Frogmouths!

  1. Might the predator have been the wedge-tailed eagle? Or is it more likely a non-flying predator, such as the huge goannas that we have?

    (P.S. You may wish to edit “dirunal”.)

    1. I’ve seen Frogmouths and Wedgies in the same area. Perhaps it’s all those rabbits that the Wedgie feasts on that makes a Frogmouth less appetizing?

  2. Tawny frogmouths live in Australia, New Guinea, and Tasmania

    Uhm, Tasmania is part of Australia. It was even joined less than 10,000 years ago. Well, it still is joined, just a bit of water blocks land travel.

  3. In a paper on predator avoidance by tawny frogmouths, Körtner Geiser (1999) state that “raptors and mammalian carnivores are known occasionally to prey upon these birds” then give some citations to back this up. Unfortunately I can’t seem to track down digital copies of the sources that they cite. Wedge-tailed eagles seems like a good bet though, and perhaps Goshawks. It’s also probably worth considering the diverse suite of medium to large marsupial predators that are now extinct. And I suspect varanids might be a potential predator of frogmouths too.

    Incidentally I did track down some references to predation on tawny frogmouths by owls – presumably they are more vulnerable to predation when they are out and about at night.

    1. Well, Quolls are pretty much on the way out. At least on the mainland. They are good climbers I believe.

  4. Perhaps someone could e-mail Professor Fritz Geiser (he’s a Professor of Zoology) & ask him about the diurnal hunter idea – he is at the University of New England in New South Wales…

  5. It just occurred to me that as owls & other birds of prey are often mobbed by other birds when they are spotted, perhaps disguising themselves by freezing is also a way of avoiding getting pestered & expending unnecessary energy?

    1. That’s a good idea. One wonders how they manage being constantly mobbed by corvids, thrushes, etc.

      Maybe one of our birdwatchers has observed such behaviour?

      I’ve occasionally seen owls in the wild but never while they were being mobbed. (Buteos and falcons, yes, but they generally don’t try to hide themselves when it happens.)

      1. I might have seen Frogmouths in the wild without knowing it!
        They are alarmingly cryptic. There are a few in Adelaide Zoo, and even when pointed out, within a few yards, they look just like the branch that they are sitting on.

        1. They’re quite common around Greensborough in north-eastern Melbourne. Especially during the summer.

  6. We had a tawny frogmouth in the Nocturnal House when I worked there briefly (at the zoo, this was – Woodland Park). It was kind of fun feeding it. Never fun killing the mouse, but fun feeding the bird – because of the frogmouth, I guess. Gape, glom, gulp.

  7. Thank you!!! I love tawny frogmouths. They were fairly well represented in northern NSW where I used to live.

    I miss quite a lot of birds from there. I had a family of butcher birds who lived in the vegetable garden, several magpies who would try to pinch the butcher birds’ food and four kookaburras who woke me up in the mornings. They are extremely territorial and noisy about it!!!

    I might have to go back and visit, sob!!

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