The concealing behavior in owls

posted in: Owls | 4

“Sometime ago I was sent a YouTube link on an owl that is capable of transforming into three modes: LINK. The video features a White-faced Owl (Ptilopsis leucotis) encountering two other owls of different sizes. When it encounters a Barn Owl that is slightly larger than itself, it would puff itself to enlarge its size. I am familiar with many other species that would attempt to do that, by spreading its wings to ‘enlarge’ itself. However, the surprise comes during the second part of the video when a much larger owl, a species of Eagle Owl was brought forward. Seeing that this owl is much too big, it chooses not to confront it but rather makes itself appears thinner and smaller, so as to escape the attention of the large threat. This behavior is described as ‘concealing behavior’ that is well documented in smaller owl species when threatened (Denver et al., 1990).

“The concealing behavior is achieved by facing the threat sideways, revealing the narrowest profile to the threat. Besides this, it will attempt to keep its face feathers flattened to create a thinner face. It will also partially close its eye so that it will not attract attention. With its dull coloration, these strategies will effectively help it to disguise itself as a thin dead branch of the tree it is perching on (the tufts in some species further help to create this illusion), similar to the practice by some distantly related nocturnal species of Caprimulgiformes, such as nightjars and frogmouths.

“On 25th September 2011 when I was doing my regular birding in an oil palm estate around my neighbourhood, a nightjar caught my attention. While attempting to get a day shot of it roosting, I walked through the overgrown parts of the oil palm with no success. Filled with disappointment, I suddenly noticed some black clumps in the shade. I took it to be a leaf that looked like an owl, something that had happened to me on many occasions when I thought I saw an owl from far, but would turn out to be something else. I was wrong this time. It was a Brown Wood-owl (Strix leptogrammica maingayi) sitting quietly on the branch. This was exciting for me as it was the first owl I had ever seen in my neighborhood within the last 13 years of birdwatching, and after having heard owls calling four times from late last year to early this year at two other spots. One of the calls I heard earlier was in fact of this species from a limestone hill habitat. This species is more commonly sighted in forested habitats from lowland to highlands in much of its range. It was also recorded in an oil palm estate in Borneo (Phillipps & Phillipps, 2009) – usually not known to enter oil palm estates.

“I made a video of the owl on tripod to capture the moment that included seeing it give its diagnostic eye blinking. When I processed the video, I was surprised to find that I documented the owl slowly moving its body to present a more concealing posture, to become more concealed towards the end of the video. It may have been because it saw me walking towards it that it started to conceal itself. This is an interesting behavior showing that large owl species like this wood-owl would also use this technique when it faces threats but it did not conceal itself as rapid as the scops owl. When I left, it had not fully concealed itself, so it is uncertain to what degree it would. I was forced to leave the location after taking the video as I noticed some local bird poachers who were regularly coming to trap doves arriving. I quickly left the spot so that they would not notice that I was looking at an owl.

“Along with the article, I attach a picture that was extracted from the video to show the slow change of the posture (top) and a higher resolution static image of mine (above-left)

Tou Jing Yi
Department of Computer Science (DCS)
Faculty of Information and Communication Technology (FICT)
Universiti Tunku Abdul Rahman (UTAR)
11th November 2011

References:
1.
Denver, W. Holt, Rick Kline, Lynn Sullivan-Holt, 1990. A description of tufts and concealing posture in Northern Pygmy-owls. Journal of Raptor Research: 24(3): pp 59-63. LINK.
2. Quentin Phillipps & Karen Phillipps, 2009. Phillipps’ Field Guide to the Birds of Borneo. John Beaufoy Publishing Ltd.

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4 Responses

  1. FYI, I’ve also observed this behaviour in Spotted Wood Owls (there’s one that likes to hang around the Faculty of Arts and Social Sciences at NUS in the late afternoon). If there are humans nearby, it will twist its body such that its back faces the observer and it will try to flatten its body against an adjacent branch so that it looks like part of the branch. Given the patterning on the Spotted Wood Owl’s back, this serves as a pretty darn effective camouflage and renders the owl almost invisible from that angle in spite of its relatively large size

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    • Tou Jing Yi

      Interesting observation, I was expecting more to see Spotted Wood Owl in oil palms, but surprised to see this species instead, I had also seen a Buffy Fish Owl here, but Buffy Fish Owl unlike other owls, did not seemed to prefer this tactic, they seemed to be able to see rather well in daylight and will choose to fly off like any other diurnal bird. Buffy Fish Owl is an exceptional case in local owls, being one of the few owls that would start to get active before full darkness.

      However the only true diurnally active owl in the region must had been the Collared Owlet, if not mistaken, the Eurasian Eagle Owl should also be active in the day as well in Europe.

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  2. DAISY ONEILL

    Good observation Tou!

    Do watch out for cobras that lurk notoriously in oil palm estates.

    Cheers!

    Daisy

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    • Tou Jing Yi

      Thanks, ya, I always look out for snakes, but one of the buffalo owner in the area told me there are snake poachers here (including him) over the years and snakes had therefore became rare there.

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