I stumbled upon a video clip on the fascinating
behaviour of an owl on Youtube and decided to find more videos regarding it.
Although the video was not taken in the natural habitat of the owl and a great
amount of human involvement (especially the sound effects, very anthropomorphic) can be seen, it sparked off my great interest in
the tiny owl and led to this blog entry.
Japanese crazy over "funny" owl
(sorry for the lack of subtitles in the video, I can't seem to find another one that can show the behaviour so well)
Photo by Gerhard Theron
After much researching, I finally found out
that the owl was a Southern White Faced Scops Owl (Ptilopsis granti). From
the family of Strigidae, the Southern White Face Scops Owl is
characterised by its distinctive white facial disc with broad black outline,
ear tufts and orange eyes. They originate from South of Africa and feed mainly
on insects, arachnids, small birds and mammals. They produce a call only at
night that sounds like a repeated bubbling ‘pooo’, this probably gave rise to
the name of the owl, 'popo-chan', in the video.
It is interesting to note the stark
difference in the behaviour of the Southern White Faced Scops Owl when
different threats were detected.
1. Flaring its plumage to increase size.
2. Contracting of plumage, stretching of body and showing of side
profile to resemble a tree branch.
The behaviour of the owl is based on the cost
benefit analysis that animals often rely on in their decision-making.
Is it more advantages for it to get into a defensive mode or simply camouflage
itself? This all depends on who the opponent was.
As seen in the video, the owl chose get
into an aggressive mode when it saw the slightly larger barn owl. The Southern
White Faced Scops Owl in the video raised its wings high and pumped up its
plumage to increase its volume. This can be seen to be a form of warning to the
perceived threat. The threat falls under the range whereby an aggressive stance
can be more advantages, hence the owl’s behaviour.
On the other hand, with the vastly larger Eagle
Owl (please correct me if I’m wrong), the costs involved were too great and the
Southern White Faced Scops Owl decided to camouflage itself as a tree branch.
This is done so by stretching their body and contracting their plumage, as well
as facing their threat with their side profile. This effectively reduces the
size of the owl and in turn camouflages it.
Similar Behaviour in Screech Owls
Other species of owls also use the same
method of disguise to hide it, sometimes even with their eyes closed, as mentioned
and shown during lecture previously. Further research reveals that the
concealing posture is also used by the Screech Owl. (Follow link to the
relevant article.)
The Screech Owl (Otus asio) was also
found to use the same ways as the Southern White Faced Scops Owl to camouflage
it, as described in the quote below:
“The owl immediately twisted its body
sideways to the sparrow, raised the front margins of the wings slightly and
held the rear margins tightly against the back, at the same time compressing
the body plumage and so presenting a very narrow silhouette as seen from the
sparrow’s position.”
One main difference can be seen from the
Southern White Faced Scops Owl in the video, and the description of the Screech
Owl’s behaviour. The latter concealed away from sparrows that are very much
smaller than itself. It was also mentioned in the article that the Screech Owl
did not pay attention or conceal itself from noisy children and dogs that
passed by it. Was the owl afraid of being mobbed by the sparrows? Or does the
Screech Owl assume this posture in the presence of prey?
As we can see, the same behaviour can mean very different things to even similar species of animals. Hence there is a need to dig deeper in order to gain a better understanding about animal behaviour.
P.s.: I hope this entry will motivate readers to read up more about the fascinating owls!
References:
Wm. L. Putman, 1955. Use of Concealing Posture by a Screech Owl. The Auk, Vol. 75, No. 4. (Oct., 1958), pp. 477-478.
Perrone, M.J., 1981. Adaptive Significance of Ear Tufts in Owls. The Condor, Vol. 83, No. 4. (Nov.), pp. 383-384.
Ecopains d'abord. (2008). Southern
White-faced Scops Owl. Retrieved March 20, 2008, from http://www.oiseaux.net/birds/southern.white-faced.scops-owl.html.
Siyabona Africa Travel. (2008). Kruger
National Park: Scop Owls. Retrieved March 20, 2008, from http://www.krugerpark.co.za/africa_scops_owl.html.
BirdLife International (2007) Species
factsheet: Otus leucotis. Retrieved March 20, 2008, from http://www.birdlife.org.
World Owl Trust.
(2008). Southern White-faced Owl Ptilopsis granti. Retrieved March 20,
2008, from http://www.owls.org/Species/ptilopsis/southern_white_faced_owl.htm.
Video Source:
Retrieved on March 20, 2008, from http://www.youtube.com/watch?v=ChTsGDPcCdY
Photograph Source:
Retrieved on March 20, 2008, from http://birdquest.net/afbid/birdspecies.php?func=view&slideno=9&af_bs_id=815.