‘Broken wing display’ in an unfledged Indian Eagle Owl Bubo
bengalensis
M. Eric Ramanujam
Principal Investigator (Faunistics), Pitchandikulam Bioresource Centre
/ Pitchandikulam Forest Consultants, Pitchandikulam Forest, Auroville,
Tamil Nadu 605101, India
doi: http://dx.doi.org/10.11609/JoTT.o3791.5781-3 | ZooBank: urn:lsid:zoobank.org:pub:CB1F2784-AD74-4BFD-908A-6B246E6E8017
Editor: Reuven Yosef, Ben Gurion University of
The Negev, Eilat, Israel. Date
of publication: 26 May 2014 (online & print)
Manuscript details: Ms #
o3791 | Received 28 September 2013 | Final received 17 May 2014 | Finally
accepted 18 May 2014
Citation: Ramanujam, M.E. (2014). ‘Broken wing display’ in an unfledged Indian Eagle OwlBubo bengalensis. Journal of
Threatened Taxa 6(5): 5781–5783; http://dx.doi.org/10.11609/JoTT.o3791.5781-3
Copyright: © Ramanujam 2014. Creative Commons Attribution 4.0 International License. JoTT allows unrestricted use of this article in any medium,
reproduction and distribution by providing adequate credit to the authors and
the source of publication.
Funding: Self funded.
Competing Interest: The
authors declare no competing interests.
Acknowledgements: I wish to thank Dr. Claire Elouard, ex HOD Ecology, French Institute of Pondicherry,
for providing the photographs for reproduction.
Deception is a well known phenomenon in the
animal kingdom and feigning death or injury occurs in invertebrates (e.g., Ebermann 1991; Fabre 1900; Miyatakeet al. 2008), fish (e.g., Howe 1991), amphibians (e.g., Escobar-Lasso &
Gonzalez-Duran 2012), reptiles (e.g., Santos et al. 2010; Vogel & Han-Yuen
2010), birds (e.g., Sargeant & Eberhardt 1975) and mammals (e.g., Francq1969). Injury feigning or paratrepsis has been well documented in birds defending
nests/young (Armstrong 2008; Gochfeld 1984; Yosef 1994) and in Strigiformes(Bent 1980; Fischer et al. 2004). The ‘broken wing display’ (BWD) has been documented in adult Indian
Eagle Owl Bubo bengalensis (Dharmakumarsinhji 1964; Madras Ramblings 2008; Mikkola 2012) but no records exist of young owls indulging
in this behavior.
In this short communication I show that BWD is exhibited by young B. bengalensis and present photographic evidence.
We came across a nidicolous and semi-altrical young (protoptile) B.bengalensis in a ravine in Merveille(11058’N & 79046’E) near OusteriLake in the vicinity of Puducherry in southern India
on 28 February 2001. This was a
single offspring since the other egg found at the nest did not hatch. This subject was monitored for a period
of >6 months. It was the same
specimen with which we conducted some basic experiments (Ramanujam2003) and was accustomed to our presence. However, on 07 April 2001, when at ca. 40 days old (beginning of prebasic moult obvious in photographs), it exhibited BWD.
Description of behavior: We first came upon this owlet after it had
left its nest on 1 April 2001. On 7
April we found it well concealed in scrub (Image 1). When we approached, it got up and
scurried away in an awkward and unsteady manner with its left wing trailing
limply and dragging on the ground (Image 2). Bill clicking, hissing and low intensity
squealing was audible. So realistic
was the display that we thought the bird had injured itself. On gaining the edge of the ravine it
made a fast dash for freedom on foot and used both its wings to balance itself
[In spite of flight feathers being developed it could not fly - true flight is
possible only around 58 days in this species (Pande& Dahanukar 2011)]. We encountered this subject regularly
after that and it made no attempt to replicate this behavior.
Discussion: Dharnakumarsinhji(1964) and Ramanan’s online report in Madras
Ramblings (2008) describe BWD. But
one fundamental difference seems to stand out, not only between our observation
and the previous two, but also between the aforementioned ones. While Dharmakumarsinhjistates “……. she began flapping her wings from side to
side ….” the online report by Ramanan mentions “……
acts as if the wing is broken ….”. Our single observation of this phenomenon was that the wing was limp and
dragging, there was little or no movement of the wing and there was definitely
no flapping motion. Photographic
evidence from both the online report and Mikkola(2012) suggests both wings are involved, but in this case only the left wing
was involved. All this shows that
there could indeed be more than one unrecognized facet of behavior—just
like the spread winged agnostic displays of Bubo bengalensis(Ramanujam 2010)—and until these have been
recorded in detail and sorted out keeping in mind the morphology, causation and
function, there will always be ambiguity and a sense of unfulfillmentto any exercise that aims to address the issue of paratrepsisin any life form.
Both paratrepsis and thanatosis (death feigning), which are both anti-predator behavioral devices using deception, have for long been the
subject of intense debate. The BWD has generally been classed as a
nest protection behavior (Caro & Girling 2005) but here we present a case where it was used
in a young bird that was unable to protect itself by flying away from the
potential threat.
In conclusion, I present my observation that the BWD occurs in young Bubobengalensis. Furthermore, I cannot draw parallels with the BWD exhibited by adult Bubobengalensis and have to rely on published accounts
for the simple reason that I have not observed this behaviorat the nest in spite of studying the taxon for close to 15 years. In conclusion, I can only state that
‘deception’ has obvious survival value, and is innate.
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