Unusual
nocturnal feeding by Brown Rock-chat Cercomela fusca (Passeriformes: Muscicapidae)
in Bikaner, Rajasthan, India
PartapSingh
PG Department of
Zoology, Govt. Dungar College, Bikaner, Rajasthan
334001, India
Email: partapsk@yahoo.com
Date
of publication 26 April 2009
ISSN 0974-7907
(online) | 0974-7893 (print)
Editor: Rajah Jayapal
Manuscript
details:
Ms # o1852
Received 03
September 2007
Final revised
received 08 April 2008
Finally accepted
19 July 2008
Citation: Singh, P.
(2009). Unusual nocturnal feeding by Brown Rock-chat Cercomela fusca (Passeriformes: Muscicapidae)
in Bikaner, Rajasthan, India. Journal of Threatened Taxa1(4): 251.
Copyright:© Partap Singh 2009. Creative Commons Attribution 3.0Unported License. JoTTallows unrestricted use of this article in any medium for non-profit purposes,
reproduction and distribution by providing adequate credit to the authors and
the source of publication.
Inter-specific
and intra-specific competitions have been observed in animals that show behavioural plasticity to optimize their foraging
success. Brown Rock-chat Cercomela fusca , which is one of the most common birds around human
habitations in Bikaner, Rajasthan, is one such species showing plasticity in
its feeding behaviour. The species though diurnal has been observed
to engage in nocturnal feeding. Bright
sodium lamps attract large number of insects during monsoon period and the
Brown Rock-chats voraciously forage upon them. Due to large congregation of insects the capture success in nights is
much better as compared to capture rates during the day. Monsoon is the period when their nutritional
requirements are very high as they have to nurture young ones. With this behaviouraladaptation of nocturnal foraging, Brown Rock-chats have evolved an effective
mean to optimize their feeding efficiency.
Because there is
a limited amount of organic material that can function as food, a great deal of
food competition exists among animals. This competition can be inter-specific or intra-specific. To avoid the competition and to get optimum
quantity of food, behavioural evolution has been
observed among many birds and mammals. Foraging at night by a diurnal bird is one such example of behavioural adaptation.
Black Drongo Dicrurus macrocercus has been widely observed to engage in
nocturnal feeding (Khan 1990; Nameer 1990; Sharma
1991). Even I had observed the species
feeding on insects under sodium lamps in Karauli,
Rajasthan. Sharma (2003) has observed
White-bellied Drongo Dicrurus caerulescens feeding under street lamps during
night. Same behaviourhas been observed in Tickell’s Blue Fly Catcher Cyornis tickelliae(Sharma 2006) and Grey Mongoose Herpestes edwardsii (Sharma 2005).
Brown Rock-chat
is one of the most common birds around human habitations in the desert town of
Bikaner in Rajasthan. Though Brown Rock-chat is known to be markedly
crepuscular in its activity pattern, nocturnal foraging has not been documented
before. I have observed that the species
in Bikaner has unusual behaviour of being active very
early in the morning (0300 to 0500 hr) and remain active till very late in the
evening (1830 to 2100 hr). In winters
the species remains active till 1830 hr and were foraging till 2000 hr in
summers. In particular, Brown Rock-chats
were observed feeding under sodium lamps during south-west monsoon in
July-August. This strange behaviour of normally diurnal bird to forage during nights
requires some explanation. The studies
on reproductive biology indicated that the species has two peaks in
reproduction, one in April and the other in July (Singh 2007). During this period their nutritional
requirements are very high as they have to nurture young ones. Nocturnal foraging gives species better
opportunity to capture insect preys, which congregate under artificial
light. In fact, I observed that their
capture success is significantly higher during night (13 per hour) than during
day (2.5 per hour). By staying close to
human habitations they also avoid natural predators of night. The dark brown body color gives them added
advantage of becoming invisible in the darkness. It is therefore speculated that Brown
Rock-chats in the city of Bikaner have developed nocturnal foraging as a behavioural adaptation which tend to increase its feeding
efficiency and optimize food acquisition with less competition.
References
Khan, A.R.
(1990). Feeding
habits of Black Drongo. Newsletter
for Birdwatchers 30(10&11): 11.
Nameer, P.O. (1990). Midnight feeding by Black Drongo. Newsletter
for Birdwatchers 30(7&8): 9.
Sharma, S.K. (1991). Nocturnal feeding by Black Drongo.Newsletter for Birdwatchers 31(3&4): 8.
Sharma, S.K. (2003). Nocturnal feeding by White-bellied Drongo Dicrurus caerulescens.Journal of Bombay Natural History Society 100(1): 144.
Sharma, S.K. (2005). Unusual nocturnal activity of a Grey mongoose Herpestes edwardsii in BandipurTiger Reserve, Karnataka. Zoos’ Print 20(7): 21.
Sharma, S.K. (2006). Nocturnal feeding by the Tickell’s Blue
Flycatcher Cyornis tickelliae.Zoos’ Print Journal 21(2): 2171.
Singh, P. (2007). Ecological and
ethological studies on Brown Rock-chat Cercomela fusca in Bikaner region of Thar desert. Final Project Report submitted to UGC.