On 31st January 2019 at around 6:20 pm, a friend Sagar K and myself, observed about 100 wagtails in flight. It was surprising to see such a large group of wagtails in the lateritic habitat of the Mangalore University Campus (12.81° N, 74.93° E). The area had a shallow dry pond which in the monsoons will fill up with water, turning it into a habitat for many species of snakes, frogs, etc. It has been the normal roosting and dust bathing site for Green Bee-eater Merops orientalis. Along with the grey and yellow coloured wagtails, I also observed a pair of White Wagtails Motacilla alba, an addition to the species checklist of the Mangalore University Campus. We sat on a rock and observed the wagtails in the dim evening light. Most of them flew towards an Acacia tree nearby and continuously flitted within the tree chirping along. On moving a little closer, I found a dead bird on the ground; I took some close up pictures of this bird. From the pictures as well as the calls produced by the wagtails which I recorded, the group of birds was identified as Grey Wagtails Motacilla cinerea, though initially I thought that they were Western Yellow Wagtails Motacilla flava.
I visited the roost site the next day also. At around 6:00 pm Grey Wagtails arrived. I did not find the White Wagtail on the second day. I revisited the spot for a third time on 4th February 2019 around 6:00 pm and I could see around 100 Grey Wagtails and two White Wagtails. It was almost dark around 6:30 pm and the wagtails moved to another Acacia tree nearby, accompanied by the usual chirping sounds and flitting around.
Wagtails are known to roost communally and this has been well documented (Ali, 1962; Praveen, 2006; Sashikumar et al., 2011; Arlot, 2015).
I thank Ashwin Viswanathan for helping me to confirm the identification of the wagtail from the photograph. and also from the recorded call.
References
Ali, S. (1962). Migratory wagtails in Kerala. Journal, Bombay Natural History Society, Vol.59 (1).
Arlott, N. (2015). Birds of India: Pakistan, Nepal, Bhutan, Bangladesh and Sri Lanka. William Collins. 400pp.
Praveen, J. (2006). On the roosting of Large Pied Wagtails. Malabar Trogon. Vol.4 (2, 3& 4).
Sashikumar, C., Praveen, J., Palot, M. J. & Nameer, P. O. (2011) Birds of Kerala: Status and Distribution. Kottayam, DC Books.