The great Indian monsoon migration

Chennai: Ornithologists are monitoring the nesting pattern of migrant wetland birds in the sanctuaries as they could provide vital clues about the rainfall that is expected over the next two months. According to bird watchers, if the nests are built at the top of the canopy, they forecast heavy rainfall and if the nests are laid somewhere in the trunk of the tree, then there will only be moderate rainfall. And if certain species of birds avoid nesting then it means the rainfall will be scanty.

Dr R. Nagarajan of A.V.C. College, Mayiladuthurai, professor in wildlife biology, says, “Studies by Bombay Natural History Society have proved that the birds do have intellectual qualities to forecast rain. My thesis study on the Oystercatcher bird done in England proved that the birds could even identify the prey base in a water body from a distance and also avoid molluscs that are infected by parasites.

“My decade long research study (1996 – 2007) published in university of Exeter United Kingdom revealed the foraging behaviour of Oystercatcher birds in connection with water and their prey base”. Most of the bird trackers in our state do have traditional knowledge on nesting and its interface with monsoon, but these are yet to be documented in our country, he adds.

“Many bird populations migrate long distances along a flyway. The most common pattern involves flying north in the spring to breed in the temperate or Arctic summer and returning in the autumn to wintering grounds in warmer regions to the south”, says K V R K Thirunaranan, founder, The Nature Trust.

Migratory routes and wintering grounds are traditional and learned by the young during their first migration with their parents. Some ducks, such as the Garganey, move completely or partially into the tropics. The European pied flycatcher also follows this migratory trend, breeding in Asia and Europe and wintering in Africa, Thirunaranan, adds.

“Koonthankulam in Tirunelveli district is famous for its large number of migratory birds, particularly Bar-headed geese. This season so far about 2,000 of them have arrived and they come from Mangolia and Siberia. Annually around 10,000 geese arrive here,” says Balpandi, a bird tracker of the state forest department for more than a decade.

Mosquitoes, houseflies can travel far

If you believe there is no water stagnation in and around your flat which is why you are hoping for an insect free monsoon this year, beware because mosquitoes and houseflies can migrate.

An adult housefly can travel upto 30 kilometres. For instance, from Nandanam junction, a housefly can reach Tambaram or even further. Similarly, the dreaded mosquitoes that breed in a choked storm water drain near Chennai Central railway station can travel up to Chintadripet or Triplicane targeting the bachelors staying in mansions.

“Recent studies by the Tamil Nadu Veterinary and Animal Sciences University and earlier proven studies by entomologists have shown that 30 per cent of houseflies can easily migrate up to 1.6 kilometres,” explains professor in Parasitology T. J. Harikrishnan of Tanuvas.

Studies in Namakkal had shown houseflies migrating from dairy and poultry farms to distant areas during the monsoon. Studies abroad have proved that houseflies can travel distances ranging from 11 to 32 kilometers, says the professor who had authored several journals on parasites and has published a book on integrated housefly management.

“Mosquitoes are a predominant problem in tropical countries and they migrate for short distances.

Arresting of breeding source has been a vexing problem in Chennai and the city corporation has conducted several meetings on the subject.

To arrest their breeding and control their movement have always been Herculean tasks as there are three major water ways in Chennai promoting mosquito breeding and their movements,” says an IAS officer who has served at the city corporation.

“Insects do migrate like other species, but their movement are hardly studied and recorded.
Insects do play a major role in biodiversity and needs more in-depth research,” says Poochi Venkat of Madras Naturalist’s Society.

Next: Winged visitors are late this year

Winged visitors are late this year

It is the monsoon season again and it is arrival time for migrants and winged visitors are in their tropical havens in Tamil Nadu and Andhra Pradesh. Pelicans have started arriving at the Pallikarnai marsh. The renowned Vedanthangal bird sanctuary near Chengalpattu will be open to the public from Friday.

Speaking to this newspaper, city wild-life warden Ms Geethanjali said so far about 2,000 migratory birds, including open bill stork, grey heron, darter and cormorants have arrived at the sanctuary. Normally, the sanctuary starts receiving migratory birds from various parts of the world by the first week of November and this year due to the delay in the onset of NE monsoon the migration has also been delayed by a few days.

Wildlife personnel are now pinning hopes on receiving more birds with rains expected over the next few days. As a pre-monsoon arrangement for the winged visitors desiltation works, strengthening of bunds and cleaning up of adjoining water channels had been completed as per schedule and the water level in the lake is gradually picking up. Once arrival of birds gains momentum, fishlings will be introduced into the lake, according to wildlife management sources.

Vedanthangal is the oldest bird sanctuary in the country, measuring around 73 acres and has a history dating back more than 300 years. The other spec­ies normally recorded in large numbers here include Pelicans, Egrets, Spoon Bills, Pintail, Darters and White Ibis.

“Pallikarnai, Pulicat and Nallapattu  bird sanctuaries located across the Andhra border have also started attracting birds and the migration is all set to reach a peak by mid December”, said Mr N Balaji, an avid bird tracker.