Zoo all tanked' up for better innings

Nov 20, 2010, 05.37am IST
http://timesofindia.indiatimes.com/city/chennai/Zoo-all-tanked-up-for-better-innings/articleshow/6957122.cms

CHENNAI: Every year during monsoon, a large number of migratory birds flock to the Otteri tank inside the Arignar Anna Zoological Park at Vandalur, some 32km from Chennai, for nesting, but return disappointed as the environment does not enough trees.

All that is set to change soon with zoo authorities coming up with ideas to encourage these birds to stay longer. They have planted 230 saplings of Barringtonia, a species native to mangrove habitats, inside the tank. "As the branches of these trees are strong and net-like, it is easy to for birds to nest. In fact, many nests can be built on a single branch due to its net-like structure. Though we already have a few Barringtonias in the tank, we are planting some more, hoping to attract more birds to visit," zoo director, KSSVP Reddy, who is also chief conservator of forests, told TOI.

According to biologists, Barringtonia, which is locally known as sea poison tree or fish poison tree, is a native to mangrove habitats on the tropical coasts and islands of the Indian Ocean and western Pacific Ocean from Zanzibar east to Taiwan, Philippines and Fiji. It is a small to medium-sized tree growing between 7 and 25 metres tall. All parts of the tree including fruits are poisonous.

"These trees also encourage visiting birds to perch here," said Reddy.

Due to heavy showers in the past two months, the water level in the tank is on the rise. With zoo authorities now tapping rainwater by constructing a series of channels at several locations inside the zoo which connect to the tank, the water level is consistent throughout the year. Consequently, the flow of migratory birds has also improved.

On an average, every year, around 10,000 migratory birds visit the tank at Vandalur. These include open bill stock, grey heron, night heron, cormorants, darters, egrets, dabchicks, pelicans, great pelicans, painted stork, white ibis, glassy ibis and moorhens. Darters, also known as snake bird, found mainly in tropical regions, are the most popular. They have been classified as near-threatened by the International Union for Conservation of Nature.

"Water is the main attraction for birds. Most of the migratory birds stop at Vandalur before going to Vedanthangal bird sanctuary. So, we are taking all efforts to make Vandalur an ideal place for them," Reddy noted.

Biologists point out that another key reason to plant saplings inside the tank, is that psychologically, birds prefer nesting on trees located inside waterbodies. This is because the environment is safe from intruders.

"Barringtonia is ideal since the tree can withstand waterlogging for an indefinite period," said zoo biologist, Dr Manimozhi.

In addition, since these trees are tall, it is easier for migratory birds to catch their prey. "This plant species is the preferred one in most locations including Vedanthangal," he added.