THOOTHUKUDI: As we commemorate the World Migratory Bird Day on May 14, let us check out our winged visitors’ grim state of affairs in the grasslands of the southern states. Researchers say the number of migratory birds such as harriers is on the decline due to the expansion of developmental projects and industries in Thoothukudi and Tirunelveli. The aggressive rise of windmill projects in the semi-arid regions between Kayathar and Aralvaimozhi has dealt a severe blow to the grasslands’ biodiversity, they say.
The vast expanse of semi-arid land in both the districts is a habitat for hundreds of animal species, including snakes, Indian small fox, mongoose, different kinds of rodents, and over 80 bird species. Lindernia minima, a new plant species, was discovered here recently.
The endangered Madras hedgehogs are also found in this landscape in large numbers. Harriers, a winter migratory bird, reach the Thamirabarani region by the end of September all the way from Central Asia and Russia, and leave by March. Montagu’s harrier (circus pygargus), pallid harrier (circus macrourus) and Eurasian marsh harrier (circus aeruginosus) are extensively found in the grasslands and shrublands of Tirunelveli and Thoothukudi, where they forage and roost during the winter.
“This migratory raptor bird mills over its prey before catching them. It mainly feeds on grasshoppers and also on other insects, rodents, small birds and some reptiles. Interestingly, the harriers follow communal roosting on the ground, with at least five individuals and a maximum of 75 in a cluster,” Vinod, a birder, said.
A Saravanan, a research associate at the Ashoka Trust for Research in Ecology and the Environment, has been researching the characteristics of harriers since 2015. “The major clusters of harriers involve grasslands of Vagaikulam-Vallanadu in Thoothukudi, Moolakaraipatti and Radhapuram in Tirunelveli district. A new species of pied harrier (circus melanoleucos) was found at Vagaikulam in Thoothukudi, and Radhapuram and Moolakaraipatti in Tirunelveli during a survey in 2021,” Saravanan said.
Harriers are under threat due to various anthropogenic disturbances such as canal construction, agriculture and urbanisation. According to an ongoing study, there is a declining trend in the arrival of harriers. The species population was 398 in 2015-16, 276 in 2016-17, 387 in 2017-18, 198 in 2018-19, 212 in 2019-20, 217 in 2020-21 and 201 in 2021-22, said Saravanan.