It’s mid-May with monsoon just around the corner, and the migrant wildlife in the Wayanad Wildlife Sanctuary is planning to go back home.

Bigger mammals like elephants and gaur will soon be returning to their home turfs in the forests of Tamil Nadu and Karnataka. Whereas the migratory passerines will bid adieu to the Western Ghats and fly back to their far-away homelands in the Himalayas, South China, North East Europe and Siberia.

In large numbers

“When we talk about migratory birds, quite often the focus is on the large congregation of water fowls including shorebirds, as they are easy to spot and arrive in large numbers. But there are thousands of passerines that arrive from far-off places to the Western Ghats,” C.K. Vishnudas, ornithologist, says.

The State hosts one of the largest tracts of pristine forests of the Western Ghats and is home to a large number of forest birds, Mr. Vishnudas adds. A study led by ornithologist C. Sasikumar recently found that 88 species of avian population in the Western Ghats are annual migrating birds. Passerines form 48 species of these migratory birds — black birds, Orioles, Drongos, Flycatchers and Thrushes. There are also nearly 40 species of waterfowls and waders such as Pipers, Clovers and shanks.

The migration to the Western Ghats occurs usually in August when the monsoon recedes from southwest India. The birds come in hordes and fill the forests.

The tiny brigade

The study also revealed that a few among the species add to the density of avian population in the State’s forests during this phase. The density of Greenish leaf warblers in south Kerala forests is 44 birds per sq km. For migratory bird Blyth’s reed warbler, it is 25 birds per sq km. These birds are so tiny that the average body weight is 8-10 grams.

Yet, the most densely found bird in south Kerala is a native species — the Hill myna that has a count of 50 birds per sq km.

“Most of the migratory forest birds are insectivores and thus play a major role in keeping the insect population in balance. Whatever threat our forests face will thus have an impact on these migratory species,” he adds.