MIGRATORY BIRDS OF INDIA

Bird migration is a special type of behavioural adaptation found in some special groups of birds – migratory birds.

Asif Raja Khan

They move from one place to another in search of better resource availability and better breeding ground on seasonal basis. They face different types of challenges during their journey; several natural calamities, predation, and habitat destruction cause high cost in mortality. According to Sekercioglu (2007) and Rolland J. et al (2014), among world’s 10000 bird species, 1800 are migratory in nature.

In the Indian subcontinent, more than 220 types of migratory birds can be found every year, most of them choose the Indian subcontinent as their wintering ground, though some of them are monsoon and summer visitors. They come here from different corners of the world – some of them come from Arctic tundra region; some of them come from Europe, Northern Asia, and even from Iceland. But not all migratory birds do long-distance migrations, some bird species are short-distance migrant in nature; they travel only some hundreds of mile in search of better food resources. In the Indian subcontinent, some short-distance migrants of Himalaya change their altitude only, in response to the weather condition – this is called altitudinal migration.

WHY THEY CHOOSE INDIA?

Generally birds migrate from an area with decreasing resources to an area with high resources. We all know, because of the geographical condition, Indian subcontinent is always full of resources throughout the year. Indian subcontinent is geographically, as well as ecologically very variegated; different types of habitats, like large wetlands, green grasslands, a super long coastline, warm desert, evergreen forests of great Himalayas, Mangrove forests, dry deciduous forests of central India have adorned Indian subcontinent. A large number of winter migratory birds choose different types of habitats for wintering. Some summer migrants and monsoon migrants arrive in the Indian subcontinent every year.

Birds of northern hemisphere can’t tolerate the freezing temperature of Northern latitude during winter. Every year in winter, they try to escape from the deadly cold by migrating towards South and choose some areas with preferable weather condition and enough food resources for wintering. The mild cold weather of the Indian subcontinent during winter is very comfortable for them. Large number of migratory birds from the northern hemisphere terminate their migratory journey after reaching the Indian subcontinent.

HOW BIRDS MIGRATE?

There have been so many debates over a century about this topic – How birds migrate? Great researchers from all around the world proposed their own hypothesis about this mysterious behavioural adaptation of birds. Let’s try to list up some of the popular hypotheses about bird migration. We are not scientist, it’s very tough for us to understand those research articles; we will try to discuss in very simple language.