As autumn approaches, all over the Northern latitudes, the birds, be they passerines, (perching birds), waterfowl, raptors et al begin to prepare. They have spent the spring and summer in the vast reaches of Siberia, Central Asia and northern Europe bringing up their broods on the generous bounty of life that thrives here during this time.

But now, as the days shorten and the nights get colder they are restless. They eat frantically, putting on weight and practice their flying skills with their young. Ahead lies the greatest challenge of their lives, especially for their fledglings, perhaps. And then, one day, when photoperiodism (the number of daylight hours and probably specific to each species) tells them so, they are up and away in huge flocks. The smaller ones fly by night, the larger ones in groups by day. And, of course, they are followed by gimlet-eyed raptors, harriers, hawks and eagles, keeping track of the young and weak.

Birds, like swallows that have bred in drizzly UK, head for the sunny climes of Africa as do many others. Waterfowl, waders, cranes and storks as well as tiny-tot warblers and flycatchers that had made the endless prairies and forests of Russia and Central Europe their breeding grounds, stream down towards the great Himalayas, flying past the mountains from either end, some – like the bar-headed geese – even daring to overfly mighty Everest. They’re heading towards wetlands and grasslands and forests of the subcontinent, where they plan to spend the winter holidaying. Some, like the astonishing little Amur falcon flying west all the way from China, across the subcontinent, resting in places like Arunachal Pradesh – and even here in Goa – before setting off to cross the Arabian Sea towards west Africa. Some, like the bar-tailed godwit have enormous stamina – winging 13,600 km non-stop from Alaska to New Zealand. The magnificent Siberian cranes, that have raised their chicks in northern Siberia, will head to Lake Baikal in China. (Another smaller flock made the Keoladeo National Park in Bharatpur their holiday resort, before they were shot to pieces over Afghanistan and Pakistan.)

All of them know one thing: the breeding homelands which they left behind, will for the next three or four months be covered with snow and ice. Prey species such as insects and rodents will either die or disappear underground and the trees will be bereft of foliage, the ground hard as granite.

While many will be happy enough to splash down in the wetlands near Delhi, for instance, (notwithstanding the pollution) delighting large groups of bundled up birders, others will fly further south, to places such as Pulicat lake and Point Calimere.

And on a similar note, I will check the date that Diwali falls on and will pack my bags and head for the sunny climes of Goa before firecracker lunacy and Dickensian gloom and doom falls on this masochistic ancient capital of our country.

Now all these places where our migratory guests decide to stay for much deserved R&R have their own resident species, who have lived there the year round and brought up their families here. The spot-billed duck is one of them for instance. Unlike residents in other countries of the world they do not take affront to the arrival of the visitors or even demand to see their passports or visas. Nor do they take offense to the somewhat casual way in some of these visitors, dress – the waders for example, all in confusing splotches and dapples of brown, grey and white – making identifying them difficult for those huddled up birders. Little warblers, weighing maybe 10 gm and having flown maybe 8,000 km to be here, are usually dressed in various shades of brown and beige and will drive birders nuts. Many just settle the issue by calling them ‘little brown jobs’. But none of these birds are handcuffed and caged and deemed criminal and put on the next flight home in leg-irons: at the most they may be radio tagged so their migratory route can be traced – and protected.

It is immensely heart-lifting to watch the arrival of a flock of migratory birds. High up, skeins of cranes and storks spread across the sky in great echelons, calling hauntingly to each other, geese may fly lower in classic V formation, honking their arrival and if you hear a fighter-jet like whine, look up – there will be ducks speeding past, then jinking and whiffling as they seemingly drop out of the sky with heart-stopping suddenness and splash-land and wag their tails on a job well done.

Then as spring approaches, some of the gentlemen migrants, especially among the salt-and-pepper waders, will begin to change into suits rich with russet, gold, grey and black. Bickering will break out and among the ducks too, there will be indignant racing and chasing over the water as the ladies are sought out. And then one day, the waterbody will lie still and silent, save for its faithful, forlorn residents. Up in the breeding grounds of the vacationers, life hums back as the exhausted birds arrive and proceed to start new families, some with new partners others remaining faithful to their betrothed.

And if you thought this was impressive enough, well here’s something: Even insects are capable of such prodigious journeys. The monarch butterfly of North America flies down to Mexico on the approach of winter and hibernates here. As spring approaches, it flies back north, dying en route but leaving its flight plan to its young, which still have to hatch into adults. One generation does the southwards journey, three or four the subsequent northern one. Go figure!