The caw of the house-crow is replaced by the deeper note of the corby. Instead of the crescendo shriek of the koel, the pleasing double note of the European cuckoo meets the ear. For the eternal coo-coo-coo-coo of the little brown dove, the melodious kokla-kokla of the hill green-pigeon is substituted. The harsh cries of the rose-ringed paroquets give place to the softer call of the slaty-headed species. The monotonous tonk-tonk-tonk of the coppersmith and the kutur-kutur-kutur of the green barbet are no more heard; in their stead the curious calls of the great Himalayan barbet resound among the hills.

The dissonant voices of the seven sisters no longer issue from the thicket; their place is taken by the weird but less unpleasant calls of the Himalayan streaked laughing-thrushes. Even the sounds of the night are different. The chuckles and cackles of the spotted owlets no longer fill the welkin; the silence of the darkness is broken in the mountains by the low monotonous whistle of the pigmy-collared owlet.

The eye equally with the ear testifies to the traveller that when he has reached an altitude of 5000 feet he has entered another avian realm. The golden-backed woodpecker, the green bee-eater, the “blue jay” or roller, the paddy bird, the Indian and the magpie-robin, most familiar birds of the plains, are no longer seen. Their places are taken by the blue-magpies, the beautiful verditer flycatcher, the Himalayan and the black-headed jays, the black bulbul, and tits of several species.

All the birds, it is true, are not new. Some of our familiar friends of the plains are still with us. There are the kite, the scavenger vulture, the common myna, and a number of others, but these are the exceptions which prove the rule.

Scientific ornithologists recognise this great difference between the two faunas, and include the Himalayas in the Palæarctic region, while the plains form part of the Oriental region.

The chief things which affect the distribution of birds appear to be food-supply and temperature. Hence it is evident that in the Himalayas the avifauna along the snow-line differs greatly from that of the low, warm valleys. The range of temperature in all parts of the hills varies greatly with the season.

At the ordinary hill stations the minimum temperature in the summer is sometimes as high as 70°, while in the winter it may drop to 23° F. Thus in midwinter many of the birds which normally live near the snow-line at 12,000 feet descend to 7000 or 6000 feet, and not a few hill birds leave the Himalayas for a time and tarry in the plains until the severity of the winter has passed away.