This vast shallow swampy area (max. depth 1.7 m) with abundant aquatic vegetation, fish, snail, frog, insects etc. and plenty of Babool, Kadam, Ber, Ficus and other trees provide an idle habitat for nesting of over 120 species of birds. A large number of migratory birds come to the Park during winter season (Oct. to March). In fact Keoladeo National Park is a paradise for ornithologists and Photo-naturalists. Presence of over 374 spp. of birds in this small area makes it the richest bird habitat in the World. During monsoon herons and egrets breed on the Babool trees in the lake areas. Ideal time for watching migratory birds is between Nov. to March.
Open billed storks arrive 2-3 days before the first shower. Beginning of monsoon in July brings spectacular changes in the Park. Suddenly it is flooded with thousands of birds and is humming with nesting activity. Common species found are Darter, Cormorants, Egrets, White Ibis, Grey Herons, Spoonbill, Painted Stork, Spot bill, Comb duck, Cotton Teal, Bronze winged Jacana, Purple Moorhen, White breasted Water hen, Indian Moorhen, Purple Herons etc. Adjutant Stork leaves after first showers. Sarus Crane also disperses to agricultural fields. Nesting and breeding activities of all these birds is a treat to watch.
Migratory birds start arriving in October for wintering. During winter, Park has maximum bird population when congregation of thousands of migratory and resident birds with juveniles making it a marvelous sight. A white Ibis nesting feeding almost from stomach of the parent or a painted Stork shielding its young from sun by spreading its wings or Sarus Crane parents taking their turns for hatching and protecting makes humankind feel wanting. Important migratory birds are Garganey Teal, Coot, Common Teal, Pintail, Shoveller, Tufted Pochard, Gadwall, Widgeon, Graylag Goose, Pelicans, Brahman Duck, Siberian Crane, Mallard, White Stork, Flamingo etc. Pythons can be seen basking. In India this Park is the only place where the Siberian Cranes come to spend their winter. Every year between 20 to 30 birds and their young ones come to the Park. But their numbers are decreasing every year......
Towards end of February migratory birds start departing with fading winter. By end of March most of Graylag Goose, Pintail, Mallard, Reforested Pochard, Common Pochard, Tufted Pochard, Common Teal, Siberian Crane, Coot, Gargany, Teal etc. are gone.