15 January 2014

Cattle Egret

The Cattle Egret (Bubulcus Ibis and Unni Kokku = Tamil) is a species of Heron found in the tropics, subtropics and warm temperate zones and is seen throughout Tiruvannamalai. In non breeding birds its pure white plummage is distinguished from the Little Egret by the colour of its bill which is yellow not black. The Cattle Egret is white and adorned with buff plumes in the breeding season. 

Cattle Egret, notice the yellow bill

Its wingspan is around 22 in and the bird weights up to 18 oz. It has a short, thick neck, sturdy bill and hunched posture. The positioning of the egret's eyes allows for binocular vision during feeding and it may be capable of nocturnal activity.

Cattle Egret with retracted neck

Cattle Egrets exploit drier and open habitats more than other Heron species. Although the Cattle Egret sometimes feeds in shallow water, unlike most herons it is typically found in fields and dry grassy habitats, reflecting its greater dietary reliance on terrestrial insects rather than aquatic prey. This bird often accompanies cattle, catching insects and small creatures such as frogs disturbed by its attendant cow. 

Arunachala Field with Cow and Egret

The Cattle Egret adapted to a relationship with large browsing animals, but was easily able to switch to domesticated cattle and horses. When foraging with cattle, it has been shown to be 3.6 times more successful in capturing prey than when foraging alone. Its performance is similar when it follows farm machinery, but it is forced to move more. In urban situations cattle egrets have also been observed foraging in peculiar situations like railway lines 

Egret and Grazing Cow

Egret with Grazing Horse

This species gives a quiet, throaty rick-rack call at the breeding colony, but is otherwise largely silent. Its nesting season in South India is around November to March. It often nests in mixed colonies in large leafy trees, not necessarily near water. The male displays in a tree in the colony, using such behaviour as shaking a twig and pointing into the sky with a vertically upward bill. 

Male with material for nest

Its nest is a platform of sticks in trees or shrubs and is constructed by both parents with the male collecting sticks and the female arranging them. 

Nests in large colonies of mixed birds

The clutch size can be anywhere from one to five eggs, although three or four is most common. Eggs are pale bluish-white. 

Abnormally large clutch of Egret eggs

Cattle Egret in Breeding Plummage

Incubation lasts around 23 days, with both sexes sharing incubation duties. The chicks begin to leave the nest and climb around at 2 weeks, fledges at 30 days and become independent at around the 45th day. 

Bird in Breeding Plummage with chicks

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