25 July 2013

Indian Bird Nests—Part Two


The first part of this narrative which covered the main types of bird’s nests found in India, can be found at this link here

This second part of this narrative deals with four birds found in India who have a less conventional arrangement with nests and raising their young. This second part is also compiled from the works of the famous Indian ornithologist and naturalist, Salim Ali. 

Whatever its pattern, the nest is always true to the type of the species that builds it, and is primarily the outcome of instinct fixed and inherited through countless generations of builders. Experiments have shown that birds hatched in an incubator who can therefore have no idea of the sort of nest built by their kind, will, at the appointed time, build nests after their own specific pattern. A great deal of other seemingly intelligent behaviour of nesting birds, such as solicitude or love for their offspring, and the ‘broken wing’ trick practised by many different species to draw off an intruder from the nest or young, prove upon analysis to be largely the working of a spontaneous intellect. 

The below are examples of four remarkable nesting habits and behaviour of some common Indian birds. 


The Hornbill 
At mating season, after courtship, the female Hornbill retreats to a natural hollow in some tree-trunk, perhaps even the same that has been used for a numerous number of Hornbills. The bird incarcerates herself within the hollow, singer her droppings as plaster and the flat sides of her enormous bill as trowel to wall up the entrance, merely leaving a narrow slit through which to receive food brought in by the male It is ascertained that besides the female’s own excrement there is a considerable proportion of mud or clay mixed in the cement, thus it seems likely that the male assists his mate in the work of closing up the next by bringing mud to her. 




Hornbill at Nest


The plaster sets so hard that it prevents predatory animals from entering the nest. The female remains in this self-imposed confinement until after the young (two or three in number) hatch and are about a fortnight old. All the time the female is in the nest with her young, the male brings her food. Foraging for his mate wears the male Hornbill down, while the female becomes enormously plump during her chose confinement. 



Female inside nest with Chicks


When the young are about a fortnight old the female breaks down the wall by hammering away at it, and thus releases herself. After her exist the wall is usually built up once more and thenceforth the parents forage to feed the young until they are old enough to be let out to fend for themselves. 



This bird is a polygamist with a unique system. At the beginning of the rainy season, the colourful males start to build their pendant shaped nests, chiefly on Babool trees or date palms and preferably standing in or overhanging water. When the building of the next reaches the crucial ‘bell’ or ‘helmet’ stage, there is a sudden visitation from a party of prospecting hen Bayas. The females inspect the nests, entering to inspect the interiors and seemingly indifferent to the amorous advances of the male. 




Construction of Baya Weaver Nest


If a hen is satisfied with a particular nest she calmly ‘adopts’ it and moves into possession. Thenceforth she and the builder are husband and wife. The male works to complete the nest while the female busies herself with tidying the egg chamber. 


 
Male Weaver completing nest

As soon as the next is completed and the hen settled on the eggs within, the male commences to build himself another nest on a nearby twig. In course of time this too if approved, is similarly appropriated by a second prospecting female who then becomes the second wife. The process may continue until the male simultaneously finds himself husband of up to four wives and father of numerous chicks. 


The Buttonquail 
Normally the male bird is more brightly coloured than the female. However in the case of the Buttonquail, the role of the sexes is reversed. Here it is the female who is the larger and more brightly coloured and who is the aggressor in courtship. She decoys males by a loud drumming call, courts them, displays her charms and engages in battle with rival hens for the ownership of the male. 
 



As soon as a husband is secured and the eggs are laid, the hen leaves the male and wanders off in search of new conquests. The husband is then left with the entire responsibility of incubating the eggs and tending the young. The roving hen may manage to attract three or more cocks as husband. And in this manner each hen may lay several clutches of eggs during a single season. 


The Parasitic Cuckoo 
A large section of the cuckoo family are parasitic on account of building no nests of their own but instead utilising those of other birds for laying in, and foisting their own responsibilities upon the proxy parents. 



Crow's Nest


Examples of parasitic cuckoos are the Brainfever Bird who lays in the nests of Babblers, often removing one of the rightful eggs to make room for its own, and the Asian Koel who habitually parasitizes the House and Jungle Crows. The eggs of parasitic cuckoos usually bear a close resemblance to those of their hosts or foster parents. 


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