The Cuckoo......

Cuckoo Egg Mystery:

We were not knowing that Cuckoo is having mystery in our childhood. We only know that it sings well in Monsoon. But in the year 1930 what makes Edgar Chance Research Ornithologist passionate about the singing bird Cuckoo.

It is also a unsolved question for science. We all know Study of birds is Ornithology.One who studies the behavior of birds is called Ornithologist. Indian famous ornithologist Dr.Salim Ali. If you want to know more about him then read his book: The Book of Indian Birds (Salim Ali, et. al.)

Cuckoo is widely famous for her singing. But behind the this beauty it hides its birth mystery. Actually mother cuckoo lays her egg in neighbors nest. Here in India crow will be having the nest, where the cuckoo lays her egg.What we saw in 3 Idiots film of Cuckoos behavior.Its all the way correct.

Why cuckoo will lay her egg in others nest, by killing others egg. Its because of its long time incubation. Normally birds need 21 days long incubation to hatch their eggs. But cuckoo is not capable to do incubation for 21 days. So no other way it has lay her egg down. Nature's gift is it will find the nest of others. here we have to appreciate the intelligence of cuckoo. Those are listed below

1) It will lay its egg when some other birds will also lay down their eggs. Means same season.

2) It will search the nest, where already eggs are present. Normally cuckoo will give three eggs (egg per day). It will push one egg from the neighbors nest, lays her own.Next day neighbor bird lay her egg. After this cuckoo will come and push another egg from the nest here both the eggs are change in size not more little, this can be identified by cuckoo, so that it will push other birds egg not its own, and lays its second egg.

3) 24 hour internal incubation for each egg so that they will take birth one day before the other birds egg and hatched chicks will push the remaining eggs, competition over. Here why the chicks will push the remaining eggs. Its because their voice and their size and the color is completely different from other birds chick. Advantage for chicks, loss for other bird. It will feed like its own chicken. But for other bird it will be very late to recognize that these chicks are not similar to me. But the science it will never understands. It will think, what is this these chicks are not similar to me. It will try to avoid the chicks. Thats all story over.

Now what science will say regarding this,

Only seven groups of birds in the world have evolved as brood parasites, laying their eggs in other birds' nests, and ecologists have long been fascinated by this behaviour as an example of evolution in action.

The Cuckoos are the most variable birds in social behavior and parental care: a few cuckoos are among the most social of ll birds and rear their young in a common nest; most cuckoos ae caring parents that rear their own young with some females laying a few eggs in the nests of others; while many cuckoo species are brood parasites who leave their eggs in the nests of other birds to rear, with their young maturing to kill their foster nestmates.

In The Cuckoos, Robert B. Payne presents a new evolutionary history of the family based on molecular genetics, and uses the family tree to explore the origins and diversity of their behaviour. He traces details of the cuckoos' biology to their original sources, includes descriptions of previously unpublished field observations, and reveals new comparisons of songs showing previously overlooked cuckoo species.

"The eggs are analogous to a bank note, in terms of the variety and complexity of markings, perhaps to make them very hard to forge by the parasite."

To find out exactly how Prinias detect the foreign eggs, Spottiswoode and Stevens set up more than 100 rejection experiments in southern Zambia, putting one Prinia egg into another's nest and waiting to see if the egg was rejected.

They also collected data to feed into a computer model to give them a bird's eye view of the world, using a spectrophotometer to measure egg colours and a digital camera to analyse the eggs' complex patterns.

In the past, this kind of analysis was tackled by humans comparing eggs by eye, but human vision differs hugely from that of a bird. Birds can see ultraviolet light and because they have four types of cone in their eyes, compared with three in humans, they see a greater diversity of colour and pattern.

Spottiswoode and Stevens found that Prinias are amazingly good at rejecting foreign eggs, and that they use colour and several aspects of pattern to spot the parasite's eggs. Mysteriously, however, they do not seem to use the scribbles that uniquely occur only on the Prinias' eggs.

The specific traits used to distinguish foreign eggs were exactly those found to differ most between host eggs and real parasitic eggs. This suggests that natural selection is currently acting to make Cuckoo Finch eggs better mimics of their hosts', and also that Prinias use the most reliable information available in making rejection decisions.

A small brown warbler the size of a wren, the Tawny-flanked Prinia (Prinia subflava) is common in most parts of Africa south of the Sahara, feeding on insects and other invertebrates. Its nest is a loosely woven oval, beautifully stitched among the leaves of small shrubs among the long grass.

The Cuckoo Finch (Anomalospiza imberbis) is an elusive and little understood bird, a touch smaller than a sparrow. The male is yellow and the female brown.

If the Prinia fail to spot the parasite's eggs it pays a heavy price. The Cuckoo Finch chick hatches first, is bigger, and quickly outcompetes to the death its host foster sibling. Soon the nest contains just one or two giant Cuckoo Finches. They are twice the size of the Prinia's own chicks and take much effort to feed.

mpshridhar

Reference:

1) Wildfilmhistory website.

2) www.pnas.org/cgi/doi/10.1073/pnas.0910486107