Callous! Freeloaders! Noisy! Parasites! Pests! Selfish! Cuckoos shamelessly qualify for all these epithets, yet go about their everyday life without concern for what the world thinks of them.
The Common Cuckoo (formerly Eurasian Cuckoo), with its cuckoocuckoo call – cutely captured by cuckoo clocks- bestowed cuckoos their family name, though others have different calls. About 40% of cuckoos are brood parasites (they lay their eggs in another bird’s nest and do not build their own) and for this reason, their breeding has to coincide with the breeding of host parents.
Most resident birds, in whose nests cuckoos lay eggs, breed in the summer (as by the time their young are born, the rains would set in and there will be plenty of food for their chicks), and this is why cuckoos also breed in this season. Thus, they are vocal at this time to mark their territory, woo a mate, and to divert the attention of host parents when the female makes a dash to lay her egg in their nests!
In most of India, this is the best time to hear them as resident cuckoos come alive for mating and breeding, as do migratory cuckoos who arrive here for breeding.
Cuckoos happily skip all the efforts of lovingly building a nest, laying eggs, hatching them, feeding its young and teaching it the ways of the world. All these efforts are left to a foster parent as the female cuckoo simply lays its egg in another bird’s nest. The Indian Cuckoo may lay its egg in the nest of drongos and crows; the Asian Koel in the nest of crows, Common Myna; the Drongo Cuckoo in the Ashy Drongo’s nest; the Common Hawk Cuckoo in the Jungle Babblers nest, crows or Ashy Drongo’s nest; the Banded Bay Cuckoo in the nest of Common Iora, bulbuls and babblers.
Typically, a female cuckoo lays one egg in the host parent’s nest. When she is ready to lay the egg, both parents often conspire to carry off the act keeping an eye on the host nest, waiting for a moment when it is unattended or using some tactic to draw the host parent away from its nest. When the moment is ripe, the female cuckoo quickly reaches the nest. Typically, she will not lay eggs in an empty nest (to arouse suspicion of the host parent), and on reaching the host nest, she will make space for her egg. This may involve removing one or more with her beak or eating one to make space for her own. To adapt to the possible impact of a quick dropping of the egg in the host nest, cuckoo eggs have evolved to form thicker shells than those of other birds!
The cuckoo’s egg is small for a bird of her size, and this means she can lay many eggs, in many different nests, during the breeding season. As she lays eggs in several nests, over time many cuckoo chicks hatch in the area. This distribution minimises the chances of losing her eggs to nest raiders; so in a way parasite breeding helps cuckoos to lay more eggs and increase their numbers.
Growing its Wings
After laying an egg in the host nest, the cuckoo parents leave it to the foster mother to hatch the egg and the foster parents to feed their young one. The foster parents invariably take on the task with full responsibly of looking after the chick (that appears different and which may be much larger than their own) that is not their own and often have to work doubly hard to keep up with the pace of growth of their ‘adopted’ chick.
“The Banded Bay Cuckoo is smaller than other cuckoos, so it lays its eggs in nests of birds that have smaller eggs. In the Dandeli forest, we saw a Common Iora feeding the chick of a Banded Bay Cuckoo. Often the cuckoo chick is the only chick in the nest or the largest of the brood in the nest. This is possibly because a cuckoo’s egg is more developed in the female cuckoo’s body before it is laid. Thus, it hatches fast and then the cuckoo chick, taking advantage of being the first child and through its own persistent cheeping, gets ample nourishment,” says birder Mandar Khadilkar.
Some cuckoo parents may keep an eye on their chick from a distance and when they feel it has grown up enough, just may stake claim to it! “In the Tashiding Valley in Sikkim, we saw an interesting sight. A Drongo Cuckoo had evidently laid its egg in the nest of an Ashy Drongo. We saw two adult Drongo Cuckoos on a wire, and both were calling at an Ashy Drongo perched on a tree with a Drongo Cuckoo fledging. The two Drongo Cuckoos then shooed the Ashy Drongo away and took the fledging with it. The chick innately responded to the calls of its real parents.” And so the cycle of life goes on, with the baby cuckoo going by its instinct, embedded over years in its DNA, growing up and perpetuating in its being, one of the mysteries of nature.
Words: Brinda Gill