Not So Cuckoo
from the book, "Petrified Lightning"
Not So Cuckoo
For many centuries the cuckoo has been regarded in a variety of contradictory ways. It has been the herald of spring and a symbol of good fortune. As a voracious eater of insects, especially the larvae of many species harmful to crops, it has been considered a friend of the farmer. Its name represents the loud insistent call of the common cuckoo of Europe and Asia; the word for cuckoo in many languages is also a phonetic representation of its call.
The slang use of "cuckoo" to mean crazy or foolish seems appropriate for a noisy creature with such a reprehensible lifestyle, for the cuckoo is best known as a self—serving, insensitive, ruthless parasite. Not only does it not build its own nest, but it lays its eggs in the nests of other birds, dumping an egg of the nest builder to make way for its own. The nest builder becomes the foster parent charged with the task of brooding, feeding, and raising the squatter to maturity. Meanwhile the mother cuckoo has taken off for a trip of 2,000 miles or more to an ancestral wintering place.
Of the 127 species of cuckoo, fewer than half are wholly parasitic. These include the Old World species of Europe, Asia, Australia, and the Pacific Islands. Those of the Americas usually build nests (however shabbily), brood, and care for their young. An exception is the American striped cuckoo, a typical parasite whose eggs are deposited for adoption.
The striped cuckoo is best known for its melancholy, whistlelike call and because it doesn't know when to shut up. People subjected to its song for hours would doubtless like to quiet it permanently. However, the striped cuckoo has a very effective defense: a talent akin to ventriloquism. By varying the amplitude of its whistle while turning its head, it gives the illusion that it is moving about. In spring 1992 an ornithologist attempting to record the birds whistling to each other felt he was stationed near enough to the bird to tape the song, because the whistle seemed about 10 feet away. He was absolutely astonished to discover that the elusive but stationary bird was actually several hundred feet from him. The frustrated ornithologist was never able to get close enough to activate his recording instruments effectively.
The common cuckoo of Eurasia is typical of the legendary parasitic cuckoo. The female's most advanced parenting skill is her selection of a proper foster parent, thus ensuring that her offspring will have a good chance for survival. She keeps watch on a smaller bird, typically a perching bird, as it builds its nest. Immediately after the foster parent completes the nest, lays her eggs, and flies off in search of food or relaxation, the female cuckoo flies down. She lifts an egg out of the nest, swallows or drops it, and lays one of her own in its place—all within about eight seconds. Then she is off and away!
The common cuckoo, which winters in Africa or India, begins her migration immediately after she has deposited her last egg in a host parent's nest. She will never meet her offspring, but she can be confident that they are receiving the best possible care.
The parasitic egg is safest if it resembles the eggs of the host in color and markings. The natural parent has also been careful to select one of over 300 species of birds that nest high in trees and do not begin to brood their eggs until all are laid. Interestingly, each female cuckoo chooses a single host bird species for all the eggs she lays. Possibly when she was reared by her own foster parents she was imprinted with the type of nest, eggs, and bird that had been adequate to her needs, and she retained this impression for life.
The returning foster parent seems not to notice that one egg is larger than the others. Occasionally clutches of eggs containing a cuckoo egg will be abandoned by the foster mother, but usually she obeys instinct and accepts whatever is in the nest. The cuckoo egg hatches in 121⁄2 days, a half—day or more before its nest mates. This, along with its larger size, gives it a decided advantage over the natural offspring. The newborn cuckoo will first attempt to evict the other eggs or hatchlings; it maneuvers itself to the bottom of the nest, balances an egg in a depression between its wings, and hoists it overboard. Any that survive being tossed out will be ignored by the parent, for her only concern is the occupants of the nest.
The baby cuckoo is usually successful in removing all competition for food. Even if any eggs or babies remain after it cleans house, they will surely be no match for a larger, older, rapidly growing cuckoo. A widely gaping brightly colored mouth triggers the parent to drop food in, so nest mates will probably starve.
The foster parent is hard put to keep the young cuckoo fed, and it becomes more unwieldy as it grows. By about three weeks it is too large for the nest and is soon larger than the parent. A grotesque caricature of bird family life is a tiny host parent perched on the back of a large, noisy foster child, trying to push enough insects and grubs down its gaping beak. The well—chosen parent continues to nurture the offspring until it is fledged and ready to fly.
Most amazingly, the young cuckoo makes a completely unguided flight across 2,000 miles of unknown territory. Both the flight path and the destination could have been reckoned only by instinct. After that, even a chance meeting with its natural mother in their ancestral home should not be surprising.