To attract females. Many species call to attract females even if they don’t defend territories. And feeding territories aren’t the only kind of territory. Males may call to defend their area against other males in order to have exclusive access to any females that enter it. And in any case small birds nesting in the male’s territory can be seen as a “resource” needed for breeding. A male defending nesting areas for small birds could be more attractive to females for that reason.
Why are you assuming that the cuckoo calls at any time besides the breeding season? In temperate areas small birds may breed raise two or even three broods in a spring/summer, so a cuckoo may want to call throughout the potential time nests are available to females. (This said, I haven’t checked to see what the actual calling period is.)
A couple decades or so ago it was discovered that female birds sing quite a bit too. Female bird researchers found this out, and male researchers were hard to convince of the fact. The idea of men I mean male birds defending territories and attracting women I mean female birds was too entrenched in their minds. It is still understudied.
I am not sure about that but I can confirm that the Indian Hawk Cuckoo has a pretty large territory. Usually you only hear one cuckoo at a time so I would guess it has a terrritory of about a mile in diameter.
Also as a child, I would mimic the cuckoo’s call by whistling and it would look around like crazy to spot its competitor.
Well, no. It’s been known for a long time (not just “a couple decades”) that female birds sing, especially as duets with males. No, it wasn’t “found out” by those female researchers, and male researchers didn’t need to be convinced, since it was already well known. They are correct to point out, however, that female song has been understudied, and that many studies do assume that all singing birds are male. However, in most species, especially in the temperate zone, males do almost all the singing, and its function in defending territories and attracting females has been well documented.
I understood the term Cuckold to imply the wife was unfaithful and so the husband was unwittingly raising someone else’s child as his own - a similar concept as the bird itself. The other thing I recall from popular wisdom was that the cuckoo chick would often grow much bigger than the other chicks, being from a bigger bird typically than the unfortunate host. It may even (deliberately?) push rival chicks out of the nest, leaving us with the image of a tiny adult bird like a sparrow frantically instinctively trying to feed a fluffy demanding (greedy) chick even bigger than itself. One can imagine the social commentary in that image, along with the image of a doting husband being fooled by an unfaithful wife.
In Robert E Horward’s Pigeons From Hell he mentions that Whiporwills are believed to be precursors to death. Having been cursed with one once or twice I can believe it’s call would drive you crazy.
