Going Cuckoo Over the Cuckoo

There seems to be a lot of excitement about a BBC film on the European cuckoo (Cuculus canorus) (http://www.bbc.co.uk/programmes/b00gmxl7) in which the bird is described as "a cheat, a thief and a killer". The clip of the 'murderous' chick throwing the host's chick out of the nest was, apparently, too rich for breakfast time TV! I think that people are getting a bit anthropocentric about the bird's interesting lifestyle. The first thing to note is that brood parasitism (the taking over of parental care and/or resources) is quite widespread in the Animal Kingdom (it's certainly not limited to birds) and obligate brood parasitism (where the animal is incapable of rearing its own young) is not limited to the cuckoo. So far as the cuckoo chick is concerned, killing the young of another species of bird is not 'murder'. It is simply ensuring that it doesn't have to share the resource of parental foraging, an activity that probably couldn't rear the cuckoo chick and natural fledglings (so it's not unlike a parasitic wasp utilising the tissues of a caterpillar). Certainly, this is no 'crueler' than a bird of prey chick consuming a smaller nest mate (from a second egg laid as an 'insurance policy'). A predator eating its prey, a gut parasite consuming the host from the inside, a caterpillar being raised in an ant colony and a virus replicating in host tissues are no less exploiting! A commentator intelligently raised the issue of why the cuckoo chick doesn't inappropriately imprint on its host species as a potential mate etc. It appears that most of this bird's behaviour is programmed (they effectively don't have real parents or siblings to copy). The fact that brood parasitism can be quite ubiquitous and opportunistic is further illustrated by the fact that quite a high percentage of human 'fathers' are genetically unrelated to their 'offspring'. The habit of the photographed Moorhen (Gallinula chloropus) of depositing additional eggs in the nests of their neighbours or even in the nest of a nearby Coot (Fulica atra) is also brood parasitism (although not, in this case, obligate). The whole process of brood parasitism is just a remarkable method of exploiting available resources.