"So, naturalists observe, a flea has smaller fleas that on him prey; and these have smaller still to bite ’em; and so proceed ad infinitum."
- Jonathan Swift

January 14, 2010

January 14 - Cuculus canorus

Parasites aren't all squirmy worms or microscopic organisms. Sometimes they are devious birds. The common cuckoo, Cuculus canorus, is the classic example of a brood parasite - an organism that lets another raise its offspring. Female cuckoos lay their eggs in the nests of other birds, tossing out one of the host's eggs (because birds are very good at counting!). The young cuckoos often hatch first, grow larger, and will kick out the baby host birds. Cuckoos have even evolved the capacity to mimic the eggs of most of their hosts.


  1. The big mooch...That looks so ridiculous.

  2. That's one of the oddest aspect of the cuckoo-host coevolutionary arms race - many birds which are cuckoo hosts have evolved to be extremely good at distinguishing colours and patterns of eggs to exclude those laid by brood parasites.


    Yet at the same time, they seem to overlook very obvious cues like shape and size of the eggs. Same with the chicks they are feeding. It is possible that the bright red mouth gape of the cuckoo chick presents what's know as a "supernormal stimulus" which hijack the normal nurturing behaviour of the host bird.