When talking about avian parasites, there is one bird that demands attention above all others — the Common Cuckoo (Cuculus canorus)
We all know they lay their eggs in other birds’ nests, but did we also know this is called brood parasitism? Well … it is, and that’s why we’re here.
If I’m going to be honest, I can’t blame the Cuckoo. I mean, babies are a huge hassle, always demanding food, leeching off their parents, creating all sorts of fuss … and noise. Wouldn’t life be so much easier if you could just dump them on someone else so you could get on with the business of being a London socialite? I know what I’d do.
For some strange reason though, the Cuckoo’s favourite host, the Reed Warbler (Acrocephalus scirpaceus), is never keen on volunteering for the job, so you’ve got to trick them.
So here is the Cuckoo’s 3 step guide to offloading the kids.
Step 1: You need to scare the host parents away from their nest. To do this, the Cuckoo has evolved to closely resemble a Sparrow Hawk (Accipiter nisus). They have the same grey colour and barred breast. When a little Reed Warbler sees what it thinks is a Hawk it’ll momentarily flee its nest providing the Cuckoo with the chance it needs.
Step 2: Eat one of the host’s eggs, because, hey, why not?
Step 3: Lay your own egg in the nest. The whole process takes about ten seconds. Craftily, they’ve also evolved so their eggs look very similar to that of the host, making it hard for them to spot an alien. Then, you’re done and your baby is on its own.
But don’t worry, because once the blind baby Cuckoo hatches it picks right up where its mother left off. The first mission is to push any other eggs out of the nest. Have those eggs already hatched? No problem, push your foster brothers and sisters out as well.
Somehow the blind baby knows to eliminate the competition, and uses its back to force anything else that’s in the nest up and out.
After all that you’re on easy street, my friend. The baby Cuckoo has a great knack for sounding like an entire nest of babies, and its begging calls make the host parents super motivated to feed it up. Within 14 days the chick is generally bigger than its hosts, and it kinda makes you wonder if they ever notice their baby is a monstrosity…?
After that the Cuckoo moves out and starts going about its Cuckoo life, trying to pick up work in the clock industry.
It does raise one interesting question though. How does the Cuckoo know it’s a Cuckoo, even though it was raised by other birds? Why doesn’t it think it’s a Reed Warbler? Such are the mysteries of the bird world.
24/11/2019
Bird of the Week 