26 February 2009
Dunnocks are fairly quiet, unassuming birds. You'll often see them lurking underneath bushes or shuffling around flowerbeds, looking quite boring. But did you know they have riotous sex lives that might make Russell Brand blush?
We often think about birds living perfect lives as if in a Disney movie. They snuggle up together in their nest, have lots of fluffy babies and stay faithful for life, right? Not true, unfortunately.
Dunnocks have adapted to make use of different breeding strategies. Both males and females want make sure their genes are passed on to the next generation. Where food is plentiful, territories need not be so big, and so there's less opportunity for overlap with those of other birds. Where life is tougher, the territories need to be bigger and that means more interaction with other dunnocks.
For females, that may mean mating with more than one male, in the hope that they'll both help rear her chicks.
Clearly, that doesn't suit the males. So before mating, they may try to remove a rival's sperm by pecking the female's rear end (the cloaca - through which both poo and eggs exit) and encourage her to eject it!
However, what works for one pair of dunnocks might not work for another. There are several different strategies they might use:
A male paired with a female (monogamy)
More than one male paired with the same female (polyandry)
A male paired with more than one female (polygyny)
'Pairs' with two males and two females (polygynandry)
And it's all going on in your shrubbery...