Watching the birds in the back garden gives a fascinating insight into the way that seemingly similar creatures can occupy different niche positions in nature. Each species has something slightly different in its physiology or behavior that allows it to carve out a living. There are birds that hang off the nuts on our bird feeder, there are those that grub under leaves looking for invertebrates and there are those that will eat other small birds and carrion.
Then there is the fat pigeon as we call it. The common wood pigeon that wakes us up each morning with its cooing and wanders about underneath the bird feeder, opportunistically looking for leftover scraps. He (I am making an assumption here as it may be a she) is too big to make use of the feeder though it is not for the want of trying.
I’ve noticed though, when he takes off he does so with a great clattering noise as if his wings are slapping together. We used to have a pigeon duckett behind our house, a throwback to a forgotten time, and I recall how the birds would circle overhead, the air filled with whistles and claps of their wings.
This got me thinking, which is always a dangerous thing. Flight is a costly exercise. We know that evolution has led many species of birds to give up flying when the energy could be used better elsewhere and so why waste energy making such a noise? Surely, evolutionary pressure would have perfected the flight of the pigeon to avoid wasting kinetic energy. Noiseless flight must be more efficient than noisy flight.
Clearly there must be some other explanation and a quick visit to my favourite search engine tells me that the common wood pigeon is a gregarious bird, normally living in flocks. Our garden is too small to hold more than one or two but this is not typical of their normal habitat. Out in the open they are prey to predators both land based and from the air.
Making a loud racket when taking off will warn the other members of the flock that they need to make themselves scarce and will also confuse any predators, making a kill less likely. Any losses in the less efficient use of energy in flight is more than made up for in survival rates. This makes sense when you see the birds in flocks but not when only seeing fat pigeon.
Everything is for a reason and survival is a fine balance.