I once watched a city pigeon fly down to a rough border of dried grass and weeds and start selecting a suitable piece of grass for its nest. It was my lunch break and I’d found a quiet space with suntrap to eat and drink, an older part of the city that was surrounded with stone and brick and tile. There was just enough room for the sun to get through and warm up the bench I was sitting on.
So down flew this pigeon. An ordinary city bird, nothing special to look at you could be forgiven for thinking. But as I sat there munching away I saw this busy focused parent go through just about the whole border, a ten yard stretch. It was looking for loose dry lengths of grass – not just any length of grass but of a specific measurement. This bird knew exactly what it wanted.
I watched half in admiration half in puzzlement as this caring nest-builder picked up stem after loose stem, rejecting all until it found one that was just right for the job. This was a fascinating exercise. It seemed to me that this bird was actually measuring the length as it manipulated the stem through its beak in a weighing up fashion.
Eventually the pigeon flew off, up to its nest site under an eave on a solicitor’s office – another part of the nesting jigsaw about to be slotted into place.
I had a think. That bird must have sized the situation up, got an idea of the length of grass needed to fit exactly where it wanted it and knew where that piece could be found.
Hardly a bird-brain, more of a nest-wizard. And to think, this process is going on for most birds – ok not the cuckoo, which has evolved a crafty way of getting out of nest building – using their intuitive powers of measurement and detection to gauge precisely what is needed for their crafted nests.