We often talk about ‘birdwatching’, but this isn’t the only way to spot birds. This year I’ve been on a bit of mission talking about listening as much as looking, and I’ve had another great illustration of that this week.
Parliament Street in York is a great example of a winter roost for Pied Wagtails. When you get later in the year they are very obvious, with hundreds of them filling the bare trees. But when you are still in Autumn with leaves on the trees, how do you know they are there?
Here’s how (be ready on your volume control…):
Bear in mind when watching that, there is currently a load of joiners putting up the wooden huts for the St Nicholas Fayre. You hear the drills a few times. But the overwhelming, near-deafening, sound is that of hundreds of Pied Wagtails chattering as they jostle for their place in the roost.
So what’s the roost for? There are several benefits. Most obviously, more bodies means more warmth. Thermal cameras have shown the birds at the centre of a roost can be several degrees warmer, critical on a cold night.
You are also safer, as numbers actually make loife more difficult for predators. This may seem counter-intuitive, but actually the more there are on a flock, the harder it is for a hunter to single one individual out to track.
Finally, and this is what we hear above, it’s about exchanging local knowledge. In the morning this flock will break up and go off in ones and twos all over the city, travelling many miles to feeding sites. For a bird that’s maybe had a few bad days, it’s a chance to pick up on the vocal and healthy birds, then follow them the next day. In this way, the whole population benefits.