It was a bright but coats-on day in early summer when we took a walk on Islay in the company of Dave Winnard, birder and conservationist, founder of Manchester’s Discover the Wild. Here’s what we learned about our avian community through Dave’s account of the birdsong we could hear. (Taken from a transcript of a recording made that day.)
Jane Carswell, The Botanist [JC]: Tell us about these bird calls.
David Winnard, Discover the Wild [DW]: The one we can hear in the background – there’s quite a few of them – these are skylarks. You can barely even see the birds cause they’ll be singing so high up. The reason they do that, is it’s all about marking territory. Attracting a mate. And the louder you can sing, the more impressive you are, as the male.
So birds have evolved different ways of kind of being able to really shout out. Birds like bittern, and cetti’s warbler that live in reed beds have had to evolve very loud calls to get heard, because as soon as you start calling it a reed bed it gets muffled very quickly by all the reeds. They say you can hear a bittern from a few kilometres away. It’s a really deep booming call – they call it the booming bittern.
Skylarks, if we had one in the hand and it was singing, it wouldn’t be overly loud. So to compensate for that, they fly very high up into the sky. You can see that one just up there towards the cloud. So they fly very, very high up, and then the soundwaves spread it out, so you can hear them from further away. It’s why blackbirds always sing from tops of telegraph poles and things like that, because it helps them spread the sound. But it’s also the reason they sing at dawn and dusk, because the air’s thinner. Whereas if you start singing at midday when the air’s denser, with the same amount of effort, your song’s not going to travel as far.
JC: And earlier we heard a curlew…
DW: We heard a curlew before, which was making an alarm call. That suggests that it’s definitely got young nearby. Letting them know to take cover, basically, or letting us know to keep away. But curlew’s an interesting one, because they take roughly about 28 days to incubate the eggs. Some birds have a short incubation time, then chicks are going to spend a couple of weeks, three weeks maybe, in the nest. Whereas things like curlew, because they’re nesting on the ground, they’ve got to get the young away because the nest will give off a bit of a scent so things like foxes, badgers, predators will be able to find them. So a lot of these wading birds like curlew, lapwing, and dunlin have evolved to have the female or the male so well camouflaged, they can sit on the nest for as long as necessary. Then as soon as the eggs hatch, within a couple of hours, the young are so developed they’ll just be running around, and that’s it. They’ll just hide in amongst the grass and follow the mum around, keep moving, try to lose their scent.
A curlew nest is a nice, you know, traditional kind of nest lined with grasses, it looks nice and comfy. But it’s basically just there on the ground. A curlew might lay three or four eggs and the chances of those four eggs becoming adult birds is so, so remote. If they can get one away, it’s a good result.
JC: Really, is it only about 25%?
DW: Where I am in Greater Manchester, we monitor quite a few nests as part of the kind of nest record / monitoring scheme for the British Trust for Ornithology. You do one visit finding it, and then you follow it up with another visit to see if it’s been successful or not. And with some species, you can be talking about 85, 90% fail rate. Either eggs aren’t fertile, or more likely, the nests have been ragged by crows, magpies, foxes, badgers. We’ve even had camera traps up at certain nests and deer have just been walking past, stumble across a nest and eaten the eggs. And you never think that deer were going to predate things, would you!