Bog Myrtle & Peat

It’s been hard to find curlews over the last few weeks. Not only have the birds turned out to be more scarce than I had feared, but I begin to see that there are also some behavioural tricks that tip the scales against the would-be surveyor.

In a cold spring like this, breeding pairs seem to be running late. They might have a clear idea of where they intend to lay their eggs, but they’re only showing a vague interest in nesting habitats. They’ll scope out good spots, but I’m finding that they don’t linger there for long, and even where I know a pair is present and intending to breed, the birds might spend much of their time elsewhere, returning every few hours to perform a few brief displays. That’s confusing, and it makes it hard to see what’s happening.

Combine this with the theory that when the number of curlews falls below a certain local density, displays become less obvious. That makes sense; there’s no point riding the marches all the time if you don’t have any neighbours. I feel confident that isolated pairs are more secretive at this stage of the breeding cycle than those birds which live in thriving colonies, but I have no evidence to prove this one way or another. If it’s true, there will be a neat irony in the fact that it’s easier to count birds that don’t need to be counted.

I suppose that pairs will become more obvious as we approach the act of egg-laying, but it’s worth remembering that curlews can often almost vanish during the incubation period. There’s no advantage to flagging your presence when you have so much to lose, so curlew activity is often very subdued during late April and early May. Each year I am surprised by curlews that turn up with chicks as if from nowhere, and this is a constant reminder that when birds choose to remain unseen, they simply disappear.

Of course the sad reality is that many pairs in Galloway will fail during the incubation period. Because they’re already quiet during this time, it’s not always easy to interpret their behaviour or monitor their movements in the aftermath of a lost or predated nest. They’ll usually reset and go again, but these second sittings are often much quieter than a first attempt – yet another reason why curlews can be harder to find than you might expect.

Contrast all this against the fact that curlews with chicks are impossible to overlook. They’re always complaining about something, and their frequent alarms make them noisy, obvious and easy to count. But curlews rarely have chicks in Galloway, so it’s hard to use this period of highly conspicuous activity as an opportunity to count what’s where. This is where the rubric is reversed on thin populations being harder to find.

A lone pair of curlews will have to attend to every threat they perceive to their chicks. They’ll mob anything with vigour, and the pressure is never-ending. But when curlews nest in larger, healthier populations, some pairs will take more than their fair share of security detail. This can mean that other pairs simply keep their heads down and let the noisy birds do the talking. That’s great – it’s a healthy behavioural function amongst birds that evolved to work as part of a community – but if some pairs are obvious and others are not, it makes it hard for humans to count them. I have to say that I consider “too many pairs to count accurately” a problem I’d love to have, and it’s certainly not an issue where I’m searching, but it’s yet more grist to the mill for a project that’s already buried up to its neck in geeky detail.

So it’s clear that the best time to get a sense of curlew presence is when the birds have chicks, but I can’t afford to base my survey on something that happens so rarely here. Instead I need to focus on where birds are trying to breed, and within the complexity of that paradigm I start to believe that there must be a pre-chick sweet-spot where all these contradictory concerns align in such a way that would-be parent birds are at their most conspicuous. I’d reckon it’s during laying or immediately before incubation begins, but that’s a window of a few short days that will vary from pair to pair. There’s more to this than meets the eye.