Eyes on the sky

The Perthshire moors are home to some of my favourite insects, and a rich spot for examining ecological patterns...

Kestrels aren’t the everyday sight they once were but they’re still out there if you know where to look.

It was the white that stopped me in my tracks; not a shiny brilliant white but more a shimmering paleness that shone out from the grass and heather of this Perthshire moor.

At first I thought it may have been a flower, but when I crouched down closer I realised it was a magpie moth; a real dazzler of an insect with a beauty to rival any butterfly. The pattern was quite dramatic — symmetrically arranged splashes of black and orange beautifully offset by its pallid wings.

It’s a shame that butterflies get all the plaudits when moths and so many other types of insect are equally as striking. And even those that are not top of the beauty league are no less fascinating for it. I admire these underdogs of the animal kingdom and make a point of seeking out such creatures whenever I can.

Magpie moths often occur on hill and moor but they are found in gardens too, where their caterpillars are a pest on currant bushes. Birds tend to avoid them as they are toxic to eat and the caterpillar advertises this fact through its bold warning coloration.

As I examined the moth, I was aware of the continual (and rather monotonous) seagull-like cries of a family of buzzards from a nearby forestry plantation. But in amongst the buzzard noise, I could hear a higherpitched chattering.

It was a kestrel family: a mother and two fledged youngsters working their way along the forest edge and passing right beneath the soaring buzzards. The young kestrels were incredibly noisy; right little livewires who were finding life so very exciting and which contrasted starkly with the mournful mews of the buzzards.

From being common 30 or 40 years ago, kestrels are now much less so. Conversely, buzzards have had a remarkable turnaround in fortunes and are currently our most abundant bird of prey, having soared in numbers in recent decades.

I reckon there is a connection here, in that the buzzard has displaced the kestrel by out-competing it for food. Rising populations of goshawks and peregrine falcons may also be adding to this pressure through direct predation, whereas in the past kestrels had a free rein and limited competition. So maybe there is a bit of a natural reset going on here.

But then again, things are seldom black and white in nature and most likely there are other factors at work too. The most obvious one is habitat loss — particularly in areas of rough grassland — which has resulted in fewer voles and mice being around for kestrels to prey upon.

The kestrels disappeared over the rim of a small hill and I wondered what the future holds for these wonderful little falcons. They are up against so many complex environmental challenges and I doubt they will return to their former abundance any time soon. Kestrels typically hover when scrutinising the ground for voles and mice. They also eat a range of invertebrates. The male has a grey head and tail, whilst the female is largely brown all over.