Wednesday, 19 June 2013

Let it shine for butterflies

The run of poor weather through the early part of the month is likely to have had some effect on our butterflies, potentially limiting their development and reducing opportunities for active flight in search of a mate. On the few occasions when the sun has shone it has been reassuring to see familiar butterfly species on the wing. One particularly pleasing sight has been the presence of several small heath butterflies over the short turf of my local nature reserve.

The small heath is a somewhat inconspicuous species and easily overlooked. Even when located it remains a somewhat fidgety butterfly, quickly on the move and reluctant to reveal its upperwings. Often, all you will see are the grey and brown hind underwings and, if you are lucky, a glimpse of the eye-spot that appears on the underside of the forewing.  As the name suggests, this is a small species and one that is associated with grassland habitats on well-drained soils, where the sward is short and rather sparse. Some might refer to this species as being rather drab but I prefer to think of it as understated.

Small heaths are colonial in their habits and the males gather together within a breeding area to form what is known as a lek. Here they compete with each other for the best positions and the resulting access to visiting females. The best areas seem to be those with some form of landmark, perhaps a bush or small tree and it appears that the females visit these specifically to mate, as opposed to feed. Once mated, the female will leave the lek to lay her eggs on the leaves of fine grasses.

Although easily overlooked and, as a result, unfamiliar to many casual butterfly watchers, the small heath is very widely distributed across Britain. It also shows a greater tolerance of altitude than most of our other species, occurring in upland areas across parts of northern Britain. For me though it is a species of lowland heath and rough grassland, a butterfly that I can recall from my childhood and one for which I have a good deal of affection. It is wonderful to have what appears to be a thriving colony here on the Nunnery Lakes Reserve in Thetford.

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