If you visited us in the early months of the year you may have noticed small pieces of string adorning some of the blackthorn bushes around the nature trail. These were marking the locations of brown hairstreak butterfly eggs found during our annual survey.
These beautiful, but rather elusive butterflies, lay their eggs in the fork of a blackthorn twig, favouring the junction between old and new growth. Another good reason for our hedgerow and scrub management - cutting the blackthorn back helps to prompt the nice new growth that they like. Doing this on a rotation basis ensures that there should always be several stretches of blackthorn hedgerow that are suitable.
Photo from Phil Thornton
Close up, the detail on these tiny eggs is revealed - they almost look like sea-urchins!
Searching for and counting the eggs is the most reliable method for assessing the population of these butterflies who spend much of their time high up in the canopy of the tallest ash tree they can find. They seem to prefer the sweet honeydew from aphids more than nectar from flowers.
But now is the time to look for the adults. There is just one generation each year and the butterflies start to emerge in late July and are 'on the wing' through August and into September. If you're keen to find one, use binoculars to scan the canopy around any ash trees, but also look for a smallish orange butterfly flitting around the blackthorn.
I was lucky enough to spot two female brown hairstreaks this week - one as I descended down the zig zag path and another as I walked towards West Mead hide. Both were egg-laying, perching briefly in the sunshine before wandering lower and deeper into the blackthorn to lay their eggs.
Photos by Anna Allum
It was great to be able to watch them searching out a suitable spot and then laying a single egg before flying to a nearby twig and laying another - it certainly helps to explain why we find them in clusters when we search for the eggs in winter-time.
I returned to the Visitor Centre delighted - I'm also feeling that my team will have a bit of a head-start on our 'alternative egg hunt' this coming winter!