Britain’s rarest Fritillary has its stronghold on the south coast of the Isle of Wight, but has also been introduced at sites in south-east England. I interested Ewan in going to the IoW to see them but went off the idea on finding the ferry fare for a car and two people is £70. In the meantime Adam had told me about a site near Croydon where the species was introduced in 2011, so Ewan and I went there instead today.
Hutchinson’s Bank (TQ381616) is a London Wildlife Trust reserve covering an extensive area of a dry chalk valley. The steep grassland slopes support a diverse flora and up to 28 butterfly species. We left Oxford in reasonable sunshine but arrived on site mid-morning in largely overcast conditions. Entering the reserve from the end of Farleigh Dean Crescent (CR0 9AD), off Featherbed Lane we joined a group of observers from far and wide who were staking out a sheltered area of the track that they said is a Glanville hot spot. But some people had been there for a couple of hours without seeing any.
A man who seemed to know the site well then suggested another location and most people followed him. Through the next gate and around a few corners we came across an observer who had found a Glanville Fritillary near the valley bottom. This butterfly was perched open-winged on the ground to absorb what warmth it could and hence allowed a close approach. I feared a scrum but each person present took their turn to photograph the insect and so my own pictures were secured.
This was the only Glanville we saw today though 39 were reported a week earlier. Emergence typically begins in mid-May and peaks in early June before numbers decline quickly, so there is a limited opportunity to observe them. The species has long been extinct on the British mainland and introductions have generally been short-lived. The Wrecclesham colony was wiped out by the wet summer of 2012 and I learned today that site is being developed.
Hutchinson’s Bank also supports good numbers of Small Blue. Here’s the underwing shot that I didn’t manage at Hagbourne two days ago. And then there was the big handsome fellow at the bottom – it’s a Roman Snail. Breakfast anyone?!