Glanville Fritillary

I made a return visit to Hutchinson Bank today to see how the Glanville Fritillary colony was progressing. When I visited in 2014 the colony was only just becoming established and despite an extensive search I could only find one butterfly, a female. Today I saw somewhere in the region of fifteen to twenty of them. I am told that the transect is showing twenty four and that we have not yet reached the peak emergence.

This is the rarest of the UKs butterflies with only this colony and one on the Isle of Wight. It is on the northernmost edge of its territory and a bad winter, parasites, or other threats could see it become extinct in this country.

Attempts, by persons unknown, have been made to establish other colonies. These have been at Sand Point in Somerset, Avon Gorge, and Wrecclesham in Surrey, probably using stock imported from the continent. All these colonies seem to have died out, although they are not declared as such, until they have completed three clear years without sightings being made.

There have also been short lived colonies at Hurst Point and other locations on the Hampshire coast but these could well have been seeded by migration from the Isle of Wight.

The population of the Isle of Wight colony fluctuates wildly. This may be due to bad weather or perhaps the impact of parasites that exist alongside the colony. Parasites that at the moment do not appear to be present at Hutchinson Bank.


At the moment it looks like another bad year for the IoW with very few sightings being made so far. They should recover, weather, if that is the cause will improve and it is rare that a parasite wipes out its host completely. If anything should happen to it, at least we now have Hutchinson Bank as a back up holding UK stock.


Update: Good news - fifty plus Glanville Fritillaries reported on Compton Cliffs on the 29th May.


Are the Hutchinson Bank Butterflies real or "plastic"? Well the colony seems to be self sustaining with eggs, caterpillar, chrysalis and imago all being found at the site. However, there is a butterfly house and breeding program to provide a back up to the site. 

Evidence of natural breeding at the site is shown below.

With plenty of the caterpillars food plant on the site it looks as though next years generation are safely on their way.


See my blog of May 2014 to find the story behind the naming of the Glanville Fritillary butterfly.

and below my first Small Blue of the year

Small Blue

See a recent blog by the warden for the site, also a Martin, for some more great pictures and in particular for a shot of an aberration ab.wettei. It would be worth going back just for the chance to see one of these.

Glanville Fritillary

The Glanville Fritillary is named after Eleanor Glanville, an ecentric 17th and 18th century English butterfly enthuisiast - a very unusual occupation for a woman at that time. She was the first to capture British specimens in Lincolnshire during the 1690s. A contemporary wrote:-

This fly is named for Eleanor Glanvil, whose memory had like to have suffered for her curiosity. Some relations that was disappointed by her Will, attempted to let it aside by Acts of Lunacy, for they suggested that none but those who were deprived of their senses, would go in pursuit of butterflies.           Moses Harris 1776

Wikipedia        

The population has shrunk a little since those days. Now the only reliable place to see them is on the south coast of the Isle of Wight. There have been small colonies reported on the mainland at Hurst Castle, Wrecclesham in Surrey, and in the Avon Gorge but I have not seen any reports of these so far this year. That leaves Hutchinson's Bank near Croydon as the only reported sightings on the mainland. These are probably the result of a relocated population by a member of the public from the Wrecclesham site.

Hutchinson's Bank is certainly a promising butterflying location with 29 reported species. I searched it for a couple of hours today but only managed to come up with one Glanville and I only had that for about 30 seconds. I was momentarily distracted by a Jay flying through and when I turned back it was gone never to be found again. The second I took my eyes off it I knew I had made a mistake but it was too late. Fortunately the 30 seconds was long enough to get a couple of record shots.

Glanville Fritillary (Female)

Glanville Fritillary

Strange to think that if I could only find this one butterfly it may well have been the only one of its kind flying in mainland UK today.

Hutchinson's bank also yielded a number of Common Blue and Speckled Wood, two Small Heath, two Dingy Skippers, one Small Blue, one Peacock, and dozens of Brimstones. There seems to be large numbers of Brimstones at every site I visit.

Brimstone

Common Blue

Common Blue

Speckled Wood

I also stopped off at Mill Hill NR to look for the Adonis Blue. The photographs never seem to reproduce the vivid colours you see on the Adonis in the field.

Adonis Blue

Adonis Blue female

Green Hairstreak

Small Heath

Still no sign of the Small Pearl-bordered Fritillary in Sussex