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NEWSLETTER No. 10 -  Winter 1983/84

WEST MIDLANDS BRANCH, BUTTERFLY CONSERVATION

 

Clouds of Yellows

The Clouded Yellow is a migrant species whose true home is in North Africa and the Mediterranean, where it is continuously brooded throughout the year. Each year it migrates up through France and odd specimens turn up in this country. Every so often, however, something quite extraordinary happens and the Clouded Yellow comes over in huge numbers. 1983 was one those years - a Clouded Yellow year - which will no doubt go down in Lepidopterist folklore alongside the golden days of 1947 and other pre-war years when other such invasions took place.

I'm not sure who can claim the prize for seeing the first in the West Midlands (I know it wasn't me!) but one of the first I heard about was the one seen by branch member, Phil Parr, at Ashlawn Railway Cutting Rugby on June 8th, which had overtaken him on his bike! These first migrants were certainly not messing about and the urge to migrate was obviously still strong. Most of the early records seemed to come from Warks, although one was seen by Bob Sim near Droitwich, Worcs on June 12th, where it basked on a woodland ride with its wings open! (Some people get all the luck!). By the middle of the month, Roger Smith had already heard of six sightings in Warks over a period of 10 days. Something quite remarkable was happening, and sightings began to come in from all over the country.

Invasion had clearly taken place on a wide front, in fact all along the south coast. The BBCS Hampshire branch newsletter reported their first Clouded Yellow on June 6th (interestingly only 2 days previous to our first West Midlands record) and recounts how on a trip to the Isle of Wight on June 15th members were able to watch Clouded Yellows coming in from the sea. A friend of Jack Green's in Devon counted 115 Clouded Yellows in an hour passing through a quarry near Totnes.

The weather conditions seemed to suit the butterfly well and it soon settled down to breed. As the Summer progressed, the places Clouded Yell were reported from became stranger and stranger. By and large, tradition butterfly haunts were flaunted and pieces of waste land next to BL at Longbridge (Phillip O'Connor), sewage farms at Tewkesbury (Garth Lowe) and rubbish tips at Stourport (writer) were amongst the more esoteric of locations. A fact that says a lot not only of the haunts of the Clouded Yellow but also of some of our members!

Numbers gradually built up as the original migration was reinforce and as the progeny of the early arrivals took to the wing. Normally, the Clouded Yellow breeds in Britain once (if we are lucky!) but as can be seen clearly from the following graph (based on Roger Smith's Warks records there was a second brood in some areas in late September and no doubt this would have been more widespread if only the weather had held.

Clouded Yellows are, of course, a very difficult group to distinguish, especially as we have had so little chance to practice in previous years. Three species have been recorded here: the Clouded Yellow itself, Pale Clouded Yellow and Bergers Clouded Yellow. I am not aware of any claimed sightings of the latter but there have been several unconfirmed reports of Pale Clouded Yellow. The situation is a bit complicated, however, by the existence of a paler female form of the Clouded Yellow - var. helice - which certainly was present, and when some people talk of the "pale" Clouded Yellow it is this form to which they are referring. "Helice" has the normal Clouded Yellow markings on a white background, and occurs quite commonly throughout the butterfly's range.

Although seen in large numbers along the south coast, most West Midlands' sightings were of smaller gatherings, singly or twos/threes being the norm. There were, however, a few favoured areas where larger groups were seen. Terry Green, for example, saw 10+ along the old Great Central railway line near Catesby tunnel, where he also saw a pair in cop and a female lay up to sixty eggs. The Hattons, through the local branch of the National Farmers Union, managed to find a field of Lucerne in Glos which proved rewarding. The two best sites in Warks were Bishops Itchington and Charlecote quarries. Charlecote, as some readers will remember, was the place where 70 Clouded Yellows were seen in 1981. It is clearly a favoured spot, and another 60 were seen there this year by David Brown on October 2nd.

In 1947 Clouded Yellows were seen right up to Scotland and it will be interesting to learn whether the same has happened this time. Unfortunately it is not thought that the butterfly can survive our Winter (although if very mild again, it will be interesting to see), so the bonanza of 1983 is unlikely to be repeated perhaps for some years. So if you were one of the few members to miss out and you still want to see Clouded Yellows, then I'm afraid it will have to be out with the holiday brochures and on with the sun lotion...... but then again, you never can tell.

Mike Williams