22
The Essex Naturalist
New protection for Fisher's Estuarine Moth
The Environment Minister made an announcement in March 1998 of the
addition of a number of species to Schedules 5 and 8 of the Wildlife &
Countryside Act, 1981. Relatively few of these are of relevance to Essex,
although bluebell and water vole were both given partial protection, against
trade in their bulbs and destruction of their burrows respectively. Deptford pink,
a rare plant with a tenuous foothold on the north Thames bank near Southend,
is now fully protected. The most significant addition is the full protection given
to Fisher's Estuarine Moth Gortyna borelii lunata, which has long been recognised
as one of the key Essex rarities. This large autumn-flying moth is known only
from sea walls and coastal grassland in the north-east of the county, where its
larval food plant hog's-fennel Peucedanum officinale grows. Whilst also rare, hog's
fennel is found elsewhere - a few plants have recently been discovered near
Southwold (Suffolk) and there is another population on the sea walls and cliff
slopes around Faversham (Kent). But despite repeated searching Gortyna has not
been seen outside north-east Essex.
As a localised native species, it has inevitably become a focus for collectors.
To avoid such depredations, to both moth and food plant, was one reason why
English Nature and the Essex Lepidoptera Panel proposed the moth for special
protection. It was also hoped that scheduling the species would lead to more
sympathetic management of its sea wall habitat. Which is all very well if we
know what the optimal management regime is. With a view to uncovering such
crucial details, an experiment has been established by the Environment Agency,
English Nature and interested local naturalists. It is hoped that the results of this
experiment, comparing the effects of different mowing regimes, will lead to more
effective management of the sea wall grassland, for this and other key species.
At the same time, we are trying to shed light on some of the mysteries of the
moth's life cycle. Where actually does it lay eggs? The food plant rots down to a
soggy mess in the autumn: not, one would think, an ideal egg over-wintering
location. In late spring, there are numerous signs of larval workings, sometimes
more than ten to a plant; in July, that's down to one per plant. What happened
to the rest? And in October, emerging adults are few and far between in many
sites, but relatively dense in others. Why? We need answers to these and other
questions if we are ever going to be in a position to ensure its survival.
Moreover, all the research and all the protection could come to nought if
calamity strikes, and the moth and food plant are killed off by tidal inundation
at a vulnerable time of the year. Now is the time to prepare for such an
eventuality, establishing new populations on safer, high ground. One of the
challenges set by the Essex Biodiversity Action Plans for Peucedanum and G.
borelii is to ensure that we start the new Millennium with workable plans which
will guarantee the future of these characteristic and charismatic Essex
specialities in the face of an increasingly uncertain global future.- CHRIS
GIBSON, English Nature, Harbour House, Hythe Quay, Colchester C02 8JF.