Introduction

About this guide

These web pages show the butterflies with resident colonies in the counties of Gloucestershire and South Gloucestershire, England. Common migrants and recently introduced species are also shown. The guide is based on observations made during 1975 - 1999.

The guide is in four sections:

Introduction - this section, which gives background information about the area covered and butterfly recording within it, and about the contents of the species pages

Species - there is one page for each of the butterfly species. The main species index is text-only, and there is also a photo index grouping species by type, with one page of photographs for each group

Habitats - this describes and illustrates the main types of butterfly habitat in the area, including some of the sites open to public access

Conservation - this section indicates some of the conservation issues, particularly habitat loss caused by lack of appropriate management

Gloucestershire and South Gloucestershire countryside

The area is shown in green on the map, with ground over 175m in altitude shaded. The Cotswold Hills are in the east, the Forest of Dean in the west, and the river Severn divides the county as it runs southwards into the Bristol Channel.

The Cotswold Hills rise steeply from the Severn Vale. Within them there are many hillsides and valley slopes which are too steep for growing crops. Cattle and sheep are farmed on grassland, though much of it is "improved" by the use of fertilisers.

Although much reduced in total area during the 20^th century, there are still many patches of unimproved flower-rich grassland in the Cotswold Hills. There are also many woods. There is a long tradition of quarrying Cotswold limestone for buildings and field walls, resulting in numerous disused quarries.

The Forest of Dean has large areas of forestry plantation, deciduous and coniferous, and also the remains of heathland which was more extensive in the past. Old industrial sites (from quarrying and coal mining), disused railways and the many wide woodland tracks provide relatively open habitat for butterflies. So too do recently-felled blocks of woodland.

The Severn Vale is quite intensively farmed. Some of the woods in the Vale have good populations of the woodland butterfly species. Unimproved grassland is scarce, and some butterflies found quite commonly in the Cotswolds and the Forest of Dean are uncommon or absent in most of the area.

In the north-west, the Malvern Hills just reach southwards into the county. From the south-east corner at Lechlade westwards along the course of the river Thames towards its source at Kemble, there are many lakes resulting from gravel extraction.

Butterfly recording in the area

Several organisations encourage butterfly recording in Gloucestershire. Most of the records used to produce the species distribution maps were made by members of Butterfly Conservation, the British charity dedicated to saving wild butterflies, moths and their habitats. Butterfly Conservation ran a Millennium Atlas project, taking records from the 1995 to 1999 seasons to show distribution of butterflies throughout Britain and Ireland. The Atlas was published in 2001 (ISBN 0 19 850565 5). I was Butterfly Recorder for the Gloucestershire branch of Butterfly Conservation from 1994 to 2000.

The Gloucestershire Naturalists Society (GNS) encourages its members to record all forms of wildlife, and to pass their records to the appropriate recorder. I was Butterfly Recorder for the GNS from 1981 to 2001.

The Gloucestershire Wildlife Trust (GWT) runs a local wildlife records centre for Gloucestershire, the Gloucestershire Centre for Environmental Records (GCER). The GCER's records are used for conservation purposes including advice to councils and government agencies such as English Nature. I provided butterfly records and site information to the GWT.

The Bristol Regional Environmental Records Centre (BRERC) covers the former county of Avon, including the area which is now South Gloucestershire. The Avon Butterfly Project organises butterfly recording in that area. I exchanged South Gloucestershire records with BRERC.

Members of various other wildlife and conservation-oriented organisations also provided records. Directly or indirectly, at least 360 people contributed to a total of over 85,000 records from 1975 to 1999. I personally made over 25,000 of these records, and enjoyed visiting not just the best (and well-recorded) butterfly sites but also many other interesting places throughout the area.

Species pages

The information shown for each species includes:

Species name and scientific name - I have used the scientific names given in some recent books, with an alternative genus name shown in brackets in cases where the books differ

Photographs - a selection of photographs of the adult butterflies, and in a few cases also of an earlier stage. Identification features are pointed out in some cases where there are two very similar species. The photographs are mostly from Gloucestershire sites. They are all highly compressed JPEG images, to reduce file sizes and transfer times over the internet

Habitat - the type of place where you might expect to see the species when the adults are flying. Photographs of some suitable habitats are shown

Conservation issues - any particular concerns about the species. More general conservation topics are mentioned in the Conservation section of the guide

Flight Period - the best time(s) to see the species in an average year. Weather conditions may result in an earlier or later flight period, and there are often some much earlier and later individuals compared to the majority of their generation. A few species hibernate as adult butterflies (rather than at an earlier stage of egg, larva or pupa). Particularly warm days may bring them out of hibernation at any time during the winter

Distribution - a brief description of where the species occurs in the area

In most cases, a dot-map at 2Km scale (using the even-numbered grid lines on Ordnance Survey maps) shows records made during 1995 - 1999 as solid dots, and other records from 1975 - 1994 as open dots. For species recorded in less than 20 2Km x 2Km squares since 1995, no map is shown because of the vulnerability of the remaining colonies (a Conservation issue)

An open dot, or no dot at all, does not necessarily mean the absence now of the species from the location, just the absence of a recent record. Some of the records shown are of "wanderers", specimens seen quite far from their nearest breeding habitat. There are comments about this on some species pages. Specimens of some species have been deliberately released into the wild (another Conservation issue)

The commonest species occur almost everywhere in the area, so gaps on their distribution maps indicate a lack of sufficient records to provide full coverage.

For some of the less common species, particularly those restricted to unimproved limestone grassland in our area, a lot of effort has been put into finding their colonies during the past 20 years, with special checks during 1995 - 1999 for the continued existence of colonies known from earlier years. For such species, the solid dots give a reasonably accurate indication of their current status

Above each map is a chart showing when records were made, excluding late autumn and winter months. The bar heights in the chart reflect relative numbers of records made and butterflies counted (where this information was available). Weather conditions affect flight periods, so in any one year the flight period for a generation of the species is unlikely to be quite as long as shown on its chart. In many cases, there are a few exceptionally early or late records for the species shown as very short bars

Need a book on British butterflies to use out in the countryside?

For a field guide with illustrations of adult butterflies and early stages (eggs, larvae and pupae), one book I would recommend is the Hamlyn Guide to the Butterflies of the British Isles by J A Thomas