Information and Advisory Note Number 131
Back to menu
NATURAL HERITAGE TRENDS Species diversity: butterfly species
1. Introduction
1.1 Although Scotland supports only half of Britain's resident butterfly
species, several Scottish species and populations are particularly important in
the UK context. Within the UK, three species - the chequered skipper, mountain
ringlet and scotch argus -are almost entirely restricted to Scotland, while
several others with important Scottish populations (e.g. pearl-bordered
fritillary, marsh fritillary and large heath), have declined significantly in
England and Wales.
1.2 Of the 28 butterfly species currently resident in Scotland, 16 are
considered to be habitat 'generalists', or use habitats that are widespread. The
remaining 12 are regarded as habitat specialists, in that they are restricted to
scarce or very 'narrow' habitats. Four of the latter are UK Biodiversity Action
Plan (BAP) Priority Species (chequered skipper, northern brown argus,
pearl-bordered fritillary and marsh fritillary).
2. Trends
2.1 The geographic ranges of the majority of resident Scottish butterfly species
appear to have been relatively stable in recent years. Trends for habitat
specialists and generalists have, however, differed markedly. While 42% of
habitat specialists have shown substantial declines in their range size in
recent decades¹, none of the generalist species
have done so; indeed, 31% of these have expanded their ranges in Scotland
[Figure 1].
2.2 Factors influencing the two groups are also thought to differ markedly.
Declines shown by the specialists have been associated with the continued
destruction and deterioration of their habitats, while increases shown by the
more widespread species have largely been attributed to climate change. These
latter species are able to move through the modern landscape, finding places to
breed, even in intensively managed agricultural and urban areas. They therefore
have the potential to track shifts in climatic zones as these move north with
global warming. Habitat specialists, on the other hand, are becoming
increasingly isolated in small patches of semi-natural habitat, and may not be
able to keep pace with climate change.
2.3 Butterfly species whose geographic ranges are considered to be expanding in
Scotland are the large skipper, orange-tip, peacock, speckled wood and ringlet.
Those species considered to be declining, or whose status is unclear, are listed
in Table 1.
¹ Adequate trend data are lacking for a further 17% of habitat specialists.
Table 1. Habitat specialists showing range contractions, or for which data are
poor
2.4 The speckled wood is a widespread woodland butterfly whose previously
extensive Scottish distribution contracted to a
small area on the west coast around the end of the nineteenth century.
Populations have since expanded eastwards. Over the past two decades one
particular population, centred around Inverness, has expanded rapidly through
Moray into Aberdeenshire, as well as to the north and west. Recent records from
the Mull of Galloway suggest that there may also be small populations in
south-west Scotland, perhaps the result of immigration from Northern Ireland.
3. Source
3.1 This profile has been developed using Asher et a/, (in press), and
information kindly provided by Butterfly Conservation.
4. References
Asher, J., Warren, M., Fox, R.t Harding, P., Jeffcoate, G. and Jeffcoate, S. (in
press). The millennium atlas of butterflies in Britain and Ireland. Oxford:
Oxford University Press.
5. Further Information
Further detailed information on Natural Heritage Trends: Species Diversity can
be found in Information & Advisory Note No. 129.
6. Contact
To obtain further information about any of the issues raised in this l&A Note,
please contact
Dr Phil Shaw or Ed Mackey
Environmental Audit Group
Chief Scientist's Unit
Scottish Natural Heritage
2 Anderson Place
EDINBURGH EH6 5NP
Tel: 0131-446 2464
Fax:0131-446 2405
E-mail: phil.shaw@snh.gov.uk
Species mentioned in the text
Back to menu