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Butterflies Crash In Fourth Worst Year On Record
UK butterflies suffered their fourth worst year on record in 2016 with the majority of species
experiencing a decline in numbers, a study has revealed.
A mild winter followed by a cold spring contributed to conditions that saw both rare and widespread
species struggle despite many parts of the UK enjoying a warm and dry summer.
Some 40 of the 57 species studied recorded a decline compared with 2015, the annual UK
Butterfly Monitoring Scheme (UKBMS) led by Butterfly Conservation, the Centre for Ecology &
Hydrology (CEH), British Trust for Ornithology (BTO) and Joint Nature Conservation Committee
(JNCC) revealed.
The highly threatened Heath Fritillary had its worst year on record for the second year running,
while the Grizzled Skipper, Wall, Grayling, White-letter Hairstreak and White Admiral all recorded
their worst ever years.
The Heath Fritillary, restricted to just a handful of sites in southern England, saw numbers slump
by 27% compared to 2015. This ongoing decline raises fears for the long-term future of the
butterfly whose numbers have fallen by 82% in the last decade.
The rare Grizzled Skipper, found in southern England and parts of Wales, saw numbers tumble by
24%. The butterfly is a spring-flying species emerging from April, a month that was around a
degree colder than the long-term average in 2016.
The Grizzled Skipper’s struggles mirrored a bad year overall for the skippers with all but one of the
UK’s eight species suffering a fall in numbers compared to 2015.
The White Admiral, White-letter Hairstreak and Grayling slumped by 59%, 42% and 27%
respectively while more widespread species also struggled with the Wall down 31%, the
Gatekeeper down 48% and Meadow Brown falling by 31% compared with 2015.
Research suggests that the UK’s increasingly mild winters are having a negative effect on
butterflies as they may lead to increased disease, predation or disruption of overwintering
behaviour.
Cold springs can also cause problems for butterflies by reducing or delaying emergence leading to
shortened lifespans.
Some species bucked the trend to record reasonable years. The previously extinct Large Blue, one
of the UK’s rarest butterflies, recorded its second best year on record with numbers up 38% on
2015.
The butterfly has responded to conservation work to improve the specific grassland habitat that it
relies upon to thrive and has showed a significantly increasing population trend since its
reintroduction in 1983.
The widespread and migratory Red Admiral recorded a rise of 86% compared to 2015 and the
Clouded Yellow, another mainly migrant species, saw its numbers rise by 35%.
Professor Tom Brereton, Head of Monitoring at Butterfly Conservation, said: “Worryingly, not even
the pleasant summer weather of 2016 was enough to help butterflies bounce back from a run of
poor years.
“The results show that butterflies are failing to cope with our changing climate and how we manage
the environment. As butterflies are regarded as good indicators of environmental health this is
hugely concerning for both wildlife and people.”
Dr Marc Botham, Butterfly Ecologist at the Centre for Ecology & Hydrology, said: “The weather at
critical times of species development can cause dramatic changes in population numbers in the
short term. What is of greatest concern is the regularity with which these short-term changes in
recent years are negative, resulting in significant long-term declines for many species.”
“Furthermore, this is becoming more and more commonplace for many of our most widespread
and abundant species equating to large reductions in overall butterfly numbers with knock-on
effects to their ecosystems.”
Sarah Harris, Breeding Bird Survey (BBS) National organiser at the British Trust for Ornithology,
said: “Our understanding of just how our butterflies are doing would be much poorer without the
huge amount of effort our volunteers put in.
“The data they collect allow us, working alongside our partners, to monitor the UK’s butterflies in
the detailed and long-term way we do, and bring attention to those species in trouble and those
enjoying conservation success, as seen in the Large Blue. Thanks must go to all who contributed.”
Anna Robinson, Monitoring Ecologist at JNCC said: “We are really grateful to the thousands of
volunteers who get involved in monitoring the UK’s butterflies.
“The evidence provided by the UKBMS is of great importance in showing the need for conservation
action to improve the situation.”
The UKBMS has run since 1976 and involves thousands of volunteers collecting data through the
summer. Last year a record 2,507 sites were monitored across the UK.
The scheme is organised and funded by Butterfly Conservation, the Centre for Ecology &
Hydrology, the British Trust for Ornithology and the Joint Nature Conservation Committee.
CONTACTS
For interviews and images contact the Butterfly Conservation Press Office on 01929 406005
[email protected]
Butterfly Conservation is the UK charity dedicated to saving butterflies, moths and our environment. Our research
provides advice on how to conserve and restore habitats. We run projects to protect more than 100 threatened species
and we are involved in conserving hundreds of sites and reserves.
www.butterfly-conservation.org
The British Trust for Ornithology (BTO) is the UK’s foremost independent bird research organisation and organises a
range of annual and periodic surveys, mainly on birds, and including the BTO/JNCC/RSPB Breeding Bird Survey.
Information on population trends in birds and other wildlife are provided on our website (www.bto.org) and you can follow
the latest news and developments via twitter @_BTO.
The Centre for Ecology & Hydrology (CEH) is the UK’s Centre of excellence for integrated research in the land and
freshwater ecosystems and their interaction with the atmosphere. CEH is part of the Natural Environment Research
council (NERC), employs more than 450 people at four major sites in England, Scotland and Wales, hosts over 150 PhD
students and has an overall budget of about £35m. CEH tackles complex environmental challenges to deliver practicable
solutions so that future generations can benefit from a rich and healthy environment. www.ceh.ac.uk You can follow the
latest developments in CEH research via twitter www.twitter.com/CEHScienceNews and our rss news feed
http://www.ceh.ac.uk/rss.xml
The Joint Nature Conservation Committee (JNCC) is the statutory adviser to the UK Government and devolved
administrations on UK and international nature conservation. Its work contributes to maintaining and enriching biological
diversity sustaining natural systems.