Why we all need to worry about the decline in native butterflies
2nd August, 2012
Butterfly populations are an important gauge of the health of local habitats and wider climate change. Faye Dobson explains what population changes mean, and how you can get involved in helping monitor them.
Although butterflies may seem like an attractive addition to your flower garden they are a more important insect than most people realise. Acting as a vital wildlife indicator, butterflies can tell us almost everything we need to know about the health of an ecosystem. But from the Meadow Brown to the Swallowtail, British native butterfly species are slowly disappearing.
According to a report by the Dorset-based charity Butterfly Conservation, 72 per cent of butterfly and moth species have declined in the last ten years, and 54 per cent have decreased in the UK. Even the abundance of common garden butterflies, such as the Red Admiral, has dropped by 24 per cent.
Butterflies react extremely quickly to even minor changes in the environment, making them both a good indicator of biodiversity and providing an early warning system for other reductions in wildlife. As a result, they are now the best-monitored group of insects in the world.
But British butterfly numbers have hit an all time low in the last three years due to poor summer weather.
Tropical World in Leeds is home to between 30 and 40 butterfly species that fly around in the tropical environment of exotic flowering plants and Citrus trees. Stephen Dickie, head keeper, said: “Obviously we’ve had lots of rain and quite unpleasant weather recently. British butterflies tend to be most abundant in the summer months but it needs to be sunny, dry, and warm to get them flying around. If they’re not flying around, they’re not feeding and if they’re not feeding they’re not going to survive for very long.”
Richard Fox from the charity Butterfly Conservation adds: “We’re concerned that many butterflies may have suffered extremely poor breeding seasons this year as a result of the record-breaking wet weather. We are drawing parallels with the wet summer of 2007, which also resulted in widespread flooding and saw butterfly numbers plummet.
“Many species are likely to be affected from widespread butterflies such as the Common Blue to rarities such as the Duke of Burgundy.”
A decline in butterflies would also have a knock-on effect on other British species, in particular birds such as blue tits, jays and sparrows.
Stephen Dickie explains: “Birds plan their whole breeding season around when caterpillars will be most abundant. If the butterfly and caterpillar numbers are depleted then there’s not going to be a lot of food for developing chicks.”
Plants will also be affected. Butterflies are a major pollinator of both wild and cultivated plants. Without them and other important pollinating insects flying around, there will be a significant decline in viable seed produced.
Marsland Nature Reserve, on the border between Devon and Cornwall and now under the auspices of Devon Wildlife Trust, specialises in the cultivation of butterfly habitats, in particular the Pearl and Small Pearl Bordered Fritillary. Stephen Threlkeld, an officer at the reserve, said: “Most Fritillaries are struggling across the country but they are doing well on our site. We have a large area of pristine habitat suitable for them. Maintaining the early successional habitats, especially bracken, means they’re coping well. We’ve also got a lot of violets growing – the preferred food plant for Fritillary larvae.
“The problem for butterflies in most other areas is their habitat is disappearing – whether it’s because of agriculture or even just neglect.
“Grassland species in particular are struggling – probably as a result of the weather. But the Ringlet is doing well this year because it can fly in the rain.”
Since 2010, ‘citizen scientists’ across the UK have been taking part in the Big Butterfly Count to help monitor the ailing butterfly species. That year, 10,000 people took part in the count, which rose to 34,000 in 2011. This year’s event is taking place between now and next Sunday (August 5).
The count involves members of the public counting butterflies for 15 minutes, recording what they see and entering the data onto the website. This then helps the organisers, Butterfly Conservation, to identify trends in butterfly species and better plan how to protect them from extinction.
Spokesman Richard Fox says: “We can’t do anything about the weather, but everyone can do something to help butterflies this summer by taking part in the count. It is the perfect thing to get the whole family involved in and to help hard-pressed butterflies at the same time.”
Another benefit of the butterflies’ extreme sensitivity is that it can help experts to judge the effect climate change is now having on wildlife. Certain butterfly species, for instance, can only survive in specific global territories due to the temperature. So as climate change triggers higher temperatures (global warming), these species are forced to move northwards to new areas, which, also as a result of climate change, now have a climate more similar to their original habitats.
According to a report in Nature, from a sample of 35 non-migratory butterfly species, 63 per cent have ranges that have shifted to the north by between 35 and 240 kilometers, reflecting the shift in climate.
So what hope is there for the declining populations of British butterflies?
Many species from Europe migrate to Britain over the summer, but this year, because of the wet weather, they have not migrated. With some warm weather this trend would reverse and the European butterflies will come across and join the remaining native species. “We only need a short spell of sun. Butterflies are egg machines and they don’t need a lot of hot weather to get the population back up,” says Stephen Threlkeld.
The good news is that there are a number of ways we can all help encourage more butterflies into our gardens to lay their eggs.
Butterflies prefer open spaces that are sunny but sheltered, as it would be in a woodland glade, so the idea is to recreate this environment in your garden. Large trees and shrubs are good to provide shelter, as well as plenty of vegetation, reduced use of pesticides and some good sources of nectar. Food plants for caterpillars are also essential, including holly, ivy and buckthorn.
Leaving an area of long grass will encourage species such as Meadow Brown, Ringlet, Gatekeeper and Large Skipper, as well as giving caterpillars and pupae somewhere to hide along with other creatures such as beetles and spiders.
Faye Dobson is a trainee journalist at Leeds Trinity University College. She has a background in Environmental Geography.
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