Three steps to save Britain’s butterflies

British populations of butterflies, including some of the most familiar countryside species, will begin disappearing within decades unless we take action. This is the alarming conclusion of new research published in Nature Climate Change by a group of British scientists.

Butterflies are naturally sun-loving creatures, and with the UK sat on the northern edge of many species’ ranges, previous studies have forecast possible benefits to UK populations from a warming climate. However, as the climate changes, extreme weather events including droughts are expected to become more common. Droughts can be a problem for butterflies, especially if they harm the plants upon which caterpillars rely for food. With less food around, populations can crash, and may take several years to recover to pre-drought levels.

The new study used models to predict the frequency of droughts like that of 1995 under different scenarios of greenhouse gas emissions, and examined factors affecting the likelihood and speed of recovery for populations of six species of butterflies that experienced population collapses after the 1995 drought.

While droughts as severe as 1995 have previously only occurred as little as once in 200 years, allowing plenty of time for butterfly populations to recover, the study found that they may become far more frequent. If greenhouse gas emissions continue to increase at current rates, they might even occur on average once every 1.29 years (effectively every summer).

The red admiral is one of the UK’s most common butterflies.
Kenneth Dwain Harrelson, CC BY-SA

Under “business as usual” scenarios, the research forecasts the widespread extinction of local colonies of butterflies as soon as 2050. So, what can be done to conserve our butterflies? Here is my simple, three-step guide:

Step 1: stop global warming in its tracks

Butterflies don’t have to be colourful.
Soebe, CC BY

Clearly, reducing the impacts of climate change will be important. Delegates from around the globe will meet in Paris later this year for the 2015 UN Climate Change Conference, hoping to reach the first deal on reducing emissions since Kyoto 1992. Under the study’s best case scenario for emissions, 1995-like droughts might occur only every six to seven years, giving butterfly populations much more opportunity to recover in between.

Step 2: protect butterfly habitats

Ensuring the availability of suitable habitats for butterflies can also make a big contribution. The researchers found butterfly populations were more likely to persist through droughts and recovered more rapidly if situated in areas with larger, less fragmented patches of semi-natural habitat, such as grassland. Larger areas are likely to contain more abundant and diverse food-plants, helping more species of butterfly, and can also better resist edge effects associated with drought, such as moisture loss from woodland.

Highly fragmented habitats have more edge relative to their area, and therefore experience more severe edge effects. Well connected habitats, through which butterflies can easily mingle and locate breeding sites, could add decades on to the survival of certain populations as the climate warms.

Buddleia, also known as the butterfly bush, is one of the UK’s best plants for encouraging butterflies.
Andy Fogg, CC BY

Step 3: create more butterfly-friendly gardens

While large-scale habitat management programmes, such as the establishment of nature reserves, are an important means to preserve semi-natural habitat, the restoration of connectivity is where butterfly enthusiasts can help at home.

According to Richard Fox from the charity Butterfly Conservation, many drought-prone species can be encouraged to breed in gardens by leaving grass to grow long. “You don’t have to let your prize lawn go to rack and ruin, you can just leave a strip along the fence”, Fox told me. Depending on how much is left, this could provide breeding habitat for species including the speckled wood, ringlet, meadow brown and large skipper.

A female speckled wood butterfly
Charles J Sharp, CC BY

Meanwhile, other species can be helped by choosing garden flowers with care, or letting them choose themselves. “Large and small white will breed on Nasturtiums and love to nectar on flowers like buddleia and perennial wallflower,” advises Fox, while “green-veined white caterpillars can feed on lots of weeds, so not being too tidy can help”. If you have a garden, why not plant some butterfly-friendly plants of your own?

So while butterfly lovers will be among those waiting with bated breath for the outcome of the Paris summit, they may also be able to help closer to home. Habitat availability will be vital to the survival of butterflies when drought strikes, and by providing such refuges in back gardens anybody can help them survive and flourish.

The Conversation

Callum Macgregor, PhD student in Ecology, University of Hull

This article was originally published on The Conversation. Read the original article.

Coming out of the closet: why I will always love moths

Ask people to describe what they associate with butterflies, and you will probably get an image of a sunny summer’s day, with a beautiful peacock drifting gently on the cooling breeze.

Ask the same question but for moths, and you are more likely to be told about holes in a favourite woollen jumper, or something small and brown beating itself to death against a bathroom light fitting. We don’t view moths with the same affection as their day-flying cousins, and the irrational fear of moths is even common enough to have a name: mottephobia.

To my mind, this is unfair. Let’s start with the clothes-eating accusation. According to the charity Butterfly Conservation (which also protects moths), there are around 2,500 species of moths found in the UK; of these, only two will attack clothes. They prefer dirty items in undisturbed places: that means that if your jumper has been attacked, you probably weren’t wearing it often enough anyway.

In fact, there are also moth species that are crop pests, such as the diamondback moth, and some which produce irritant hairs as caterpillars – the non-native oak processionary moth currently infesting London is one such example. But again, these examples are very much in the minority among the total diversity of moths, and there are very many more reasons to love moths than to hate them.

Birch or buff-tip?
Callum Macgregor, Author provided

Many moths are just as beautiful as butterflies; some even look like butterflies! A particular favourite of mine is the brimstone moth: exactly like the brimstone butterfly, it is so-called for its vivid sulphur-yellow colour. Some are superbly camouflaged, like the buff-tip – easily mistaken for a broken twig of silver birch. And some have attractive names to match their appearance, such as the fabulous Merveille du Jour (“marvel of the day”), pictured at the top of this article.

Moths are vital pollinators

But beyond their beauty, moths also perform vital roles in the natural communities to which they belong. Along with colleagues, I recently examined the scientific literature to establish how important moths are to flowering plants as providers of pollination services. Most moth species that feed as adults do so by drinking nectar, and in doing so accidentally carry pollen between flowers.

We found examples of moths serving as important pollinators across many important habitats and in every continent except Antarctica. Several studies suggested that moths were the second most important pollinators in the area surveyed, behind only bees. In the UK, moths might be pollinating wildflowers near you including honeysuckle, bramble, white campion, wild carrot, thistle and ragwort. In North America, moths pollinate many types of cactus, and milkweed (beloved of caterpillars of the monarch butterfly). Globally, they are also well-known pollinators of many orchid and lily species.

If you’re a bird or a bat, a moth makes for a tasty treat. Researchers from the University of Bristol have examined the diet of two species of long-eared bat in England, revealing that their main food source was large-bodied moths from the Noctuidae (or owlet moth) family. Whereas bats (and the eerie nightjar) eat adult moths, moth caterpillars provide a vital food source in the spring for young birds including blue tits, which can munch their way through 35 billion caterpillars in the UK every year.

The moth-munching blue tit.
OliBac, CC BY

Especially important in this regard are those moth species that are active as adults through the winter, including the aptly named winter moth; these species reach the caterpillar stage of their life cycle at exactly the right time of year for busy blue tit parents to exploit.

And did you know that one species of moth has been domesticated into a valuable commercial livestock species, at the centre of a multi-billion dollar global industry? When spinning a cocoon in which to undergo the transformation to an adult moth, the caterpillars of the domesticated silkmoth Bombyx mori produce lustrous threads several hundred metres in length. These threads, once unravelled, are spun into the fine textile silk.

And if none of this has convinced you, know this: butterflies are actually just a minor subset of moths!

The Conversation

Callum Macgregor, PhD student in Ecology, University of Hull

This article was originally published on The Conversation. Read the original article.