Year of strong grass growth was bad for bees and butterflies

By Chris Derrick in Environment

BEE and butterfly numbers have slumped after a tenth year of unsettled weather, National Trust experts have said.

Mild winter and spring weather led to extremely high grass growth, leading to a good year for farmers with livestock and for making silage or hay. But the grass growth meant a difficult year for warmth-loving insects, including common meadowland butterflies.

The assessment comes as the National Trust marks ten years of its annual weather and wildlife review, which aims to understand how changing weather patterns affect wildlife.

The conservation charity is working with its tenants and partners to reverse the alarming decline in UK wildlife, with 56 per cent of species seeing their numbers fall in the last 50 years.

Local naturalist, Gordon Waterhouse said: ‘It is quite early in the winter and we could have cold weather around the corner - mild weather isn’t good for hibernating species.

‘For example, hibernating dormice in Andrew’s Wood can wake up early because of the warm weather and use up vital energy. When the weather gets cold, they’ve used up too much energy and cannot survive.

‘But then there are other species who thrive, such as the Dartford Warbler. They almost died out during the hard winters we had in the 1960s. But now they are found on Dartmoor and all around the coast - so there are winners as well as losers.’

Gordon continued: ‘But it isn’t good news for bees or butterflies - their numbers have declined. Records show that most species are in decline - particularly bumble bees. Bees are the most important of all - without them, we have no pollination.’

‘The weather doesn’t help, it’s better to have a harder winter, but of course we’d all be complaining,’ Gordon added.

Matthew Oates, nature and wildlife specialist at the National Trust, said: ‘Another year of unsettled weather has seen extraordinary grass growth – good for livestock and hay making, but bad for many plants and insects which like short turf grassland, like the common blue butterfly.

‘Our rangers have had to work closely with farmers and graziers to get grazing levels right for these plants and insects.

‘2016 comes on top of an unsettled decade, with many species struggling in the face of climate change and more intensive farming practices.’

A mild winter, cold spring and mild, wet weather in May and June led to very high grass growth in early summer. Grass grew at a rate almost a third faster than in previous years, according to Agriculture and Horticulture Development Board figures.

Rampant grass growth was good news for farmers making hay in many parts of the country.

But in much of the country strong grass growth badly affected butterfly and bee species reliant on small plants that were crowded out by vigorous-growing grasses.

In the past decade, National Trust nature experts have noticed that winters are becoming milder and summers wetter, which could have a devastating effect on warmth-loving insects, their bird and bat predators, and many low-growing plants. Over the last 50 years more than half of UK species have declined.

National Trust nature expert Matthew Oates said: ‘In the ten years we’ve been reviewing wildlife at our places we’ve noticed pulses of unsettled weather become the norm. We last enjoyed a good summer in 2006.

‘Mild winters and periodically wet summers have seen common wasp numbers apparently slump in many parts of the country, along with common ‘meadowland’ insects like the common blue butterfly. This could have a knock on effect on the invertebrates, birds and bats that eat them. And what affects insects today could well affect us tomorrow.’

Climate change has had a clear effect on weather and wildlife in the last decade.

In ten years the growing season has extended by almost a month, the Met Office announced earlier this year. Both the Met Office and the World Meteorological Organization have predicted that 2016 will be the hottest year on record – the third year in a row of record-breaking surface global temperatures.

Warmer temperatures, higher levels of carbon dioxide in the atmosphere and a longer growing season are leading to vegetation growing more quickly. According to a study published in November, this increase in vegetation growth is also leading to a drop in the amount of CO2 in the atmosphere.

Common wasp numbers appear to have crashed in many districts in recent years, perhaps suffering during milder winters and wet springs.

Matthew Oates added: ‘Long term, changes in how we manage land has also led to wildlife declines – with more than half of species experiencing a drop in numbers in the last 50 years.

‘But one of the great successes of the last decade have been the ways farmers and conservationists have worked together to reverse wildlife declines in many of our places.’

In south west England work by conservation charities and arable farmers to benefit wildlife have resulted in numbers of cirl bunting, a rare bird that has retreated to Devon and Cornwall, increase by over 800 per cent since 1989. 15 per cent of Britain’s cirl bunting population live on National Trust farms along the south west coast.

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