Bats are flying, butterflies are basking and flowers are blooming in winter more often in South Bristol, says Alex Morss

Published on: 19 Jan 2017

Dormice found in South Bristol, awake in winterPicture: A pair of dormice, found active in the winter in South Bristol. Photo: Alex Morss

Bats are flying, butterflies are basking and flowers are blooming in winter more often, says Alex Morss

How future-proof is your garden? Pioneering invaders from abroad are poised to migrate into Bristol gardens, parks and wild places, if scientists’ predictions are correct. And we are likely to see changes among our favourite visitors, too. Recent sightings and climate change forecasts show that wild populations are on the move.

 Our city offers the perfect ‘des res’ to invading opportunists, for several reasons. We are close enough to the continent for migratory birds, bats, sea life, insects and spiders to drift or fly across from southern regions. Also, rarer, migratory species from Europe will probably increase in frequency amid forecasts for milder, wetter winters in Bristol. 

Those on the edge of their natural range are more likely to survive the milder winters and breed natively. What’s more, alien species thrive on urban land and places near waterways, roads and railways. These factors combined make your little green corner of Bristol a potential hot spot for harbouring some surprising fair-weather friends and foes in future. 

This winter, residents in Windmill Hill and Bedminster found plagues of ladybirds – thousands of them clustering on buildings and under sycamore and lime trees. This behaviour tends to be from the alien harlequin ladybird, which first arrived in Bristol 10 years ago and are now abundant. They prey on our 46 native ladybird species, introduce a disease and rob them of food.  The UK Ladybird Survey says these variable-colour beetles are the most invasive ladybird on Earth. They are prolific breeders and foragers. Scientists say harlequins invade cities faster than surrounding countryside and there is a link between their increase and climate warming.

Other recent Bristol arrivals have included purple herons, small red-eyed damselflies and not far away, rare, migrating Geoffroy’s bat and Nathusius’ pipistrelle bats. Many native moths and butterflies are also being boosted by milder weather in our region too, says the UK’s Environmental Change Institute. Sadly, farming and habitat loss reduce this gain.  

Bleak winters are rare in Bristol, but last winter was the mildest on record, the Met Office said. Those of us who record or survey wildlife saw unseasonal activity. I frequently found several of Britain’s 18 bat species foraging into late November. This is not unheard of, but milder temperatures seemed to be rousing bats more frequently than I expected from their winter torpor. 

When a bat’s metabolism and body temperature rises, it needs to hunt for insects, and they can be spotted emerging from crevices in buildings and trees. In December 2016, I watched pipistrelle and noctule bats flying in Victoria Park and Arnos Vale cemetery. They would normally be hibernating in December.

I have also spotted red admirals and peacock butterflies in winter flight and basking in sunny spots, sheltered from the winds by our city’s urban skyline. For any hungry winter- awakening pollinators, wild flowers are in blossom even on New Year’s Day in Bristol – I counted 37 wild species in bloom around the Northern Slopes and Victoria Park (see below, left). 

Milder winters can help or hinder survival. Species that normally hibernate may awaken more often in milder weather, such as bats, hedgehogs, insects and dormice. On a protected site not far away, I recorded Britain’s rare dormouse active in February 2016, when the cold would normally render them torpid. There is concern that hibernating species such as dormice could fare worse in a warmer climate, because if they awaken at the wrong time there may not be enough food and they could die.

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