Ups and downs for nocturnal species

The winter solstice marks the shortest day of the year and the longest night. But how are things looking for the animals exploiting this nocturnal niche?

How British nocturnal species are faring




A barn owl in flight

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Barn owl

67% increase in their range since the late 1980s according to the British Trust for Ornithology’s (BTO) recently published Bird Atlas 2007-11

Experts are still investigating why populations have been increasing but point to the provision of nest boxes and environmental schemes on farms as possible factors.

Paul Stancliffe from the BTO describes 2013 as a “lean year” for the birds due to a cold start but remains hopeful for next year’s breeding season.

A nightjar on ground

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Populations have increased by 128% since 1981.

Restoration of heathland habitats has helped the birds to recover from dramatic declines in the late 20th Century.

A lesser horseshoe bat hanging

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Horseshoe bats

Last year, lesser and greater horseshoe bat populations both showed an annual increase of around 5%.

Bat numbers suffered significant declines before the 1980s but better protection has helped some species to stabilise.

A nightingale

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Numbers have fallen by 46% since 1995.

Degradation of breeding grounds and general habitat loss have been identified as the key factors behind the bird’s decline.

Conservationists are now managing the remaining strongholds to provide scrub habitats specifically for the birds.

A moth on a tree

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Primarily summer specialists but two of the latest flying moths, the aptly named December moth and Winter moth, have suffered population declines of 68% and 19% since 1970.

Habitat loss and the “deteriorating condition of the countryside” are behind the losses according to charity Butterfly Conservation.

A natterjack toad on sand

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Natterjack toad

Disappeared from 70% of its former range in the last century and by 1970 only remained in 50 locations.

Numbers have stabilised following conservation efforts to restore habitats and recolonise nature reserves.

Continue reading the main story

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This year’s State of Nature report, described as a stocktake of UK nature, suggested 60% of animal and plant species studied have declined in the past 50 years.

Species that are adapted to ecological niches have fared particularly poorly compared with generalists able to adapt to changing temperatures and human developments. Dusk and dawn sightings of hedgehogs have dwindled as the species has dramatically declined by over a third since the millennium.

Experts from the People’s Trust for Endangered Species have been investigating the mammals’ plight and are concerned that a lack of food in the wider countryside could be responsible for their problems.

The animals traditionally feast on beetles, worms, caterpillars and other invertebrates. But could artificial light be having an adverse effect at the small end of the biodiversity scale?

“We’re very worried about light pollution and the effect it’s having on invertebrates,” says Matt Shardlow, CEO of charity Buglife.

“Invertebrates perceive the world a lot differently to how we perceive it, we are after all a daylight species used to being in bright light all the time. But for animals living at night, bright light is anathema.”

Experts are concerned about the impacts for certain species that are more sensitive to light than others, especially those that use light to communicate such as the glow worm.

“The female glows in the grass and the male has to find her. If the area is flooded with artificial light then the male has no hope of finding the love of his life,” explains Mr Shardlow.

This year, Buglife has been conducting surveys in Scotland to establish how light pollution effects glow worms and they are now crunching the data from 300 records.

“In Dumfries and Galloway they have declared a dark sky reserve, where they have brought in new planning guidance restricting the amount of light pollution,” says Mr Shardlow.

The charity will monitor whether this effort helps night-specialist species with further surveys.

The glow worm, with its unique light signature, is one of few nocturnal species that can be monitored with relative ease but the lack of light poses a major obstacle in the study of other night-time specialists.

Scientists have found inventive methods of tracking some from high-frequency bat detectors to moth traps, but the future prospects of others remain in the dark.

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