Changeable year boosts migrant insects – but leaves some wildlife struggling

Changeable weather in 2019 saw an influx of migrant wildlife – but mixed fortunes for some of the UK’s native species, the National Trust said.

A slightly “stop-start” spring with intermittent warm spells of weather in the early half of the year saw migrant butterflies, moths and dragonflies from the south and east arrive in Britain.

But the changeable summer, with bouts of heavy rainfall, harmed species such as water voles in the Yorkshire Dales, which were hit by sudden flooding, while seabirds on the Farne Islands lost chicks in June downpours.

And there were knock-on consequences from last year’s drought and heatwave, ranging from devastating fire on Marsden Moor over the Easter weekend, to a good year for orchids.

The National Trust said climate change was driving more erratic weather, and it was important to protect and expand habitats to help support wildlife under pressure and allow species to move across the landscape.

Keith Jones, climate change expert at the Trust said: “This year’s changeable weather is a symptom of the warming climate.

“The more our temperatures go up – the more erratic our weather will become. This will force changes to the life-cycles of many species as food webs are knocked out of sync.”

Ben McCarthy, head of conservation and restoration ecology at the Trust, added: “Sightings of migrant insects and birds are becoming more common. This is a result of our changing climate.

“Although this can seem exciting, the obvious flip-side is how these changes will start to affect some of our native species already under pressure from intensive land use, habitat fragmentation and climate change.”

Among the migrants spotted were the long tailed blue butterfly, from the Mediterranean, which set new records with 50 seen along the south coast of England, mating and laying eggs.

The Clifden nonpareil, a rare moth which became extinct as a resident species in the UK in the 1960s but has been trying to re-establish itself, was recorded at Killerton in Devon, with many more spotted in the south of the country.

There were also high numbers of migrant dragonflies including the red-veined darter and vagrant emperor in June, July and August.

Southern migrant hawker dragonflies, which first bred in the UK in 2010, consolidated their numbers and possibly colonised new counties, Dorset and Yorkshire, while the small red-eyed damselfly made it to Lancashire.

The biggest influx of migrant wildlife was hundreds of thousands of painted lady butterflies, turning this year into a once-in-a-decade “painted lady summer”.

Rare vagrant birds were also seen, including the first sighting of the brown booby, usually at home in the Caribbean, and American black tern and a red eye vireo were spotted in the autumn, probably blown off course by low pressure systems.

Among native wildlife, sandwich terns and little terns fared well at Blakeney Point in Norfolk, and grey seals appear to be thriving around the UK’s shores.

Wildflowers such as orchids did well, possibly due to last year’s drought which reduced competition from grasses, with bee orchids, dark-red helleborine and green-winged orchids flourishing in places such as south-east Cumbria this year.

The weather pattern of the past two years resulted in a bumper or “mast” year for seeds and berries, but warm wet conditions also meant a strong year for grass growth which could lead to problems for wildflowers and pollinators.

Sudden rain in June, July and August also hit breeding water voles in Malham Tarn, with sudden flooding causing the loss of young who cannot swim.

Significant rainfall on the Farne Islands in June caused losses for Arctic terns, puffins, shags and guillemots, as it came just at the time their chicks were most vulnerable.

Natterjack toads suffered the opposite problem, with pools of water in their dune habitat drying out in May and June, wiping out spawn and tadpoles, while another attempt in August was wiped out by exceptionally high spring tides.

The National Trust said rangers also recorded the earliest and latest spawning dates for the past decade, possibly indicating how natterjacks are trying to adapt to the changing climate.