The UK has experienced a “blurring” of the seasons once again this year in the face of rising temperatures, the National Trust said.
Nature expert Matthew Oates said: “It’s hard to put any single event down to climate change but the overall impact is quite staggering.
“It’s not just on land, it’s sea, it’s the ocean warming and what turns up here on our shores, Portuguese man o’ war, jellyfish, bluefin tuna, minke whales, which also suggests it’s not just a terrestrial issue.”
Bumblebees appeared in January due to mild conditions, spring flowers bloomed early, storms and warm seas brought Portuguese man o’war and bluefin tuna to UK waters and purple emperor butterflies were on the wing unusually early.
The organisation said its plans to reverse declines in nature – including creating 25,000 hectares (62,000 acres) of new habitat on its land by 2025 – were more urgent than ever in the face of changes in the climate.
And with year-round “thuggish vegetation” growth becoming a trend as a result of mild winters and damp summers, experts warn they will have to find new ways of managing special habitats to benefit the plants and animals that rely on them.
The National Trust’s annual review of the year showed a mild, dry start prompted many flowers to arrive early, including wild daffodils blooming in the Teign valley in February and elder and dog rose, usually June blooms, flowering in April.
Balmy weather in May led to a good nesting season for birds, with little terns doing well at Blakeney Point in Norfolk, and spring insects did well.
The elusive purple emperor butterfly, made its earliest appearance in 120 years, at Bookham Common, Surrey on June 11.
Then it was the “summer that nearly was”, nature expert Matthew Oates said, with clouds assembling just as the state schools broke up and leading to another in a string of wet Augusts – followed by a damp September.
Winged insects were hit, but it was a prolific year for fungi, including the rare powdercap stranger, which was found at Clumber Park, Nottinghamshire.
The fine spring spelled a good apple harvest and a bumper autumn for nuts and seeds, attracting a remarkable influx of elusive hawfinches from the continent with flocks of up to 50 reported.
Mr Oates said the year “was a bit all over the place yet again, there’s this issue of the blurring of the seasons, particularly through mild winters and damp summers”.
Although this spring did not see strong vegetation growth, allowing small annual plants and insects which need barer earth to do well, it is a trend that is hitting conservation of grasslands and woodland glade areas.
New measures, such as working closely with farmers to increase grazing, are needed to help these habitats and their wildlife cope with climate change, he said.
Mr Oates has urged people to sign up to citizen science projects monitoring nature, to help inform experts about what was happening in the countryside.