The latest data comes from Nature’s Calendar, which asks the public to record signs of the changing seasons. The butterflies, newts and nest-building blackbirds have been spotted months before they would normally appear. An analysis of the conditions in 2019 found that all but one of the 50 spring events the scheme tracks were early last year, amid warmer winter temperatures. The Woodland Trust, which runs the Nature’s Calendar scheme, warns that many species are losing their seasonal cues as winters warm and seasons shift.
Increasingly erratic weather could tempt some animals out of hibernation too soon, only to be hit by plummeting temperatures.
And some birds appeared to be breeding too late as they make the most of vital food sources that appear earlier than normal, the Trust said.
Lorienne Whittle, at the Woodland Trust, said: “It seems that last year we almost lost winter as a season – it was much milder and our data shows wildlife is responding, potentially putting many at risk.
“Our records are showing random events such as frogspawn arriving far earlier than expected, possibly to be wiped out by a late cold snap.”
And she said: “It appears that some species are able to adapt to the advancing spring better than others. Oak trees respond by producing their first leaves earlier and caterpillars seem to be keeping pace.
“But blue tits, great tits and pied flycatchers are struggling to react in time for their chicks to take advantage of the peak amount of caterpillars – the food source on which they depend.”
This winter’s surprise sightings include two December records – peacock butterflies on the wing in Kent and Cornwall, thought to have been woken early due to mild weather in the south of the country, and a red admiral in the Channel Islands.
Active newts were recorded in late December in Cheshire and a blackbird was spotted building a nest at the beginning of January.
Meanwhile, campaign groups have stressed the need to keep up environmental standards after the UK’s departure from the European Union.
A report for The Wildlife Trusts, RSPB and WWF, warned that the UK was at risk of losing regulations that prevented hedgerows being cut during the nesting season and buffer strips from being ploughed or sprayed by pesticides.
Rules ensuring bare soils are protected from draining or blowing away and safeguarding ponds and their wildlife, could also be lost without additional regulation, it added.
The report, by the Institute for European Environmental Policy, says a new system of regulation is needed.
A spokeswoman for the Department for Environment, Food and Rural Affairs, said: “We will continue to be a world leader on the environment as we leave the EU, and both the Agriculture Bill and the Environment Bill are a crucial part of that.
“We will not lower the exceptionally high environmental standards we already hold.”