Wildlife is being confused by "lost" winters, conservationists have warned, as butterflies, newts and nesting blackbirds are spotted earlier than normal.
The latest data from UK-based wildlife group Nature's Calendar shows active butterflies and newts and blackbirds building a nest have already been spotted months before normal.
Analysis of the conditions in 2019 found all but one of the 50 spring events the scheme tracks were early last year, after warmer winters.
The British Woodland Trust, which runs the Nature's Calendar scheme, warns many species are losing their seasonal cues as winters warm and seasons shift.
Some could be tempted out of hibernation too soon and be hit by plummeting temperatures amid increasingly erratic weather, while some birds appeared to be breeding too late to make the most of vital food sources.
Lorienne Whittle, Nature's Calendar citizen science officer 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 when a late cold snap occurs.
"It appears 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.''