This spring has seen a return to the Victorian era, with the season arriving at a rate more similar to the 19th century than to recent years, experts have said.
The speed at which key signs of spring, such as sightings of swallows, orange tip butterflies and hawthorn coming to leaf, moved up the UK from the south slowed to 1.2 miles per hour (mph) in 2016, analysis shows.
That puts the arrival of the season in 2016 in line with averages between 1891-1947, which were also around 1.2 mph, based on records from the Woodland Trust's Nature's Calendar scheme which records signs of the changing seasons.
It was much slower than 2015's 1.9 mph or the 1.8 mph seen on average between 1998 and 2015, according to analysis by Professor Tim Sparks of Coventry University.
Sightings of frogspawn, swallows, oak leaves and hawthorn flowering all showed spring making much slower progress up the country in 2016 than in 2015.
The analysis reveals spring took roughly four weeks to travel the length of the country this year, compared to three weeks last year.
This year a mild wet winter, an early spring and then a cool March and April prolonged activity such as flowering and leafing.
The Woodland Trust warn the stretching of the season could have proved problematic for some nesting birds, such as tits, which rely on the leafing of oak as an indicator of when to brood their young to ensure a steady source of food.
Woodland Trust citizen science manager Dr Kate Leithwaite said: "It's without question that wildlife reacts to the arrival of spring flowers and trees.
"Whilst this analysis perhaps throws up more questions than it answers, it does highlight the delicate balance success and failure is for a number of species."
Nature's Calendar is a continuation of seasonal records which go back to the 18th century when they were first compiled by Norfolk landowner Robert Marsham. Now tens of thousands of records are added by members of the public.