Lepidopterists, butterfly spotters, have been rubbing their eyes and checking their calendars in what is proving to be a remarkably early spring this year. In my native Northamptonshire, a Small Tortoiseshell was out and about on New Year’s Day.

Brimstones, Speckled Wood, Painted Ladies, Peacock and Comma had all been recorded on the wing by the end of January.

I love butterflies, the first sight of a buttery pale yellow Brimstone is usually the first indication that winter is past.

It is the pale hue of the Brimstone that is the origin of the word butterfly.

Another favourite is the huge Swallowtail, Britain’s biggest butterfly, doing so well in my beloved Broads National Park.

It is always a welcome site on summer boating days.

The clouds of the palest blue butterflies fly up in clouds disturbed by walkers on high-chalk grasslands. They always seem to be most numerous around the chalk figures and horses cut into the hillside.

Flying high in the woods near my Northamptonshire home you may spot the most spectacular rare, exotic and curious Purple Emperor. No wonder poet John Clare, who knew those woods so well, called all butterflies “Queen of all the insect race.”

Now, despite an early start to the year, those wonderful, fragile, colourful species are in trouble. More than three-quarters of Britain’s butterflies have declined in the past 40 years, according to a report by the charity Butterfly Conservation.

The study drew on local observations and surveys by thousands of volunteers lepidopterists and butterfly-spotters.

Agricultural intensification, the loss of wildflower rich grassland and changing woodland management are believed to be the main causes.

More recently the use of neonicotinoids — so harmful to bees and other flying insects — has also had a drastic effect on butterfly numbers. Climate change and pesticide use are further factors in the widespread decline.

The report found that a number of species such as the Wall, Essex Skipper and Small Heath now rank among the most severely declining butterflies in Britain.

Not all the news is bad. While the main conclusions suggest a bleak outlook for these beautiful creatures, some rare species were benefiting from targeted conservation.

The report reveals that intensive conservation efforts have started to turn around the fortunes of some of the most endangered butterflies.

According to Richard Fox, author of the report, this was as a result of landscape-scale projects — protecting and restoring threatened habitats such as managed wildflower-rich grasslands and heath land.

The threatened Duke of Burgundy butterfly, for example, has seen a recent increase in abundance of 67 per cent, following years of decline, thanks to grassland restoration, while the Pearl-bordered Fritillaryhas experienced a 45 per cent rise.

Numbers of Britain’s most threatened butterfly, the High Brown Fritillary, has also been boosted, particularly by conservation work in Exmoor National Park. Dingy Skipper and Silver-studded Blue have shown 21 per cent and 19 per cent increases respectively.

Other species continue to struggle. The long-term decline of the Wood White, White Admiral and Marsh Fritillary show few signs of halting. 

The report reveals a north-south divide among butterflies with species in England declining and those in Scotland holding their own.

The report also reveals that more butterflies are migrating to Britain from overseas. Since the 1970s, visits from the three common migrant species — Clouded Yellow, Red Admiral and Painted Lady — have all increased dramatically.

Even rare migrants such as the Scarce Tortoiseshell and Long-tailed Blue have arrived in unprecedented numbers in the last few years.

Fox, head of recording at the charity Butterfly Conservation, told us: “Thanks to tens of thousands of people who help to count butterflies in Britain each year, we have a clear picture of the changing fortunes of these captivating insects.

“Overall the situation is stark. Most butterflies have decreased since the 1970s and an alarming number of common species have declined severely.

“On the other hand, trends over the past decade provide grounds for optimism and show that our approach to conserving threatened butterflies can stem and even reverse declines.

“It’s about protecting these sites from being destroyed,” Fox continued: “Co-ordinated management of a landscape in a whole series of sites — that gives the butterflies a fighting chance.”

The charity’s vice-president and broadcaster Chris Packham told the Morning Star: “This report reveals that UK butterflies are in real trouble. Yet again we are presented with sobering evidence that our much-cherished wildlife is in dire straits.

“As a society we are guilty of standing idly by as once common species, never mind the rarities, suffer staggering declines. This is a situation that should shame us all.

“The future of the UK’s butterflies does not have to be bleak. This report shows conservation work can and does turn around the fortunes of our most threatened butterflies.”

Let’s hope that all those early sightings are a harbinger of a really bright and colourful butterfly summer.