Crimes including badger-baiting and the poisoning, trapping and shooting of raptors all increased last year while restrictions were in place.
And there was a “shocking” 220 per cent increase in claims of developers interfering with badger setts, according to the study by the Wildlife and Countryside Link (WCL).
The link, a coalition of dozens of nature organisations, warned that countryside crime was proliferating, fuelled by lockdowns that allowed criminals to go unchecked.
The organisation’s fifth annual report, covering England and Wales, reveals many types of crime were at their highest or second-highest level last year, outlining how bats, buzzards, hares, kestrels, seals, dolphins and bluebells were all targeted.
But the document also warns the figures represent only “the tip of the iceberg” because the Home Office has no specific crime codes for wildlife offences so police cannot gauge crime levels.
Convictions for fishing and hunting crimes during the pandemic fell by at least half, to their worst ever rate in five years of records.
Experts said the low levels of prosecutions and convictions was partly down to fewer investigations.
“Crimes therefore never even reach the prosecution stage or fail in prosecution due to lack of expertise or last-minute bringing-on of the prosecutor to the case,” a WCL spokeswoman told The Independent.
“The recognition of the impact of this lack of expertise is reflected in the fact that new CPS training on the Hunting Act is being rolled out to prosecutors from early next month.”
Reports of crimes against badgers rose by 36 per cent last year, with potential fishing crimes also up by more than a third (35 per cent), according to the data.
Numbers of birds of prey being killed hit their highest level ever, rising from 54 to 104 even though raptor persecution is a priority for the National Wildlife Crime Unit. Raptors are targeted because shooters consider them a threat to game-bird numbers.
And as more people took holidays in the UK, reports rose of tourists in Cornwall physically approaching seals and dolphins.
Fishing crime convictions fell from 2,037 in 2019 to 679.
Martin Sims, chairman of WCL’s wildlife crime group, said: ‘‘Wildlife crime should concern everyone – it inflicts pain, harm and loss for much-loved wildlife and fuels wider criminality against people and property.
“Despite this, the police still don’t gather centralised data on these serious crimes, leaving an incomplete picture from charities, which could be just a drop in the ocean of wildlife crimes.
“It is high time the government stepped in to treat wildlife crime with the seriousness it deserves. Making key crimes notifiable would enable police forces to better target resources and track repeat offenders.
“Better police and prosecutor training and resources would help raise the pitiful 32 per cent conviction rate for hunting prosecutions alone.”
The UN Office of Drugs and Crime has produced recommendations for the government to consider.
Dawn Varley, acting CEO of the Badger Trust, said some developers seemed to see habitat protection “as an inconvenience to be quietly bulldozed over, rather than a legal requirement to conserve”.
The WCL says police record most wildlife crimes as “miscellaneous” so they are invisible in records, and numbers of offences are likely to be far higher than charities’ data.
A government spokesperson said: “We recognise the importance of tackling wildlife crime, which is why we directly fund the National Wildlife Crime Unit, who provide intelligence and support to police forces protecting our precious wildlife.
“We are clear those found guilty of harming animals should be subject to the full force of the law. Significant sanctions are available to judges to hand down to those convicted of wildlife crimes.”
A CPS spokesperson said: “We are working even more closely with the police and other partner agencies to bring about an improved performance in the investigation and prosecution of wildlife crimes,” they said.
“The pandemic reminded us about the importance of the natural environment and wildlife for economic, health and wellbeing reasons so the CPS stands ready to prosecute those who wish to harm this.”