A number of people monitoring the activities of the unnamed hunt on land near Selby submitted video footage of alleged illegal hunting to the police, but only one of them agreed to provide a formal statement required for the case to proceed to court.
Two individuals were interviewed over the incident but there was not enough evidence to bring criminal charges against anyone.
North Yorkshire Police have now published a full account of the investigation and explained why many wildlife crimes are difficult to prosecute without the co-operation of witnesses, including those who reported the offence.
The alleged incident took place on October 1 last year.
The police statement reads: "Video footage was supplied but although a number of witnesses were present, only one individual would come forward to give a formal statement.
"Having carried out extensive enquiries, reviewed the limited video footage available, and conducted interviews with two individuals involved, the case was then reviewed by a senior wildlife crime officer. Upon reviewing the information, the decision was made that there was insufficient evidence to successfully bring about a case under the Hunting Act 2004. This decision was made in consultation with the Crown Prosecution Service.
"All wildlife crime investigations are extremely complex and without sufficient, strong evidence, it can be very difficult to bring about a successful prosecution. We know this is frustrating to members of the public and it is frustrating to our officers but we can only act within the legislation available.
"If anyone takes video footage or photos, or witnesses a wildlife crime offence we ask that you contact the police immediately without taking action yourself. We have 28 specially trained wildlife crime officers in the force who are experienced in the complexities of these investigations and can ensure that evidence is gathered correctly and meticulously to give the investigation the best chance of reaching prosecution.
"We want to reassure our communities that we take all reports of wildlife crime very seriously and will continue to do everything we can to protect the diverse range of animals and birds which makes their home in our beautiful county."