The census also shows details of their conservation status, abundance, legal protection and distribution.
The latest figures show that since 1961 there has been a significant increase in the gamebag index of nine of the species ? brown hare, grey squirrel, brown rat, sika deer, roe deer, muntjac (pictured), fox, stoat and weasel.
Dr Nicholas Aebischer, deputy director of research with the GWCT, said: ?The National Gamebag Census is important because it is the only scheme that monitors trends going back 50 years or more, and hence provides the historical context.?
?It is extremely important that we understand the current status of our UK mammal populations, so that, when necessary, we can put in place the right conservation measures.?
The rapid increase in numbers of non-native species is particularly noticeable in the latest figures.
The Trust believes many already pose a threat to the UK?s native species and habitats, and point to the deleterious effect of the muntjac on woodland structure and plant species such as bluebells.
Native animals such as the brown hare are also increasing, benefiting from the set-aside and agri-environment schemes that have restored habitat diversity to farmland.
However, the figures also record a significant decline since 1978 in American mink, which experts suggest may be due to the recovery of otter numbers and increased efforts to conserve water voles.