Off-road motorcyclists are being warned against riding across greenlanes and greenway roads.
The government says to stick to designated tracks to 'protect wildlife, habitat and livestock'.
It comes after a visitor was found riding illegally through an upland Area of Special Scientific Interest (ASSI) in the Central Hills last week. The man was issued with a fine by the police after a farmer tipped off DEFA rangers.
Environment Minister Clare Barber said: 'While I understand the temptation to find a new spot to watch the bikes we urge riders to be responsible.
'The uplands are home to protected ground nesting birds, such as hen harrier and curlew, important peat habitats that are easily destroyed and livestock, none of which should be disturbed. Both motorbikes and birds contribute to our unique UNESCO Biosphere, so we must ensure that one does not spoil the other.'