Could face fines of up to £2,500
A blanket rule which requires all dogs to be kept on a lead at the Ayres Nature Reserve in the north of the Island comes into force today (1 April).
Owners who breach the bylaw could face fines of up to £2,500 between now and 31st July.
The rule's being imposed to protect ground nesting birds, whose eggs and young are threatened by predators - including dogs.
There's a particular concern this year, as numbers of birds such as terns, skylarks and curlews, have declined recently.
Forestry warden Louise Samson says it's a precarious time for the precious species: