Alderney Police say the Longis Nature Reserve was damaged around 14:00 on Thursday 15 September.
It’s not known who the motorcyclist was but he has been described as “an unknown male”, who was “witnessed riding an off-road motor bike”.
The police spokesman said the rider has damaged bird netting and then ridden off.
Witnesses should call Alderney Police, via Guernsey Police on 222 222, or Crimestoppers anonymously on 0800 555 111.
Pictured: The Longis Nature reserve is managed by the Alderney Wildlife Trust.
The Longis Nature reserve is to the north of Alderney and has bird hides, reedbeds, grasslands, and a picnic area.
A sweeping coastal reserve including high energy intertidal wetlands, species rich coastal grassland, freshwater wetlands and scrub.
It has two bird hides, which overlook the reserve’s freshwater ponds, offering views of waterfowl, songbirds, and migrating birds.
