The States of Jersey Department of the Environment said incidents included the ‘deliberate destruction of birds’ nests’, wildlife disturbance and littering.

The warning follows an incident last week on Maîtresse Île, Les Minquiers, where visitors cleared a sizeable area of vegetation, leaving bare soil exposed to the erosive action of the weather and sea spray.

Other recent activities that may have damaged the ecologically sensitive reefs include building bonfires; discarding disposable barbecues ashore; and disturbing seals and dolphins.

All Jersey’s offshore reefs (Les Écréhous, Les Minquiers, Les Dirouilles and Paternosters) are recognised as wetlands of international importance under the Ramsar Convention and the main islands are part of Jersey’s Coastal National Park area.

All parts of the reefs are considered to be ecologically sensitive. Between March and August the main islands are home to nesting seabirds, which it is an offence to disturb under Jersey’s Conservation of Wildlife Law 2000.

In the autumn large numbers of migrating birds are dependent on the vegetation on the reefs for shelter and food.

Up to 200 people onshore

The reefs are a popular summer destination for Jersey and French boats as well as organised day trips by commercial companies. On warm days a large number of boats can congregate in the anchorages and there may be up to a couple of hundred people onshore.

Dr Paul Chambers from the Environment Department’s natural environment team said: ‘We would like to make sure that boat owners and their passengers are aware of the ecological importance and fragility of our offshore reefs.

‘Aside from the recent uprooting of vegetation on Les Minquiers, we have also had reports of boats coming too close to seals and dolphins, the deliberate scattering of birds’ nests, and boats and jet-skis exceeding speed limits.

‘We would ask that all visitors to our reefs keep well away from nesting birds and that they don’t interfere with any local wildlife, including plants.’

Take litter and waste away

The Department is reminding boat owners that they are responsible for the conduct of their passengers and should respect Jersey’s wildlife laws.

Visitors should take all their litter and waste food with them when they leave.

French visitors are not allowed to land their dogs on the reefs and Jersey dog owners are strongly discouraged from bringing their animals on to the reefs.

The Department of the Environment would like to receive reports of any interference with wildlife on Jersey’s offshore reefs or any evidence of environmental degradation or damage.

The Jersey Biodiversity Centre would like to receive reports of any wildlife sightings (including species that might be considered as common).