Wildlife of
Guernsey

Primary Threats

• Because Guernsey is small and relatively densely settled, even modest housing, tourism, and coastal facility development can fragment remaining semi-natural habitats (coastal grassland, heath-like cliff tops, wetlands/pond margins). Reclamation/armouring and changes to shoreline management can reduce the extent and quality of intertidal habitat used by waders and shore invertebrates.
• Sea-level rise and more frequent/intense storm events increase erosion and pressure for hard coastal defenses, which can squeeze intertidal habitats. Warming seas and marine heatwaves can shift the timing/availability of prey for seabirds and affect kelp and other cold-temperate marine communities, while warmer winters can also favor invasive plants and pests.
• Runoff from roads and agriculture, intermittent wastewater/sewage overflow risks, and contamination from marinas/harbors (fuel residues, antifouling paints, heavy metals) can degrade nearshore water quality. Marine litter and microplastics accumulate on beaches and in wrack lines, affecting wildlife and the visitor economy that supports conservation funding.
• Invasive plants (e.g., aggressive coastal and garden escape species) can outcompete native cliff and dune flora, reducing habitat value for invertebrates and ground-nesting birds. Invasive predators such as rats can threaten seabird nesting success on offshore rocks/islets and coastal sites, requiring ongoing biosecurity and control.
• Seabird colonies and coastal bird assemblages are vulnerable to episodic disease events (notably avian influenza), which can cause rapid population declines and complicate monitoring and rehabilitation efforts. Small, localized populations on islands also have limited resilience to sudden mortality events.
• Pressure on inshore fisheries (notably shellfish such as lobster/crab and other nearshore resources) can alter food webs and reduce prey availability for marine predators. In a small-island setting, local depletion can occur quickly if effort concentrates in accessible bays and reefs, especially during good weather seasons.
• High recreational use of the coast-cliff-path walking, dog walking, coasteering, boating/kayaking, and shoreline foraging-can disturb roosting waders, breeding seabirds, and sensitive intertidal communities. Repeated disturbance at popular viewpoints and access points can reduce breeding success and push birds away from high-quality feeding areas.
• Harbor works, sea defenses, coastal road protection, and utilities placed in constrained coastal corridors can directly remove habitat and create barriers between cliff-top habitats and the shore. Hard engineering solutions can also simplify shoreline structure, reducing refuge and nursery space for intertidal species.
• Routine grooming of beaches, removal of seaweed wrack, drainage/management changes to ponds and wet depressions, and stabilization/reshaping of coastal slopes can reduce habitat complexity. These changes especially affect invertebrates and the birds that depend on them, as well as native coastal plant communities adapted to dynamic disturbance.
• While large-scale expansion is constrained by land limits, intensification (field enlargement, hedge/bank removal, higher nutrient inputs) can reduce farmland biodiversity and increase nutrient and sediment runoff into bays and streams/ponds.
• Ongoing infill and redevelopment pressure increases light and noise along the coast and reduces remaining semi-natural patches within the settlement matrix. This can particularly affect bats, nocturnal seabirds, and other species sensitive to artificial lighting and habitat fragmentation.