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About the territory

The Bailiwick of Jersey is located in the English Channel at latitude 49° 13’ North, 2° 12’ West, approximately 161 km south of England and 22km west of the Cotentin Peninsula, France. It is the largest of the Channel Islands.


Map of Jersey

The earliest evidence of human activity on Jersey dates to about 250,000 years ago when Neanderthal hominids used caves as a base for hunting mammoths. Jersey was linked to the continent until approximately 8,000 years ago when a rise in sea level created what is now the Channel Islands. Although politically part of the Duchy of Normandy, in 1204 the Channel Islands elected to remain with the English Crown when Normandy became part of France. Today Jersey forms part of the Bailiwick of Jersey and is one of the three Crown Dependencies off the coast of Great Britain; the other two being the Bailiwick of Guernsey and the Isle of Man.

The Bailiwick of Jersey is made up of the main island Jersey (which is the largest of all the Channel Islands) and smaller islets and reefs including; Les Minquiers, Les Écréhous, Les Pierres de Lecq and Les Dirouilles. The Bailiwick is comprised of approximately 120 km² of land and 2,455km² of marine waters. Jersey has an official population of 97,857 (2011 census), although recent estimates put that number closer to 108,000 (estimate end 2019), over a third of whom live in the capital, Saint Helier. None of the other islands that make up the Bailiwick of Jersey have a permanent population. Tourism, agriculture and finance are very important to the economy of Jersey.

Jersey’s position as an island in the English Channel has a significant effect on its environmental conditions and this has helped shape its unique mix of wildlife as well as it’s landscape and seascape character. It is influenced by the warming effect of the Gulf Stream and colder northern waters, allowing species from both north and south to be found here at the limit of their ranges. Jersey has one of the highest tidal ranges in the world (up to 12m on Spring tides) which has a profound effect on the character and habitats of the coast and the offshore reefs and islands. Jersey’s climate is also the product of several influences and the reactions between them. There is a strong maritime influence (including the Gulf Stream), which tends to modify both summer heat and winter cold. As it is so close to France there is also an influence from continental Europe. Jersey therefore has a unique climate, distinctive from the other Channel Islands, the UK and France. Average summer temperatures are 13-19°C, average winter temperatures are 9.7-15.3°C. Annual rainfall averages about 900mm.


Over half of the land in Jersey consists of arable farmland and pasture. Semi-natural habitats (wetlands, heathlands, sand dunes, cliffs and coastal slopes, scrub and woodlands) cover about 26% of Jersey and support a large amount of Jersey’s unique mix of biodiversity with the remainder found in urban settings. Jersey’s only National Park currently extends down to Mean High Water across all Islands of the Bailiwick covering approximately 16% of the land cover.

Within the Bailiwick’s marine environment key subtidal groups include Seagrass meadows Zostera spp. , Kelp beds Laminaria spp. , Maerl beds coralline algae, species rich coarse sediment and sandmason worms. Intertidally Seagrass meadows Zostera spp., sandmason worm beds Lanice spp.,high diversity clam beds and the ‘flooded gully’ complexes on the intertidal platforms are significant. Importance is also noted in the complex mosaics exemplified by the offshore reefs, intertidal areas and parts of the sedimentary basins.

The Wildlife (Jersey) Law 2021 lists all protected species including; 72 plant species, 2 fungi, 2 lichen, 7 species of amphibian and reptile, as well as selected mammals (including all species of bat), birds, invertebrates, fish, dolphin, seal, porpoise, whale and turtle. Read the full schedule of protected species in the Wildlife (Jersey) Law 2021

All wild birds found in Jersey whether resident or migrant are protected by the Wildlife (Jersey) Law 2021, apart from the Magpie Pica pica, Carrion crow Corvus corone, Wood pigeon Columba palumbus and Feral pigeon Columba livia,

There are currently 370 avian species recorded in the Working List of Birds of the Channel Islands (at 2018, the latest available issue).

Acting as a key indicator species for habitat quality butterflies are closely monitored in Jersey. The State of Jersey Butterflies 2015 recorded that there are approximately 34 butterfly species seen 24 of which are generally more common with the remaining 10 either rare residents or migrants.

The Jersey Biodiversity Centre (JBC) collates and manage biological records for Jersey. The Centre provides high quality, accurate and timely data which are used by decision makers and planners to safeguard the Island’s biodiversity for future generations. Currently the centre holds approximately 430,000 records dating back to the 17th century.

Policy and legislation

The Bailiwick of Jersey has been included in the UK’s ratification of several multilateral environmental agreements (MEA’s), including the Convention on Biological Diversity, Convention on International Trade in Endangered Species, the Convention on Migratory Species of Wild Animals (with its associated agreements including Eurobats and the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA)) ,the Convention on the Conservation of European Wildlife and Natural Habitats, the Ramsar Convention on Wetlands of International Importance, and the World Heritage Convention.

At local level the main piece of legislation that protects wildlife in Jersey is the Wildlife (Jersey) Law 2021. Guidance to accompany this Law is currently being developed.

Read the Wildlife (Jersey) Law 2021

The Planning and Building (Jersey) Law 2002 provides for legal protection to be afforded to Sites of Special ecological Interest (SSI).

In addition to the three local Ramsar sites covering 180 km², Jersey has three marine protected areas (covering 150 km²) where destructive fishing practices are prohibited.

The Biodiversity Strategy for Jersey (2000) outlines the island’s commitments to conserve and enhance biodiversity, through the implementation of action plans at local level to help rare or significant species and habitats and to contribute towards the conservation of global biodiversity.

The Biodiversity Strategy is accompanied by The Biodiversity Action Plans (BAPs) which were first published in 2006. These are part of the Island’s response to the Biodiversity Convention. From 2006 to 2011 these Action Plans were published for individual species and habitats, that are under threat and require protection, with the aim of outlining the  actions required to protect them.  Post 2011, the Biodiversity Convention adopted a revised and updated Strategic Plan for Biodiversity 2011-2020 which included 5 strategic goals and  20 ‘Aichi Biodiversity Targets’ as a basis for halting and eventually reversing global declines in biodiversity. This new approach will be adopted in Jersey. Jersey’s Biodiversity Action Plans provide an important and valuable reference source which assists in identifying vulnerable species that may require greater protection through being added to the Schedules of protected species in the Wildlife Law.

Read the Government of Jersey Biodiversity Strategy

Invasive species & biosecurity

In 2017 a review of all non-native marine species within the Channel Islands identified 43 established species with a likelihood there being another 25 resident species which have yet to be discovered. Horizon scanning suggests that there are at least 134 NNS marine species which have the potential to reach the island.

Threat assessments identified Crepidula fornicata (Slipper Limpet), Sargassum muticum (Wireweed) and Crassostrea gigas (Pacific Oyster) as having had the greatest overall impact on the marine environment. Future ecological and economic impacts may be expected from Rapana venosa (Rapa Whelk), Didemnum vexillum (Carpet Sea Squirt) and several species of seaweed.

At a terrestrial level the JNCC has a comprehensive list of invasive species highlighted locally. There are more than 50 invasive plant species, thirteen terrestrial invasive invertebrates, two invasive reptiles (Red-eared slider Trachemys scripta Elegans and Corn snake Elaphe guttata), one invasive amphibian (Pool frog Rana lessonae), one invasive bird (Pheasant Phasianus colchicum ), and four invasive mammals (including the feral cat Felis catus and feral ferret Mustela furo).

Jersey has completed some preliminary work with a view to developing its own NNS and Biosecurity Strategy that will draw all the existing threads of knowledge and understanding together to contribute to action plans designed to tackle the threats posed.

Problems with invasive non-native species

The need to develop its own NNS/Biodiversity Strategy comes from a recognition that without a co-ordinated assessment and action plan the issues (some of which are highlighted below) will only increase and continue to get worse. The value of a strategy is that we will have the ability to: quantify and manage the threat posed by resident INNS; prevent or prepare for the arrival of new INNS; and to coordinate the gathering and dissemination of information. Developing an Implementation Plan or “road map” that aligns the Jersey’s response to INNS to that of the UK and Europe is critical.

Jersey’s location within the Normano-Breton Gulf and close transport links with southern England and Northern France make it susceptible to the outward spread of NNS from the Bay of Biscay, English Channel and North Sea ports. Hotspots include St Helier Harbour from which newly arrived species may spread into the wider marine environment. As the most southerly area of the British Isles, Jersey has received several marine NNS before the UK including the Asian Shore Crab (Hemigrapsus sanguineus) and Asian Bryozoan (Watersipora alata). As such, the Channel Islands may provide an early warning for species spreading northwards into the English Channel.

Other examples include green fleece which fouls shellfish beds and causes a myriad of impacts on shellfish communities. It has been documented to alter benthic communities and habitats, causing serious environmental implications. American limpet populations are well developed in bays, estuaries or sheltered sides of wave-exposed islands. It competes with other filter-feeding invertebrates for food and space, and often occurring in enormous numbers. Few management options are available to combat this species.

Dense stands of Japweed may reduce light, decrease flow, increase sedimentation and reduce ambient nutrient concentrations available for native kelp species. Leathery sea squirt can reach extreme densities and out-compete native organisms for food in the water column. It also predates on the larvae of native species causing population declines. Both Asian kelp and Japanese kelp form dense underwater forests, resulting in competition for light and space which may lead to the exclusion or displacement of native plant and animal species.

Japanese knotweed Fallopia japonica is relatively widespread and even found on parts of the coast. The dense stands it produces shades out the understorey decimating localised biodiversity. Treatment is slow and resource hungry and the plant is quick to spread if left unchecked. Recent problems associated with the built environment need further investigation.

The Asian Hornet Vespa velutina first identified in Jersey in 2016 has increased its density and distribution despite a very successful, co-ordinated effort to track and eliminate individual and their nests. The threats to local biodiversity and local apiculture are very real and the increasing understanding of the ecology of the insects undertaken by local volunteers and scientists has enabled an action plan to be implemented and regularly reviewed.

Spanish bluebell Hyacinthoides hispanica is widespread, hybridising with and outcompeting the native common bluebell Hyacinthoides non-scripta. White stonecrop Sedum album is a non-native stonecrop species. It is widespread in Jersey and may represent a threat to the native species.

Sour Fig Carpobrotus edulis and other members of the Aizoaceae family are becoming dominant in coastal grasslands, dune and heath habitats having an impact on the biodiversity of these areas. Control of these plants is continually targeted by volunteers and other means.

New Zealand pigmyweed Crassula helmsii is an extremely invasive aquatic plant that has escaped from garden ponds and is potentially a major threat to native aquatic life. Forming dense mats in freshwater environments this plant blocks out light and spreads particularly easily via associated vectors. Trialling control are underway for this and a number of the succulent species using pressurised heated foam and these are proving successful, although resource hungry.

Priority invasive non-native species and actions

There has been a severe outbreak of the Oak Processionary Moth (external link) in Jersey which the government trying to control. Oak Processionary Moth is a risk to human health as its caterpillars are covered in hairs that contain a toxin and can cause skin irritation and allergic reactions in anyone who inhales them or comes into contact with them.

Sour fig Carpobrotus edulis covers extensive areas of coastline to the detriment of the native flora and fauna, but due to the terrain, is often extremely difficult to manage. On steep cliffs rope access teams hand pull and stack whilst on more accessible terrain large areas of the fig can be pulled up by hand or using heated pressurised foam water (via a lance) to kill in situ.

Purple dew plant Disphyma crassifolium is an invasive succulent that is spreading across the coast. Significant resources are used to remove succulents from protected sites ranging from hand pulling and collection to more recently the use of heated pressurised foam water to kill in situ.

The Government of Jersey are gathering data on the spread of Japanese knotweed. This species is aggressive and there is no quick solution for its control. Indiscriminate cutting as a control method is not effective giving rise to increased opportunities for establishment so locally the most effective treatment used has proven to be stem injection with herbicide (where conditions allow). Use of electricity via a lance has also been tried with some success in Jersey although access can be a limiting issue.

See Japanese knotweed guidance in Jersey

Holm oak Quercus ilex is widespread in Jersey, thousands of growing saplings are pulled up by hand each year. In 2011-2012, 258 man/days were dedicated to removing mature trees and saplings.

Cortaderia selloana is proving to be a highly invasive plant species, the grass that forms dense clumps is removed where possible but is difficult to totally eradicate unless in an agricultural setting.

The ‘Birds on the Edge’ project is using a herd of Manx Loaghtan sheep to help with the restoration of Jersey’s coastline. The extensive grazing helps prevent the spread of invasive scrub and bracken, opening up areas for more sensitive plants to grow, allowing a mosaic of heathland vegetation to develop. http://www.birdsontheedge.org/


Useful information


Scott Meadows, Head of Biosecurity, Government of Jersey s.meadows@gov.je