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Providing evidence to improve practice

The journal, Conservation Evidence

Our online journal publishes research, monitoring results and case studies on the effects of conservation interventions. All papers include some monitoring of the effects of the intervention and are written by, or in partnership with, those who did the conservation work. It includes interventions such as habitat creation, habitat restoration, translocations, reintroductions, invasive species control, and education or integrated conservation development programmes, from anywhere around the world.

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A volume is created each year with peer-reviewed papers published throughout the year. We now accept Short Communications as well as standard papers.

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Volume 3

An integrated island biodiversity restoration programme was initiated in 1999 on the Seychelles. It has inspired both governmental and non-governmental organisations to undertake numerous conservation programmes on several islands in the archipelago.


On a Fijian island a decision was made to remove feral dogs Canis familiaris as they were predating upon endangered fauna. Rather than trapping or shooting, by offering food and gradually habituating them to people, almost all were captured unharmed and moved to the main island of Fiji.


An abandoned Bermuda petrel Pterodroma cahow (a critically endangered seabird) chick, about two thirds grown, was successfully fledged and returned to the wild.


A second population of the endangered Laysan duck Anas laysanensis, was successfully established on Midway Atoll by translocation and release of wild birds from the only extant population on Laysan Island in the Hawaiian archipelago.


The endemic subspecies of perennial knawel Scleranthus perennis ssp. prostratus is found only in the Breckland area of eastern England. Here it was restricted to north Suffolk, having been extirpated from all know Norfolk sites. In the mid 1990s an attempt was made to reintroduce it to one of its old Norfolk sites. Through a combination of transplanting locally cultivated plants, seed sowing, grazing, and occasional soil disturbance management. By 2005 perennial knawel had become well established and the introduction appears to have been very successful.


The endemic subspecies of perennial knawel Scleranthus perennis ssp. prostratus, is found only in the Breckland area of eastern England. Due to marked recent declines, an attempt was made to reintroduce it to a 'conservation path' in the county of Suffolk. Plants were introduced and seeds sown in what appeared suitable areas. Members of the public visiting the site have provide sufficient soil disturbance to ensure the ground is suitably bare for establishment of new seedlings with little additional management required except occasional removal of encroaching heather Calluna vulgaris. To date, the reintroduction has been successful.


The endemic subspecies of perennial knawel Scleranthus perennis prostratus, is found only in the Breckland area of eastern England. Due to marked recent declines, an attempt was made to reintroduce it to a site known to have historically supported the species in the county of Suffolk. Habitat conditions appeared suitable to support it. Locally cultivated plants were transplanted in the spring, but probably due to summer drought, all died. A second attempt the following year also failed, it is suspected due to a large increase in rabbit Oryctolagus cuniculus numbers with many perennial knawel plants appearing to have been scuffed up by their digging activies.


The endemic subspecies of perennial knawel Scleranthus perennis ssp. prostratus, is found only in the Breckland area of eastern England. Due to marked recent declines, an attempt was made to reintroduce it to a site known to have historically supported the species in the county of Suffolk. A total of 45 flowering perennial knawel plants cultivated locally, were transplanted in spring to this sheep-grazed site. A year after planting all the transplants had died and no seedlings were observed. The following spring a further 84 adult plants were transplanted, but again all had died by the following year and no seedlings were present. It is thought that sheep-grazing was not intensive enough to keep surrounding vegetation short enough and to keep the ground sufficiently bare to enable successful establishment and germination.

The endemic subspecies of perennial knawel Scleranthus perennis prostratus is found only in the Breckland area of eastern England. Due to marked recent declines, an attempt was made to reintroduce it to a former site in the county of Suffolk. Eighty seedlings were planted in a ploughed plot and well-watered in. Some plants were initially scuffed out by rabbits Oryctolagus cuniculus, but steadily numbers increased over the subsequent two years to 240 plants. However, over the next three years numbers fell to only six individuals. It is thought that too much grazing and digging up of the plants by rabbits occurred in these latter years.

The endemic subspecies of perennial knawel Scleranthus perennis prostratus is a declining plant found only in the Breckland area of eastern England. In 1992, at a locality where perennial knawel had been recorded in 1985, the ground was disturbed using a vibrating subsoiler. As a result of this soil disturbance, in 1994 two plants appeared. From seeds of these plants, seedlings were propagated and transplanted. After initial success the population dwindled and none were observed in 2005, additional mature plants were therefore planted. It is believed that the basic soil pH (7.5) and herbicide drift from neighbouring fields has been deleterious to the site and reduced habitat suitability for perennial knawel.

The endemic subspecies of perennial knawel Scleranthus perennis prostratus is a declining plant found only in the Breckland area of eastern England. In 1978, a population of 1,670 individuals was recorded in a small 6.8 ha patch of heathland. In 1994, a survey found only 32 mature plants. In an attempt to enhance habitat conditions, old furrows were re-ploughed and sheep-grazing introduced to break up the ground and reinstate patches of bare ground suitable for germination and seedling growth. As a consequence of management, and also rabbit Oryctolagus cuniculus grazing, the perennial knawel population increased, by 2000 several thousand plants were recorded. An experimental exclosure showed that in the absence of sheep and rabbit grazing, and period disturbance management, the perennial knawel died out.

The endemic subspecies of perennial knawel Scleranthus perennis ssp. prostratus is a declining plant found only in the Breckland area of eastern England. In a small 3 ha patch of heathland, in1974 approximately 1,000 perennial knawel plants were recorded. Although numbers fell to very low levels, a combination and refinement of management techniques including periodic rotovation and ground scarification appears to be maintaining a reasonable perennial knawel population.

The endemic subspecies of perennial knawel Scleranthus perennis prostratus is a declining plant found only in the Breckland area of eastern England. At a site in north Suffolk in the early 1980s the plant was found to be thriving. Regular mowing and consistent small-scale ground disturbance at this site has proved perhaps the ideal management regime for the species.

The critically endangered Antiguan racer Alsophis antiguae, used to be abundant throughout the Lesser Antillean islands of Antigua (and its satellite islands) and Barbuda. Non-native black rats Rattus rattus were identified as a serious predator of the snake on Great Bird Island, therefore the decision was made to eradicate the rats. A poison-baiting programme proved successful, with the racer population more than doubling in only 18 months in response. Other fauna, including several species of seabirds and hawksbill turtle Eretmochelys imbricata, also benefited greatly from rat removal.

Following black rat Rattus rattus eradication, the Antiguan racer Alsophis antiguae population on Great Bird Island increased by over 300% over the next nine years.

Ten Antiguan racers Alsophis antiguae were introduced to Rabbit Island in 1999. Breeding was first recorded in 2002 and by 2006 the population was estimated at 40-50 individuals.

Between 2002 and 2005, a total of 46 Antiguan racers Alsophis antiguae were introduced to Green Island. A radio-telemetry study undertaken in 2003 of four of the founding females, confirmed the racers were adjusting well to their new environment. Young snakes were first observed in 2005.

Scrapes totalling 0.2 ha were dug and the excavated material used to create windbreaks in an attempt to enhance silver-studded blue butterfly Plebejus argus habitat at a quarry in southern England. Populations of silver-studded blue and small blue Cupido minimus butterflies increased over the next two years; however, it is unclear whether management alone and/or recent favourable weather in winter and spring was responsible for these increases. The scrapes led to re-colonisation by black ants Lasius alienus and an increase in the silver-studded blue's food plant, bird's-foot trefoil Lotus corniculatus.

Artificial macrophytes have been suggested as a means of improving water quality by providing zooplankton refugia. Plastic brushes provided a short term reduction in phosphates as they were absorbed by the periphyton growing on the brushes. They also provided a refuge for invertebrates. After two years, the brushes became colonised by sponges, which greatly reduced their long term usefulness as invertebrate habitat.

Following a community-based conservation programme started in 1996, with the endangered Matschie's tree kangaroo Dendrolagus matschiei as the project's flagship species, a joint proposal for the regions first protected area, comprising over 60,000 ha, was submitted to the regional government and approved in 2006.

The grassland at Witch Lodge Field, Somerset has been cut annually since 1979 using a brush cutter to maintain butterfly habitat. Despite management, many butterfly species have declined on the site including several species of conservation concern. These declines may be attributable both to the increase in the proportion of grass in the sward and grass 'greening'.


Non-native floating pennywort Hydrocotyle ranunculoides had colonised and grown to dominate parts of Gillingham Marshes, eastern England, where it was outcompeting native plants. Removal was undertaken using a mechanical digger and by monthly picking by hand. This greatly reduced its cover but did not completely eradicate it. The native aquatic vegetation is re-establishing.


In May-June 2004, 58 adult Seychelles warblers Acrocephalus sechellensis were translocated to Denis Island. The first pairs started nest-building within three days of release. By August 2005, their numbers had increased to 75. Of the 35 breeding territory vacancies created by the translocation on the source island of Cousin, all but three were occupied within an average of 5.4 days, by sub-ordinate birds.

Nylon Italian cobweb brushes were added to Alderfen Broad to provide a refuge for zooplankton and other invertebrates. These were colonised quickly, initially largely by chironomids but then by a greater diversity of taxa. In the second year, there was a vigorous build-up of sponges.


A total of 105 (44 wild, 61 captive-bred) Campbell Island teal Anas nesiotis were transferred to Campbell Island in 2004 and 2005. They were kept in pens and released once above normal weight. At least 78% of the 2004 cohort survived five months after release and a minimum of 41 out of 55 survived a similar period in 2005. Successful breeding was proven when two nests and four immature teal were found in 2006.

A core heath fritillary Mellicta athalia breeding site had become dominated by bracken Pteridium aquilinum. Following bracken control by burning and herbicide spraying there was a considerable increase in common cow wheat Melampyrum pratense (the larval food plant) and a 10-fold increase in fritillary numbers. There had also been grazing and trampling by red deer Cervus elaphus, which might have also improved the habitat quality. Two other burnt and sprayed areas did not show an increase in butterfly numbers, perhaps because at higher elevation and therefore constituting less suitable habitat.

Native wetland species were planted within coir pallets to encourage plant colonisation along a shallow wetland margin in an attempt to improve water quality. Although some species initially grew well they were unable to withstand a period of hot weather and low water levels.

Removal of overhanging alder Alnus glutinosa and grey sallow Salix cinerea carr from the edge of an East Anglian broad led to a vigorous growth of riparian plants around the water's edge.

An island made of coir pallets supported by PVC floats was created with the objectives of producing an island of emergent vegetation and to cover a navigation hazard. Many of the planted species grew well and resulted in a reasonable cover of emergent vegetation. The island edges needed replanting where eroded by wave action.

Removal of alder Alnus glutinosa and grey sallow Salix cinerea carr from the edge of Hoveton Great Broad led to restoration of vegetation around the littoral margin; after removal of trees from some of the wetland edge emergent littoral plants showed vigorous growth.

On a newly acquired improved grassland, chisel ploughing was used on a two year rotation to break up the surface of the sward to create small hummocks and divots amongst which it was hoped lapwings Vanellus vanellus would nest. The water level was also increased and a seasonal sheep and cattle grazing regime introduced. Between 2000 and 2005, lapwings increased from 10 to 81 pairs and redshank Tringa totanus increased from 11 to 29 pairs.

An area of improved grassland was dominated by rushes Juncus spp. and purple moor-grass Molinia caerulea. In order to try and attract breeding common snipe Gallinago gallinago, the rush was cut in 2003 with tractor mounted mowers and then grazed. In addition, 18 small scrapes were dug and higher water levels were maintained. The number of snipe increased from one nesting pair in 2003 to 11 nesting pairs in both 2004 and 2005.

Patches of rushes Juncus spp. were cut in mid-winter with the objective of creating open nesting areas the following spring for wading bird on islands in Lower Lough Erne. Lapwing Vanellus vanellus nested almost exclusively in the cut areas. Redshank Tringa totanus nested in uncut areas, but their chicks benefit from the presence of the adjacent short, open areas for feeding. The breeding populations of both species increased considerably in response to this management intervention.

A range of approaches were adopted to deter large gulls Larus spp. from competing with nesting terns Sterna spp. A gas gun, scarecrows, rockets, taped distress calls and direct human disturbance were all effective. A 'humming line', a grid of binder twine and 'scarer' rope all had associated practical problems. A number of methods are deployed over the breeding season in order to prevent the gulls from habituating to any one technique.

Hay and cuttings rich in red clover Trifolium pratense, were added to five former arable fields and established well in four of them (present in over 10% of 2 x 2 m² quadrats).

Wetland depressions in coastal shingle at a site in southeast England the 'Open Pits', once had a Carex-rich marsh vegetation, which included many locally scarce species, but following lowered water levels and increasing willow Salix scrub invasion, much of this community disappeared. Scrub removal and summer sheep grazing was introduced in 1997. Seven scarce wetland species reappeared and another two previously unrecorded species of conservation interest colonised.


Transplanted reed Phragmites australis rhizomes, fenced from grazing waterfowl, became well established in the shallow areas of a newly created wetland three growing seasons after planting.


A series of gravel islands were once important for breeding terns and small gulls, but their numbers declined with none breeding in 2002. The possible causes included vegetation succession and competition and predation from large gulls. In February 2005, invading scrub was removed and the islands re-profiled and lowered to encourage winter flooding in an attempt to improve breeding habitat. Single pairs of common tern Sterna hirundo nested in 2005 and 2006 and five pairs of black-headed gull Larus ridibundus in 2005. However, high numbers of herring gulls Larus argentatus also bred in both years.

A 15 ha saline lagoon was created in 2002 as part of a flood defence scheme at a site on the east coast of England. It has subsequently been used by a range of wintering and breeding waders and waterfowl.

The sea wall at Freiston Shore, eastern England, was breached in three places in 2002 to create 66 ha of intertidal habitat. By September 2005, 70% of the site was covered by salt marsh plants. The area now supports large numbers of wintering geese, duck and waders, as well as smaller numbers of passerines. It has proved popular with people with 57,000 visitors in 2005.

In a Caledonian pine forest in the Scottish Highlands, the effects of cutting and burning on fungal fruiting differed between species, and especially between mycorrhizal and decomposer species. Mycorrhizal species seem to fruit more abundantly in cut or burned areas, whereas fewer decomposers fruit under these treatments. This suggests that burning or cutting small areas could help increase fruiting fungi diversity, but that it should probably be avoided in areas where important litter decomposer species occur. Most fruiting records were from control plots, there was just over a 50% decline in the number of fungal fruit bodies in the burnt and cut plots.

Despite initial concern, a haylage cut of herb-rich meadow in mid-June 2006 did not reduce the numbers of common blue Polyommatus icarus butterflies. Red clover Trifolium pratense flowered later in the cut area and attracted up to eight clouded yellow Coleas croceus butterflies. July 2006 was exceptionally hot and this undoubtedly benefited the second generation of common blues in that year.

Manx shearwater Puffinus puffinus and Atlantic puffin Fratercula arctica ceased breeding on Lundy Island due to nest predation by introduced rats Rattus spp. Following successful rat removal, both seabird species have successfully resumed breeding on the island.

Mink rafts positioned along stretches of the River Wensum proved very successful in terms of American mink Mustela vison detection and trapping effectiveness. Survey results indicated that there has been an expansion in the range of water voles Arvicola terrestris along the river from 2003 to 2005, perhaps in response to the removal of American mink.