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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 4

Since the mid 1970s the number of nesting roseate terns Sterna dougallii had declined on Coquet island. In 2000, tern nest boxes were installed on an artificial terrace on the island to provide shelter for tern eggs and chicks from their main nest predators, larger Larus gulls. Since 2003, all roseate terns breeding on Coquet Island have used nest boxes as nest sites and the number of breeding pairs has risen steadily.

Rudd Scardinius erythropthalmus introduced to a wetland nature reserve as a potential food source for bitterns Botaurus stellaris, successfully became established within 3 years of release.

A practical method of excluding non-native African giant land-snails Achatina spp. from trees containing bird nesting cavities was developed on Mauritius following previous snail incursions in two successive breeding seasons that proved fatal to echo parakeet Psittacula eques chicks. The use of a copper strip attached below nest cavities in susceptible trees has to date proved a successful technique.

During attempted habitat restoration on Round Island, in response to plants being lost during revegetation attempts due to burrowing activities of nesting wedge-tailed shearwater Puffinus pacificus, plant cages were developed to enhance plant survival. With modification, the cages also had additional benefits including reduction of damage due to salt spray and wind. Wedge-tailed shearwater continue to exploit areas undergoing vegetation restoration.

A practical, cost-effective method of packing securely items destined for Round Island was required. Since 2001, re-sealable plastic barrels have been used for the transport of almost all materials onto the island. No unwanted 'stowaway' species have since been recorded when using this method of packing. The barrels are very versatile and are increasingly used in the transport of materials to other Mauritian offshore islets.

Nest boxes have been provided for echo parakeets Psittacula eques in order to overcome a shortage of natural tree cavities and to facilitate intensive conservation management of this critically endangered species. Despite initial refusal to use nest boxes, a high percentage of successful nesting attempts now occur in them. In the 2006/07 breeding season, 73% of nests in which eggs were laid were in nest boxes (n = 56); 71% of attempts in nest boxes that season were successful (i.e. chicks fledged).

A field trial showed that a newly designed, post- or tree-mounted 'hockey stick' rat bait dispenser incorporating 20 g fixed bait blocks, was both more practical and more efficient in terms of rodenticide bait use, compared to a traditionally used 'ground pipe' dispenser containing loose, 5 g bait blocks. Bait in the hockey stick dispenser was less affected by mould and slower to breakdown, therefore making it more effective for longer and reducing the bait replacement rate required compared to the old design. It was also considered that there was also less incidental bait take by both introduced A field trial showed that a newly designed, post- or tree-mounted 'hockey stick' rat bait dispenser incorporating 20 g fixed bait blocks, was both more practical and more efficient in terms of rodenticide bait use, compared to a traditionally used 'ground pipe' dispenser containing loose, 5 g bait blocks. Bait in the hockey stick dispenser was less affected by mould and slower to breakdown, therefore making it more effective for longer and reducing the bait replacement rate required compared to the old design. It was also considered that there was also less incidental bait take by both introduced giant land snails Achatina spp., and of greater concern, endemic snails.

Breeding of the endangered Fijian ground frog Platymantis vitianus coincided with the Fijian wet season (December/January) during captive management in a purpose-built outdoor enclosure at the University of the South Pacific, Fiji. Two fertile egg masses (around 40 eggs in each) were laid. A low hatchability of 10.8% (n = 40) was recorded for the first egg mass found, which was left in the outdoor enclosure to develop. The second egg mass was taken into the laboratory for incubation where hatching success was very much higher at 87.5% (n = 42). The hatchability difference was attributed to appropriate incubation techniques in the laboratory which reduced infection and hence mortality, of the eggs.

A 'water pathway' was devised for allowing otters Lutra lutra to pass into an area enclosed by an electric fence to prevent fox access. After its construction, several otter spraints (some close to the water pathway) were subsequently found within the fenced area. There was no evidence that foxes Vulpes vulpes, entered by this route.

At a site in eastern England, wire mesh cages were placed over little ringed plover Charadrius dubius nests to protect their eggs from predation. The adult birds continued incubating their eggs and no nest desertions were attributed to cage placement. Protection with cages resulted in an increase in productivity, measured as fledged young per pair (1.6 young fledged per pair in protected nests, 0.6 per pair in unprotected nests). Provision of nest cages, in conjunction with extending suitable breeding habitat, has resulted in a gradual increase in numbers of breeding little ringed plover pairs over a 10-year period.

On recently created wet grassland at a site in eastern England, willow Salix spp. was invading. It was cut then 30 adult female Hebridean sheep and a Texel ram were introduced to control any regrowth. The sheep have kept the site clear of both newly sprouting willow shoots and willow seedlings.

In an attempt to enhance breeding habitat for the grizzled skipper Pygus malvae at a site in central England, a low drystone wall was laid to create egg-laying habitat in a herb-rich grassland. During subsequent egg searches, it became apparent that the butterflies preferred to lay eggs on the leaves of creeping cinquefoil Potentilla reptans which were growing over stones in the wall. The relatively high egg density found one year after the wall construction suggests that this habitat is now more suitable than a nearby, traditionally used, coppiced ditch habitat.

Creating a bat hibernaculum at Kingfishers Bridge, Cambridgeshire, England
Gulickx M.M.C., Beecroft R.C. & Green A.C. (2007), 4, 41-42

To provide a winter hibernation site for bats, an artificial cave was constructed at a nature reserve in eastern England. Subsequent to its completion, in the winter of 2005/06, two brown long-eared bats Plecotus auritus hibernated in the cave and in the subsequent winter one hibernated within it. It is considered likely that bat numbers will build up in future years.

At a newly created wetland nature reserve in eastern England, a pair of water buffalo Bubalus bubalis was introduced with the aim of maintaining early successional habitats and creating a heterogeneous vegetation structure. The water buffalo grazed the required parts of the fen and reedbed, and created submerged tracks. These tracks may be used by fish to disperse into the reedbed and provide foraging areas for bitterns Botaurus stellaris.


Barriers made from willow Salix spp. bundles were installed along sections of the River Cam to protect the river banks from erosion. Subsequently, a more gently sloping river bank was created which was colonised by a range of riparian plants. These vegetated margins developed into an attractive wildlife habitat and are effectively protecting these river bank sections from further erosion.

Over two breeding seasons, wire mesh cages were placed over the nests of two pairs of little ringed plovers Charadrius dubius to protect their eggs from predation. The birds continued incubating their eggs, and consequently no eggs protected by the cage were predated.


In 1995, holes were drilled into the face of two low limestone cliffs created to provide breeding habitat for sand martins Riparia riparia. In 1996, the first breeding season that the holes were available, sand martins did not nest in the burrows, probably as they were not wide enough to allow the birds to turn around within them. The limestone was too hard for them to dig a widened nest chamber themselves. Creation of a slightly enlarged nest chamber using a water jet rectified this problem. Since 1997 about 30 sand martins have bred annually.

After the provisioning of artificial nest-sites (nest boxes, clay pots, 'breeding walls', 'breeding towers' and nest-cavities) for lesser kestrel Falco naumanni in the Castro Verde Special Protection Area in southern Portugal, artificial nests of all types were rapidly colonized and the occupation rate exhibited a positive trend over time. The spectacular growth of the Portuguese lesser kestrel population can be explained by the increase in numbers in Castro Verde, suggesting that providing nest sites is an effective measure in the conservation of this threatened species in Portugal in localities where suitable foraging habitat is present.


Five newly hatched froglets of the endangered Fijian ground frog Platymantis vitianus were transferred into a glass laboratory aquarium upon hatching, following egg-laying by adult frogs during the wet season in a purpose-built outdoor enclosure at the University of the South Pacific, Fiji. During captive management of the froglets, their body weight and food supply in the aquarium were closely monitored. All five froglets were successfully raised to 37 days old, at which time the aquarium was invaded by brown house ants Pheidole megacephala. This event was probably caused by excess ripe fruit, placed within the glass aquarium to attract small flies as food for the froglets, attracting the ants. The ants predated all five froglets. Future ex-situ designs for rearing P.vitianus froglets may consider incorporating measures such as aquatic protective barriers to prevent ants and other unwanted terrestrial invertebrates from entering captive-rearing aquaria and other enclosures.


To try and stimulate breeding of the endangered Fijian ground frog Platymantis vitianus (n=10) in captivity, a purpose-built outdoor enclosure was built and an environment that mimicked their natural habitat created within it. We incorporated natural structures as potential P.vitianus egg laying sites, including rotting logs and hollow giant bamboo Piper aduncum stems. A range of other types of natural substrates e.g. coconut husks, rocks and decaying leaf litter, were also added thus the frogs could choose between various potential egg-laying sites and refugia. All material was sterilized in an autoclave prior to being installed in the enclosure. Pots containing native plants were also added. Nocturnal frog activity was recorded in the enclosure using digital video surveillance cameras; several male and female frogs were observed in or near potential egg-laying sites throughout much of the assumed wet-season breeding period, and on the 21 December 2006 and 7 January 2007, single clutches of P.vitianus eggs were located. The December clutch was situated underneath a moist rotting log and the January clutch inside a bamboo stem lined with soil. The frogs probably created nest scrapes amongst the leaf litter and soil within these egg-laying sites while mating. It is not known if these egg-laying sites provided ideal egg-laying conditions, but they were used successfully by two pairs of frogs.


In an attempt to protect the nationally rare red helleborine Cephalanthera rubra from herbivory by slugs and snails during the growing season, copper rings were placed over emerging shoots in the spring and summer. Subsequent monitoring revealed that there was no evidence of any slug damage to plants protected by such rings.


In order to establish if wild asparagus Asparagus prostratus fruit-set is limited by pollination, experiments were undertaken to compare natural insect pollination with hand pollination at four colonies (one in west Wales and three in Cornwall, south-west England). Hand pollination was successful in increasing fruit-set relative to natural pollination in three of the four populations. Overall, hand pollination resulted in a 4.5-fold higher fruit-set (54 fruits) compared to fruit-set of naturally pollinated plants (12 fruits).

Hand pollination of an isolated female wild asparagus Asparagus prostratus plant using pollen taken from males in two distant colonies proved successful with 44 berries (73% overall pollination success rate) producing 92 seeds. The subsequent germination of the planted seeds the following spring was high (90%). A re-introduction project using these propagated plants is likely to be carried out in suitable habitat close to the female plant in 2008.

Monitoring the use of dry culverts installed as underpasses enables their effectiveness to be evaluated. We used clay-based drain seals to record mammal tracks in three different culverts under a section of a major road in Northumberland, UK. Prints including badger Meles meles, American mink Mustela vison and hedgehog Erinaceus europaeus were recorded on the clay drain seals demonstrating animal movement in both directions through the culverts. The prints were well preserved and easily recognisable.


During experimental trials, it was discovered that 'bracken bashing' (mechanical damage) to control Pteridium aquilinum on an annual basis is not a suitable form of habitat management for the nationally vulnerable heath fritillary Mellicta athalia. It was in fact found to be detrimental to promotion of growth of desired vegetation, with lower cow-wheat Melampyrum pratense (the larval food plant of heath fritillary) and bilberry Vaccinium myrtillus cover than that considered necessary for the habitat to be in suitable condition for the butterfly. Consequently, bracken bashing was halted after 2005, but monitoring of these plots continued. Mechanical damage is a viable option for heath fritillary habitat management in the future but on a less frequent basis. Spraying plots with Asulox in 2002 (commonly used in bracken control) appeared beneficial. Bracken spraying produced favourable ground cover of bilberry and cow-wheat by opening up the previously dense bracken canopy, with bracken itself persisting at lower densities which afforded favourable micro-climate conditions for growth of these plants and shelter for butterflies. Past evidence suggests that livestock grazing is an effective and also a more sustainable management option in the longer term for control of both bracken and invasive woody species, and it is envisaged that other characteristic heathland flora and fauna will also benefit. Livestock have been introduced onto Halse Combe; grazing will be combined with rotational burning and post-burn bracken control (including spraying and mechanical damage) to maintain suitable habitat for heath fritillary in the future.


In 2007 and in previous years, as part of ongoing attempts to improve red helleborine Cephalanthera rubra seed-set, hand pollination of florets has been undertaken at a small colony of this species in Buckinghamshire, southern England. Natural pollination rarely occurs (one mature pod recorded in 10 years) at this site. In 2007, hand pollination resulted in the production of four seed pods, of which one withered and died. Upon ripening, the three remaining pods were removed for attempted micropropagation of the seeds. Ongoing conservation management has probably benefited the solitary bee Chelostoma campanularum which now appears fairly plentiful at the site, but despite the presence of this red helleborine flower visitor, natural pollination remains virtually unrecorded at this locality; field observations suggest that C.campanularum is in fact probably not large enough to act as an effective red helleborine pollinator as it can slip in and out of the flowers without removing the pollinia, unlike it larger relative C.fuliginosum, absent from the UK but which is a known pollinator of red helleborine in continental Europe.

Deforestation is one of the major global conservation issues. Solutions are being sought to tackle this ongoing forest loss, including establishment of initiatives to provide new sources of income for local communities that promote the sustainable use of forests in the interest of biodiversity conservation. One such project 'Iwokrama', demonstrates how tropical forests and associated habitats can be sustainably used. In the central Guyana wetlands of the Rupununi, illegal fishing of arapaima Arapaima gigas, had led to a huge reduction in its numbers. Iwokrama responded by initiating the Arapaima Management Plan in 2002. This highlighted the need for another source of local income from fisheries, and a business that undertakes sustainable-harvest of fish for the aquarium trade was developed. Harvesting of a few selected fish species is carried-out by members of the local community who are paid a daily wage. Fishing methods target individual species to avoid incidental by-catch. Four species are primarily caught as they are numerous in the Rupununi and are of high trade value. To ensure ecological and economical sustainability, catch per unit effort is monitored; where this begins to drop for any given species, harvesting is suspended and the population is allowed to recover before harvesting resumes. The project has developed into a self-sustaining business, managed by the community themselves. During 2005, the project reached financial sustainability with current profits of over US$3,000 feeding back into local community initiatives.