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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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To search for papers on a specific topic within the journal select Advanced search, enter your keyword(s) and within the Source box type: "conservation evidence". This will take you to a list of actions that contain Conservation Evidence papers. In order to see the list of individual Conservation Evidence papers on the topic, please click on 'You can also search Individual Studies' at the top of this page.

Download Volume 16

Volume 16

As part of the ‘Save Our Magnificent Meadows’ project, a two hectare field was converted to hay meadow on the National Trust’s Llanerchaeron Estate in west Wales. The field had previously been heavily grazed by sheep. Green hay was collected from an established meadow and spread by hand onto the receptor site in 2014, in order to increase the number of plant propagules present. The field was then managed as a hay meadow, with aftermath grazing. There was a significant increase in both positive indicator species and forb cover over the five year period from 2013-2017. In 2013, there was less than one positive indicator species/quadrat compared to 4.6 positive indicator species/quadrat in 2017. The results are discussed in relation to the change in management from intensive sheep grazing to hay making with aftermath grazing, and the spreading of green hay to increase the number of plant propagules present.

The hazel dormouse Muscardinus avellanarius has experienced a marked decline in the UK in recent years, attributable in part to habitat fragmentation associated with an expanding road and rail network. A number of arboreal crossing structures have been installed in the UK to reconnect fragmented habitat, but the only proven usage of such structures by wild hazel dormice has been associated with a large-scale land bridge. This has highlighted the need for affordable, evidence-based alternative designs. We tested the effectiveness of a new dormouse bridge, previously shown to be used by Japanese dormice Glirulus japonicas in Japan, in reconnecting two woodland patches bisected by a railway in southern England. Hazel dormice were recorded on the bridge within nine hours of its erection and exhibited a clear preference for using the bridge, with more than ten times more observations of dormice on the bridge compared to crossing the railway at ground level. Red squirrels Sciurus vulgaris, another rare UK mammal, were also recorded on the bridge. The trial provided evidence of the effectiveness of this design of crossing structure in reconnecting arboreal habitat for hazel dormice and other wildlife, with implications for hazel dormouse mitigation in infrastructure projects.

In July 2010 green hay from a species-rich donor field was used to diversify a species-poor floodplain meadow (the receiver field), which had previously been managed as a pasture. The receiver site was prepared through harrowing. Green hay was then collected from the donor site and spread on the receiver site using a bale shredder and spreader. It was then managed as a hay meadow, with an annual hay cut in July or August, followed by aftermath grazing. The vegetation in the receiver field was monitored from 2010-2017, as was an adjacent species-rich meadow, which was used as a target reference site. Over this period, the receiver field moved towards a species-rich sward, similar to the target Alopecurus pratensis - Sansguisorba officinalis floodplain community. In 2011, 12 months after the green hay application and change of management, species richness had increased significantly, as had the goodness-of-fit to the target floodplain-meadow community. The transformation from species-poor eutrophicated grassland to a more herb-rich floodplain meadow continued over the following six years, with further increases in the frequency and cover of target species.

The intervention described in this paper was designed to allow greater horseshoe bats Rhinolophus ferrumequinum to cross safely underneath a newly constructed road scheme in Pembrokeshire, Wales. The mitigation measures, consisting of bridges, culverts and underpasses, were designed and positioned to increase the likelihood that they would be used by bats. These features were then monitored to determine their effectiveness from the proportion of bats flying safely through the mitigation compared to over the carriageway. This was done using a combination of bat surveyors with hand-held detectors and night-vision equipment, and automated bat detectors. Effectiveness of the different mitigation features increased with increasing cross-sectional area, with a culvert of 1500 mm diameter used less frequently than a larger culvert of 1800 mm x 3000 mm. The larger mitigation measures were generally more than 85% effective. Position in the landscape and the presence of features to guide bats into the mitigation are also likely to be important. In order to assess the likely impacts of a new road scheme on a designated bat population this study also considers local bat population trends, the time of night when most bats cross the road and approximate traffic volumes at these times.

Common swifts Apus apus have shown significant declines in the UK over recent decades, and one possible cause is loss of nesting sites. Nest boxes have previously shown to be effective for this species. Here we test whether the addition of an artificial ‘nest form’ affected the occupancy of nest boxes. Nest boxes that contained a form were 4.6 times more likely to be occupied by common swifts than nest boxes without a form. The design of the form did not appear to affect occupancy rate. Further study is needed to discover whether nest forms increase overall occupancy rates.

The Juan Fernandez Archipelago is a global biodiversity hotspot, where 67% of plant species are endemic, but competition with invasive plants threatens many native plant species with extinction. Murtilla Ugni molinae is a prevalent invasive plant in the archipelago which displaces native vegetation. This study aimed to determine an efficient one-time control method for murtilla that required little or no follow-up. We used an adaptive management framework to conduct chemical control trials of murtilla in order to identify an effective treatment. Eight different combinations of chemical treatments and manual cutting were tested in four trials between 2015 and 2017. The herbicides Rango (glyphosate) and Garlon 4 (triclopyr) were tested along with a surfactant, an emulsifier, ammonium sulphate and urea. Cutting stems at the base followed by stump application of triplocyr proved ineffective. All other treatments used foliar spraying. The most effective treatment was a foliar application of 3% triclopyr, 2% glyphosate and 15g/l of urea diluted in water, which completely eliminated murtilla in 12 months. This treatment can be used for the control of murtilla over large areas and may also be useful to control other invasive shrubs that have leaves with thick cuticles resistant to herbicide absorption.

Sea wall flood defences provide important grassland habitats for bumblebees in the UK but cutting in July and August could be deleterious for declining species, such as the shrill carder-bee Bombus sylvarum. The effect on the abundance of bee species of changing the timing of cutting to an annual late cut (after 15 September) on a sea wall at Goldhanger Creek on the Essex coast was compared with a control sward which was cut annually in July or August from 2013-18. On the late cut sea wall there was a significant increase in the overall abundance of threatened bee species, probably because the later mowing avoided the destruction of nests constructed close to the ground. The increase in bee numbers did not correspond with a change in overall forage plant species richness or red clover Trifolium pratense abundance. Late-nesting bumblebees are likely to be favoured by delaying the timing of cutting to later in the season.     

Displacement is a form of mitigation that involves the removal of habitat to relocate water voles Arvicola amphibius from <50m sections of watercourse where their presence conflicts with small-scale development works. The technique is permitted under license in England to minimise negative impacts of development on water voles that are protected under UK law. Despite its widespread use, displacement as a mitigation tool is controversial due to the paucity of evidence relating to its effectiveness and disparity in the methods used to remove habitat. This study aimed to investigate the response of water voles to displacement when using a combination of water draw-down and vegetation removal. We radio-collared 20 water voles and used recapture data to monitor the movement and fate of individuals at three displacement sites and two control sites located in grazing marsh habitat in England during spring 2017. We found that all voles moved to alternative habitat following the removal of vegetation and water and no individuals were discovered in the works area following a destructive search of burrows seven days later. There was no significant difference between the fate and movement of displaced and control individuals. We conclude that displacement of water voles was effective when using both water draw-down and vegetation removal, but recommend further research is carried out to investigate other potentially confounding factors including population density and habitat type.

Coastal management practices have shifted in recent decades to recognise afforestation of sand dunes as a principle factor in mobile dune system degradation and ecological decline. However, removal of conifer plantations to re-establish dune dynamics may be restricted by the presence of protected species and public antagonism to clear-felling. Alternatives include creation and management of canopy gaps such as glades and firebreaks, but little is known about the ecological value of these features. We investigated the effects of scrub clearance and livestock grazing on habitats and plant communities in pine plantation firebreaks at Ainsdale Sand Dunes National Nature Reserve, Merseyside. The results were compared with nearby open dunes, both unplanted and formerly afforested. Although the open dunes had significantly higher species richness, larger numbers of positive indicator species and significantly lower numbers of negative indicator species, the firebreaks showed signs of dune habitat and plant community recovery 10-14 years after creation. Greater similarity in plant community composition between firebreaks and open dunes occurred in quadrats subject to livestock grazing and/or regular scrub clearance. We conclude that managed canopy gaps within existing pine plantations can increase valuable dune habitat and provide an alternative where large-scale clear-felling is not feasible.

Re-establishment of an extinct local population of the Valcheta Frog, Pleurodema somuncurense, in a restored habitat in Patagonia
Martínez Aguirre T., Calvo R., Velasco M. A., Arellano M. L., Zarina O. & Kacoliris F.P. (2019), 16, 48-50

In March 2017 and March 2018, we reintroduced 196 and 50 individuals Valcheta frogs Pleurodema somuncurense, respectively (tadpoles and juveniles). The individuals were translocated from an ex situ colony to a restored habitat at the hot springs of the Valcheta stream (Rio Negro, Argentina). The aim was to re-establish a local population of this species that had gone extinct at this site. After the individuals were released, we monitored them using night visual encounters to register the number of individuals and other relevant records that suggested acclimatization (feeding, escaping and reproduction). In addition, we performed a Capture-Mark-Recapture study to estimate the density of the reintroduced population using POPAN models. By September 2018, the estimated density was 62 ± 27 SD in a stream area of 50 m2. This does not differ from density estimates of wild populations of the Valcheta Frog. Additionally, reproduction of reintroduced frogs was recorded in September 2018 and January 2019. Egg clutches, tadpoles and juveniles were all observed at the reintroduction site. These results suggest that the reintroduction of captive bred individuals to the wild might be an effective management action to restore local populations of this species that had gone extinct.