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 14



Widespread pollinator and bumblebee decline has been documented across Europe and North America and much of this can be attributed to pressures from agricultural intensification. A greater area of pollinator and bumblebee habitat is needed to reverse this decline. We utilised the Bumblebee Conservation Trust ‘Beewalk’ to assess the effect of hay meadow restoration on bumblebee numbers in the Yorkshire Dales National Park and Forest of Bowland Area of Outstanding Natural Beauty. The abundance and diversity of bumblebee species significantly increased with restoration, even within the first year post-restoration, and restored meadows were not significantly different from ancient meadows. Data on flowers visited by bumblebees demonstrated that the most important forage plants for bumblebees had been transferred to the restored meadows.

The Pen y Cymoedd windfarm in South Wales, UK, is set in an upland area currently dominated by coniferous forestry with a varied age structure resulting from standard forestry management practices. The site supports an important population of European nightjar Caprimulgus europaeus. The activities associated with wind farm construction have the potential to damage and disturb nightjar nests during the breeding season whilst long term operation has the potential for collision mortality. To mitigate for potential impacts during construction, we implemented measures to allow nest avoidance including the identification and demarcation of active nest sites. Due to the difficulty in locating nightjar nests and the potential for false negative results, additional measures were deployed at 17 turbine locations to deter nightjars from establishing nesting territories. Deterrent measures involved regular removal of vegetation on the construction areas. We tested the effectiveness of the deterrent measures by comparing levels of male nightjar territorial display activity in treated and untreated locations over one breeding season. Territorial behaviour was recorded using standard nightjar presence-absence survey methods. We found no significant difference between levels of territorial display activity in treated and untreated areas. This suggests that the deterrent measures utilised at Pen y Cymoedd in 2016 were ineffective in deterring male nightjar display activity during windfarm construction.

The aim of this intervention was to create a new flight-path and roost access point for lesser horseshoe bats (Rhinolophus hipposideros) in Gloucestershire, UK. Their existing access point was to be enclosed within an extension to the building they occupied, as part of a redevelopment project. Two designs were tried, and detailed observations were made of bats exiting and attempting to return to their roost. The initial design required the bats to execute a 90° turn at the base of a short vertical shaft, and very few bats returned to the roost through this access point design. The final design provided a clear ‘line-of-sight’ through the structure enclosing the flight-path; bats did return to the roost via this access point. Before the intervention colony numbers did not exceed 35 bats (adults and young); during the construction period, numbers dropped to just seven individuals. Post-intervention (after 15 years), numbers of lesser horseshoe bats (adults and young) have exceeded 400 individuals.

Surveys were undertaken in 2010 to assess the potential impacts on maternity roosts of brown long-eared bat Plecotus auritus and common pipistrelle bat Pipistrellus pipistrellus before the demolition and redevelopment of a converted farm house and associated outbuildings in the Cotswolds Hills near Bath, UK. As all bat species and their roosts are afforded statutory protection in the UK, a licence was required before the buildings could be demolished. This licence required the construction of two new purpose-designed bat structures in compensation, with the specific goal being the re-establishment of the displaced maternity colonies. Separate bat house and bat wall structures were completed by early spring 2011 with the primary purpose of attracting void-dwelling brown long-eared and crevice-dwelling common pipistrelle bats respectively. Roosting brown long-eared bats established in the Bat House from late 2012, with observed numbers peaking at 20-25 in summer 2013, indicating that a maternity colony had probably re-established. Although a common pipistrelle maternity roost had not established by 2017, small numbers of common pipistrelles were using features within both the bat house and bat wall.

We tested the effectiveness of low-level roadside fencing to direct wildlife towards existing culverts beneath the road (underpasses) in order to reduce road deaths of small terrestrial vertebrates. While our results showed a reduction in roadkill count (from eight to one) along the stretches of road where we installed barriers (from an average of 0.33 roadkill/day/km to 0.04 roadkill/day/km), this decrease was not significant, possibly due to the small number of dead animals detected across all sites. Our trial highlights the challenges in acquiring robust evidence for roadkill reduction interventions and, given the small sample size, we were unable to elicit firm conclusions for this study. We therefore propose further testing of the efficacy of roadside fencing to reduce roadkill.

Boma fortification is cost-effective at reducing predation of livestock in a high-predation zone in the Western Mara region, Kenya
Sutton A.E., Downey M.G., Kamande E., Munyao F., Rinaldi M., Taylor A.K. & Pimm S. (2017), 14, 32-38

Lions Panthera leo kill livestock in the pastoral steppe of East Africa. The subsequent lethal retaliation by livestock owners has helped reduce lion numbers by more than 80% and driven the species from most of its historic range. This conflict is especially intense along the western edge of the Maasai Mara National Reserve in Kenya, where some of the densest lion and livestock populations in Africa overlap. We evaluated the effectiveness of implementation for one proposed solution – the Anne K. Taylor Fund’s subsidized construction of fortified, chain-link livestock fences (‘bomas’) – in reducing livestock loss to depredation. Between 2013 and 2015 we collected 343 predation reports, based on semi-structured interviews and predation records. We used these data to study the impact of subsidised boma fortification on the depredation of cattle, sheep and goats. Of 179 fortified bomas, 67% suffered no losses over one year whereas only 15% of 60 unfortified bomas had no losses over one year. Furthermore, losses of greater than five animals per year occurred at only 17% of fortified bomas, compared to 57% of unfortified bomas. The overall reduction in losses to predation at fortified bomas equated to savings of more than $1,200 USD per household per year.

 

 

Understanding factors causing the low breeding success of capercaillies Tetrao urogallus is important for the conservation of this species. Here we investigate possible causes of spatial variation in breeding success in two neighbouring Scots pine Pinus sylvestris woods in Scotland, Abernethy Forest and Craigmore Wood. Breeding success declined with increasing June rainfall at both sites, but there was a stronger effect at Abernethy. Average productivity (chicks/female) during 2000-2011 was 1.61 (95% C.I. 1.08-2.41) times greater at Craigmore than Abernethy. It was possible that the difference was due to increased wetting of chicks by vegetation during and after rain at Abernethy, where the vertical density of the shrub and grass layer was greater than at Craigmore. Wet chicks may then die. To test this hypothesis, 2 m wide routes were cut through tall heather Calluna vulgaris at Abernethy, so that broods could move between bilberry Vaccinium myrtillus feeding areas without having to brush against tall dense vegetation. However, there was no improvement in breeding success in the treated area compared to a control area. Possible explanations are that the capercaillies did not use the cut routes, that cutting did not provide sufficiently short vegetation, that rain affects capercaillie chicks in other ways (e.g. through insect availability), or that broods shelter from rain using pine thickets.

 

Fencing is the most commonly used management intervention to prevent damage to young woodland regeneration from deer. However, damage can also be prevented through reducing red deer numbers and alleviating browsing pressure. We investigated the effect of reducing red deer Cervus elaphus density on browsing impact and growth of Scots pine Pinus sylvestris seedlings at Mar Lodge Estate, Cairngorms, UK. Red deer numbers were reduced significantly between 1995 and 2016, and there was a concomitant significant reduction in deer pellet densities and browsing incidents. Positive growth of seedlings was small in the years soon after the deer reduction programme began, and was still being suppressed by browsing in 2007. However subsequently, seedling growth has increased as red deer numbers have been maintained below 3.5/km2. Red deer reduction appears to have been effective in reducing browsing impacts on Scots pine seedlings, allowing successful growth and establishment of regeneration.

 

Education workshops conducted with forest departments in Western Ghats resulted in improved ability to identify four of five amphibian species and their habitats.

In 2015 seven captive-bred red-and-green macaws Ara chloropterus were experimentally released into the Iberá National Park, Corrientes, Argentina. After a month in a pre-release cage, they were hard released. Two birds were preyed upon, three flew beyond our detection range, one transmitter was recovered underwater, and one bird was recaptured. We identify ways in which future releases of captive-bred macaws could be improved.

The Asian musk shrew Suncus murinus is an invasive insectivore that first colonised Mauritius in the eighteenth century. It is a significant predator and poses a threat to terrestrial endemic reptiles in Mauritius. On the islet nature reserve Ile Aux Aigrettes, Mauritius, shrews predate juvenile Telfair’s skink Leiolopisma telfairii, limiting the recruitment of this threatened species. It is therefore important to reduce numbers of Asian musk shrews, and live and fatal trapping are potential methods that can be used to control or eradicate invasive vertebrates. This study tested whether Asian musk shrews preferred the bait currently used for trapping shrews on Ile Aux Aigrettes compared to a novel bait, crushed cockroach. We also tested whether shrews preferred bait in the presence or absence of musk, a chemical attractant. Shrews were observed in a specially designed choice box where a behavioural tally recorded their activity. Their strongest preference was for compartments containing no bait, although they also displayed a significant preference for crushed cockroach in the presence of musk, and a lack of interest in the existing bait. These results suggest that the use of this novel bait plus musk could improve the success of trapping shrews on Ile aux Aigrettes and elsewhere.

 

We tested the effects of herbaceous vegetation enhancement on the abundance and richness of plants and arthropods in a wine-producing vineyard in Israel. We compared the abundance and species richness of plants and arthropods between a plot seeded with local annual plants and an unseeded plot. We also compared soil content and grape quality parameters in seeded versus unseeded plots in the vineyard. Seeding increased plant cover and plant species richness in the spring, but reduced plant cover and did not affect species richness in summer. Arthropods, and especially parasitoids and generalist predators, were more abundant and diverse in the seeded than in the unseeded plots in spring, both on the herbaceous vegetation and on the vine foliage. Arthropods were more abundant in the herbaceous vegetation than on the vine foliage in spring, but not in summer. The soil in seeded plots was richer in ammonium nitrogen and organic matter, while the grapes were smaller and sweeter. Our findings showing a general increase in biodiversity, combined with additional considerations, led the managers of the vineyard to implement these vegetation enhancement practices in 85% of their vineyards.

 

The value of tourism for gaur Bos gaurus in the Khao Phang Ma reforestation area at the edge of Khao Yai – Dong Phaya Yen World Heritage Site decreased when a large number of gaurs moved away from the watching area of the former grassland in the middle of the secondary forest. A major cause appeared to be an increase in the number and size of pioneer trees Macaranga siamensis that overshadowed their food patches. We constructed a 5.7 ha pilot plot where 407 pioneer trees were cut down in an attempt to attract gaurs back to the area. Since tree cutting was a controversial practice, especially with the local people, we engaged with, and were supported by, a local non-governmental organization throughout the process. We monitored the density of gaurs using the total counts of dung piles. The estimated density of gaurs was significantly higher in the pilot plot compared with an adjacent control plot (8.62 individuals/km2/day versus 3.95 individuals/km2/day), demonstrating a positive impact of tree felling in attracting this species back to an area.

 

Coppicing is a commonly used management intervention to increase structural diversity in woodlands, but coppiced trees are vulnerable to browsing by deer. We investigated the effect of coppicing hazel stools at different heights on the survival of trees, and also the species richness of the ground flora. Plots were cut at experimental heights of 0.7 m and 0.8 m, with plots cut at 1.2 m and ground level as controls. All the stools cut at 1.2 m were alive five years after cutting. In the plots cut at 0.7 and 0.8 m, some shoots were eaten by deer but less than 10% of stools died. Less than 5% of stools in the plot cut at ground level survived.  After 7–8 years, coppicing at 0.7 m and 0.8 m supported a higher species richness of angiosperm ground flora than either of the control heights. We conclude that high-level coppicing offers a cost-effective opportunity to achieve a rotation frequency that increases tree survival and supports a diverse coppice-woodland angiosperm flora.