Conservation Evidence strives to be as useful to conservationists as possible. Please take our survey to help the team improve our resource.

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.

Watch a brief video on our journal here

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

Special issues contain new papers on a specific topic.

Virtual collections collate papers published in the journal on specific topics such as management of particular groups of species.

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.

Volume 11

Introduction of Short Communications in the Conservation Evidence journal
Sutherland W.J., Smith R.K., Mitchell R. & Dicks L.V. (2014), 11, 1-1

Short Communications can now be submitted for publication within the journal.  These will be a maximum of one printed page. Our aim is to make it even easier for practitioners to share their experiences about the effectiveness of conservation interventions.

Comparative effectiveness research: the missing link in conservation
Smith R.K., Dicks L.V., Mitchell R. & Sutherland W.J. (2014), 11, 2-6

This editorial highlights the deficit of studies that directly compare different conservation interventions for the same threat. Most studies test a single intervention (86% in Conservation Evidence), comparing it against a control that lacks the intervention. Such studies can provide evidence that a particular intervention is effective, but do not inform a practitioner whether that intervention is the best option relative to others. Comparing results from different studies is difficult, as outcomes depend on factors such as the site, species and method of measurement.  We suggest that a key step to understanding the effectiveness of conservation interventions is to compare different interventions in the same context within studies. If widely adopted this could transform global conservation practice. We provide some guidance on how to design and conduct comparative studies.


Fifty-three captive-bred, sub-adult red-billed curassow Crax blumenbachii were reintroduced to the Guapiaçu Ecological Reserve, Brazil, from 2006 to 2008.  Post-reintroduction movements were monitored for 25 months, but little information on breeding was collected during this period as few of the birds had reached sexual maturity. However, in the period 2009-2014, six observations of probable breeding were made. This positive outcome will help inform the feasibility of further reintroductions.

Bear-proof fences reduce livestock losses in the Tibetan Autonomous Region, China
Papworth S.K., Kang A., Rao M., Chin S.T., Zhao H., Zhao X. & Corrasco L.R. (2014), 11, 8-11

Tibetan brown bears Ursus arctos pruinosus in the Tibetan Plateau attack and kill livestock and ransack homes for food, causing significant economic costs for local herders. Although a government fund compensates herders for livestock lost to bear attacks in the Tibetan Autonomous Region (China), compensation may not reflect the real cost of losing livestock and payments can be delayed. We investigate whether bear-proof fences are a cost-effective method for reducing bear attacks and livestock losses. In January 2009, 14 bear-proof fences were constructed from wire mesh and steel posts around households which had previously experienced substantial losses to bear attacks in the Nagqu Prefecture of the Tibetan Autonomous Region. These households lost 162 animals to bears in the year before fence construction, whereas just three animals were lost in the year after fence construction. Fences were still standing 4.8 years after completion and any small damage has been repaired by households. For households that suffer substantial losses to bear attacks, bear-proof fences appear to be an effective and cost-saving intervention to reduce human-bear conflict.

The provision of nest-boxes was tested as a low cost method to increase fledging success in the rifleman Acanthisitta chloris, a declining endemic New Zealand species that is at risk from introduced mammalian predators. Nest success of riflemen in nest-boxes (80%) was five times higher than those in natural nest sites (16%). This difference was due to a reduction in the rate of predation in nest-boxes. However, aluminium nest guards did not further increase nest success in nest-boxes (82%). This outcome indicates that nest-boxes can provide a low cost and non-lethal method to protect rifleman nests from predators and increase fledging productivity.

Restoration of a degraded dry forest using nurse trees at Dambulla, Sri Lanka
Medawatte W.W.M.B.A., Amarasinghe J., Iqbal M.C.M. & Ranwala S.M.W. (2014), 11, 16-19

We determined the effect of over-storey nurse tree cultivation on species composition in a naturally regenerated dry forest in a dry zone arboretum in Sri Lanka. The forest had previously been abandoned shifting cultivated land. One area was restored using nurse trees, one area was restored without nurse trees, and one area was left unmanaged as a control. Species dominance, richness and diversity of regenerated trees were assessed within random plots in the three treatment types. Regenerated tree species richness and diversity were greater in the restored land with nurse trees than in the restored land without nurse trees or in the control area. Dry forest tree species were dominant in the plots with nurse trees, while light-demanding and competitive pioneer scrubland species were dominant in the plots without nurse trees and the control area. We suggest that monospecific tree plantations that have been established for reforestation or agroforestry purposes could be used as nurse trees for dry forest restoration.

In December 2011, 59 adult Seychelles warblers Acrocephalus sechellensis were translocated between two islands in the Seychelles. Birds were captured on Cousin Island and translocated to Frégate Island using a hard release method, with minimum time in captivity. Frégate had been previously identified as a suitable host for a substantial population of Seychelles warblers, although the presence of the species had never been confirmed on this island. It was estimated that Frégate currently has the potential to support about 500 Seychelles warblers, rising to over 2,000 after habitat regeneration. All birds survived the translocation and were released unharmed at the new site within 24 hours of capture. Close monitoring of both the new and source population was undertaken over a period of 18 months. By June 2013, the Frégate population had increased to 80 individuals, which included 38 of the original translocated birds and 42 birds which had hatched on Frégate. There was also evidence that multiple generations had already hatched on the island. This shows that the Seychelles warbler responded well to a hard release translocation, with observed population growth on Frégate comparable to previous warbler translocations. The source population on Cousin recovered to carrying capacity within a single breeding season. This is the fourth translocation of this species, fulfilling the species action plan requirement of five populations of this endemic island passerine.

The use of helicopters for spreading bait pellets in rodent eradication operations for conservation programmes is increasing. While aerial applications generally have a high success rate at eradicating rodents, operations that tackle extensive areas of steep terrain (slopes >50°) are more challenging, as the effectiveness of spreading bait pellets at the targeted density in these areas is unknown. We undertook an aerial baiting trial on Gough Island, where predation by the non-native house mouse Mus musculus is devastating the globally important seabird populations. It is therefore critical to deliver bait to the island’s large areas of vegetated cliffs that contain burrowing petrels and mice. Using a helicopter and bait hopper we spread non-toxic bait pellets on two areas of coastal cliffs and the adjoining flat ground, and measured the resulting density of pellets using teams of roped climbers and distance sampling. Compared with adjacent flat areas, the vegetated cliff areas retained an average 66-76% of pellets (lower 95% confidence interval 45-60%). While baiting rates on cliffs were lower than adjoining flat areas, the recommended best practice for aerial eradications prescribes applying two additional drops on steep areas. Consequently, current best practice would be sufficient to ensure coverage at densities at or above the targeted baiting rate. While these trials were focused on Gough Island, the results should be useful for eradication operations on other islands with cliffs with similar terrain and vegetation cover.

A dramatic decline in American eel Anguilla rostrata abundance led to the species being assessed as endangered in Ontario (Canada) and the closure of fisheries. As part of efforts to recover populations, four million eels (glass eels and elvers) were released over a five year period into the upper St. Lawrence River and Lake Ontario. A large-scale electrofishing survey of eastern Lake Ontario tributaries was undertaken to assess the distribution and survival of the released eels. Four hundred and seventy-six eels were collected from 37 sites along seven watercourses. Eels were well-distributed along five rivers close to the release site. By contrast, distribution along the two largest rivers surveyed was restricted to a few kilometres upstream of Lake Ontario because of multiple impassable dams. The average length of eels caught in these two rivers was 40 mm shorter than eels in other watercourses. Eels were not detected in five smaller and colder creeks further west.


California winegrape growers interested in merging conservation with agricultural production have established nest boxes for songbirds in their vineyards. A common occupant, the native western bluebird Sialia mexicana consumes arthropods during the breeding season. We measured the effect of enhanced avian activity on arthropod pests and natural enemies by experimentally establishing songbird nest boxes in one section of a 50 ha vineyard. During avian brood production and shoot extension of the grapevines, we compared the composition of the arthropod community in the nest box area with that of a no-nest box control area. During peak nest box occupancy, the nest box area had significantly fewer herbivorous arthropods, including leafhopper pests, than the control area. There were also significantly fewer large, beneficial, predatory arthropods in the nest box treatment compared to the control area. After chicks hatched, small arthropods decreased in the nest box treatment area, while increasing in the control area. Therefore, although avian foraging near nest boxes reduced the abundance of beneficial arthropods, harmful herbivorous insects did not increase in the nest box treatment even when they increased in the control area. This indicates an overall positive effect of nest box provision on pest abundance in a large, commercial vineyard.

The breeding success of obligate secondary cavity nesting birds, including most parrots, can be limited by the availability and quality of nest cavities. Habitat degradation can reduce the number of large cavity-containing trees. This reduction in available cavities can be exacerbated by destructive nest poaching practices, which leave cavities damaged and unusable. Yellow-shouldered Amazons Amazona barbadensis inhabit degraded dry-forest areas on the island of Bonaire (Caribbean Netherlands), and were suspected to be limited by the number of suitable nesting cavities. We compared two approaches to increasing the availability of nesting sites, measuring occupation rates of 10 nest boxes and 10 repaired natural cavities over three years. While none of the nest boxes were used, two of the restored cavities were occupied within five months of repair, and a third in the following year. Only one of the breeding attempts in restored cavities (33%) was successful, compared to the population average of 56%. Sample sizes are small, but restoring natural nest cavities led to a higher rate of uptake than nest boxes and was a considerably quicker and cheaper intervention. However the effectiveness of this intervention depends on the threat of poaching, and there is a risk that restoring poacher-damaged nests may attract breeding pairs away from safer cavities.

Fifteen-hundred Scots pine trees were ring-barked (as individuals, groups of five or 15) on Mar Lodge Estate, Scotland in order to create structural diversity and deadwood habitat in two plantations. A sample of 220 was monitored annually and compared with a control sample of 10 non ring-barked trees, to quantify structural changes as well as use by saproxylic invertebrates and woodpeckers. Eight years after ring-barking 26.1% (±6.13% S.E.) of the trees had snapped off and 2.4% (±1.37%) had fallen over completely; 48.0% (±12.5%) had lost 60-90% of their branches and 34.9% (±24.2%) had lost more than 50% of their bark. Additionally 98.5% (±0.92%) of the trees showed signs of wood boring invertebrates and 74.5% (±11.6%) were used by woodpeckers. Six species of beetle, four of which were saproxylic, and a single species of saproxylic fly were identified from fallen deadwood from the ring-barked trees. The control trees remained largely structurally unchanged and none were colonised by saproxylic invertebrates or woodpeckers. There were significant differences in structural change and use by woodpeckers between the two plantations but none in the occurrence of saproxylic invertebrates. Group size had no significant effect on colonisation, except for woodpeckers which used small groups of trees significantly more than larger groups. Ring-barking can provide an effective management tool to create structural diversity and deadwood habitat within a short period of time. However it is necessary to regularly repeat ring-barking in groups of different size in order to maximise structural variation and ensure niche diversity of such a dynamic substrate.

Where sufficient seeds of a rare plant species are available, out-planting small populations may be an effective conservation practice, given certain rare species persist naturally as small populations, sometimes within metapopulations. I investigated the feasibility of out-planting small populations of the rare and declining fen plant spreading globeflower Trollius laxus, which is easily grown in greenhouse and garden settings. In 2004 greenhouse-raised seedlings were planted at 14 plots (n = 10 plants per plot) located within a protected area where a well-studied metapopoulation of T. laxus already occurred. Suitable plots were identified using a GIS-based, macroscale habitat model; seven were under canopy gaps and seven were under intact canopy. The populations were monitored one, two, three and eight years after out-planting. Two plots that were lost less than one year after out-planting were not included in subsequent monitoring and analysis. I compared survival between gap and non-gap populations and quantified the vigour of the surviving plants over time. Overall, survival was very poor (only 10 of the original 120 transplants survived to year eight), but surviving plants were vigorous, showing increases in size and flower production. Plant survival to year three was significantly greater under canopy gaps than intact canopy. These results suggest that out-planting T. laxus at new sites may be difficult, that success will be greater under canopy gaps than intact canopy, and that out-planted populations may need regular supplementation with new transplants in order to be viable over the long-term.

A former military airfield at Orford Ness had naturally developed into a coastal grazing marsh, but limited water control and high evaporation caused it to be highly prone to drying out in summer. With the intention of attracting higher numbers of breeding waders, six large shallow pools and two deeper ponds were created by building low bunds linked by new ditches and water control points. To replace water losses to evapotranspiration, new sluices were built into the river walls to allow estuary water to be drawn into two new lagoons at high tide, and from there into the ditches and pools to maintain desired water levels. The number of breeding waders in the modified areas increased from an average of eight pairs in the two years prior to the works to 23 pairs in the year after the creation of pools. Pied avocet numbers increased from zero to five pairs, common redshank from five to 13 pairs, and northern lapwing from three to five pairs.

A former military airfield at Orford Ness had naturally developed into a coastal grazing marsh, but limited water control caused it to be deeply flooded in winter. With the intention of attracting higher numbers of waders, six large pools were created with low bunds each surrounded by shallower water and linked by new ditches and water control points. A new water pump was installed to enable excess rainwater to be evacuated into the adjacent estuary. The number of wintering waders in the modified areas increased tenfold in mid-winter from pre to post-works, and the waders showed increased use of areas that had become shallowly, rather than deeply, flooded. The rise in wader numbers was not due to within-site movement, as an adjacent, unmodified marsh showed no change in bird numbers. Late summer wader numbers, which may include passage migrants, were 2.5 times higher after the management work.

The response of glow-worms Lampyris noctiluca to winter scrub clearance on a sea wall flood defence in Essex, England was monitored. The number of glowing adult females did not show a significant difference in the two seasons (one life cycle) after scrub clearance, or at a control site with no clearance.

Population density of endangered pileated gibbon Hylobates pileatus in 9 km2 of North Ta-riu watershed, located in the centre of Khao Soi Dao wildlife sanctuary, dramatically declined from 6.4 groups/km2 in 1979 to 2 groups/km2 in 2006. Opportunistic poaching during non-timber forest product (NTFP) collection and insufficient patrolling were considered the main cause of decline. An alternative strategy is needed to enhance pileated gibbon conservation. We applied diffusion of innovation theory to change and expand conservation behaviour among NTFP collectors, although this study does not endorse illegal NTFP collection. After a meeting with NTFP collectors in May 2009, a network of NTFP collectors for pileated gibbon conservation was successfully established with 16 members. The aim of the network was to abstain from poaching on pileated gibbon during NTFP collection. Interpersonal persuasion along with social marketing were used to expand the network. In December 2009, the network had expanded to 101 members. In 2012, six new groups of pileated gibbons (24% increase) were found in the North Ta-riu watershed. The density had increased to 2.8 groups/km2.

Spanish catchfly Silene otites (L.) Wibel is an endangered plant declining in its UK stronghold of the Breckland. At Cranwich Camp, Norfolk, UK, formerly an important site for the plant, an area was stripped of turf to stimulate germination to attempt to revive the population. This led to significant colonisation of the area, with over 2,900 Spanish catchfly plants present on the experimental site three years after the management was carried out. These may have derived either from incoming seed or seed lying dormant beneath the turf and have begun to restore the population to its former high levels.