Regularly de-activate/remove ground snares

Overall effectiveness category Likely to be beneficial
Number of studies: 3
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How is the evidence assessed?

Effectiveness

60%
Certainty

40%
Harms

0%

Calculating overall effectiveness category

Background information and definitions

Some primate species, especially larger and more terrestrial species, such as gorillas Gorilla spp. and chimpanzees Pan troglodytes, may be injured by getting caught in snares typically set out to catch animals such as duikers Cephalophus spp. and bush pigs Potamochoerus larvatus. These primate species can get their hands or feet trapped in snares while travelling through the forest, often resulting in life threatening injuries and even death. This intervention involves the regular patrolling of teams to de-activate/remove ground snares.

The patrolling of areas by anti-poaching teams to reduce hunting is discussed separately under ‘Conduct regular anti-poaching patrols’, and the providing of training and equipment to anti-poaching patrols is discussed under ‘Provide training to anti-poaching ranger patrols’, and ‘Provide better equipment (e.g. guns) to anti-poaching ranger patrols’, respectively. The use of monitoring surveillance strategies and/or monitoring data to improve effectiveness of wildlife law enforcement patrols is discussed under ‘Implement monitoring surveillance strategies (e.g. SMART)/use monitoring data to improve effectiveness of wildlife law enforcement patrols’.

Study locations

Key messages

One before-and-after study in the Democratic Republic of Congo and Rwanda found that mountain gorilla numbers increased over five years in an area that was patrolled for snares, alongside other interventions.
One before-and-after study in the Democratic Republic of Congo, Rwanda and Uganda found that a mountain gorilla population declined in an area where snares were removed regularly, alongside other interventions.
One before-and-after study in Ghana found that the number of snares declined in an area where they were regularly removed, alongside other interventions.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

A before-and-after trial in 1984-1987 in tropical montane forest in the Virunga ecosystem in Rwanda and the Democratic Republic of Congo found that mountain gorillas Gorilla beringei beringei ranging in habitat that was regularly patrolled for snares alongside other interventions, increased from 242 to 279 individuals (15% increase) in 1981-1986. Average group size increased from 8.5 to 9.2 individuals (17% increase) and immature proportion increased from 39.7 to 48.1% (8% increase) over the same time period. Regular total counts of this population were conducted since 1973. Anti-poaching guards regularly patrolled the area. Guards were provided with cars, radio communication, uniforms, more rations and other equipment that allowed them to increase patrol frequency and effectiveness. In 1985, a gorilla viewing tourism programme was started during which three gorilla groups were habituated for tourist viewing. The study does not distinguish between the effects of the different interventions mentioned above.
Study and other actions tested
Referenced paper
Aveling R. & Aveling C. (1987) Report from the Zaire Gorilla Conservation Project. Primate Conservation, 8, 162-164.
A before-and-after study in 1967-2008 in tropical montane forest in Volcanoes-, Mgahinga-, and Virunga National Parks located in Rwanda, Uganda, and the Democratic Republic of Congo, respectively, found that despite the regular removal of snares alongside other interventions, the mountain gorilla Gorilla beringei beringei population decreased over time. Annual population decline was 0.7%, resulting in an overall population decrease of 28.7% over the entire study period. However, no statistical tests were carried out to determine whether this decrease was significant. Rangers patrolled the whole park and confiscated more than 1,500 snares/year. They also conducted regular anti-poaching patrols and when necessary, herded livestock out of the park. Additional interventions included local conservation education and community development projects. The study does not distinguish between the effects of the different interventions mentioned above.
Study and other actions tested
Referenced paper
Robbins M.M., Gray M., Fawcett K.A., Nutter F.B., Uwingeli P., Mburanumwe I., Kagoda E., Basabose A., Stoinski T.S., Cranfield M.R. & Byamukama J. (2011) Extreme conservation leads to recovery of the Virunga mountain gorillas. PLoS ONE, 6.
A before-and-after trial in 2007-2009 in tropical forest in Kakum Conservation Area in Ghana found that the regular removal of ground snares alongside other interventions, led to a decrease in the number of snares recovered by teams over time as well as fewer illegal attempts to hunt primates. More specifically, the number of snares recovered decreased from 452 to 114 (75% decrease). However, no statistical tests were carried out to determine whether this difference was significant. In addition, in 2008-2009, the number of illegal hunting activities and attempts to hunt the bush baby Galagoides demidoff, Bossmann potto Perodicticus potto, Lowe’s monkey Cercopithecus campbelli lowei, spot-nose monkey Cercopithecus petaurista petaurista, olive colobus Procolobus verus, Geoffroy’s pied colobus Colobus vellerosus decreased from 1182 to 874 (26% decrease). Snare removal took place during foot patrols. Teams also regularly conducted randomized anti-poaching patrols. The study does not distinguish between the effects of the different interventions mentioned above.
Study and other actions tested
Referenced paper
Wiafe E.D. & Amoah M. (2012) The use of field patrol in monitoring of forest primates and illegal hunting activities in Kakum Conservation Area, Ghana. African Primates, 7, 238-245.

Please cite as:

Junker, J., Kühl, H.S., Orth, L., Smith, R.K., Petrovan, S.O. & Sutherland, W.J. (2020) Primate Conservation. Pages 431-482 in: W.J. Sutherland, L.V. Dicks, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2020. Open Book Publishers, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

All the journals searched for all synopses

This Action forms part of the Action Synopsis:

Primate Conservation

Related Actions

Actions	Effectiveness	Studies	Category
Regularly de-activate/remove ground snares Action Link	Likely to be beneficial	3	Synopsis Link
Introduce ammunition tax Action Link	No evidence found (no assessment)	0	Synopsis Link
Implement local no-hunting community policies/traditional hunting ban Action Link	Likely to be beneficial	5	Synopsis Link