Legally protect primate habitat

How is the evidence assessed?
  • Effectiveness
  • Certainty
  • Harms

Study locations

Key messages

  • A review on the status of rhesus monkeys and grey snub-monkeys in China found that primate numbers increased or no more individuals were killed after the area was legally protected, alongside other interventions.
  • One before-and-after study in Kenya found that Tana River red colobus monkey and crested mangabey numbers decreased despite the area being declared legally protected, alongside other interventions.
  • One before-and-after study in China found that Hainan gibbon numbers increased by 34% over nine years after the area was declared legally protected.
  • One before-and-after study in Brazil found that most golden lion tamarins did not survive over seven years despite being reintroduced to a legally protected area, alongside other interventions yet they reproduced and surviving offspring partly compensated adult mortality.
  • Two before-and-after studies in the Republic of Congo and Gabon found that most central chimpanzees and lowland gorillas reintroduced to areas that received legal protection, alongside other interventions, survived over 4–5 years.
  • One controlled, site comparison study in Mexico found that black howler monkeys in protected areas had lower stress levels than individuals living in unprotected forest fragments.

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

  1. A review on the status of rhesus monkeys Macaca mulatta in 1976-1983 in tropical montane forest in Nanwan Nature Reserve, China found that their population increased in numbers by more than 90% over seven years after the area was proclaimed an internationally protected nature reserve along with provisioning monkeys with supplementary food. Their numbers increased from ‘a few dozen’ in 1976 to 600-700 individuals by 1983, excluding the >100 monkeys that were captured and supplied to scientific and medical institutions. However, no statistical tests were carried out to determine whether this difference was significant. The study does not distinguish between the effects of the different interventions mentioned above.

    Study and other actions tested
  2. A review on the status of grey snub-nosed monkeys Rhinopithecus brelichi in 1978-1985 in tropical montane forest in Fanjingshan Nature Reserve, China found that no individuals were killed or captured in the area after it was proclaimed a provincial nature reserve in 1978, although 13 individuals were trapped and/or killed by poachers in 1962-1977. The population was reported to be young or sub-adult, further indicating that it was increasing in size. The reserve administration appeared to be preserving the virgin forests effectively. The area also represents a sacred mountain for pilgrims, which forbids the killing of wildlife. There were few killings (<1 individual annually) of grey snub-nosed monkeys reported in the area even before it was proclaimed a nature reserve. Surveys conducted in 1981-1983 had discovered eight groups totalling 450-500 monkeys, and estimates of the total population in the area were as high as 2,000-3,000 animals.

    Study and other actions tested
  3. A before-and-after trial in 1975-1985 in swamp and riverine forest in Tana River Primate Reserve, Kenya found that after proclaiming the study area a National Reserve alongside other interventions, resident populations of Tana River red colobus Colobus badius rufomitratus and crested mangabeys Cercocebus galeritus galeritus decreased over ten years. Overall population size decreased from 1,200-1,800 to 200-300 individuals (83% decrease) for colobus and from 1,100-1,500 to 800-1,100 (25% decrease) individuals for mangabeys. In addition, the number of forest patches inhabited by these two species also decreased over time. No statistical tests were carried out to determine whether these decreases were significant. Results of total counts in 1985 and in 1973-1975 were compared to estimated population changes. A permanent ranger post was built in 1976 and from 1977-1981, a tourism enterprise with a permanent lodge was established in the reserve. The study does not distinguish between the effects of the different interventions mentioned above.

    Study and other actions tested
  4. A before-and-after trial in 1978-1987 in tropical montane forest on Hainan Island, China found that the population of the Hainan gibbon Hylobates concolor hainanus increased from 7-8 individuals to 22 gibbons (34% increase) over nine years after the area was proclaimed the Bawanglin Nature Reserve. However, no statistical tests were carried out to determine whether this increase was significant. The total breeding population consisted of four adult males and seven adult females. In 1980, an area of 13 km2 was declared protected from hunting and logging activities. Three of the four remaining groups had a composition that was unusual for this species; they consisted of one adult male and two adult females with 2-4 young per group. The authors suggested that this may be a result of the small size of the group’s habitat, which may have encouraged individuals to remain in their natal group instead of dispersing to establish new territories.

    Study and other actions tested
  5. A before-and-after trial in 1984-1991 in coastal forest in Poço das Antas Reserve, Brazil, which was proclaimed a protected area in 1983 alongside 14 other interventions, found that the majority of reintroduced golden lion tamarins Leontopithecus rosalia, did not survive over seven years. Fifty-eight out of 91 (64%) reintroduced tamarins did not survive in the wild. However, 57 infants were born (reproductive rate=63%) during the study period, of which 38 (67%) survived. The Reserve falls into the IUCN category 1a and has the protective status of a ‘Strict Nature Reserve’. Different groups of captive-bred or orphaned tamarins were introduced in different years into habitat already occupied by the species and predators. Groups were provided with supplementary food, water and nesting boxes, and allowed to adapt to local habitat conditions before release. Tamarins were quarantined, underwent veterinary checks and were treated for parasites before release. Sick or injured animals were rescued, treated and rereleased. In 1983, a long-term research study was implemented. The study does not distinguish between the effects of the different interventions mentioned above.

    Study and other actions tested
  6. A before-and-after trial in 1994-1999 in mixed tropical forest in Conkouati-Douli National Park, Republic of Congo, which was upgraded from reserve to national park in 1999 alongside 16 other interventions, found that the majority of reintroduced central chimpanzees Pan troglodytes troglodytes survived over five years. Out of 20 reintroduced chimpanzees released into the legally protected area, 14 (70%) survived. No statistical tests were carried out to determine whether the population decrease was significant. Individuals were radio-collared. Rehabilitated orphaned chimpanzees underwent vaccination, parasite treatments and veterinary screens before being translocated in four subgroups from the sanctuary to the release site where resident conspecifics occurred. Staff members were permanently present to monitor primate health, provide animals with additional food if necessary and detect and examine dead animals. Local people were relocated from the release site to a nearby village. TV and radio advertisements were used to raise chimpanzee conservation awareness and local people were provided monetary and non-monetary benefits in exchange for their conservation support. The study does not distinguish between the effects of the different interventions mentioned above.

    Study and other actions tested
  7. A before-and-after site comparison study in 1996-2006 in tropical forests of Lesio-Louna Wildlife Reserve, Republic of Congo (Congo) and Batéké Plateau National Park, Gabon found that the majority of reintroduced western lowland gorillas Gorilla gorilla gorilla that were released into regions that received protected status alongside other interventions, survived for at least four years. Twenty-one of 25 gorillas (84%) released in Congo and 22 of 26 gorillas (85%) released in Gabon survived for at least four years. Nine females gave birth to 11 infants, of which nine survived. Released gorillas underwent disease screening and vaccinations during quarantine. Gorillas were released in groups, allowed to adapt to the local environment and supplemented with food prior to release. Gorillas were released into habitat with no resident gorillas to re-establish populations. Released gorillas were treated for parasites and when sick. So-called ‘problem-animals’ were removed and relocated and bodies of dead gorillas were examined to determine their cause of death. Forty-three individuals were rehabilitated wild-born orphaned gorillas and eight gorillas were ex-situ captive-borns. Both sites were proclaimed protected areas before reintroduction procedures commenced. The study does not distinguish between the effects of the different interventions mentioned above.

    Study and other actions tested
  8. A controlled, site comparison study in 2006-2007 in tropical forest in Campeche State, Mexico found that stress levels of black howler monkeys Alouatta pigra that lived in protected areas were lower than of those living in highly fragmented and unprotected forest patches. Overall mean stress levels, measured by faecal glucocorticoid metabolite (FGM), of individuals living in unprotected habitats were about 20% higher (338.9 ng/g) than those of individuals living in protected habitats (266.2 ng/g). However, agonistic interactions among group members occurred at similar frequencies during sampling weeks in both habitats (protected: 57.1%, unprotected: 62%). Furthermore, seasonal variation in FGM concentrations was only detected in protected habitats. The results of this study were based on 371 faecal samples from 21 adults belonging to five groups, two from protected habitats and three from unprotected habitats. FGM concentrations were determined with radioimmunoassays and 1,200 h of agonistic within-group and between-group interactions were recorded in total.

    Study and other actions tested
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

Primate Conservation

This Action forms part of the Action Synopsis:

Primate Conservation
Primate Conservation

Primate Conservation - Published 2017

Primate Synopsis

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What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

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