Action: Create/protect habitat corridors
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- One before-and-after study in Belize found that black howler monkey numbers increased by 138% over 13 years after the protection of a forest corridor, alongside other interventions.
Corridors are areas of natural habitat that are contiguous or isolated (i.e. linkages or stepping stones) and enable particular plant and animal species to disperse and migrate, processes which are necessary for their survival (Rouget et al. 2006). For example, a simulation study by Bruford et al. (2010) examined the genetic implications of management options for the highly fragmented orangutan population in the Lower Kinabatangan Wildlife Sanctuary in Malaysia and demonstrated that a combination of modest translocation rates (one individual every 20 years) and corridor establishment enabled even the most isolated subpopulations to retain demographic stability and constrain localised inbreeding to small levels. Simiarily, a study in Kenya (Anderson et al. 2007) found that perennial plantations of cashew nut, mango or coconut as well as timber plantations and remnants of indigenous shrubland vegetation were frequently used by Angolan black-and-white colobus Colobus angolensis palliatus to move between fragments of their main coastal forest habitats.
Anderson, J., Rowcliffe, J.M. and Cowlishaw, G. (2007) Does the matrix matter? A forest primate in a complex agricultural landscape. Biological conservation, 135, 212-222.
Bruford M.W., Ancrenaz M., Chikhi L., Lackman-Ancrenaz I., Andau M., Ambu L. & Goossens B. (2010) Projecting genetic diversity and population viability for the fragmented orang-utan population in the Kinabatangan floodplain, Sabah, Malaysia. Endangered Species Research, 12, 249–261.
Rouget M., Cowling R.M., Lombard A.T., Knight A.T. & Kerley G.I.H. (2006) Designing large-scale conservation corridors for pattern and process. Conservation Biology, 20, 549–561.
Supporting evidence from individual studies
A before-and-after trial in 1985-1998 in secondary riparian forest in the Community Baboon Sanctuary, Belize, South America found that a population of black howler monkey Alouatta pigra, for which a forest corridor along the river was preserved alongside ten other interventions, increased by 138% over 13 years. The population increased from 840 to more than 2,000 individuals (138%), although no statistical tests were carried out to determine whether this difference was significant. Additional interventions included the protection of the sanctuary by the communities surrounding it, preserving forest buffer strips along property boundaries, constructing pole bridges over man-made gaps, preserving important howler food trees in large clearings, involving local communities in the management of the sanctuary, creation of a museum for education purposes, an eco-tourism and research program, presence of permanent staff, and monetary (income from tourism and craft industries) benefits to local communities for sustainably managing their forest and its wildlife communities. The study does not distinguish between the effects of the different interventions mentioned above.