Use nets to keep primates out of fruit trees
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
Background information and definitions
Tree nets can be used to close off tree canopy travel pathways of primates in order to protect the fruit from being eaten by the primates. Netting is cheap to install but can be labour intensive for subsistence farmers.
Supporting evidence from individual studies
A controlled, replicated, before-and-after trial in 2007-2009 in an agro-forest system in Batang Serangan region, north Sumatra, Indonesia found that in areas where farmers used tree nets, crop-raiding by orangutans Pongo abelii was reduced. In areas where farmers used no mitigation technique, the frequency of crop-raiding events did not change. Crop yield increased from 69 kg to 176 kg (61% increase) after trials on farms where farmers used tree nets (n=10 farms) and decreased from 64 kg to 47 kg (27% decrease) on farms where no mitigation technique was trialled (n=15 farms). In addition, interviews with 50 farmers (of which 50% participated in the trials) showed that attitudes towards orangutan management had changed after the study. The proportion of farmers who wanted orangutans removed from their farms decreased from 58% before the study to 28% after the study. However, all farmers stopped using nets as a mitigation technique five months after the study. Barrier nets of 5 x 5 cm2 mesh stitching nylon rope were placed to partially or entirely cover the canopy of 14 separate jengkol Archidendron pauciflorum trees.Study and other actions tested