Impact of Electric Shock and Electrocution on Populations of Four Monkey Species in the Suburban Town of Diani, Kenya

Electric shock and electrocution affect at least 31 primate species, but studies of how electrical infrastructure affects primate populations are rare. We investigated 320 cases of electric shock and electrocution in four sympatric monkey species in Diani, Kenya, 1998–2019: Peters’s Angola colobus (Colobus angolensis palliatus), Zanzibar Sykes’s monkey (Cercopithecus mitis albogularis), Hilgert’s vervet (Chlorocebus pygerythrus hilgerti), and the Southern yellow baboon (Papio cynocephalus cynocephalus). These represent 16% of the total welfare cases reported to a local conservation organization. Deaths occurred in 73% of cases. The number of cases did not increase through the study period, presumably because mitigations implemented by the power distribution company and a local conservation organization offset the risks associated with the electrical infrastructure expansion. Colobus accounted for 80% (N = 256) of cases, representing ca. 4.6% of the population annually, which is likely unsustainable. Adult male colobus were shocked or electrocuted more than expected, while all other age–sex classes were involved in proportion to the population structure. The number of cases was low for Sykes’s monkey (13%, N = 42), vervets (5%, N = 16), and baboons (2%, N = 6). Our findings show that electrical infrastructure affects species differentially; larger arboreal species with individuals ≥8 kg are at higher risk of injury and death than smaller arboreal species and terrestrial species. Other organizations can estimate risks in their areas based on the factors we reviewed. Further understanding of how body mass impacts risk will have implications for designing electrical infrastructure as part of conservation planning.