Habituation and decline of anti-predator behaviours in colobus monkeys in dog-dense suburban Kenya

What is it about?

Animals instinctively avoid predators, yet in suburban southeastern Kenya, colobus monkeys are vulnerable to domestic dog attacks. Our study explored why these forest-dwelling primates remain at risk from this invasive terrestrial predator. While many wildlife species avoid areas with dogs or respond with anti-predator behaviours—alarm calls, fleeing, or displays—the colobus in our study did not show these reactions. Even when dogs approached within 20 metres, the monkeys did not flee, but moved to a safer distance while monitoring the dog. They often continued feeding and showed few stress indicators such as scratching or yawning. This behaviour contrasts with 1969 observations in the same area, when colobus responded to dogs with alarm calls, displays, and retreating into trees. This shift likely reflects changes in the local predator landscape. Natural predators such as leopards and crowned eagles are now absent, while free-roaming domestic dogs are widespread, with densities around 250 per km²—far exceeding those of native predators. Due to their specialised leaf diet and limited foraging options, colobus may have little choice but to use areas where dogs are present. Avoidance may not be viable without losing access to key food resources. Repeated exposure may have led to habituation, reducing perceived risk. This reduced response could reflect an energy-saving trade-off, helping colobus balance feeding, digestion, and survival in a human-dominated landscape.

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