Landscape of Fear: Monkey Alarm Calls

Predators, Primates and Humans in a Landscape of Fear;

A seminar by Prof. Russell Hill, Evolutionary Anthrophology; Durham University.

Samango monkey and Vervet Monkeys were studied by Hill in 2014 at the Lajuma Research Centre, located in the Soutpansberg Mountains. The study aimed to bring a better understanding of predator-prey relationships in primates and to see if monkeys have differing calls depending on the predator. The landscape of fear (or: the effects that fear has on the environment) offers a valuable approach to understanding predator-prey interactions.

In the seminar, Hill talked about how predation structures the feeding habits and territory of primate populations and how predators can be used to control overpopulation in prey species. Hill reflected on the experiment where wolves were successfully re-introduced to Yellowstone National Park in the 1990s to control the overgrowing caribou population, you can read more about this here.

Image taken from Prof. Hill’s website

What Does That Have to do With Monkeys?

By studying prey we can understand the predators. In this case, one of the key predators of the monkeys are leopards (IUCN: Vulnerable, decreasing population).

Primates are a good study species because they are vocal. They have a variety of calls that they use in response to different predators: Leopards, reptilian or avian predators.

These differing calls can be used to create maps and compare distributions of alarm calls to plot the distribution of predators.

Samango monkeys are arboreal, they were chosen for this study for the following reasons:

  • They have acoustically different alarms
    • Which are lower pitched
  • Predation risk was a significant factor in habitat choice

The monkeys vigilance was measured by the individual’s glance rate (looking around). Their vigilance was seen to increase as you go up the tree: eagles are ambush predators from the tree canopy.

Avian predator of monkeys; the Crowned Eagle. Source: Flickr

The crowned eagle’s staple diet is mostly mammalian

However, from Hill’s research it is suggested that eagles have no effect on the distribution of monkeys. This is possibly because eagles are ambush predators and can travel long distances in search of prey.

Expected results: Arboreal monkeys feed for longer periods of time at the top of the tree as this is where they feel the safest.

Reality: Monkeys were more vigilant at the top of trees to avoid being ambushed by eagles.

Human Impact:

Vervet Monkey

Often when we observe animals in their natural habitat, we have to get close to the study species and sometimes, animals become habituated to us humans. In this study, Hill found that:

  • Monkeys feel safer around humans
    • And forage for longer periods of time when around humans
  • Humans reduce predator presence
  • Leopards don’t like humans

 

Personal Opinions:

Overall I greatly enjoyed this seminar and it helped me gain an understanding of vigilance across multiple species – I have been studying foraging and vigilance in wading birds for my dissertation. The seminar was well delivered and presented in an enjoyable way.

I was once interested in studying old-world monkeys and I am glad that this seminar was able to bring back my previous interests, however, I have found that monkeys are not my favourite study species and I am more interested in bird behaviour.

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