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King of the Swingers

Why should we protect the spider monkey

Costa Rica is one of the most biodiverse countries in the world; having over 5% of the worlds wildlife in only 0.03% of the landmass. This high level of biodiversity is largely due to the Osa Peninsula on the South Pacific coast. Occupying just 5% of Costa Rica’s land mass, it holds over half of the countrys' biodiversity, making it ‘the most biodiverse place on earth’ (National Geographic).


Despite large areas of the peninsula being protected through the creation of Corcovado and Piedras Blancas National Parks, the wildlife in this area is under threat. Outside of the parks the forest is fragmented in a matrix of palm oil and teak plantations, cattle farms and urban areas. Hunting and illegal logging is a real problem across the peninsula, even in the national parks. Other factors such as pollution, invasive species and climate change are also threatening ecosystems. Fragmentation of forests alters their structure and diversity; therefore, small or isolated fragments of forest have a reduced ability to support many wildlife populations.

Spider monkeys (Ateles spp) are particularly affected by these processes; they rely on ripe fruits to survive and require large areas of mature forest, as they cannot exist in small fragments of forest or cross areas of open land.


Spider monkeys are also hunted on the peninsula; as are many other species. The spider monkey is already listed as endangered by the IUCN (International Union for Conservation of Nature); its populations being wiped out in most of Costa Rica and other countries. They are essential for the overall functioning of the ecosystem; dispersing the seeds of over 150 plant species, which thousands of other species rely on. Many of these plants are hardwoods- essential for carbon storage and hence important in our fight against climate change.

What is the project about?

The aim of this project is to restore and connect native habitat and reduce the threats to the endangered spider monkey (Ateles geoffroyi) on the Osa Peninsula in Costa Rica. The spider monkey is both an umbrella and keystone species, therefore protecting the spider monkey will in turn protect native habitat and the thousands of species that rely upon it.


To do this we will use acoustic and machine learning methods to investigate how the presence of spider monkeys is related to forest cover, land use, hunting, other illegal activities and human activity. We aim to assess dietary and behavioural change across a gradient of anthropogenic threat and land use change providing further evidence regarding the sensitivity of the species to human disturbance and change.


Using this information this project will design landscape management strategies and policy guidance to reduce anthropogenic influences and increase forest cover and connectivity between three national parks in the area, protecting native habitat and the species that rely on it.

How will we do it?

We are using acoustics, recording the sounds of the rain forest, to produce the biggest tropical acoustic database in the world. This is considered a major research gap by scientists. Spider monkeys are very vocal animals, therefore we will use these recordings to determine their location across the area and from their repertoire of calls we can also assess behaviour. Using detailed maps that tell us about habitat type and human presence we can then assess the presence of the spider monkey against factors such as human density, forest cover and land use (Figure 1).


We have divided the peninsula into 4 x 4 km squares using a grid system adapted from the Costa Rican Government, which aids the implementation of scientific research. In each square audio devices will be  placed, where they will continuously record the environment (Figure 1).

Gunshot and chainsaw noise will be extracted from the audio recordings and assessed against presence or absence of the spider monkey, determining the effects from hunting and other disturbances.

Due to the high volume of recordings that will be obtained, over 150,000 hours, we will create an automated analysis system to analyse the data, training a machine to recognise spider monkey calls, gunshots and chainsaws.


Figure 1- Habitat classification of the study area overlaid by grid design

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