Spider monkeys are frugivorous primates that live in complex societies characterised by high degree fission fusion dynamics whereby members of the same community are rarely all together and spend their time in fluid subgroups that constantly change in size and composition. Subgroup size is adjusted to food patch size and when fruit is abundant the spider monkeys can be found in large groups. Group size and composition can have a notable effect on activity budgets, ranging and social interactions, particularly as there are notable sex-differences in the quality of social relationships and the type of social interactions exchanged by males and females. A large community of spider monkeys in the Calakmul Biosphere Reserve has been studied each summer since 2013. The summer months are associated with the onset of rainy season and high fruit production resulting in large subgroups of spider monkeys. However, between 2015-2016 the reserve suffered a severe drought and during this time virtually no fruit was available. By 2017 rainfall and fruit production had returned to normal. Using the long-term dataset students can investigate changes to ranging patterns, subgroup composition and the associated effect on rates of social interactions in relation to rainfall patterns and food availability. Another project could focus on spider monkey activity and habitat use. Spider monkeys can have large home ranges that encompass different forest types, but it is not clear if they use all forest types for food and shelter. An investigation of how spider monkeys use the different forest types will determine whether spider monkey populations could survive in disturbed areas with limited availability of high forest. Activity budget data will be recorded using instantaneous scan sampling, noting the behaviour of each individual in view, the GPS location and forest type. Subgroup composition will be recorded in real time throughout the day and all occurrences of social interactions will be recorded noting the individuals involved, behaviour and context.
The Calakmul Biosphere Reserve (CBR) in Mexico is an UNESCO World Heritage Site of Culture and Nature and is part of the largest expanse of neotropical forest north of the Amazon, filled with ancient Mayan ruins and supporting one of the highest biodiversity levels in the world. The CBR is also an extremely important wildlife corridor that is crucial for migrating birds and animals with extensive ranging patterns such as jaguar and Baird’s tapir. Over the last 10 years the reserve has experienced a notable reduction in rainfall. Monitoring data on birds, bats, herpetofauna, butterflies, ungulates, felids
and primates are being used to evaluate the impact of climate change and changing rainfall patterns on the abundance, ranging and diversity of fauna to help determine when and where mitigation should be used to restore water sources. Data are also used to assess the efficacy of a range of sustainable development projects with buffer zone communities designed to minimise forest encroachment. In addition, there are specialist studies on jaguar and their preferred prey, behaviour of spider monkeys and population levels of Morelet’s crocodiles.
In Mexico it is hot and humid. Temperatures rarely drop below mid 20s even at night. It is unlikely to rain much, but you do get occasional heavy showers during the season.
Fitness level required
Medium in the forest, low on the marine site. There are some reasonably long walks through the forest, terrain varies by camp with some being almost completely flat and others more undulating. On the marine site lower levels of fitness are required (although you will likely be very tired at the end of the day after the in-water sessions).
Facilities in the forest are basic (sleeping in tents or hammocks in a camp site), with a mixture of dry and trench toilets. There are freshwater showers but water conservation is particularly important to bear in mind. There are some limited opportunities to buy snacks at some forest camps and there is no phone signal at any of the sites. On the marine site the facilities are a little less rustic – you sleep in bunk beds in dormitories about 10 minutes drive from the beach. There is good phone signal and the site is well supplied with shops.