Time and distribution: a model of ape biogeography

Abstract

We use data from 20 chimpanzee, bonobo and gorilla study sites to develop an African great ape time budgets model to predict the animals' capacity to survive in a range of habitats across sub-Saharan Africa. The model uses body mass and climatic data to predict the time animals must allocate to key activities (feeding, moving, resting and social interaction), and then uses these to assess the limiting group size that could be sustained in a particular habitat. The model is robust against changes in minimum cut-off values, and predicts the current biogeographic distributions of the two African ape species remarkably well. Predicted group sizes for Pan and Gorilla are close to observed averages. The model also indicates that moving time plays a crucial role for both Pan and Gorilla site presence: i.e. at sites where they are absent it is primarily moving time that is increased as compared to other time budget variables. Finally, the model demonstrates that Pan and Gorilla distributions and group sizes can be accurately modelled by simply modifying the body mass variable, indicating that both share a similar underlying ecological bauplan.

Biogeographic Variation in the Diet and Behaviour of Cercopithecus mitis

“…The PPI has been shown to equate to the length of the growing season, which itself yields a very strong correlation with primary productivity [Le Houerou, 1984]. Williamson [1997] highlighted the value of PPI for describing rainfall seasonality and previous studies have illustrated its value in explaining biogeographic patterns of primate dietary variation and behavioural ecology [Hill and Dunbar, 2002;Lehmann et al, 2008aLehmann et al, , 2010. To complement [Rudran, 1978] Obs.…”

The Effects of Climate Change on Orangutans: A Time Budget Model

“…Similarly, among the African great apes, it was found that feeding time increased as the percentage of fruit in the diet increased (Lehmann et al, 2008b). These relationships may reflect the reduced foraging and processing times required to eat leaves.…”

“…Time budget models have been shown to predict species distributions as accurately as climate envelope models Willems & Hill, 2009), but can also be used to understand the mechanisms that determine distributions, both now and in the future, as well as potential impacts on behaviour Lehmann et al, 2010). Time budget models have been created for three species of great apes to date: gorillas, chimpanzees and bonobos (Lehmann et al, 2008a(Lehmann et al, , 2008b. In this chapter we investigate the potential effects of climatic change on orangutan distribution patterns using a time budget model.…”

Investigating Constraints on the Survival of Orangutans Across Borneo and Sumatra

“…This is interesting compared to the other species of great apes that all live in larger and more cohesive groups. Although chimpanzees have a fission-fusion social system, their average party size far exceeds that of the orangutan [29,[52][53][54]. For orangutans, group size was found to be a major predictor of resting time allocations, with resting time demands increasing as group size increased.…”

“…Time budget models can be used to investigate how the environment, through its effects on behavior, shapes biogeography and social organization [25]. These models provide valuable insights into the factors that determine the habitats in which a species can live [7,[25][26][27][28][29], the group sizes that they can adopt [9,30], and the amount of time budgeting stress that they face in any given environment [8,31]. Time budget models can therefore provide an indication of habitat suitability for conservation planning.…”