Comparative ecology of Guinea baboons (Papio papio)

Abstract

Thorough knowledge of the ecology of a species or population is an essential prerequisite for understanding the impact of ecology on the evolution of their respective social systems. Because of their diversity of social organizations, baboons (Papio spp.) are a useful model for comparative studies. Comparative ecological information was missing for Guinea baboons (Papio papio), however. Here we provide data on the ecology of Guinea baboons in a comparative analysis on two geographical scales. First, we compare climate variables and land cover among areas of occurrence of all six baboon species. Second, we describe home range size, habitat use, ranging behaviour, and diet from a local population of Guinea baboons ranging near the Centre de Recherche de Primatologie (CRP) Simenti in the Niokolo-Koba National Park, Senegal. Home ranges and daily travel distances at Simenti varied seasonally, yet the seasonal patterns in their daily travel distance did not follow a simple dry vs. rainy season pattern. Chemical food composition falls within the range of other baboon species. Compared to other baboon species, areas occupied by Guinea baboons experience the highest variation in precipitation and the highest seasonality in precipitation. Although the Guinea baboons' multi-level social organization is superficially similar to that of hamadryas baboons (P. hamadryas), the ecologies of the two species differ markedly. Most Guinea baboon populations, including the one at Simenti, live in more productive habitats than hamadryas baboons. This difference in the ecology of the two species contradicts a simple evolutionary relation between ecology and social system and suggests that other factors have played an additional role here.

Figure 1

Sketch of the social organization of baboons. (a) Uni-level organization of COKY baboons (Papio ursinus, P. anubis, P. kindae, and P. cynocephalus). In these species, a group consists of several adult males and females with their offspring. Group sizes can reach more than 100 individuals. Females are predominantly philopatric and form kin-based social networks. (b) Multi-level organization of Guinea baboons (P. papio) and hamadryas (P. hamadryas). At the Centre de Recherche de Primatologie Simenti, units (u) consist of 2–10 individuals (at least one adult male and one to several adult females and their offspring), parties (p) of 30.5 ($\pm \mathrm{6.4}$), and gangs of more than 60 individuals. The size of our study population at Simenti is 350–400 individuals ($\mathit{>}\mathrm{7.5}$ individuals per square kilometre) and is most likely equivalent to a local population. In hamadryas baboons, corresponding levels of the social organization are one-male unit (OMU), clan, band, and troop (Kummer, 1995).

Figure 2

(a) Approximate distribution of Guinea baboons (brownish) and position of CRP Simenti within the Niokolo-Koba National Park (PNNK, dark shading). Species distribution after Wallis et al. (2020) and derived from the IUCN spatial database (https://www.iucnredlist.org/resources/spatial-data-download, last access: 19 January 2021). (b) Climate graph of the Simenti field site after Walter and Lieth (1967). Depicted are monthly temperatures (red line denotes mean; red band the min, max) and monthly precipitation (blue) in millimetres. Red dotted area demarcates the dry periods (i.e. dry season), the blue area depicts the occurrence of precipitation, and the blue hatched area the humid periods (i.e. rainy season).

Figure 3

Comparison of monthly normalized difference vegetation indices (NDVI (mean $\pm$ SD); measure of “greenness”, i.e. plant productivity) of the Guinea baboon habitat at Simenti, Senegal, and the hamadryas baboon habitat at Filoha, Ethiopia, for 3 years from 2010 to 2012. Since the NDVI can be regarded as an indirect measure for precipitation, the two periods of rain at Filoha (unpredictable short rains from February to May and long rains from June to September, both light grey) and the one in Simenti (June to October, dark grey) are reflected by respective maxima in the graph (source: MODIS NDVI – MOD44/MYD44 (16 d) – TERRA (AM) only; DiMiceli, 2015).

Figure 4

Distribution of habitat classes within the area of interest around CRP Simenti. The black dot indicates the position of the field station of the Centre de Recherche de Primatologie (CRP). We defined the area of interest as the total extent of monitored baboon occurrences in 2010–2012.

Figure 5

Average annual precipitation (a) and coefficient of variance of monthly precipitation (seasonality) (b) at occurrence sites of the six baboon species (means $\pm$ SE $\pm$ SD). Triangles indicate respective values at Simenti (data from WorldClim, variables bio12 annual precipitation and bio15 seasonality of precipitation). Baboon species (number of occurrence sites): multi-level social organization Pp – P. papio (177), Ph – P. hamadryas (64), uni-level social organization Pa – P. anubis (120), Pc – P. cynocephalus (96), Pk – P. kindae (32), Pu – P. ursinus (244).

Figure 6

Proportion of land cover classes at sites of the six baboon species (GlobCover, Arino et al., 2012). Baboon species (number of occurrence sites): Pp – P. papio (177), Ph – P. hamadryas (64), uni-level social organization Pa – P. anubis (120), Pc – P. cynocephalus (96), Pk – P. kindae (32), Pu – P. ursinus (244).

Figure 7

Position, extent, and overlap of annual home ranges (95 %) and core areas (50 %) of Guinea baboon gangs (G) and parties (P). The grey line depicts the Gambia River. Note that the scales vary slightly among years.

Figure 8

Annual and seasonal variation in home range and daily travel distance (DTD). Boxplots depict the median (black line) and the IQR with the lower (25 %) and upper (75 %) quartile. Boxplot whiskers represent the 1.5 IQR of the lower and upper quartile.

Figure 9

Minimum daily travel distances (DTD) of Guinea baboons in Simenti on a daily temporal scale. Grey dots represent individual DTD values, the black line is the smoothed mean travel path distances derived by the generalized additive model, and the grey shaded area represents the confidence bands at 99 %. The green bars indicate the rainy season (June to October).

Figure 10

Distribution of main sleeping sites in 2010, 2011, and 2012. Star shapes depict locations that had been used in $\mathit{>}\mathrm{20}$ % of all sleeping events. Diamond shapes represent 10 %–20 %, while triangles represent 5 %–10 % of all sleeping events. Sleeping locations $\mathit{<}\mathrm{5}$ % are not depicted. Numbers depict the various wetland features: 1 – Mare Simenti, 2 – temporary wetland Simenti, 3 – temporary wetland Mare Kountadala. The two parallel lines represent the Gambia River.

Figure 11

Habitat availability and habitat use of Guinea baboons in Simenti. Availability: proportion of habitat classes allocated within the area of interest. Use by baboons in dry and rainy season: proportion of location points of individual baboons within respective habitat classes in dry and rainy seasons. Individual variability in habitat use is displayed as the standard error. F/GF – forest/gallery forest; SW – savannah woodland; TS – tree savannah; GS – grassland; M/SM – Mare, seasonal wetland.