Can concurrent speed and directness of travel indicate purposeful encounter in the yellow baboons (Papio hamadryas cynocephalus) of Ruaha National Park, Tanzania?

Abstract

I used components of baboon foraging behavior (concurrent fast and direct travel) to categorize core dry-season foods as purposefully or randomly encountered. I then compared the categorized foods to published, a priori predictions for core dry-season foods. Using focal-animal techniques on 6 males from two baboon troops, I collected precise locational data with a differentially corrected Global Positioning System (GPS) over 6 mo. The data analysis yielded the speed and directness of baboon travel between a food-handling event and a prior location. To distinguish purposefully encountered foods from randomly encountered foods, I calculated the average speed and the average observed deviation from straight-line travel exhibited to each resource type. A linear regression describes the relationship between these variables for each resource type. Baboons demonstrate both relatively high speeds and direct travel towards 3 food types: Combretum obovatum, impala, and baobab trees. Baboons were hypothesized a priori to encounter these resources purposefully. Baboons were also hypothesized a priori to encounter corms and perhaps Commiphora paniculatum purposefully, however, they travel neither quickly nor directly to these resources. I interpret this finding in terms of the costs accrued by traveling quickly and directly to fall-back resources. I discuss the ability of concurrent speed and directness to distinguish purposefully encountered foods from randomly encountered foods.