Spatial Analysis and Group Territoriality

We live within a spatially explicit world, but the analysis of biological questions in a spatial context is only a recent development within the fields of behavior and ecology. Anna Mosser is examining the evolution of group territoriality, applying GIS (geographical information systems) spatial analysis to our long-term database of demographic, behavioral and spatial records of lions in the Serengeti. While this type of analysis has not been feasible in the past, the development of GIS techniques and tools now make multivariate spatial analysis possible.

Animals are considered to be territorial if they exclude others from the space in which they live. This home space is the animal's territory and will often contain all the basic life resources (water, food, and shelter). Group territoriality can be defined as the mutual defense of shared resources, in this case, the resources that are in the pride's home territory. Lions live in groups and defend their territories in groups. This is a trait that has evolved independently across a broad diversity of animals (wolves, wasps, and woodpeckers, to name a few) and is an important driving force in the evolution of social and cooperative behavior.

1992 pride ranges

As the only consistently social member of the cat family, research on lion behavior has often focused on determining the causal factors behind lion sociality. Past studies have found potential benefits of group living (e.g. advantages of group hunting or shared defense of cubs) important but insufficient in explaining why lions are gregarious (see Packer et al. 1990; Packer & Pusey 1994). In addition, there is numerical advantage in inter-pride aggressive interaction and cooperative behavior is most frequently associated with threats to territorial space by other lions (see McComb et al. 1994).

Anna's research will test the hypothesis that sociality in the African lion has evolved as a result of a survival advantage attributed primarily to the group defense of a shared territory. An important first step is to use the long-term ranging data, which consist of GPS locations indicating where each pride was seen on a given day, to map the ranges of each pride. For example, the figure to the right estimates the ranges of all of the prides in our study area in 1992 by including 75% of the location points recorded for each pride during the year. Actual ranges are larger than shown and vary from dry season to wet season, but the ranges shown are a good indication of where each pride spend most of its time. After the ranges are mapped, they can be compared to measures of habitat quality and reproductive success.

References:

McComb K, Packer C and Pusey AE. 1994. Roaring and numerical assessment in the contests between groups of female lions, Panther leo. Animal Behaviour 47:379-387.

Pusey AE and Packer C. 1994. Non-offspring nursing in social carnivores: minimizing the costs. Behavioral Ecology 5:362-374.

Packer C, Scheel D and Pusey AE. 1990. Why lions form groups: food is not enough. The American Naturalist 136:1-19.

Return to Main Page