Cape Ground Squirrels

The Cape ground squirrel project is a collaborative long-term project with Prof. Jane Waterman at University of Manitoba,  Canada, that has been operating at S.A. Lombard Nature reserve in South Africa for over 20 years.

Research has been focused on factors influencing the evolution of sociality, cooperation and mating systems in Cape ground squirrels, using an integrative approach and incorporating the effects of environmental factors on the morphology, physiology and behaviour of Cape ground squirrels. Current conservation projects focus on using CGS as a model system to look at how small social mammals respond to the impacts of climate change. 

Background on the Cape ground squirrels

Cape ground squirrels (Xeris inauris) are an arid-zone adapted species that live in Southern Africa. Compared to temperate ground squirrels, Cape ground squirrels have unusually low levels of aggression (no physical aggression, non-territorial) and and docile personalities. They engage in a variety of cooperative behaviours such as vigilance, predator mobbing, allocare and cooperative breeding.

Cape ground squirrels exhibit two types of social groupings: 1) Mixed-sexed matrilineal family groups consisting of plurally breeding related adult females, and subadults of both sexes, and sexually mature males that have delayed dispersal (‘natal males’); 2) all-male bands (of up to 19 individuals) of dispersed sexually mature males (‘band males’). These all-male bands (of up to 19 individuals) are a fission-fusion social system with males forming ephemeral foraging sub-bands of two to eight individuals. The type and extent of cooperative and collective behaviours exhibited in these two types of social associations (female, natal male, band male) varies. 

Effects of climate change

Cape ground squirrels live in open grasslands throughout southern Africa and have typical arid adaptations such as concentrated urine, high thermal conductance and a low resting metabolic rate. They face thermoregulatory challenges dealing with cold night-time temperatures and hot daytime temperatures. Cape ground squirrels deal with heat in several different ways. They dig large burrow clusters (aggregations of burrows), and sleep with their groups at night in shared burrows. And during the day individuals may shade themselves with their tails while exposed to the sun  or may retreat to underground burrows during unfavourable weather conditions. As arid environments incur large variations in daily and seasonal ambient temperatures, and Southern Africa is experiencing rapid changes in climatic conditions, Cape ground squirrels may be affected by changing climatic and ecological conditions in their habitat. At our field site, daily maximum air temperatures at have risen by more than 2°C.  So far, we have found that the relative size of ground squirrel feet has increased, while their bodies have become smaller. These proportionally bigger feet may help the ground squirrel cool off by allowing them to shed more heat even faster than those squirrel with smaller feet. Likewise, smaller bodies are predicted to help animals shed heat at a faster rate than larger-bodied animals. This result suggests that ground squirrel bodies may be changing in response to the greater heat stress that these animals are experiencing in recent years.