Immunity and reproduction are important and costly life-history traits and a large part of eco-immunology focuses on trade-offs between investing in reproduction versus immunity. Male Cape ground squirrels (Xerus inauris) are a good organism to test these trade-offs as they invest heavily in sperm competition, evidenced by their large testes, and exhibit alternative reproductive tactics. My research objective was to determine 1) if testosterone suppresses immunity, or if immunity suppresses testosterone, and 2) if alternative reproductive tactics differ in their investments in immunity and reproduction. I found evidence that testosterone was suppressed after an immune challenge, and that manipulatively increased testosterone had no effect on immunity, body condition or parasites. The dispersing tactic males were in worse condition, had higher parasite abundances, but showed no difference in their innate immune ability to non-dispersing males. Males incur increased costs with dispersal and may focus their energy into reproduction instead of immunity. / October 2015

Predator harassment is an anti-predator behaviour that may increase a harasser’s risk of predation but decrease the potential for predation for other members of a group. The Cape ground squirrel (Xerus inauris) is a facultative cooperative breeder from southern Africa that harasses venomous snakes. The objective of my study was to examine predator harassment to determine: 1) whether predator harassment was part of alloparental care by comparing harassment behaviour among age and sex classes; 2) how individuals adjusted their behaviour against different snake species; 3) whether olfaction was used in discrimination of snakes; and 4) if individuals possessed venom resistance against venomous snakes. I found that females with juvenile offspring harass snakes longer and more intensely than other individuals, suggesting that predator harassment was a maternal behaviour. Squirrels increased harassment, inspection and vigilant behaviours with risk when exposed to both live snakes and snake odours suggesting they can use olfaction to discriminate snake predators. I also found no venom resistance in Cape ground squirrels concluding the cost of envenomation was significant.

Predator harassment is an anti-predator behaviour that may increase a harasser’s risk of predation but decrease the potential for predation for other members of a group. The Cape ground squirrel (Xerus inauris) is a facultative cooperative breeder from southern Africa that harasses venomous snakes. The objective of my study was to examine predator harassment to determine: 1) whether predator harassment was part of alloparental care by comparing harassment behaviour among age and sex classes; 2) how individuals adjusted their behaviour against different snake species; 3) whether olfaction was used in discrimination of snakes; and 4) if individuals possessed venom resistance against venomous snakes. I found that females with juvenile offspring harass snakes longer and more intensely than other individuals, suggesting that predator harassment was a maternal behaviour. Squirrels increased harassment, inspection and vigilant behaviours with risk when exposed to both live snakes and snake odours suggesting they can use olfaction to discriminate snake predators. I also found no venom resistance in Cape ground squirrels concluding the cost of envenomation was significant.