No evidence that Mycoplasma infection causes cognitive impairment during foraging in Allenby's gerbil (Gerbillus andersoni allenbyi)

Abstract Pathogens can impose substantial ecological costs on infected individuals, including reduced cognition, foraging ability, and predator avoidance. In a prior experiment, gerbils infected with Mycoplasma haemomuris-like bacteria had higher giving up densities, despite spending more time foraging, and were more likely to be killed by predators. One hypothesis to explain this is that infected gerbils suffer from cognitive impairment that reduces their ability to forage efficiently, causing them to spend more time foraging and placing themselves at higher risk of predation. We tested this hypothesis by comparing the ability of gerbils uninfected, acutely infected, or chronically infected with Mycoplasma to equalize giving up densities (GUDs) in seed patches with different initial abundances and detect micropatches within seed patches in a semi-natural vivarium enclosure. We predicted that uninfected gerbils would equalize GUDs and detect micropatches better than infected gerbils. Contrary to our predictions, infected gerbils performed equally well as uninfected gerbils on both tasks. These experiments did not support the hypothesis that cognitive impairment explains past results regarding Mycoplasma and gerbil foraging.