Learning and Cognition
The costs of investing in higher brain function like cognition, learning and memory seem justifiable when considering the benefits: in a long-lived and highly mobile animal like a bat, remembering roost sites and profitable foraging grounds gives you an advantage. But even short-lived animals may well have developed foraging strategies that require learning capabilities. Thus it seems that cognitive abilities are under strong natural selection.
We investigated whether an animal’s life history affects the choice of foraging strategies. Natterer’s bats (Myotis nattereri) have slow life-history traits and we expected them to use associative learning. Common shrews (Sorex araneus) have fast life-history traits and we predicted that they would rely more heavily on routine-based search. Other than their life-history traits, these two mammals are similar in body size, brain weight, habitat, and diet. We studied their foraging strategy and associative learning ability in a four-arm maze; the rewarded arm was marked with four sensory stimuli. Most bats learned to associate the sensory stimuli with the reward and remembered this association over time. Most shrews searched the maze using consistent decision-making rules, but did not learnthe association (Page et al. 2012).
During hibernation, bats reduce their body temperature to ambient temperatures. This may influence neurochemistry and therefore brain function, such as long-term memory consolidation. Behavioural studies on this topic existed almost exclusively for rodents, and provided conflicting results at that. For the first time, we tested memory retention after hibernation in bats. We trained Greater mouse-eared bats (Myotis myotis) on a foraging task until all individuals reached 100 % correct decisions level. After a two months hibernation period, the bats performed at the same level as before and also at the same level as control bats that had been kept active over this period. The results suggest that bats may have developed a neuroprotective mechanism to prevent memory loss over the winter (Ruczynski & Siemers 2011).