Social interaction helps bats decide what to eat

Date Published: July 22, 2014

Source: Behavioral Ecology

Institutions involved: University of Konstanz; Department of Biology, Planck Institute for Ornithology; School of Human Evolution & Social Change; Arizona State University.

Summary: A study conducted by  M. Teague O’Mara, Dina K.N. Dechmann,  and Rachel A. Page  in the Behavioral Ecology journal proposes the possibility of social interaction having a great impact on what food a species of bats decide to eat.

                A study conducted by  M. Teague O’Mara, Dina K.N. Dechmann,  and Rachel A. Page  in the journal of Behavioral Ecology proposes the possibility of social cues having a great impact on what food a species of bats decide to eat. Published July 22, 2012, the journal goes into depth about the different social interactions observed among the Uroderma bilobatum species of bats. Furthermore, several conclusions are drawn about what happens when a bat returns to the roost having eaten a new or novel food.

                Researchers have long hypothesized, and now theorized, that animals have the ability to gather information from other animals that enter or pass by the roost. Although true, what is incredible is not that they have been found to have this ability, but that they can differentiate between reliable and unreliable sources in the form of cues. When individuals come into the roost, they exhibit a sort of signal, or cue, to its roostmates indicating that it had just eaten. These cues could potentially be a change in weight, increased grooming, or odor on breath or fur of the individual. A group of researchers found that these cues can affect the feeding choices of other individuals for a significant amount of time.

               The method involved novel flavored bananas, as the bats are used to a diet of banana. The Uroderma bilobatum were captured and recorded for their mass, forearm length, reproductive status, age, and sex. They were then tagged ad monitored daily for the purpose of their well-being. All of the participants came from the same roost to guarantee their familiarity with one another. The four experiments tested the reaction of bats to novel odor exposure, social information transfer in captivity and in nature, and the ability to discriminate information given by two demonstrators.

               The first experiment conducted by O'Mara and his team involved a dish of novel flavoring mixed with banana that was placed in a mesh enclosure, so that the individual bats could smell but not access it for the purpose of familiarization. The bats were then offered two dishes of food, one with the "familiar" smell and another novel flavored "unfamiliar" dish. In the second experiment, a few bats were taken out of their cage, fed a flavored sugar solution and returned to their cage to eat more bananas. The demonstrator bats were individually given a choice of either bananas with the same novel flavor or a new flavor. The third experiment began with the capture of several free range bats. They were held in a cage and fed a flavored banana-sugar water mixture then freed after two days. The group of researchers then captured members of the roosts they captured the demonstrator bats from and were offered bananas flavored with their demonstrator's flavor or another flavor. In the fourth experiment, O'Mara and his team fed two demonstrators, the first was fed novel-flavored bananas and the second was fed an unflavored sugar solution and then a novel-flavored banana juice mixture was applied to its fur.

                The team found that interaction with a novel food odor wasn't enough for a food bias to form. Furthermore, observer bats were more likely to consume food eaten by demonstrator bats earlier. The fundamental finding is that information gathered from cues was likely to remain in a roost for a few days afterward. This ties into what researchers already know; animals interact and provide one another with information about their environment to continue the struggle to survive.

CITATION:  O'Mara, M.T, D.K.N Dechmann, and R.A Page. 2014. Frugivorous bats evaluate the quality of social information when choosing novel foods. Behavioral Ecology 25(5): 1233–1239.