Social Influences on Foraging in Bats

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Hanging bats

Research Interests/Summary:

My broad research interests are animal communication, social behavior, and behavioral ecology. I am currently using studies of bats to investigate questions about information transfer, social learning, and vocal communication. Long-lived, group-living animals experiencing changing resources could benefit by acquiring information from conspecifics. Most bat species are highly social, and many rely on seasonally changing food sources. Additionally, communicative vocalizations have been described for many bat species, but function and context are known for relatively few calls. Through research with three bat species, I am working to address unanswered questions about the nature of social learning and communication in bats. My research evaluates: 1) the ability of juvenile bats to learn a new foraging task socially, 2) the function of social calls in a foraging context, 3) the rate at which and mechanism (social or individual learning) by which new skills are acquired by bats, and 4) the effects of social context and occurrence of interindividual associations in foraging bats.

Inexperienced juveniles should especially benefit from social learning, and results from my research indicate that for young big brown bats (Eptesicus fuscus), there is a social component to learning to capture prey. I found that young bats can learn a novel foraging task via interaction with knowledgeable (but not unknowledgeable) conspecifics. It appears that inexperienced bats may be using auditory cues from knowledgeable bats to learn about prey items; further data analysis is pending. During these interactions, I recorded a variety of vocalizations that appear to be communicative in function. Using high-speed video footage recorded synchronously with the audio files, I am matching bats’ behavior and interactions with their vocalizations to determine possible functions of these calls.

    In contrast to the insectivorous bats described above, research I conducted with wild-caught Jamaican fruit bats (Artibeus jamaicensis) revealed that having conspecifics present when foraging can negatively impact an individual’s foraging efforts. I found that bats took longer to find food in groups than alone and spent significantly longer trying to obtain inaccessible food if another bat was nearby. However, experiments I am conducting with a captive colony of short-tailed fruit bats (Carollia perspicillata) indicate that individuals of this species locate and access food more quickly when in groups than alone, and that males feed close in time with one another more often than expected by chance. To ascertain whether social learning or other factors (e.g., increased competition) are responsible for faster foraging in groups, I am training demonstrator bats to specific food locations and will then record times to feed for naive bats flying with these demonstrators. I am also evaluating instances of pairs of bats feed close together in time.

    bat feeder
bat close
    • Wright, Genevieve Spanjer. 2009. Hipposideros caffer. Mammalian Species 845: 1-9
    • Spanjer, Genevieve R., and Martin Cipollini. 2006. Relationship between physiochemical factors and distribution of stygobitic crayfishes in southeastern US caves. Southeastern Naturalist 5(1): 17-26.
    • Spanjer, Genevieve R., and M. Brock Fenton. 2005. Behavior al Responses of Bats to Gates at Caves and Mines. Wildlife Society Bulletin 33 (3): 1101-1112.
    • Ratcliffe, John M., Hannah M. ter Hofstede, Rafa Avila-Flores, M. Brock Fenton, Gary F. McCracken, Stefania Biscardi, Jennifer Blasko, Erin Gillam, Jazmine Orprecio, and Genevieve Spanjer. 2004. Conspecifics influence call design in the Brazilian free-tailed bat, Tadarida brasiliensis. Canadian Journal of Zoology 82(6): 966-971.
    • Spanjer, Genevieve R. 2004. How do bats react to cave gates? National Speleological Society (NSS) News 62(10): 285.