Previous work from this lab has shown that paired bats change certain characteristics of their calls relative to their call similarity with one another (Chiu et al, 2009)
when flying in relatively open spaces. Further, Chiu et al. (2008) report that bats go silent for several hundreds of milliseconds at a time, presumably to avoid signal interference or to eavesdrop.
I am interested in (1) how these behaviors are modulated by the presence of obstacles and competition, and (2) whether silent behavior is a competitive or collaborative method for the echolocating bat.
Recently, we studied whether the adaptations in call parameters and silent behavior persist when single and paired bats fly in open and cluttered spaces. We found no correlation between call similarity and call adaptation, and, importantly found no evidence for silent behavior in the open or cluttered room conditions. This stands in contrast to previous findings (Chiu et al., 2008, 2009). One major difference between the data sets was the gender of bats: previous work used almost exclusively males, whereas my recent study used only females. The single female pair of bats studied in Chiu et al. (2008) showed only little silent behavior.
The next step is to confirm a possible gender-specific role of foraging in echolocating big brown bats and test the extent to which competition may induce silent behavior.
Warnecke M, Chiu C, Engelberg J & Moss CF (2015). Active Listening in a Bat Cocktail Party: Adaptive Echolocation and Flight Behaviors of Big Brown Bats, Eptesicus fuscus, Foraging in a Cluttered Acoustic Environment. Brain, behavior and evolution, 86(1), 6-16.
Warnecke M & Moss CF. “Eine Cocktailparty unter Fledermaeusen: Wichtige von Unwichtigen akustischen Signalen trennen”. Studienstiftung des detuschen Volkes, ERP Meeting, Washington DC, April 2015.
Warnecke M, Chiu C, Xian W, Cechetto C & Moss CF (2014). Foraging among acoustic clutter and competition: Vocal behavior of paired big brown bats. The Journal of the Acoustical Society of America, 136 (4), 2185-2185.