Long-term and persistent vocal plasticity in adult bats

Abstract

Bats exhibit a diverse and complex vocabulary of social communication calls some of which are believed to be learned during development. This ability to produce learned, species-specific vocalizations – a rare trait in the animal kingdom – requires a high-degree of vocal plasticity. Bats live extremely long lives in highly complex and dynamic social environments, which suggests that they might also retain a high degree of vocal plasticity in adulthood, much as humans do. Here, we report persistent vocal plasticity in adult bats ( Rousettus aegyptiacus ) following exposure to broad-band, acoustic perturbation. Our results show that adult bats can not only modify distinct parameters of their vocalizations, but that these changes persist even after noise cessation – in some cases lasting several weeks or months. Combined, these findings underscore the potential importance of bats as a model organism for studies of vocal plasticity, including in adulthood.

A sensorimotor model shows why a spectral jamming avoidance response does not help bats deal with jamming

“…Another possible explanation for the bats’ apparent response is based on the Lombard effect, that is the effect of raising source level in the presence of noise, which is well documented in many mammalian species ( Luo et al, 2015 ; Brumm and Zollinger, 2011 ; Zollinger and Brumm, 2011 ; Brumm, 2004 ; Scheifele et al, 2005 ), including bats ( Takahashi et al, 2014 ; Amichai et al, 2015 ). It is also known that increasing the emission frequencies could be a by-product of the increase in amplitude ( Titze, 1989 ; Genzel et al, 2019 ; Hotchkin and Parks, 2013 ). In both hypotheses, the change in frequency does not aim to decrease spectral overlap and thus cannot be considered a spectral jamming avoidance response.…”

“…The independence of the signal’s parameters is reasonable because all bat signals (calls, echoes, and masking signals) in our simulation were similar. The term (in Equation 9 ) is sampled from a Gaussian distribution with a mean ± SD of 0±50 microseconds, equivalent to a range error of 0.85 cm, which is a low boundary estimation of bats capabilities to measure distance ( Genzel et al, 2019 ). 'c' is the speed of sound: 343m/s.…”

Do Bats Have the Necessary Prerequisites for Symbolic Communication?

“…Imitating new signals is one form of vocal production learning (VPL), modifying existing signals based on social influences is another Slater, 1997, 2000). VPL via social modification has been shown for social calls (Rousettus aegyptiacus: Prat et al, 2015Prat et al, , 2017Genzel et al, 2019;Saccopteryx bilineata: Knörnschild et al, 2012;Phyllostomus discolor: Esser and Schmidt, 1989;Esser, 1998;Lattenkamp et al, 2020;P. hastatus: Boughman, 1998) and echolocation calls (Rhinolophus ferrumequinum: Jones and Ransome, 1993;Hipposideros terasensis: Hiryu et al, 2006).…”

Vocal plasticity in harbour seal pups

“…Signallers can face unwanted noise that leads to signal degradation. Masking occurs when the frequencies of the noise overlap with the frequency range of the signal [6].…”

“…The current study targeted one building block of animal communication systems: vocal plasticity. Being vocally plastic allows individuals to adjust their vocal signals in response to changes in their environment [6]. Plasticity, if present in a species, can be deployed in various contexts ranging from environmental challenges to signal detection to changes in social interactions.…”