Isolation call ontogeny in bat pups (Glossophaga soricina)

Abstract

Bat pups produce isolation calls to solicit maternal care. During maturation, pup isolation calls may gradually develop into echolocation calls or exist in parallel to them, depending on the species involved. We studied the ontogeny of isolation calls in nectivorous bats, Glossophaga soricina. Isolation calls of G. soricina pups were frequency modulated calls uttered in bouts of varying length. Newborn pups already produced both isolation calls and echolocation call precursors (which developed into ‘normal’ echolocation calls), indicating that isolation calls of G. soricina pups occur independently and exist in parallel to echolocation calls during ontogeny. We found strong statistical evidence for an individual signature encoded in isolation calls. Moreover, we provide evidence for considerable changes in isolation call parameters over a short ontogenetic time span. Throughout ontogeny, the call interval decreased significantly whereas most frequency parameters increased significantly and call entropy rose (i.e., isolation calls became less tonal but noisier).

Isolation calls of the bat Saccopteryx bilineata encode multiple messages

“…Female S. bilineata are capable of differentiating own versus alien pups based on isolation calls alone , which is in line with other bat species (e.g., Balcombe, 1990;Bohn, Wilkinson, & Moss, 2007;Fanis & Jones, 1995;Knörnschild, Feifel, & Kalko, 2013). However, unlike isolation calls in other bats (e.g., Engler, Rose, & Knörnschild, 2017;Esser & Schmidt, 1989;Knörnschild, von Helversen, & Mayer, 2007;Scherrer & Wilkinson, 1993;Sterbing, 2002), isolation calls of S. bilineata remain part of the adult vocal repertoire. They are not only emitted during mother-pup interactions and in pups' babbling trains but also during agonistic male-male interactions and male courtship .…”

Finding, visualizing, and quantifying latent structure across diverse animal vocal repertoires

“…The same is true for zebra finch distance calls [ 28 ] (silhouette score = 0.615; Fig 4B ). Egyptian fruit bat pup isolation calls, which in other bat species are discriminable by adult females [ 45 , 45 , 46 ] clearly show regions of UMAP space densely occupied by single individual’s vocalizations, but no clear clusters (silhouette score = -0.078; Fig 4C ). In the marmoset phee call dataset [ 47 ] it is perhaps interesting that given the range of potential features thought to carry individual identity [ 27 ], phee calls appear to lie along a single continuum where each individual’s calls occupy overlapping regions of the continuum (silhouette score = -0.062; Fig 4D ).…”

The vocal apparatus of bats: an understudied tool to reconstruct the evolutionary history of echolocation?

“…During the last decades, research on the ontogeny of echolocation has been conducted through two main fields of expertise: bioacoustics and anatomy. In terms of bioacoustics, several studies focused on describing the development of the emitted sound for echolocation on post-natal specimens (e.g., Gould 1975;Brown and Grinnell 1980;Habersetzer and Marimuthu 1986;Moss 1988;Moss et al 1997;Vater et al 2003;Engler et al 2017;Smarsh et al 2021). Those studies state that bats vocalize from their day of birth and that FM and CF bats develop echolocation in different ways (Gould 1975;Brown and Grinnell 1980;.…”