Journal of Neuroscience, Vol 6, 2875-2879, Copyright © 1986 by Society for Neuroscience
Interspecific comparisons of the size of neural song control regions and song complexity in duetting birds: evolutionary implications
EA Brenowitz and AP Arnold
Previous studies have demonstrated a correlation between song repertoire
size and volume of song control regions (SCRs) in the brains of songbirds.
In the present study we demonstrate that 2 congeneric species of tropical
duetting wrens, the rufous-and-white wren (Thryothorus rufalbus) and the
bay wren (T. nigricapillus), share the same relationship between SCR volume
and vocal complexity. In each species, females sing in elaborate duets with
males. Males of these species have similar song repertoire sizes; there is
no significant difference between heterospecific males in the volumes of
SCRs. Female rufous-and-white wrens have less than half as large a song
repertoire as female bay wrens, and all of their SCRs measured are
significantly smaller than those of bay wren females. This interspecific
equivalence of the relationship between SCR volume and repertoire size
suggests that the neural system regulating vocal behavior in songbirds is
evolutionarily conservative in the manner in which it encodes song
complexity.