Multiple estimation methods suggest similar repertoire sizes for Gulf Coast and eastern marsh wrens with no correlation between repertoire size and migratory distance

Abstract

There are many ways for signalling systems to be complex, one of which is a large signal repertoire. However, it is frequently challenging to estimate larger repertoires accurately. We present the first description of repertoire size for a subspecies of marsh wren on the Gulf Coast of North America,Cistothorus palustris thryophilus, using four repertoire estimation techniques (simple enumeration, Wildenthal curve-fitting, Davidson & Wilkinson curve-fitting, and the Coupon Collector model). We demonstrate that the repertoire estimation methods in question perform with varying degrees of accuracy under natural conditions, and propose that rather than establishing an absolute repertoire size for a given individual it may instead be necessary to use multiple techniques to establish a repertoire range. We find thatC. p. thryophilushas a song repertoire size falling well within the range of repertoires produced by other marsh wren subspecies in eastern North America, although it may be on the larger end of this range. We find no evidence supporting a correlation between migratory distance and increased repertoire size in this species, as might be predicted under a sexual selection hypothesis.