Female audience shapes the complexity and syntax of male courtship displays in a lek-mating bird

Courtship displays of lek-mating Golden-winged Manakins (Masius
chrysopterus) are context-dependent. Presence or absence of a female
audience, and female behavior, more than male identity, determines
variation in the constituent elements (repertoire) and ordering (syntax)
of displays. We analyzed 422 display videos in three contexts: displays
without audiences (SOLO, n = 307), displays for female audiences that did
not end in copulation (AUDI, n = 102), and displays ending with
copulations (COP, n = 13). Using entropy and a metric we call
compressibility (ratio of compressed to uncompressed display strings), we
found that ordering of elements (syntax) decreased in complexity from SOLO
to AUDI to COP displays. Jaro string distance, a record-linkage metric for
assessing string similarity, showed that display string syntax
corresponded more to audience context than to performer identity. COP
displays of individual males differed more from their own AUDI or SOLO
displays than from the COP displays of other males. Males responded to
female behavior—her position upslope or downslope from him on the display
log—with simple COP displays. Courtship displays of Golden-winged Manakins
are dynamic interactions between female and male, depending more on male
response to female audience behavior, than on traits intrinsic to
particular males.