Choice overload constrains mate choice independent of energetic masking

Mate choice requires receivers to detect, remember, and compare signals across multiple potential mates. Strong preferences in simple contexts often weaken when receivers encounter numerous signalers, potentially due to energetic masking, in which overlapping signals impair discrimination, or choice overload, in which evaluating too many options exceeds cognitive capacity. Although energetic masking is well-documented, we know little about choice overload in nonhumans. We investigated both mechanisms in Cope's gray treefrogs ( Hyla chrysoscelis ) using playback experiments that independently manipulated the number of non-overlapping calls and background chorus noise. Females chose between a longer "target" call and one, three, or seven shorter "distractor" calls with and without background noise. As the number of calls increased, females became less accurate, took longer to decide, and more frequently deferred choosing. These results demonstrate that cognitive limits on information processing can subvert mate choice, even without sensory interference, highlighting an underappreciated constraint on sexual selection.