eavesdropper

https://glossary.acousti.cloud/eavesdropper

"In the case of sexual advertisement signals, the intended receivers are prospective mates, usually female conspecifics. Other receivers can also detect and respond to signals even if there was no selection on the sender to communicate with them. We refer to these receivers as eavesdroppers or unintended receivers. It is important to note that the terms intended and unintended should not imply intentionality but instead refer to hypotheses about the selection forces that favored the evolution of these signals. With few exceptions, senders and receivers do not communicate in a private channel. The world is populated by unintended receivers, eavesdroppers who are attendant to the signals of senders, often to the demise of senders." [1]

Synonyms: unintended receiver

Reference: [1] Page RA, Ryan MJ, Bernal XE. Be loved, be prey, be eaten. 2014.