Neighbors affect vocal behavior of tropical wrens: a multispeaker density-manipulation experiment

Area of Science:

• Animal Behavior
• Bioacoustics
• Ecology

Background:

• Territorial animals use vocalizations for communication, but neighbor density's impact is understudied, especially in tropical species.
• Rufous-and-white wrens (Thryophilus rufalbus) exhibit complex songs by both sexes for territory defense in tropical dry forests.

Purpose of the Study:

• To investigate how neighbor density affects vocal behavior in territorial songbirds.
• To determine if rufous-and-white wrens adjust singing in response to simulated increases in local conspecific density.

Main Methods:

• A multispeaker playback experiment was conducted on 24 pairs of rufous-and-white wrens.
• Six loudspeakers broadcast simulated territorial neighbor songs (male and female) for three days to increase perceived local density.

Main Results:

• Male wrens significantly increased their song rate by nearly 50% when exposed to simulated neighbors.
• Females showed a marginal, but not significant, decrease in song-type switching rates.

Conclusions:

• Bird vocal behavior is sensitive to acoustic cues of conspecific density beyond immediate territory boundaries.
• Rufous-and-white wrens use public acoustic information to modulate their vocal output in response to perceived neighbor density.