Presentation Details
Audience dependent acoustic crypsis in territorial tufted titmice  

Katie Sieving1, Jin Bai2, Jeff Lucas3, Todd Freeberg4.

1Wildlife Ecology, University of Florida, Gainesville, FL, USA.2Nicholas Institute for Energy, Environment & Sustainability, Duke University, Durham, NC, USA.3Biology, Purdue University, West Lafayette, IN, USA.4Psychology & Neuroscience, Knoxville, TN, USA

Abstract


We tested if heterospecific audience diversity influences vocal signaling during territorial aggression in tufted titmice (Baeolophus bicolor). Ninety playback trials were conducted in three habitats in north‑central Florida, exposing responding titmice to territorial vocal stimuli while recording vocal responses. We calculated an aggression score based on non-vocal behaviors, and production rate of four call types: chick‑a‑dee calls, songs, squeal calls, and flutter calls. Predictors included aggression score, heterospecific diversity within 20m, noise, and habitat. We found (1) titmice used more chick‑a‑dee calls and fewer songs in urban vs. forest, (2) higher aggression was associated with more squeal and flutter calls, but (3) titmice increased squeal calls with high audience diversity but emphasized flutter calls when alone. We interpret this as adaptive acoustic crypsis: flutter calls (9–11 kHz) provide a private, high‑frequency channel minimizing predator eavesdropping, while squeal calls maintain signal efficacy when a diverse audience offsets predation risk (via “many eyes”). Vocal plasticity in aggression reflects a sophisticated adaptation to socio‑ecological context.

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