Behaviour 2019
Do vermilion flycatchers sing longer songs in noise to increase the probability of detection?
Alejandro A. Rios-Chelen, Nayeli E. Chávez-Mendoza, Sandra José-Ramírez. Centro Tlaxcala de Biología de la Conducta, Universidad Autónoma de Tlaxcala, Tlaxcala, Tlaxcala, Mexico

Vermilion flycatchers (Pyrocephalus rubinus) sing longer songs (with more introductory elements- IE) in sites with higher levels of urban noise. This could increase the probability of detection. We tested this hypothesis in a population of vermilion flycatchers in the city of Puebla, Mexico. With a speaker, we exposed 15 males to long songs (with 8 IE), with and without embedded noise in the file, and 15 males were exposed to short songs (with 4 IE) with and without noise. If long songs have a higher probability of detection, we predicted that the difference in territorial response between songs with and without noise would be smaller toward long than to short songs. We measured the territorial response (flight and call responses, latency to approach, and closest approach to the speaker). We analyzed our data with a General Linear Model for repeated measures. Our prediction was not supported, suggesting that singing longer songs in noise do not improve the probability of detection. However, males increased their response (flight and calls) with ambient noise, suggesting urban noise affects intra-sexual interactions