@article {53369, title = {Soft songs in male ortolan buntings are used in an aggressive context but are not an aggressive signal}, journal = {Ethology}, volume = {124}, year = {2018}, month = {Jan-08-2018}, pages = {549 - 558}, abstract = {

Many bird species produce low-amplitude acoustic signals that have been poorly studied in comparison with loud, broadcast songs used for mate attraction and repelling rivals. In some birds, these soft signals were found to be emitted in an antagonistic context and were the most reliable predictor of a subsequent physical attack. The function of this signal is poorly understood, and several hypotheses have been proposed to explain the mechanisms and possible functions of such low-amplitude signals. The subject of this study is the ortolan bunting, a small passerine species that produces soft songs during territorial defence. In this study, we aim to study whether the soft songs of the ortolan bunting are a signal of increased aggressiveness by testing if they meet the context, prediction and response criteria of aggressive signals. We simulated stranger male intrusion into a focal male territory with three different playback experiments. We found no significant differences in the male responses to the taxidermic model regardless of whether they were or were not producing soft songs in response. The males responded more strongly to loud songs than to soft songs during the simulated intrusions, and the males did not treat soft songs as a predictor of conflict escalation. Although soft songs clearly appeared during territorial encounters and were not present during spontaneous singing before the intrusions, our results did not support the hypothesis that soft songs indicate aggressive character. We suggest that soft songs in the ortolan bunting are intentionally used by birds to modify their intentions or target-specific individuals within a close range.

}, keywords = {Aggressive signals, ortolan bunting, soft song, territorial defence}, doi = {10.1111/eth.2018.124.issue-810.1111/eth.12758}, url = {http://doi.wiley.com/10.1111/eth.2018.124.issue-8}, author = {Jakubowska, Aleksandra and Osiejuk, Tomasz S.}, editor = {Fusani, L.} } @article {52567, title = {Negative impact of urban noise on sexual receptivity and clutch size in female domestic canaries}, journal = {Ethology}, volume = {123}, year = {2017}, month = {Jan-11-2017}, pages = {843 - 853}, abstract = {

In oscines, male song stimulates female reproduction and females are known to adjust both their sexual preferences and their maternal investment according to song quality. Female domestic canaries are especially responsive to wide frequency bandwidth (4 kHz) male songs emitted with a high-repetition syllable rate and low minimal frequencies (1 kHz). We previously showed that low-frequency urban noise decreases female sexual responsiveness for these low-frequency songs (1\–5 kHz) through auditory masking. Based on the differential allocation hypothesis, we predicted that urban noise exposure will equally affect female maternal investment. Using a crossover design, we broadcast low-frequency songs to females either in an overlapping noise condition or in an alternating noise condition. Females decreased both their sexual responsiveness and their clutch size in the overlapping noise treatment relative to the alternative noise treatment. No differences were found concerning egg size or egg composition (yolk and albumen mass, testosterone concentration). Due to our experimental design, we can exclude a general impact of noisy conditions and thereby provide evidence for a detrimental effect through masking on avian courtship and reproductive output. These results suggest that noisy conditions may also affect avian communication in outdoor conditions, which may partly explain field reports on noise-dependent breeding success and reduced breeding densities at noisy sites.

}, doi = {10.1111/eth.2017.123.issue-1110.1111/eth.12659}, url = {http://doi.wiley.com/10.1111/eth.2017.123.issue-11}, author = {Huet des Aunay, Guillaume and Grenna, Marco and Slabbekoorn, Hans and Nicolas, Pierre and Nagle, Laurent and Leboucher, G{\'e}rard and Malacarne, Giorgio and Draganoiu, Tudor I.}, editor = {Fusani, L.} } @article {50490, title = {No need to shout: Effect of signal loudness on sibling communication in barn owls Tyto alba}, journal = {Ethology}, volume = {123}, year = {2017}, month = {Jan-06-2017}, pages = {419 - 424}, abstract = {

In animal communication, signal loudness is often ignored and seldom measured. We used a playback experiment to examine the role of vocal loudness (i.e., sound pressure level) in sibling to sibling communication of nestling barn owls Tyto alba. In this species, siblings vocally negotiate among each other for priority access to parental food resources. Call rate and call duration play key roles in this vocal communication system, with the most vocal nestlings deterring their siblings from competing for access to the food item next delivered by parents. Here, we broadcast calls at different loudness levels and call rate to live nestlings. The loudness of playback calls did not affect owlets\&$\#$39; investment in call rate, call duration or call loudness. The rate at which playback calls were broadcast affected owlets\&$\#$39; call rate but did not influence their response in terms of loudness. This suggests that selection for producing loud signals may be weak in this species, as loud calls may attract predators. Moreover, given that owlets do not overlap their calls and that they communicate to nearby siblings in the silence of the night, loud signals may not be necessary to convey reliable information about food need.

}, keywords = {acoustics, amplitude, begging, communication, competition, multiple signals, negotiation, playbacks}, doi = {10.1111/eth.12612}, url = {http://doi.wiley.com/10.1111/eth.12612}, author = {Dreiss, Am{\'e}lie N. and Ducouret, Pauline and Ruppli, Charl{\`e}ne A. and Rossier, Virginie and Hernandez, Lucile and Falourd, Xavier and Marmaroli, Patrick and Cazau, Dorian and Lissek, Herv{\'e} and Roulin, Alexandre}, editor = {Fusani, L.} }