Begging calls and mouth colouration as predictors of breeding success in blue tits Melero‑Romero, Pablo Garrido Bautista, Jorge Pérez-Rodríguez, Lorenzo Ramos, Jaime Albino Norte, Ana Cláudia Moreno Rueda, Gregorio Begging behaviour Blue tit Breeding success Nestlings normally exhibit a mix of traits that attract parental care, such as postural and vocal begging and carotenoid-based mouth colouration. These signals are hypothesised to be signs of nestling needs (vocal begging) and quality (mouth colouration). Therefore, we hypothesised that broods, where nestlings beg for less time and display more saturated carotenoid-based mouth colouration, would have lower nestling mortality. We tested these predictions in two wild blue tit (Cyanistes caeruleus) populations. The breeding success (here defined as the proportion of eggs that produced fledglings) was related to nestling mouth flanges’ carotenoid-based colour saturation. This means that blue tits that raised nestlings with more coloured flanges had a higher within-population breeding success. Time spent in vocal begging, by contrast, was not associated with breeding success. Hence, our findings reveal that some communication signals displayed by nestlings (carotenoid-based colouration) predict breeding success, in our study mostly reflecting the proportion of eggs that hatched, while begging intensity does not, probably because the former reflects a better maternal pre-laying condition and nestling physiological status in the mid-term. 2024-05-15T08:15:13Z 2024-05-15T08:15:13Z 2024-02-21 journal article Melero-Romero, P., Garrido-Bautista, J., Pérez-Rodríguez, L., Ramos, J.A., Norte, A.C. and Moreno-Rueda, G. (2024), Begging calls and mouth colouration as predictors of breeding success in blue tits. J Zool. https://doi.org/10.1111/jzo.13156 https://hdl.handle.net/10481/91793 10.1111/jzo.13156 eng http://creativecommons.org/licenses/by-nc-nd/4.0/ open access Attribution-NonCommercial-NoDerivatives 4.0 Internacional John Wiley & Sons