07.10.2024: Does the song of conspecifics affect the reproduction of birds? This question was investigated in an Austrian-Slovak study led by the University of Veterinary Medicine Vienna and published in the “Journal of Ornithology”. The behavior of the European reed warbler (Acrocephalus scirpaceus) was examined in an experiment using song playbacks. The findings revealed that the acoustic environment, particularly the “beautiful” songs of males in the neighborhood have a positive effect on reproductive investment and breeding success.

At the onset of the breeding season, several critical decisions must be made such as where to establish a territory and attract a mate and identify an ideal breeding site. These decisions can be influenced by the quality of potential mates, but also by the presence of other conspecifics in the environment. In birds, for example, vocal characteristics such as the complexity of a song can signal the quality of an individual.

Playback experiments test the effect of songs

“In addition to choosing the right location for reproduction and attracting mates, we suspect that the acoustic environment, for example in the form of singing neighbors, can also influence an individual´s reproductive,” explains study lead author Herbert Hoi from the Konrad Lorenz Institute of Ethology (KLIVV) at Vetmeduni, outlining the research hypothesis of the study. In particular, early maternal investment, like the resources that a mother allocates to her embryos in the eggs, is a sensitive factor that can also be influenced by the quality and attractiveness of males. This investment is reflected in the distribution of maternal resources among the offspring and ultimately affects also their development.

“In this context, we investigated whether the song quality of neighboring conspecifics stimulates reproductive parameters in the reed warbler,” says Herbert Hoi. To this end, the scientists carried out playback experiments in the field with songs of high and low complexity, simulating different acoustic environments and assess their influence on settlement decisions, early maternal investment and breeding success.

“Beautiful” bird songs have a positive effect

While the results revealed no significant difference in the number of nests and the start of egg laying, the nests were found to be significantly closer to locations where highly complex songs were heard. In addition, a significantly higher proportion of eggs were completely dark pigmented in the group exposed to highly complex songs than in the group with less complex songs. Furthermore, the breeding success of nests near highly complex songs was significantly higher, resulting in more offspring.

Herbert Hoi concludes: “Our results suggest that the acoustic environment, for example in the form of song quality, not only from male partners but also conspecifics, has a notable influence on reproductive investment and breeding success. This influence appears to be less pronounced regarding investment in embryos.” Given the importance of offspring loss due to nest predation, Hoi suggests that future studies could explore the role of neighboring males' songs and their impact on behaviors during other reproductive phases.

The article „Does complexity of conspecific song influence reproductive decisions and investment in European Common Reed Warblers: an experimental playback approach?“ by Ján Krištofík, Alžbeta Darolová, Lucia Rubáčová und Herbert Hoi was published in „Journal of Ornithology“.

Scientific article