Does vocal communication at the nest during incubation signal female’s hunger in great tits? (#801)
Although most bird species show monogamous pair bonds and bi-parental care, little is known on how mated birds coordinate their activities. Acoustic communication between partners at the nest is a good candidate but as seldom been considered. The great tit (Parus major) represents an interesting study system to investigate intra-pair communication at the nest, as males are known to address songs to their female while she is in the nest cavity, and females have been shown to answer their male with calls. In a first study, we recorded the vocalizations and observed the behavior of great tit pairs around the nest at different breeding stages (laying, incubation and young nestlings). We observed vocal exchanges between the female inside the nest and her male outside in three situations with different outcomes: (i) the female left the nest, (ii) the male entered the box to feed the female, (iii) mates stopped calling but did not move out/in the nest. The comparison of the acoustic structure of these three situations of vocal exchanges suggests that one possible function of this communication is for the female to signal her need for food to her mate. To test for this hypothesis, we conducted a second study in which each pair was recorded on two days during incubation: one day without food supplementation and one day with a feeder of mealworms into the nest box. We found that females called less with food supplementation. This result confirms our hypothesis that females indicate their need for food in vocal exchanges with their mates. Males’ response to this information remains to be determined.