Chronotype and Seasonal Timing of Reproduction Are Related in a Female Songbird

ABSTRACT

Seasonally breeding animals depend on local environmental cues to time annual events. Behaviors related to both seasonal timing and daily timing display individual repeatability, however it is not well understood whether a specific daily phenotype, such as earlier onset of activity, is linked to an individual also exhibiting a particular annual behavior, such as early seasonal timing in reproduction. Here we monitored the timing of daily activity across the reproductive season as well as seasonal reproductive timing of egg‐laying and reproductive success in free‐living female great tits ( Parus major ). We collected highly detailed daily accelerometer activity data from females prior to clutch initiation, as well as during laying, incubation and nestling feeding stages. We tested the hypothesis that females with an earlier daily phenotype, or a longer active day, initiate clutch initiation earlier in the season than females with a later or shorter daily phenotype. We found evidence of a positive relationship between onset of daily activity during the stages of pre‐laying and laying with clutch initiation day; however, there was no relationship during incubation and nestling rearing. We detected a negative relationship between pre‐laying active day length and clutch initiation date. These results demonstrate a link between chronotype and seasonal timing of reproduction, but also indicate the complexity of factors that may contribute to both seasonal and daily timing of events in wild animals.