Using automated data loggers to assess incubation behaviour in Tree Swallow (Tachycineta bicolor)
Nghia Tran, Dany Garant, Fanie Pelletier
UNIVERSITÉ DE SHERBROOKE

During the incubation period, birds must balance the time they spend incubating their eggs with other activities such as foraging. As a result, eggs are exposed to variable conditions throughout their development, especially in passerine birds, which are for the most part uni-parental incubators. We studied incubation behaviour in a Tree Swallow population nesting in southern Quebec using automated temperature data loggers (iButtons) to assess the extent of the variation in the daily proportion of time eggs are being incubated. We found that daily proportion of time spent incubating increased before clutch completion day and remained stable throughout the incubation period. Clutch size was found to be an important factor in shaping incubation behaviour, with larger clutches being incubated for a larger proportion of the daytime. Incubation behaviour may be an important aspect for fitness as the proportion of eggs hatching increases when clutches are being less exposed to ambient temperature. Although daily proportion of time spent incubating remained stable after clutch completion day, other incubation related behaviours might change as embryos age. Further analysis will be devoted to assess the importance of incubation behaviour on incubation duration.