Fixed effects explaining variation in time allocated to foraging, pecking and intake rates and the time spent in movement under vigilant posture.

A final model was backward-selected using a linear mixed effect model. The variation observed in the df's comes probably from approximations that are made for the calculation of the random effect. In fact, we used 20 individuals, with 9 trials for each bird. This small difference is commonly observed when the number of individuals is not so high.