Diel activity of foraging Eurasian red squirrels (Sciurus vulgaris) in the winter revealed by camera traps

Different animals are adapted to a range of activity patterns, from diurnal to nocturnal. Under normal conditions, the 24-hour rhythm is entrained by changes in light intensity during twilight, i.e. the light and dark cycle. Many rodent species exhibit predator avoidance by adjusting their activity in relation to space or time, which is weighed against the need for food. Hence, an individual's foraging activity consists of a compromise between foraging and predation risk, in addition to competition. Our study species, the Eurasian red squirrel, is diurnal and utilises dense forest habitats. In the present study, we used non-invasive camera traps to model diel activity during the winter months in 2014-2015 (December to February 24-hour day). We found that the Eurasian red squirrels exhibited a strictly diurnal feeding activity pattern and the shape of the modelled activity curve was unimodal and concentrated in the daylight hours, starting at sunrise and peaking in the morning.