Time budget of the common crane Grus grus

Time budget of wintering common cranes Grus grus was addressed in a number of publications (Alonso, Alonso 1992; 1993; Aviles 2003). Breeding behaviour of common cranes was described in detail, but the timing of particular behavioural patterns and their combinations and the general proportion of them throughout the day have not been determined so far (Bock 1931; Schuster 1931; Sieber 1932; Christoleit 1939; Moll 1963, 1973; Makatsch 1970; Prange et al. 1989, 2016). We timed the behaviour of common cranes during field observations from 1989 through 2015 (26 seasons) between 2 March and 14 September in eastern Ukraine and recorded the air temperature in this period. In 1989-1993, we observed 12 nests of 10 pairs from the hide during 26 days (24280 min) over the period of 1.5 months (14.04-29.05). Comparison of crane behaviour with the duration of geographical day and night showed that the daytime activity of incubating birds was shifted to the evening by 1.47 hours. Thus the birds “avoided” the coldest period of day (the difference between air temperatures at 4:00 a...