Figure 2.

Response of great tits to the presence of artificial light at night and different light spectra. (a) Proportion of minutes at night that birds spent without head tucked under feathers. (b) Oxalic acid calculated as the change in levels between baseline measurement and each treatment period. (c) Total number of trials until task completion during the cognition tests. (d) Daily energy expenditure of birds. Bars and error bars represent raw data as means ± s.e.m. (Online version in colour.)