This double plotted actogram shows activity for a representative bird over the course of approximately 30 months, including 2005 when the sleep data for this paper were collected. Vertical yellow lines indicate seasonal changes in daylight. Seasons from which birds were selected for sleep analyses are highlighted (winter (blue) n = 4, spring (green) n = 5, summer (red) n = 4, fall (brown) n = 3). Photoperiods for the winter, spring, summer, and fall seasons were, respectively, 9.5:14.5 LD, 14.75:9.25 LD, 21.5:2.5 LD, and 13.75:10.25 to 16.0:8.0 LD.
Jones et al. BMC Neuroscience 2010 11:87 doi:10.1186/1471-2202-11-87