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Figure 2 | Journal of Circadian Rhythms

Figure 2

From: Natural daylight restricted to twilights delays the timing of testicular regression but does not affect the timing of the daily activity rhythm of the house sparrow (Passer domesticus)

Figure 2

Double plotted activity recordings of three male house sparrows receiving NDL conditions in March. After initial synchronization when they were exposed to NDL all day for 2 weeks, they were exposed to NDL during twilight periods alone in two stages. First, half of them (n = 4) continued receiving NDL all day and served as control (left panel), while the other half (n = 4) was deprived of NDL from sunrise to sunset (NDL minus daylight; middle and right panels). Then, after two weeks, the lighting conditions of the two halves were swapped: the first half received NDL minus daylight (left panel), while the second half received NDL all day and served as control (middle and right panels). The movements of the birds within their cages (size = 60 × 45 × 35 cm) were detected by passive infrared motion sensors, continuously counted and recorded, and analyzed by the software program of the Stanford Software Systems (Stanford, USA). Note freerun between days 15 and 25 in one of the three representative sparrows exposed to twilight periods alone in March (right panel).

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Journal of Circadian Rhythms

ISSN: 1740-3391