Figure 1. Environmental (e.g. ambient temperature and daylight length) and physiological (e.g. body weight and food intake from the study cats) parameters during the course of the study.

Bodyweight (in kg) is expressed as median (black circles) and range (error bars) kg); daylight length (in min/day) is expressed as mean (open circles) and standard error (error bars) for each month; daily temperature (in Celsius) is expressed as mean (solid line and black circles) and minimum and maximum (dashed lines and open circles above and below the mean line); and food intake (in grams/day) is expressed as mean (white columns) and standard deviation (error bars) intake. Daylight length, temperature and food intake showed a seasonal pattern (P<0.001 for all). In contrast no seasonal pattern was observed for body weight, which increased steadily during the course of the study.