Effects of sunlight duration on the population dynamics of the red fox (Vulpes vulpes L.)
The influence of sunlight duration on a growing red fox population in the region of Munster during the period 1959/60 to 1998/99 was examined mathematically. The relationship between the fox hunting bag per 1,000 ha area and monthly, statistics on hours of sunshine, the temperature and rainfall was examined by Pearson correlations indicated that the sunlight in January is associated with the increasing fox bag. A linear, multiple regression with the dependent fox bag and the chronology of sunshine hours and the temperature was established. The sunshine duration in January was significantly and positively correlated, whereas it was negatively correlated with the fox bag in February. The fox bag trend was not favoured by the positive effect of temperature in January. The increase in sunshine hours, with the beneficial effect on the epiphyses of foxes, regulates the secretory activity of the gonads. In this month more mating can take place, and there is less suppression of fetuses during increasing sunshine hours and temperature. Field mice leave their caves so that food becomes more plentiful resulting in an improvement in condition and greater activity. Females become sexually active earlier as a result of oestrogen production and fertility is improved resulting in potentially more offspring.
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