PLACENTAL SCAR COUNTS IN THE RED FOX (VULPES-VULPES L) REVISITED

Placental scars used for analyses of reproduction in the red fox (Vulp es vulpes L.) may fade throughout the season after birth. I report a m ethod to calculate whelping frequency and mean litter size from placen tal scar analyses of 608 vixens shot during autumn and winter in three areas of Sweden. The material allowed 6-9 consecutive periods of calc ulation within the year in each area. By successively including scars of lighter shades in the counts, I established isopleths of constant w helping frequencies. The isopleth yielding the best estimate of mean l itter size as derived from analyses of vixens in late pregnancy was ac cepted for calculations in each area. Although this method appeared to be adequate for each area, there were inter area differences. Therefo re, reference material is needed for each specific area before this me thod can be used.