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Comparison of the number of progeny per breeding pair (n = 217) in selected consecutive litters of the same breeding pair. The graph illustrates a distinct decline in the number of progeny per litter with increasing numbers of litters per breeding pair, each from litter one to litter 5 and litter 5 to litter 10. Only one 15th litter was recorded with a single pup during the entire period of investigation. The most frequent are 3 and 4 offspring (58 and 48%) born in the first litter.
