After pondering and discussing our observations around the den this year and reviewing our data on Brutus' travels, we suddenly noticed that not long before he died in mid-April, Brutus had visited this den. As we indicated earlier, he had spent many days there last fall, presumably because it was a rendezvous site, to which the pack had moved the pups from the den on the south side of the fiord. However, why did Brutus visit this den on March 31, at just about the time his mate would have come into estrus? Is such a den visit common during estrus? Few researchers would have had detailed enough data to know. In any case, this March visit is evidence that Brutus was with his mate at this time, for presumably it would be the breeding female that would be interested in the den. That then means that Brutus probably bred his mate, and the pups at this den might be his. That would also explain why we have not yet identified a breeding male associated with the den.
With that hypothesis in mind, we hope to collect scats from the pups for paternity analysis via DNA. And of course we will be ever on the lookout for a breeding male. Even if we find one around the den, however, it would not necessarily mean that the pups are not from Brutus. When a female wolf is without a mate, single males floating around the population quickly determine that and try to pair with them and even help raise their "step-pups."