'the latest in a long line of celebrities to give their child an unusual name'. I agree that celebrity baby names are often quite hair-raising (and not only baby names, for mercifully young Bear will be spared his father's surname of RocknRoll). But on this occasion, the journos have not done their homework. As all readers of this blog will know, Björn was one of the most popular boy's names in the Viking Age. Lena Peterson's invaluable study of Scandinavian personal names in runic inscriptions (Nordiskt runnamnslexikon) is our best source for actual Viking Age naming practices. Her frequency tables show that Björn is the second-most popular male name in this material, topped only by Sveinn. The latter is probably due to the fact that there are many more inscriptions from the east Scandinavian area where this name was popular, whereas Björn was more widely used across the whole Scandinavian world. The popularity of Björn is also indicated by its second place in the frequency table of deuterothemes, that is the second element in compound names like Þorbjörn. In this frequency table, it is pipped to the post by -ulfr 'wolf', the monothematic version of which is no. 4 in the frequency table of most popular names.
One can only speculate as to why Vikings like to call their boy-children 'Bear' and 'Wolf', though it isn't too difficult to imagine. There don't appear to be any (certainly not any common) female names which are animal-words, and we may note that neither bears nor wolves are particularly nice animals. (Vikings did not call their children 'Sheep'). But they had lots of cool names, and let us hope that more Hollywood stars and other celebrities will study Lena's name-lists for some nice Viking names, rather than choosing to name their children after boroughs of New York, or fruit. And one day, they might even have a nice rune-stone, like the one pictured, for a certain Ulfr.