Why is there a gigantic beaver in the visitors center? Well, Fort Nisqually was a trading post, and beaver pelts were a key part of the commerce that went on there.
"Trading actually began in ernest when the supply ship Vancouver arrived in Jun 1833. Trading on the first day netted about 90 beaver pelts and many other animal furs. Each prime condition adult beaver skin was worth one 2-1/2 point blanket, the most popular item among the Indians."