Quote Originally Posted by jcustis View Post
"Build up" is an erroneous expression. They tend to go dormant, like a bear in hibernation, to some extent. The proverbial school of fish that they swim amongst starts to swim slower in the winter as well, so everyone is idling a little. They lie a little low during portions of the summer as well.
They come back every year at greater force 8at least greater quantity of incidents and casualties) after sustaining casualties in the previous year.
This increase does likely not happen in the "dormant" phase, so I conclude that they increase (build up) their strength mostly in spring.