With this stimulated increase of rodent life goes a related increase
in the number of birds and mammals which prey upon them. The close
relationship between the numbers of rodents and of the carnivores which
prey upon them is shown by the records of the Hudson Bay Company, in
which with the increase or decrease in the abundance of varying-hare
skins secured by the fur traders goes a corresponding increase or
decrease in the number of lynx skins taken.
[Illustration: