A predator-prey cycle.
<P>
   The  numbers  of lynxes and snowshoe hares oscillate in tune with each
   other in northern Canada.
<P>
   As  the numbers of hares grows, so does the number of lynxes, with the
   cycle repeating about every 10 years.
<P>
   The  number  of  hares  is  controlled  by both predators (lynxes) and
   availability of resources such as food and shelter.