The first part of our discussion was focused on general questions regarding population cycles. Population cycles integrate many of the processes we have previously discussed in this class such as predator-prey dynamics, competition, density dependence, and life history strategies, into one complex process. As such, several biotic and abiotic factors contribute to the patterns they exhibit in nature. One of the major challenges in this field of study has been to examine the multiple factors involved for their individual effects and interactions.
Predation is probably one of the most important causal factors driving many population cycles.
It is thought to be responsible for accelerating the decline phase and extending the low phase of the cycle. It remains unresolved whether predation alone is able to stop growth at peak densities in order to create cyclic dynamics. In class we discussed the role of, and tried to identify, some enabling factors that might aid predation in creating lynx-hare cycles. One factor identified was the predation by red squirrels on juvenile hares. Since the red squirrel displays a type three functional response at high hare densities it seemed likely that it was an enabling factor in the population decline.