Yesterday while skyping, I was asked about where in the 3-5 year cycle of population growth the small mammals are here at the field site. Chris, one of our scientists, estimates that this is about the peak year. Last year the numbers were very high. So he is waiting for this summer to find out whether this year will be the peak or whether last year was the peak and this year will be low again.
I explained the population cycle incorrectly yesterday on skype. Thanks to your question, I found out that the population cycle is not the result of exceeding the food supply. Instead, as the population density gets higher, the animals get more aggressive toward each other. That leads to lower survival rate, and then the population declines.
Good question, boys!