One possibility is that the cycling is inherent in the hare population due to density-dependent effects such as lower fecundity (maternal stress) caused by crowding when the hare population gets too dense. More recent studies have pointed to undefined density-dependent factors as being important in the cycling, in addition to predation. Some researchers question the idea that predation models entirely control the population cycling of the two species. The cycling of lynx and snowshoe hare populations in Northern Ontario is an example of predator-prey dynamics. When the lynx population is low, the hare population size begins to increase due, at least in part, to low predation pressure, starting the cycle anew.įigure 1. When the lynx population grows to a threshold level, however, they kill so many hares that hare population begins to decline, followed by a decline in the lynx population because of scarcity of food. As the hare numbers increase, there is more food available for the lynx, allowing the lynx population to increase as well. This cycle of predator and prey lasts approximately 10 years, with the predator population lagging 1–2 years behind that of the prey population. The most often cited example of predator-prey dynamics is seen in the cycling of the lynx (predator) and the snowshoe hare (prey), using nearly 200 year-old trapping data from North American forests (Figure 1). Populations of predators and prey in a community are not constant over time: in most cases, they vary in cycles that appear to be related. Nature shows on television highlight the drama of one living organism killing another. Perhaps the classical example of species interaction is predation: the consumption of prey by its predator.
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