When the number of animals of prey is high in an area, you’d expect that predator numbers would rise, right? Surprisingly this usually isn’t the case. According to a recent study out of McGill University, predatory animals, such as lions, do not increase in numbers when prey, like zebras are high in numbers.
The study used data that dated back 50 years that was based on a wide variety of predator-prey relationships from big predators, like great cats to small microscopic organisms, across several ecosystems. In total the studies covered a total of 2260 ecosystems and countless predators and prey.
The reason for predator populations not rising in response to high prey numbers is because they rise in response to the rate at which prey reproduce. In crowded areas where prey population is high, they have fewer offspring. This is probably because of a competition for resources and it would be of advantage for the prey to invest more into a fewer number of offspring that are more likely to survive. This then leads to lower reproduction in the predators.
In short, when the reproduction of the prey is limited, so is that of the predators. This study will likely lead to the development of a new law of nature describing predator-prey relationships.
The results of this study were a big surprise to the team, which consisted of Ian Hatton, A McGill PhD student and a biology professor Kevin McCann from Guelph University. McCann says the relationship can easily be explained using a power scale law that would show that in resource rich ecosystems, the proportion of predators to prey would be lower than expected compared to environments with fewer resources.
This study has important implications for the conservation of at risk predatory populations because it would help scientists to better understand how many predators to expect in a given area as well as help them make judgments on what areas are in the most need to conservation.