As seen in arctic hares or lemmings, when the population becomes too large, overcrowding and stress may lead to reduced rates.

In the context of wildlife populations like Arctic hares or lemmings, the phenomenon you're referring to is often related to the concept of carrying capacity and density-dependent factors. When these animals experience rapid population growth due to favorable conditions, they can surpass the ecosystem's carrying capacity. This situation can result in several consequences:

1. Overcrowding: As the population increases, individuals compete for limited resources such as food, shelter, and mates. This competition can lead to stress among animals, as their basic needs become harder to meet.

2. Stress and Health: The high stress levels associated with overcrowding can weaken the immune systems of these animals, making them more susceptible to disease. Additionally, it can result in inadequate food intake, leading to malnutrition and lower reproductive success.

3. Reproductive Rates: When overcrowding occurs, the reproductive rates of these populations can decline. Stress and competition may delay breeding or reduce the number of offspring produced. In some cases, animals may even adjust their reproductive strategies to cope with the lacking resources.

4. Population Decline: Eventually, as food becomes scarce and disease spreads, the population may begin to decline. This decline can restore balance to the ecosystem and allow remaining individuals to thrive with reduced competition.

This cyclical pattern highlights the delicate balance between population growth and environmental limits, illustrating the importance of understanding ecological dynamics in wildlife management and conservation efforts.