Answer:
a decrease in rainfall
Explanation:
A decrease in rainfall can increase the period and area over which the availability of food and shelter, for mouses, increases, initiating an increase both in the duration of the production season and in the survival of individuals for the next season.
The mouse population, at that moment, explodes and exceeds the capacity of its habitat to house the entire population, in addition, the amount of food available to this population is reduced.
The drop in the mouse population begins when insufficient food is available in the following season to support the colonizers in the receiving habitat and the population quickly reverts to a reduced level.
