Which factor contributes to an increase in a rat population?

One significant factor that contributes to an increase in a rat population is the availability of food sources. When there are abundant food supplies, such as garbage, crops, or human waste, rats can thrive and reproduce quickly. Additionally, a lack of natural predators and suitable habitats for nesting also play crucial roles in facilitating their population growth. Lastly, mild weather conditions can extend their breeding season, further boosting their numbers.