Which two species are the primary commensal rodents found in structures?

Mice and rats are considered the primary commensal rodents found in structures due to their close association with human habitats. These rodents are adept at living in and around buildings, seeking shelter and food in environments where humans reside. Their behavior and biology have led them to thrive in urban and suburban settings, often resulting in the development of strong populations within homes, warehouses, and other structures.

Mice and rats have physiological traits that facilitate their coexistence with humans. For example, they are incredibly agile and can squeeze through small gaps to gain entry into buildings. Their ability to reproduce quickly also contributes to their prevalence in human-inhabited areas. They are known to infest kitchens, pantries, and storage areas, posing health risks through the potential transmission of diseases and contamination of food supplies.

In contrast, the other groups mentioned in the options, such as squirrels and porcupines or hamsters and voles, are not typically found in close association with human structures. Squirrels may occasionally enter attics or roofs, but they don't commonly inhabit indoor spaces like mice and rats do. Similarly, hamsters and voles have different habitat preferences that do not align with the characteristics of commensal rodents. Thus, the focus on mice and rats highlights