Final answer:
The statement about the number of gray squirrels refers to the population of this species on campus; monitoring such populations is vital for urban planning and management of biodiversity.
Step-by-step explanation:
The statement, "There are 628 gray squirrels living on campus," describes the population of gray squirrels on campus. This number may have been determined by a wildlife survey or similar study conducted to understand the dynamics of species within an area. The gray squirrel, known scientifically as Sciurus carolinensis, has been documented to outcompete native squirrel species such as the red squirrel (Sciurus vulgaris) in places like Great Britain, and similar concerns are present in Italy where the species has been introduced. Assessing the population numbers of gray squirrels can be critical for urban planning and biodiversity management, especially since the presence and density of an invasive species can have significant ecological effects on native species and ecosystems.