Norway rats are an Old World species that arrived in North America on European ships in the 1700s, and NatureServe flags the Texas population as exotic rather than native. The refuges named in the records here, Aransas, Padre Island, and Brazoria, are places where people happen to submit iNaturalist sightings, not core habitat; this species tracks docks, grain storage, sewers, and farm buildings far more than open marsh or barrier-island dune.
With only 125 Texas records and no month topping 21 sightings, the reported spring and early-fall bumps are thin signals from a small sample rather than a real seasonal pattern; a burrowing, mostly nocturnal commensal rodent like this one is recorded whenever someone happens to notice it near a building, not on a predictable calendar.
Full species profile
