Please define "invasive" in the context of [birds who flew over there by themselves]. That's a natural process, fyi. "Invasive" is usually reserved for cases w

Please define "invasive" in the context of [birds who flew over there by themselves]. That's a natural process, fyi. "Invasive" is usually reserved for cases where species hitch a human-facilitated ride, and then invade native species/ecosystems.