In IUCN categories, the geographical range of vulnerable species in the form of B1 (extent of occupancy) should be up to:

Less than 500 Km²

Less than 5000 Km²

Less than 100 Km²

Less than 20000 Km

Explanation

In IUCN categories, for a species to be considered "Vulnerable" based on the extent of occurrence (B1), the geographical range should be less than 20,000 square kilometers.