Determining Black Rat from Brown Rat

Can you tell the two rat species apart based on skull characteristics?

With some experience, it is not that problematic if you just have fairly

intact skulls and jaws.

Black rats have 4 skull characteristics that are not found in Brown rats.

Skull:

On the upper side of the skull there are bone ridges (long narrow

ridges on the sides of the skull), which differ in shape and extent in the

two species. See more in handbooks.

Jaw:

The best characteristics are found in and on the jaw. The first molar has

4 root holes in Black rats, but 5 in Brown rats (very certain characteristic).

Finally, the crown outgrowth (the pin that sticks up from the back of the jaw)

is slightly pointed and spiky in Black rats. In Brown rats, it is slightly more

rounded and slightly more curved in shape.

Natural History Aarhus