This month's newsletter from Bat Conservation International highlighted some really fascinating new research. Bats have accents. Two animals of the same species from different regions may have very different sounding calls.
Past research has also noted the same phenomenon in birds. Southern-living chickadees, for example, have different accents than their northern counterparts. And cows in the UK were shown to also have regionally different moos.
Bat Conservation International always puts out a great newsletter, full of this kind of interesting info.