Here's why it's not a single species:
* Many different species: There are over 30 species of deer around the world, including:
* White-tailed deer
* Mule deer
* Elk
* Red deer
* Reindeer
* Fallow deer
* And many more!
* Subspecies: Even within a species, there can be different subspecies, like the white-tailed deer with its many subspecies throughout North America.
To know the exact species, you'd need more information about the deer in question, such as its location or physical characteristics.