What is the panthers main food source?

It's not possible to give a definitive answer to "what is the panther's main food source" without knowing which panther you're referring to.

The term "panther" can refer to a few different animals, each with their own diet:

* Black Panther: This is usually a melanistic (black furred) leopard or jaguar. Their diet varies by location, but generally includes ungulates (deer, antelope), small mammals, birds, reptiles, and fish.

* Florida Panther: This is a subspecies of cougar, and their primary food source is white-tailed deer.

* Mountain Lion/Cougar: This animal's diet is similar to the Florida Panther, focusing on deer but also including smaller mammals, birds, and even domestic livestock.

Therefore, to accurately answer your question, you need to specify which type of panther you are interested in.