* Beginning of a sentence: Just like any other noun.
* Part of a proper noun: If it's part of a species name, such as *Puma concolor* (the scientific name for the cougar, and capitalization here follows the rules of binomial nomenclature). Note that even within the scientific name, only the genus (Puma) is capitalized, not the species (concolor).
* Used as a formal name or title: For example, if you're referencing a specific organization, project, or study that uses "Puma" in its name (e.g., "The Puma Conservation Project").
In all other instances, such as when generally referring to the animal, "puma" should be lowercase.