A park naturalist is an individual who works at a state or national park, who provides educational programs to park visitors based on his or her extensive knowledge of the park. The park naturalist will understand not just the history of the park, but all of the flora and fauna found within it. It is not much of a stretch to expect a naturalist who has worked in a certain park for a number of years to be able to identify almost every single thing he or she sees, from different types of trees and birds, to various types of mosses and ground cover. She will then be able to share this information with park visitors.

The educational requirements of a park naturalist can vary. Many go to college to pursue degrees in environmental sciences or natural resource management; this is usually just a bachelor's degree, but some go on to get a master's degree depending on their career goals. Other naturalists do not have a college degree at all, and are simply self-taught, after years of studying their surrounding environments. Park naturalists typically start out with summer internships or summer employment, and then as they gain experience they might be able to become full-time staff members and offer educational programs even during the winter at other locations when visitors to the park are fewer.

One of the most common tasks of a park naturalist is to lead nature hikes or camping trips, and present outdoor programs at the park. On the hike, the naturalist will explain the surrounding flora and fauna, and why it is important to preserve it. He or she will also take questions from park visitors. The same types of information may be shared at educational programs. Naturalists often give these educational programs to people of all ages, so it is important for them to be able to communicate well with kids as well as adults.

In addition to educating the public about the nature to be found at the park, a naturalist is also an important part of a conservation or resource management team. Since he or she has such extensive knowledge about the park, the naturalist is able to offer advice regarding land management, and the best ways to mitigate damage. For instance, if the park wants to develop a new hiking trail, the park naturalist may be able to identify the areas where it wouldn't impact any sensitive ecological areas.