SLR
An SLR is a camera that uses a wide variety of interchangeable lenses. This is a highly versatile camera that is used in a wide variety of applications, from sports and journalistic photography to portraiture and hobby photography. The features of an SLR that make it ideal for nature photography include the ability to use a 300 mm or longer zoom lens for getting close-up pictures of wildlife from a distance, macro lenses for taking images of smaller subjects such as bugs, as well as manual settings for most functions.
35 mm
While many would say that cameras that shoot 35 mm film are obsolete, the price of the equipment makes a film camera more attractive for wildlife photography than digital cameras. Because of the necessity for specialized lenses, a wildlife photography camera setup can be considered quite expensive. However, there is a large market of used 35 mm equipment available on the market by photographers looking to convert to digital equipment. If a wildlife photographer is willing to forgo the luxury of an automatic focus camera, the price of equipment is even lower.
Trail Camera
A trail camera is frequently used by hunters to scout game, but it can also be used for security, by farmers looking to keep track of livestock, landowners for surveillance of fence rows, or photographers seeking to take photos of elusive wildlife. A trail camera is an easy way to record images of an animal without invading its habitat. Trail cameras consist of a housing box, a battery, motion sensor, camera and flash. While there are a large number of trail cameras that can be purchased commercially, you can find plans online to create your own trail camera from raw components. Most of these components can be purchased at an electronics store.