The most successful wildlife photographer, probably in history, would be Art Wolfe. He had a portrait studio in Seattle for 10 or 15 years that paid his bills until his book sales took off.
Another guy I know who's a working wildlife photographer started as a naturalist, and worked his way to doing just photography. He works really hard selling post cards, and $200 calendar shots to pay his bills. It seems to be me to more work than it's really worth.
Most of the National Geographic photographers who do wildlife, like Jim Brandenburg and Joel Sartore, started out as award winning newspaper photographers.
The key to being successful as a wildlife photographer is to get shots that look different from everybody else's, or to long range, in depth stories.
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