With two-thirds the island of St. John designated a National Park, you can't help but drive through it. For taking a closer look, there's many brochures published by the Park System to give guidance/information.
There are 22 hiking trails which meander around the island ranging in distances from 0.1 - 2.2 miles with various levels of difficulty determined from the steep terrains. We took the Leinster Bay Coastal Trail which is conveniently located near Maho Bay. This 0.8-mile easy walk showcased the island's waters, historical ruins of nearby sugar mills, and scrub-type vegetation which are still coming into their own since the island was cleared for sugar cane grown until the late 1800's
With little indigenous plant-life remaining, take a good look at the flowering plant pictured below while it's still there. The Century Plant, also known as the islander's Christmas Tree, is threatened by infestation of the Mexican Boll Weevil. Plants blossom every seven years, or right before dying. Needless to say, there was sadness in their abundant blooming beauty which covered the island.
There are 162-known species of birds on the island. An informative National Park checklist details best times of year/places for spotting them. Shut screened doors/windows where you're staying or birds will come in to sample fruits, and other foods.
The mongoose is looked upon as the equivalent to mainland rats with their destructive behaviors and carnivoristic diets which include bird and sea turtle hatchlings. Their random, ferret-like appearance was anything but amusing to locals. There's believed to be around a dozen illusive deer roaming the island which were released some years back, but you're more likely to see formerly domesticated animals which at one time wandered off and have evolved/repopulated in the wild.
Goats, large pigs and donkeys could be heard and seen roaming free; also being potentially destructive AND dangerous to inattentive motorists. Donkeys, somewhat tame, have caused the most brazen problems foraging off tourists. At Cinnamon Bay Campgrounds, they've had to re-fortify entries of studios and tent-cabins to keep hungry critters from just barging in to help themselves. However, the funniest story came from nearby Caneel Bay which is a maximum security resort for U.S. Presidents and other visiting dignitaries. While they might be able to trace the comings/goings of humans, they couldn't stop a pack of donkeys which gained access to the facility's kitchen and made quite the mess...including eating all the corn flakes!