St. Thomas, part of the U.S. Virgin Islands, is home to a diverse mix of native and introduced species that thrive in its tropical climate. You will frequently see iguanas sunning themselves on rooftops and stone walls; these prehistoric-looking reptiles are a quintessential part of the island's landscape. The island also hosts several non-native land mammals that have become naturalized, including the small Asian mongoose, white-tailed deer, and feral donkeys. Birdwatchers can spot the St. Thomas conure (or brown-throated parakeet) and various hummingbirds flitting through the hibiscus. In the surrounding turquoise waters, the marine life is even more spectacular, featuring green and hawksbill sea turtles, various species of whales and dolphins, and colorful reef fish. While the Caribbean monk seal was declared extinct decades ago, the island's current fauna remains vibrant, offering a rich experience for nature lovers exploring the lush hills or the vibrant coral reefs that surround this Caribbean gem in 2026.