Florida is a popular destination for birdwatching, because of the many species that can be found in the state at various times of the year. The Florida Ornithological Society maintains the official state list of the birds of Florida, which currently contains 498 species. A study published in 2003 by the Florida Fish and Wildlife Conservation Commission documented 196 species of birds which were confirmed to breed in the state, with an additional 19 species listed as possible or probable breeders. The Great Florida Birding Trail, a 2,000-mile-long (3,200 km) trail, is composed of 489 locations throughout the state which are excellent observation sites.