Loggerhead Key existed on the island in the early 1900s. Fauna of Loggerhead Key includes sea turtles, which are monitored by park rangers with the Dry Tortugas National Park to document nesting and hatching rates. The loggerhead sea turtle is also present on the island. In August 2016, a National Park marine biologist stated that 113 loggerhead turtle nests existed on the island at that time. This was the highest recorded nest rate compared previous years. The island also has brown pelicans. In 1972, hundreds of rhesus macaque monkeys were brought from India to Loggerhead Key by Charles River Laboratories. This was
Loggerhead shrike length, tail length, and colour. "L. l. migrans" have a paler forehead than the top of the head. According to Mundy et al.’s 1997 study, there is a substantial genetic difference between the island subspecies "L. l. mearnsi" and the mainland subspecies "L. l. gambeli" due to a gene flow barrier between the two species. The loggerhead shrike is a medium-sized passerine. "Loggerhead" refers to the relatively large size of the head as compared to the rest of the body. It measures approximately 9 inches from bill to tail. The wing and tail length is about 3.82 and 3.87 inches