Royal Mail has also produced a special sheet of four stamps illustrating the unique wildlife of the Galpagos Islands that includes the Flightless Cormorant, Giant Tortoise, Floreana Mockingbird and Marine Iguana, and which builds up into a contemporary map of the Galpagos Islands with the key species Darwin studied in the 1830s during his voyage as Ship's Naturalist on the hydrographic survey ship HMS Beagle.