After further surveying, "Beagle" set sail for Tahiti on 20 October 1835. Darwin wrote up his notes, and to his astonishment, found that all the mockingbirds caught on Charles, Albemarle, James and Chatham Islands differed from island to island. He wrote "This birds which is so closely allied to the Thenca of Chili (Callandra of B. Ayres) is singular from existing as varieties or distinct species in the different Isds.— I have four specimens from as many Isds.— These will be found to be 2 or 3 varieties.— Each variety is constant in its own Island...".