A dark-rumped Leach’s Storm-petrel Oceanodroma leucorhoa in the South Atlantic

On 22 January 1964, a moribund Hydrobatid resembling a dark-rumped Leach's Storm-petrel Oceanodroma leucorhoa was left by a seaman from a passing ship at Ascension Island in the tropical Atlantic in the hope that it could be resuscitated. It was said to have come on board four days before to the south, presumably on the night of either 17-18 or 18-19 January SE of St Helena. When it died, Simmons, who was living on Ascension at the time, realised it was unlike the resident Madeiran Storm-petrel Oceanodroma castro, so saved the skin and consulted Bourne. It proved difficult to identify by correspondence since nothing like it was then known to occur anywhere in the Atlantic, and there are several similar forms in the Pacific. Now that similar birds have been found all round the North Atlantic, and some have been identified by their voices (James & Robertson 1985), discriminant analyses of their morphology (Bretagnolle et al. 1991), and molecular techniques (Dawson 1992, Dawson et al. 1995) as Swinhoe's Storm-petrel Oceanodroma monorhis from the Pacific and Indian Ocean, it seems time to report this case.