Most records to date have come from the more heavily populated south and south-east of Australia. A mysterious juvenile "Calidris" sandpiper was encountered on Duxbury Beach, Plymouth Bay, Massachusetts, United States, in September, 1987, and was tentatively identified as a Cox's sandpiper. The bird was observed in the field, and also trapped and examined in the hand as well as banded. Several accounts of this individual were published. In late August, 2001, another juvenile "Calidris" showing features of both pectoral and curlew sandpipers was found at Shintone, Ibaraki Prefecture, Japan. An account of this bird, illustrated with photographs, was published in the British journal Birding World. This bird was believed to be another juvenile "Cox's sandpiper". The birds were conclusively shown to be hybrids by Christidis "et al." (1996). They analyzed 3 specimens of Cox's sandpiper and found that the mtDNA sequence of the cytochrome "b" gene was identical to that of Curlew sandpipers, while allozyme variation fit the pattern seen in curlew and pectoral sandpipers, but neither agreed with that of other proposed parent species (sharp-tailed sandpiper, white-rumped sandpiper, and ruff). Since mtDNA is inherited only from the mother, they concluded that the parentage of Cox's sandpipers was a male pectoral and a female curlew sandpiper.