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Ten samples of South Island pied oystercatchers (Haematopus ostralegus finschi) were trapped between August 1969 and June 1971. Nine catches were made at the Heathcote-Avon estuary and one at Parapara Inlet in northwest Nelson. In late summer large numbers of immatures and adults arrived at the estuary. Decreasing frequencies of juveniles in later samples suggest that young birds tend to move further north than most adults. Males outnumbered females in all samples except the one in February 1971 when there was an excess of females. This seasonal shift in sex ratio could arise from a staggered migration and/or differential mortality of the sexes. Further systematic trapping at strategically placed coastal haunts is needed to substantiate and elaborate the above findings.