The latest addition to the New Zealand bird list is a legendary shorebird so rare that there are times when it is likely that none exist anywhere in the world. Bird expert Colin Miskelly introduces the Cox’s sandpiper.

Sandpipers are small wading birds that separate people with a serious interest in bird identification from casual enthusiasts. Within the genus Calidris alone there are 19 sandpiper species, 16 of which regularly or occasionally reach New Zealand on migration from their Arctic breeding grounds.

They are all small, grey-brown above and whitish below when they visit our shores in their non-breeding season. Some refer to them collectively as ‘LBJ’s, meaning ‘little brown jobs’, rather than the 36th President of the United States.

Michael Ashbee was photographing waders at Lake Ellesmere, south-west of Christchurch, on 25 November 2016 when he found what he thought was a pectoral sandpiper – which would have been his first New Zealand sighting of this species.

Michael takes stunning bird photographs, and posted a series of images of the bird on the birders’ webforum BirdingNZ.net late that night.

The following afternoon, a series of comments from some of New Zealand’s leading wader experts suggested an alternative identification.

Although the bird was of the right size and general plumage markings for a pectoral sandpiper, the long, dark, down-curved bill and dull legs pointed to it being something much rarer, and previously unknown from New Zealand.

Cox’s sandpiper is an enigmatic LBJ that was first noticed in Australia in 1955. Sightings there gradually accumulated, with up to four birds being seen among flocks of curlew sandpipers in some seasons.

Debate about the birds’ identity raged, with the leading theories being that it was an undescribed form of dunlin (Calidris alpina), that it was an ultra-rare undescribed species, or that it was a hybrid between two known sandpiper species (with further debate about which two species they could be).

In an effort to resolve the identity of these birds, two individuals were collected in South Australia in 1972 and 1975.

These were used as type specimens when Shane Parker of the South Australian Museum described Cox’s sandpiper (Calidris paramelanotos) as a new species in 1982.

But doubts still remained as to whether they were a genuine species, or a stereotyped hybrid (i.e. a hybrid between two other species that always looks much the same).

I was an undergraduate at Canterbury University when Parker’s paper was published, and recall scanning the (then) substantial flocks of curlew sandpipers at Lake Ellesmere in the hope of finding New Zealand’s first Cox’s sandpiper. But they gradually slipped off everyone’s radar as New Zealand’s sandpiper populations declined.

Like many migratory species that use the East Asian-Australasian Flyway, several species of sandpipers have been hit hard by reclamation of mudflats around the Yellow Sea destroying their essential stopover feeding grounds.

The identity of Cox’s sandpiper was eventually resolved using genetic techniques in 1996, when a team led by Les Christidis at the Museum of Victoria revealed that the three birds included in the study all had the mitochondrial DNA of curlew sandpipers (Calidris ferruginea) – i.e. their mothers were curlew sandpipers – and that they must have been fathered by pectoral sandpipers (Calidris melanotos). They were hybrids after all!

With the realisation that Cox’s sandpiper was not a true species, and with New Zealand’s sandpiper populations dwindling, little further effort or expectation was expended in the hope of finding a Cox’s here.

Most New Zealand bird-watchers who became involved after 1996 had probably never heard of the bird – until Mike Ashbee’s astonishing discovery.

Mike agreed to his images being used to support a detailed description of the bird written by young birder Eleanor Gunby, which was submitted to the Birds New Zealand Records Appraisal Committee.

The RAC recently voted unanimously to accept their sightings of Cox’s sandpiper. It might not be a true species, but it is a genuinely rare bird with a fascinating heritage. And it provides a poignant reminder of how vulnerable our migratory birds are to events far from our shores.

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