Friday, 14 March 2014

Plight of the New Zealand Dotterel.

Without doubt the New Zealand Dotterel is one of the most beautiful, if understated, of waders. It is endemic to New Zealand and is considered to be Endangered. It is the largest of the Charadrius plovers and is divided into two subspecies. The nominate Charadrius o. obscurus is very rare and breeds just on Stewart Island off South Island. Its population has risen from a low of 62 birds to 250 after feral cats were controlled on the island. Charadrius o. aquilonius lives at the north end of the North Island, but although greater in number is not abundant by any means. Our first sighting of them was a special moment.

New Zealand Dotterel Charadrius obscurus aquilonius; Port Waikato, Waikato, North Island, New Zealand. October 2013.
We had just scored on a twitch with our friend Brent Stephenson from Wrybill Birding Tours and his colleague, 'Sav' Saville. Our target had been Oriental Plover, another stunner when in summer plumage, but this was a non-breeding bird. Oriental Plovers are a rarity in New Zealand with less than 20 records and although both our birding companions are top NZ listers, it was a tick for them both! We had seen them before in Broome, Western Australia but not nearly as well.

Oriental Plover Chardrius veredus; Port Waikato, Waikato, North Island, New Zealand. October 2013.
Once we'd seen this bird we looked for some New Zealand Dotterels on a breeding beach nearby, but the strong wind meant that the birds had made themselves scarce. However, a wrong turn through the dunes on the return journey ended with us in a small flat area, and in the middle? A beautiful pair of New Zealand Dotterels. Perhaps it wasn't a wrong turn after all!

New Zealand Dotterel Charadrius obscurus aquilonius; Our first at Port Waikato, Waikato, North Island, New Zealand. October 2013.
We saw several more near Miranda later that week and up at Point England where we twitched this Shore Plover.

Shore Plover Thinornis novaeseelandiae; Point England, Auckland, North Island, New Zealand. October 2013.
Along with the Shore Plover we were treated to some typically confiding dotterels which approached us as we sat on the grass in a field just back from the beach. New Zealand Dotterels are not hard to find, however that is because of the hard work that has been put into their management upon which they are wholly dependent.  A census in 2011 found the population to be 2175 birds. In 2004 this total had been 1700; in 1996, 1450 and in 1989 the first year a census was undertaken, 1310. However, John Dowding, an eminent New Zealand ornithologist, points out that these counts are not directly comparable as in 2011 more sites were surveyed, but the increase is thought to be about 14% over the period. One thing that puzzles conservationists is that almost all the population growth has been on the east coast of the North Island, on the west coast it is more or less static. Even within the east coast group the growth is not uniform across the area, there are two areas where most of the increase has been seen and these two sites are close to their carrying capacity, so further growth is unlikely to be long term. One positive discovery though is that the dotterels seem to be spreading south along the east coast.

New Zealand Dotterel Charadrius obscurus aquilonius; Point England, Auckland, North Island, New Zealand. October 2013.
In 2011, there was a major threat to the whole population when a tanker, C.V. Rena, went aground on Astrolabe Reef in October of that year, the beginning of the breeding season. The oil spill threatened a significant proportion of the dotterel population, at least 5% and perhaps potentially as much as 15% of the whole global population of the northern subspecies of New Zealand Dotterel was under direct threat. A plan was needed to save them in a hurry.

New Zealand Dotterel Charadrius obscurus aquilonius; Port Waikato, Waikato, North Island, New Zealand. October 2013.
Instead of simply capturing the birds and releasing them elsewhere which would most likely result in the birds returning quickly to the polluted habitat as they are very site faithful, or leave them in the wild until they became oiled and then treat them, a new and innovative effort to save the threatened birds was employed. 60 birds were caught and kept in captivity until the beaches could be cleaned and then they were released back into the wild. This captive population, much like that of the Spoon-billed Sandpiper today, was a safety net, should the wild population be wiped out or severely diminished, there would still be a healthy group of birds that could be released back to repopulate the area once it was safe to do so.

New Zealand Dotterel Charadrius obscurus aquilonius; Point England, Auckland, North Island, New Zealand. October 2013.
The gamble paid off and 90% of these birds were successfully released back into the wild some 7 weeks later. As they were being released a local Kaumatua (Maori elder) was present to bless the birds and referred to them the ''children of Tangaroa". (Maori god of the sea.)

New Zealand Dotterel Charadrius obscurus aquilonius; Point England, Auckland, North Island, New Zealand. October 2013.
Their future management however is not guaranteed it seems, as it is undertaken at a local level by local communities and other non governmental agencies. Without any management their population is shown to decline by 1% a year so continued intervention is vital for their survival. One of the major concerns expressed by John Dowding is that development is most vigorous along the east coast of the North Island and this will inevitably significantly impact on the thinly spread dotterel population. The advances in population size will cease and we will almost inevitably see a reversal of this in the long term but for now the species looks as though it is relatively secure.

New Zealand Dotterel Charadrius obscurus aquilonius; Port Waikato, Waikato, North Island, New Zealand. October 2013.
Reference:

Dowding, John. Miranda News Journal of the Miranda Naturalists' Trust. Issue 86: November 2012. pp. 8-11

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