Vanishing Birds: Part 6

New Zealand is famous for its endemic wildlife and unusual animals, being an island with no major ground predators (until the arrival of man) many bird species have become flightless and large-bodied and have diverged from their mainland cousins. There are four bird species native to New Zealand that are included in my 70’s book ‘The World’s Vanishing Birds’ by Littlewood and Ovenden, let’s see how they are faring in 2016.

Brown Teal – this not-quite-flightless duck was, when my book was published, considered a subspecies of Anas auklandica but has since been given full species status as Anas chlorotis. The book states that it was restricted to the northern peninsula and various small islands, it does not give details on the reason for its decline but according to IUCN it was threatened by predation from introduced mammals, over-hunting and wetland drainage. When its population reached dangerous levels around the turn of the century intensive management was started, this included a captive breeding programme, predator control and re-introductions to other areas of the island. It was classified as Endangered up until 2012 but has recently been down-listed to Near-Threatened thanks to an increasing population (now around 2500) and increased range. It has only just been turned back from the brink and still needs to be watched closely, but its future looks positive.

Brown Teal

Shore Plover – Thinornis novaeseelandiae was once found all around the coast of its native New Zealand but with the introduction of ground predators such as rats its population crashed until it was only found on one island – Rangatira. According to my book only 140 birds remained in 1961. This is a pretty, well-marked wader that nests on the ground under logs or rocks (as protection from aerial predators) and feeds on invertebrates in rock pools, it needs open ground for nesting so has suffered loss of habitat in places where grazing has stopped. This plover is Endangered and not far off having the word ‘critically’ added to that classification, fortunately work is under way to save this species. Numerous attempts have been made to establish new populations on other pest-free islands using birds from a captive-breeding programme. This has had failures and successes; there is now a good population on a private island and a small colony on another near Rangatira, yet the total world population still only stands at around 250 individuals. Hopefully this will increase and new, healthy populations established on other islands.

Adult Shore Plover

Takahe – (main picture) This is a fairly famous bird due to its presumed extinction and rediscovery in the mid-twentieth century, it is the largest Rail species in the world and completely flightless. In the book it is claimed only 300 birds remained in the Murchison mountains on South Island where they were re-discovered and that they are declining due to infertility. Unfortunately not much has changed in the past four decades; it is still endangered, the total population is only just over 300 individuals (350, but not all are mature) and is still suffering infertility thanks to inbreeding. What has changed is its range; new populations have been established on predator-free islands, there is captive-breeding and its habitat (alpine grassland) is managed sympathetically, which includes deer culling as they directly compete with the Takahe for food. The future is uncertain because of the low rate of reproduction and inbreeding problems which make any increases in the population very slow, but the Takahe is at present stable and well-protected.

Kakapo

Kakapo – Everyone knows the Kakapo; the only flightless parrot, the heaviest parrot, a herbivorous parrot, one of the longest-living birds, makes a strange Bittern-like booming call, has a polygynous lek, is nocturnal, sexually dimorphic in size and has a low metabolic rate. This is indeed a unique bird, it is also a very rare one, my book says that ‘It is dying out because forests are being cleared and predatory mammals are being introduced.’ and that in 1961 there were less than 100 Kakapo left on South Island. Today it is Critically Endangered and only found on four islands; Codfish, Anchor, Chalky and Maud with most of the population on Codfish and Anchor islands. As with all flightless birds it is threatened by introduced ground predators, especially cats, a recovery is also severely hampered by low egg fertility and painfully slow reproductive rates. As of 2014 there are just 126 Kakapo in existence, two islands – Resolution and Secretary – are in the process of ecological restoration with the aim of establishing Kakapo there in the future.

A mixed bag, the Brown Teal and Shore Plover are increasing with a lot of human help but the Kakapo and Takahe are barely in a better position than in 1972 despite intensive management, and have uncertain futures. As to be expected with island species the main threats are introduced predators, mostly cats, mustelids and rats, habitat loss is always a problem when there is limited space and a large and increasing human population.