Despite a remarkable level of endemicity in the Chatham Islands vascular plant flora (e.g., clubmosses, whisk ferns, ferns, and flowering plants) (de Lange et al. 2011) the islands have virtually no endemic non-vascular plants (e.g., hornworts, liverworts, mosses) (de Lange et al. 2008). Currently botanists accept one endemic species of moss (Macromitriumramsayae) and one endemic variety of liverwort (Plagiochila arbuscula var. rekohuensis) (de Lange 2011a). The taxonomic status of the moss is currently under review and it seems likely that this species will at some stage be relegated into the synonym of another widespread New Zealand Macromitrium (A.J. Fife pers. comm.).

The New Zealand scurvy grasses (Lepidium species) include the famous Cook's scurvy grass (L. oleraceum) (Fig. 1), a species which has gained almost legendary status as the plant that saved Captain Cook and his crew from the depredations of scurvy. Whilst modern research has shown that this is gross exaggeration (de Lange & Norton 1996) it cannot be doubted that this plant and its allies were important green foods for not only scurvy ridden sailors but iwi (who in New Zealand knew the plants collectively as 'nau').

It has long been recognised that the Chatham Islands populations of Cook's scurvy grass were variable (de Lange et al. 2010) but until they were subjected to critical study by Department of Conservation and Landcare scientists it was not realized that this variability had a firm genetic and molecular basis. A study initiated in 2005 is now drawing to its final stages prior to publication. In that work, aside from Cook's scurvy grass (known on the islands from only one 2006 Mangere Island collection), a further five species are recognised for the islands. Of these, with the exception of L. flexicaule, the other four are new and are now in the process of formal taxonomic description.

As progress toward the preparation of the first flora of the Chatham Islands since 1864 Department of Conservation and Landcare Research scientists have published a new checklist of the plants of the Chatham Islands group (de Lange et al. 2011). The checklist not only provides the first full vouchered listing of the endemic, indigenous and naturalised flora of the islands to ever be published but also a brief history of the discovery of the Chatham Islands flora by European and later New Zealand scientists covering the period between 1840 and 2011. The checklist also describes the origins of the Chatham Island flora, and provides the first detailed discussion and assessment of the indigenous and naturalised plants to be published since the early 1900s.

The checklist accepts 875 formally described vascular plants for the island. Vascular plants are a 'catch-all' covering a diverse grouping of plants that includes clubmosses, ferns, conifers and flowering plants. The publication also notes that a further 27 plants found on the islands are new and still require formal taxonomic description. At this stage 41 formally described plants are considered endemic to the islands, a figure which includes two endemic genera, the spectacular, world famous Chatham Islands forget-me-not (Myosotidium) and Chatham Islands sow-thistle (Embergeria). There are also 400 indigenous plants and 434 that are regarded as naturalised to the islands. Of the 27 as undescribed plants, 13 are believed endemic to the islands, the remaining 11 are known also from New Zealand. A peculiar pattern that warrants further study is that many indigenous plants are known from five or less sites on the islands, and there is some evidence to suggest that the islands are still being naturally colonised by plants from New Zealand.

A study just published in Pacific Conservation Biology reveals that the Chatham Island toetoe (Austroderiaturbaria) populations have very little significant genetic variation (Houliston et al. 2012). The discovery comes as somewhat of a worrying surprise to plant conservationists. Previously, without the ability to check levels of genetic variation the Department of Conservation has taken pains to maintain Chatham and Pitt Island populations of toetoe distinct, particularly by making sure not to mix them in cultivation or in translocations on the islands. As a further measure plants from Ocean Bay, North-Western Chatham they also kept distinct as these had a different growth habit to those seen elsewhere on the Chathams.

The study used a range of DNA markers and modern DNA fingerprinting techniques to examine a range of fresh tissue samples collected from the Chathams in 2008, as well as seedlings raised at the Landcare Research Campus, Lincoln, South Island from samples provided by the Department of Conservation.

 

Unique to the Chathams, Cox's matipo (Myrsine coxii) is a tough little plant well designed to withstand the weather with small leathery leaves and usually keeping under 2m tall. Surprisingly it flowers in winter, but not that you'd notice. You might however see the odd purple berry. It doesn't appear to waste a lot of energy on flowering and fruiting though, preferring to spread by layering itself. You'll find it in boggy margins on the edge of forest, or in boggy light gaps within forest in protected areas.

Status (2008): Population (2009): Trend:	Critically Endangered 600 individuals Improving

Larger and heavier than its mainland cousin, the parea or Chatham Island pigeon is today largely confined to the south-western corner of Chatham Island.  Like several other Chatham species the parea had a close brush with extinction, with the population dropping to 40-45 birds in 1989.  Fortunately, the protection of habitat and the control of predators has seen a dramatic recovery of the species and a 2009 census estimated the population to be around 600 birds.

 

 

Status (2008): Population (2010): Trend:	Nationally critical 309 mature individuals Stable

Many of us are familiar with New Zealand's variable oystercatcher, the black and white (or sometimes entirely black) wader with bright orange legs and bill that we encounter on beaches around the country.  What most don't know is that the Chatham Islands have their own version, the Chatham Island oystercatcher and that it narrowly escaped extinction in recent times.

The first comprehensive survey of Chatham Island oystercatcher in 1987 revealed 112 birds.  Despite the low number this was actually good news because the previous estimate, made from partial beach counts in 1970, suggested that the population may be as low as 50 birds.

The reasons behind the perilously low population were  investigated and found to be numerous.

Status (2008): Population (2010): Trend:	Nationally vulnerable 1,400 individuals Improving

Probably once abundant throughout the Chatham Islands, human exploitation, habitat destruction and introduced predators saw the Chatham petrel restricted to Rangatira or Southeast Island by the time of its discovery in 1892.

Until 1961 farming activity on Rangatira resulted in the petrels being confined to small forest patches, where they competed for burrows with the similarly sized broad-billed prion. Nesting at different times of the year, many petrel chicks were ousted from their burrows by returning prions. By 1990 the Chatham petrel population was estimated to be around 1,000 birds and heavily outnumbered by some 600,000 broad-billed prions.

Studies found that while adult Chatham petrel survival was high, less than 50% of pairs were managing to fledge a chick, placing the population in peril. So, finding a way to deter prions from entering Chatham petrel burrows was a priority.

Status (2008): Population (2012): Trend:	Nationally critical 256 mature individuals Stable

Restricted to Little Mangere Island for over 80 years, the deteriorating condition of the small area of forest available to the birds and their resulting population decline saw the seven remaining birds transferred to a larger patch of bush on adjacent Mangere Island in 1976-77.  After reaching a low of just 5 birds in 1980, intensive and innovative management combined with the extraordinary efforts of 'Old Blue', the only breeding female, saw the population increase to around 80 birds in 1989 with robins also having been established on Rangatira Island in 1983. At that time intensive management stopped, but intensive monitoring continued to monitor the growth of the population up until 1999, by which time the population had reached around 200 mature individuals. Seemingly secure on the pest-free island homes, monitoring was scaled back to allow work on other species.

Ngaio (Myoporum laetum) is an important rongoa and taonga for many iwi. As many a tramper will appreciate an infusion made from crushed leaves is an excellent way to soothe and treat grazes and infected wounds, while I can personally vouch that burning sprigs of fresh foliage does indeed, as old time Maori advised, repel even the most determined mosquitoes and sandflies! Also in Maori mythology it is a gnarled old ngaio tree that is said to have accompanied Rona on her involuntary trip to the moon. There can be little doubt that the humble ngaio has a special place in many peoples hearts, not only because of its medicinal properties and role in Maori myths but also because it is a hardy, fast growing, drought tolerant tree that provides excellent shelter in coastal areas from strong winds. Ngaio is also popular with gardeners because it produces a profusion of purple-spotted white flowers almost throughout the year, and these are followed by equally attractive quantities of purple or pink fruits. However, despite all these charms and uses it should be noted that all parts of the plant and especially the foliage are also extremely toxic (Connor 1977).