Story: Threatened species
Page 1 – What is a threatened species?
Threatened species are native plants and animals that are under threat of extinction. Their numbers in the wild have dropped to low levels. There may not be enough individuals of a species to breed and naturally increase the population to a level that is self-sustaining, or they may have such a limited range that a natural disaster could wipe out them out. Without human intervention it is likely such species will become extinct.
While a low rate of extinctions is natural, the current rate of human-induced extinctions is much higher.
The main human activities to blame are:
- over-harvesting species
- destroying habitats
- introducing weeds and pests.
New Zealand’s plants and animals evolved in isolation for millions of years. Many are found nowhere else, and have unique features. Free of predatory land mammals, a number of birds became flightless and ground-dwelling.
When humans arrived they made major changes to the environment of native species – changes that continue today. Many native species had no evolved defences against the predators introduced by humans (for example rats, which ate the eggs and chicks of flightless birds).
Birds are the most significant vertebrate life in New Zealand. It was only natural that in the early days of conservation, they were the focus – many species had become extinct and others were declining. In the 1970s, saving the Chatham Island robin, reduced to seven individual birds (and just two females), paved the way for rescuing other threatened birds.
…and other animals
Since the late 1990s there has been a move to save species that are less visible, such as freshwater fish. The remaining habitats of many animals (for example, the Canterbury mudfish) are on private land, and it is only through the goodwill of landowners that they are not destroyed.
There has also been a shift from saving single species to restoring entire habitats. Poisoning introduced predators such as possums and rats on islands gives protection to many life forms. Birds, plants and insects all benefit when predators and browsers are removed.
Some of New Zealand’s threatened native plants may always have been quite rare, or their habitats may not have been large. Many grow in open sites such as bush fringes, coastal cliffs, terraces, dunelands and wetlands. Often these habitats are on private land, much of which has been developed into farmland.
The wild one
Red-flowering kākā beak (Clianthus puniceus) is cultivated in many gardens, but is nearly extinct in the wild. A 2006 survey found just 154 wild plants growing in fewer than 20 sites.
Saving seeds and propagating
Saving threatened plant species has largely been the domain of enthusiastic botanists and plant breeders who have collected seeds and cuttings, and propagated plants in nurseries. In the 1990s, regional councils started collecting seed from local plants, rearing seedlings and encouraging people to grow them in their gardens.
While some species may be saved in the short term, they risk becoming ‘zombie species’ – plants that are extinct in their natural habitats, and live on only in gardens where they are cultivated. It is important that viable wild populations are also saved.
Plants historically a lower priority
Threatened plants have not been top of the conservation list, and since 1840, six species have become extinct. It can be hard to attract funding for a low-growing herb, but easy for more attractive plants – Project Crimson raises private funding to help protect the large, scarlet-flowering rātā and pōhutukawa trees.
In 2003 the New Zealand Plant Conservation Network was set up to stop further loss of native plants.