An Ecological Opinion by Rex Gibson
Many of the environmental concerns of farmers and outdoor recreationists hinge around the preoccupation of DOC, Regional and District councils, and other agencies, in preserving “native species” (often at the expense of acclimatised/exotic species), and the methodologies used to do this. An ethnic cleansing mentality often dominates. These attempts to recreate the mythical year of 1769 (Cook’s arrival), or c1250 (initial Maori settlement), ecosystems are often based on the belief that ecosystems are, or were, static entities. New Zealand agencies define native species as those which have evolved “on shore” or have self-introduced since the “Gondwanaland continental break up”. No assistance by man is the other aspect of their definition.
Our advocates for natives however have “Poster Species”. The Kauri however is a native of Queensland and New Guinea. Podocarps, which include Rimu, Kahikatea and Totara, are part of a plant family found from Indochina and the Philippines, across Australasia to South America. Our species were no doubt gifted to us when we broke free from Australia c70 million years ago but may in fact be later arrivals. The Southern beech family have a similar distribution.
Manuka is also a native of Australia. The Sophora (Kowhai) are found from South East Europe across southern Asia to Australia, New Zealand and the Americas. Most of our sea birds are also shared with other countries notably the southern black backed gull; probably the most widespread vertebrate in the southern hemisphere after humans and the house mouse. Our iconic hawk is correctly known as the Australasian Hawk.
Many fishers and hunters rightly bristle when “chardonnay conservationists”, and some farming hierarchy, blame trout for the demise of “native” species (and even for the waterway pollution near dairy pastures). The whole basis of “ecology” is that it involves a whole raft of biological systems in dynamic equilibrium.
Native fish face far greater threats from habitat destruction, the effects of excessive water abstraction, glyphosate (and other extensively used herbicides disrupting their food chains), excess nitrates and phosphates in run-off, industrial poisons and urban human waste, all entering their habitat. The “extinct” grayling still occurs in Australia and as an amphidromous species could well have swum the Tasman originally to get here. It had largely disappeared in New Zealand before introduced trout and salmon entered their rivers.
In simple English, all species within biological systems are constantly changing and adjusting to both environmental variations, and to changes within interacting species. Global warming will produce even more adjustments.
Classic deliberate introductions by humans include our common earthworms, bees, oaks, eucalyptus species, rye grass, wheat, canola, Pinus radiata, kiwi fruit, blackbirds, sparrows, chickens, goats, sheep, cattle, deer, opossums and mustelids (ferrets, stoats and weasels), etc., therefore they can never get “native” status. Interestingly opossums and mustelids were actually deliberately imported by past governments.
White Heron Invasion
The protected colony of white herons in South Westland is not a unique remnant of a population that once roamed widely, but a relatively recent “invasion” from Australia; like so many of our native birds. The strong winds and sea currents of the Tasman Sea are primarily from the west to east. They bring us numerous surprises.
In 2012 Australian pelicans were reported from Northland to Taranaki; up to 18 at a time. This phenomenon of uninvited Australian immigrants is not unusual, but once here they become “natives”. Their favourite food is listed as the native kahawai, also present in/around Australia where it is sold as “Australian salmon”.
Other 21st Century refugees from Australia include the plumed whistling ducks, royal spoonbills, and gull-billed terns. In the 1970s spur-winged plovers appeared in Southland following strong trans-Tasman winds. They spread rapidly throughout the country predating on many small bird species, including natives. They are now major bird-strike worries for our airports.
The common white/silver/wax-eye first made an appearance on the West Coast after a period of high winds in the 1800s. It obviously thrived and is now a nationwide “native”. The common white-faced heron is also an “Aussie” refugee. The black swan was re-introduced from Australia to replace the closely related “native” black swan which was hunted to extinction. There are also 20th Century records of the Australian black swan self-introducing itself to Aotearoa.
Our iconic swamp hen, the pukeko, has only been here about as long as Maori. Despite the lack of clear evidence of its origins it is classed as a native. Its presence on the Kermadec and Chatham Islands poses interesting questions however.
The native long finned eel is also present in Australia from whence it probably strayed. Several of our other freshwater species have very close relatives across the ditch also, as do many arthropod species. The common galaxiid (inanga or whitebait) occurs across the southern hemisphere including S.E. Australia. This brings us back to the definition of a native. Is it just a feral stray Australian refugee?
Rodent species are blamed for the decline of some native plant and animal species, but how different is that from the introductions of pukeko (which quite possibly displaced both takahe and kakapo from some habitats), or the spur winged plovers, or even the long finned eel?
Current concern is with myrtle rust affecting pohutukawa trees, but it is a natural introduction carried on the trans-Tasman winds. Does that not make it a “native”?
The dynamic ecological equilibrium of 1769 is interesting in that Maori had already been in residence for over 500 years. As cohabiters they had the kiore (Polynesian rat) and the kuri (dog). Both rats and dogs are blamed for the decline of many native birds, yet kiore and kuri had reached a balanced equilibrium with native species by this time. Most bird species now classed as endangered did not decline rapidly until Europeans arrived. Maori, with the kiore and kuri, had done most of their damage several hundreds of years earlier.
The comparison between c1250 and post 1769 is interesting in itself. Several publications have covered studies comparing the browsing of Moa, prior to their disappearance in the 15th century, with the current browsing by red deer. Moa browsing can be determined by their coprolites (fossilised faeces). Plant species consumed by deer and Moa are almost identical in species composition and preference.
A logical conclusion is that the plant species regime in the NZ bush from c1500 to 1769 changed dramatically after the removal of the Moa and that deer have simply reversed that change. This is simplistic but has a huge element of logic and evidence to support it as an example of the dynamic equilibrium.
The reality is that the destruction of so-called native habitats by humans is the primary cause of endangered species plight. Almost all of New Zealand’s habitat destruction (politely called “clearing”) has been in the interests of farming and the associated service-centred urbanisation and industrialisation. Is the “Pest Free NZ” initiative is a deliberate diversionary tactic to deflect criticism from farming and industrial practices? Predators have an important role in every ecosystem yet we are indoctrinating our children to believe that we need a “predator free New Zealand. It is just one step further for an “exotic free NZ”. The most invasive exotic is Homo sapiens, followed by rye grass, sheep and cattle. Biological publications are full of examples of weird species composition dynamics that result from predator removal.
We need to be vigilant about every attempt to demonise exotics. Such demonising actions are diversionary. The presence of “pest” exotics is usually a factor in habitats so degraded or mismanaged by urban sprawl and farming activities that they are at a tipping point. Attacking the predator, or a particular exotic, species is like blaming a race horse for its trainer’s, or jockey’s, lack of skill.
New Zealand needs to seriously reconsider its preoccupation with pre 1769 environments and look more at focussing on preserving the whole habitat of those species. We need to respect cultural values (both Maori and Pakeha), and habitats of biodiversity importance, whether they be “native” or not. Both Maori and subsequent migrant ethnicities are “exotics”.
A fresh focus on preserving soil organisms would go further in saving the species above it than shuffling the deck chairs above it. The microscopic organisms and “creepy looking” invertebrate species deserve as much consideration as our attractive native trees and “pretty” native birds. We have to get away from the nature study approach of trying to save nature one species at a time, and focus on whole habitats. Many native bird species happily nest in exotic trees. These habitats will, in the 21st Century, naturally be a mixture of so-called natives and exotics. We need to ignore the King Canutes of native fauna and flora purity. We cannot recreate that snapshot of our environment that people paint of pre-human times; unless we plan to remove all the people, bees and earthworms too.
Rex N. Gibson
Rex is a Scientist and Ecologist and a spokesperson on environmental issues for the New Zealand Federation of Freshwater Anglers Inc.