Neozoa

For many conservationists, neozoa are considered a threat to native nature.

Distinctions between “foreign” and “native” species are, however, purely artificial. Is there an entirely different problem lurking behind the biological debate?

“They come like a hostile army.” Like “a cancerous growth” they infest our nature, “infiltrating, metastasising.” With such formulations, a concerned conservationist denounced in the journal Nationalpark the invasion of non-native plant and animal species some years ago. One might dismiss this as verbal excess. But for many conservationists — most of them, probably — “the foreigners” are still regarded today as the greatest threat to native nature, second only to climate change. Or even ahead of it, because their proliferation and impact have long been visible rather than merely predicted. The ecologist Wolfgang Nentwig expresses this stance with great clarity. In the book Sinister Conquerors. Invasive Plants and Animals in Europe he calls for “at the level of the European Union … a unified institution responsible for invasive species and coordinating the necessary activities.” In this context, “blacklists … present themselves as a proven instrument … for eradication measures.”

They are, then, a serious problem — non-native species in the natural environment. Countless articles, commentaries and many symposia have been “devoted” to them. The flood of statements about them far exceeds the few conspicuous alien species themselves. This gives rise to the suspicion that what is put forward with such vehemence may be concealing something deeper — and helping to convey it. But what does the problem actually look like? What are “the foreigners” and what damage do they cause? Why did they (and how many of them?) become invasive?

Neozoa: Which species are non-native?

Surprisingly, there is no clear answer to this seemingly simple question. Common definitions refer to animals that are foreign to an area as «Neozoa», and foreign plants as «Neophytes». It is self-evident that such terminology does not in itself provide clarification. For when are species considered «new» (neo-) and at what distance from their area of origin? The (natural) distribution ranges of species, known as ranges, vary considerably in extent. They are neither fixed by nature nor de jure. For ranges expand or contract depending on how living conditions change. Only national borders are fixed — the permanence of which is, as is well known, not permanent. Yet since these borders define the scope of nature conservation laws and regulations, species that occur quite normally on the other side of the border become «new» — and potentially invasive — upon «crossing» it. In terms of natural living conditions, this makes no sense. A need for administrative action arises when the «newcomers» are deemed desirable. The greatest natural shift in distribution ranges began with the end of the last Ice Age, approximately 10’000 years ago. Since then, the occurrences and abundances of most animal and plant species have been shifting — on a global scale as well, since the cold periods brought dry seasons to the tropical zone, while the warm periods brought wet seasons. This process is still ongoing. There is no «correct» state in nature — only temporally conditioned intermediate states within long-term changes on a timescale of millennia.

«With regard to Germany, non-native plants grow on 99 percent of the country’s land area.»

Josef H. Reichholf

These naturally occurring changes have been greatly accelerated on the narrower timescale of centuries, ever since humans developed agriculture and animal husbandry in the post-glacial period and reshaped a large part of the Earth’s surface to meet the resulting demands — including the exploitation of marine resources. This process, too, is in full swing. It accelerated further after the Second World War with the massive use of fertilisers and pesticides, as well as the expansion of cultivation of non-native crops, most notably maize. This crop has since become the dominant «field crop» in Central Europe.

For more than a millennium, since the medieval forest clearances, there has been no natural landscape in our region; not even in the meager remnants that are designated as such and, to an even lesser extent, placed under nature protection. With regard to Germany, non-native and non-indigenous plants grow on 99 percent of the country's land area. They cover the agriculturally used fields almost entirely, stock the forests — which are planted, not naturally grown woodlands — and fill the gardens and parks in residential areas. Even Germany's national parks are covered by non-native vegetation. The largest land shares are taken up by maize, wheat, spruce, domestic gardens, potatoes, permanent grassland, barley and urban parks. Maize and potatoes originate from America, wheat and barley from the Near East, the spruce (plantations) from high elevations of low and high mountain ranges, and the plants of gardens and parks from all over the world. The most numerous animals living among us, domestic chickens, exist in their wild forms in Southeast Asia. Pigs and cattle were also not domesticated here but in the Near East, which equally applies to sheep and goats. Not even the honeybees, whose survival in the cultivated landscape is currently a cause for concern, are native to this region. And yet they have become indispensable. The largest share of free-living animals and wild-growing plants migrated into Central Europe following the early medieval clearing of its forests. The appropriation of land by farmers had created new, suitable habitat for them, which they have since exploited in a continuous stream of immigration. Among these once-foreign species are the European hare, the grey partridge, the skylark, the poppy and the cornflower, and almost the entire remaining diversity of animals and plants of the open fields. The greatest surge in recent times occurred in the 18th and 19th centuries. At that time, due to a rapidly growing population, the land was extremely overexploited and depleted. In this scarcely productive state, it offered many species the conditions for survival — particularly those capable of coping with scarcity. Our notions of native and foreign are now rooted in this “historical biodiversity” of the 19th century, even as specialists rightly emphasize that globalization had begun with the European discovery of America. The dividing line between (long-)established and newly arrived is drawn at the year 1492. Whatever has arrived since then belongs to the newcomers. Whatever arrived after 1900 belongs to the very newest, and whatever only reached us in our own time (or became conspicuous, even though the species had already been present in the country for over 100 years!) is classified as an “alien”.

«Foreigners must not simply be placed under initial suspicion merely because we do not know them or their behaviour.»

Josef H. Reichholf

So which species are actually alien? According to Munich satirist Karl Valentin, «strangers are only strangers in a strange land!». In concrete terms: whether a species is classified as «alien» or (already) native depends on the chosen spatial frame and the point in time. Any such classification is inevitably arbitrary, since the changes in question are processes in space and time. All distinctions are therefore artificial. Perhaps the most reasonable definition would be that what is alien (to us) is simply what we do not yet know well enough. This is an observation, not a value judgement. That is precisely the point — to become aware that «foreign» and «familiar» relate to experience and knowledge, and should not be linked in advance to value judgements. Strangers must not simply be placed under initial suspicion merely because we do not know them or their behaviour. Anyone who does so nonetheless is reacting with the wariness of a small child. In the child, such wariness represents a survival programme, as we may conclude from the findings of behavioural research — but only for the infant stage. Once we have outgrown it, we regard engagement with the unfamiliar as the curiosity that distinguishes us, when we ourselves travel to foreign lands to discover new things.

The «problem» of the strangers should therefore resolve itself through familiarity with them. That this is fundamentally the case is evident not only from the many conservation initiatives aimed at preserving formerly alien and invasive species, but also quite directly from the expenditure in the EU agricultural budget for the conservation of arable wildflowers. These one-time outsiders — fought for centuries with hoe and manual labour, then with great success chemically since the development of herbicides — are currently being preserved and «saved» at considerable financial cost through compensatory payments from the agricultural fund. A rather «charming» recent example in this context is the battle over the plane trees in the area of the expansion and redevelopment of Stuttgart’s main railway station. The plane trees are not native but alien trees, in which the (geographically) even more foreign ring-necked parakeets — parrots from India — nest, but in which the larvae of the EU-wide protected hermit beetle also live. For the sake of this beetle, the plane trees were to be preserved and the «Stuttgart 21» project brought down.

The distinction between native and foreign, however, encounters argumentative difficulties not only in such cases. Other cases also proved costly. For instance, Deutsche Bahn had to spend several million euros to protect the great bustard in Saxony-Anhalt, in order not to endanger the remaining population of this undoubtedly impressive and endangered bird species with high-speed ICE trains. The bustards live there on a completely artificial, entirely non-native agricultural steppe. In a similar situation, certain European hamsters are blocking the construction of buildings or roads in Lower Franconia. Hobby hunters had for centuries intensively persecuted native birds of prey, keeping their numbers down to the point of regional extirpation, in order to protect the ring-necked pheasant — a foreign introduction artificially settled for the sole purpose of hunting pleasure at the end of the 19th century. The pheasant has since enjoyed the protection of German hunting law as small game. The elk, which are once again returning and stand ready to immigrate at Germany’s eastern borders — and are undoubtedly indigenous — are, by contrast, viewed with hostility. The equally indigenous bear is also not permitted to return (at least for now). The fact that the European otter quietly managed a comeback provokes the anger of fishermen, while hobby hunters attempt to prevent the return of the Eurasian lynx. Being native, it seems, does not mean having the right to belong. Deliberately introduced foreigners received that right automatically! A blue card was no more necessary for the pheasant and rainbow trout than for elephant grass and hybrid maize. More on the topic Species protection and Biodiversity.

«The immediate neighbours were – and are, exceptional circumstances aside – always rather more welcome than the complete strangers, because one already knew them well enough.»

Josef H. Reichholf

The distinction between foreign and native has thus proven to be a highly subjective perspective. A dispute over this would remain academically insignificant if it concerned only the timing of recognition or proximity and distance based on origin. Immediate neighbors were — and are, with the exception of extraordinary circumstances — always more welcome than the entirely foreign, because they were already well enough known. Wherever the “eastern” penduline tit nests west of its current main range, ornithologists are enthusiastic about it. Its highly intricate nest is marveled at. The fact that cranes are once again spreading westward also elicits no complaints, even though aviation safety must accommodate far more crane flights during migration seasons and altogether much larger numbers. After all, Germany's number one airline carries the crane (stylized to the point of unrecognizability) as its symbol. That the metal crane-carriers must share airspace with half a million or more real cranes is taken for granted. But what is happening in the airspace between the treetops in the parks of Rhine cities, when Indian parakeets and South American Amazon parrots nest in the cavities of aging trees? Are they permitted to do so, given that native starlings, sparrows, and bats could make use of these tree hollows? Grave concerns might well be raised. However, no displacement of native cavity-dwellers has actually been proven.

All the more prominently are strongly suspected and feared negative effects of non-native species on native nature highlighted. The North American raccoons have been branded as creatures of menace that prey upon the eggs and young of native species, “steal” fruit, make noise, and have altogether proven far too successful at evading control by hobby hunters.The fact that something other than raccoons also inhabits their North American homeland ought really to come as a surprise. Even more so, however, the fact that in our country it is precisely those habitats that are also the richest and most densely populated with free-living animals in which raccoons are found remains unconsidered. These are the cities, above all the large cities. In these, Canada geese (from North America) foul the lawns with their droppings, just as the native greylag geese and the swans kept as ornamental waterfowl for centuries also do. Canada geese should not be allowed to foul, but greylag geese should – or should they not either? The park mallards descended from native mallards are tolerated more or less, currently once again “less” so, but must at least be kept purebred, which in plain terms means that anything that visibly deviates from purity must be eliminated (must it?). So that at least “the duck” remains pure, when all manner of colourful waterfowl, unknown to the purists in terms of species, already disfigures the urban ponds. Or might even press outward into the open!

«That they displace native species is something particularly attributed to non-native animals. This still holds true, and all the more so the less the accusations stand up to scrutiny.»

Josef H. Reichholf

The claim that neozoa displace native species is particularly persistent. This assertion remains in circulation, and the less substance the accusations have, the more forcefully they are repeated. The European (native) mink had already been extirpated across large parts of Europe when, towards the end of the 19th century and into the 20th century, the American mink escaped from “fur farms” or was deliberately released. It is now held responsible for the much earlier extinction of the native mink. A similar situation occurred with the river crayfish, tellingly referred to as the “noble crayfish.” By the time it had virtually disappeared as far as the distant Beskids, American crayfish were introduced and released as replacements. Embarrassingly, they brought crayfish plague with them — for it was the fishing industry that wanted crayfish again, and that also introduced the American rainbow trout after the European brown trout could no longer survive in the polluted, poisoned streams and rivers. Fishery exploitation, including recreational angling, has relied on artificial stocking measures for decades. Since these are sanctioned by fisheries legislation, they are not only permissible but effectively beyond ecological scrutiny — while small creatures that have spread through canals and river shipping over recent decades “cause concern,” even when they are eaten by stocked fish as well as by native herons, cormorants, and other water birds. In reality, there is scarcely a body of water left with a fish population that even approximates natural, that is, fishery-unaffected, conditions. The situation in waterways is thus no different from that on land. Everything — save for the tiniest remnants, truly everything — is artificial. This means that whatever changes any species brings about within this “human-made nature” cannot be assessed on an ecologically neutral basis. For these are invariably conflicts with those who exploit the resource. Accordingly, the species that attract the label “invasive” are precisely those that come into conflict with the interests and expectations of users. The far greater number of other species go unnoticed — or, as illustrated by the example of the penduline tit mentioned above, bring pleasure to nature enthusiasts. These same enthusiasts worry about species decline, which is indeed taking place. The culprits, however, are not the few newcomers that successfully establish themselves, but the large-scale changes in land use. These have produced the almost bizarre situation that, across wide regions of Central Europe, more species in greater diversity now live in cities than “in the countryside.” The few species that manage to become more numerous and spread “in the wild” fall under suspicion that something must be wrong with them. For in our times, “respectable species” are expected to be rare or declining. An increase, by contrast, is taken as a sign of something sinister.

This attitude guarantees that the periodic assessments of the status of species in our natural environment will continue to produce poor results. For "the newcomers" are either not included in the balance sheets at all, or are skillfully excluded, because "they simply do not belong here." In this way, they are turned into second-class species. They do not figure into the gains, while conversely every "highly endangered" species — because it is equally rare but formerly native — weighs particularly heavily on the negative balance. This has nothing to do with ecology in the scientific sense. But it has a great deal to do with ideology. Indeed, the damages actually or supposedly caused do not belong to the domain of ecology either, when such damages originate from non-native species, because damages are to be attributed to economics. It is therefore more than peculiar when economic damages are highlighted by ecologists and used as justification for the ecological danger posed by non-native species. Their proper domain should be the shifts in the local, regional, or supra-regional spectrum of existing species caused by newly arrived, spreading species. When assessing these shifts, it must be taken into account that no single state is "the correct one," and therefore not every change may automatically be judged negatively. Rather, the only task can be to determine the demonstrated or, with sufficient verifiable certainty, predictable consequences of the advance of individual species. On the basis of these findings, one can — secondarily and depending on the perspectives and objectives of those concerned — discuss (objectively) acceptance or countermeasures. This applies to all species, whether native, newly native, or just arrived! Damages are damages, where they can demonstrably be shown to be such. Changes, however, are only relevant to the perspective of those circles that refuse to accept any change whatsoever, because such changes would cause interference in their rigidly fixed conceptions.

The attitude behind the attitude

Nevertheless, they do exist — invasive species — along with the problems they cause, albeit for reasons other than those typically portrayed. Without wishing to go into detail here, they thrive best where the soil is over-fertilised. And the most invasive of invasive plants represent the visible, highly undesirable reaction to the conditions that have prevailed everywhere in the fields and forests since the 1980s, driven by mass biomass production through fertilisation. What this should mean, however, is: let whoever wishes combat giant hogweed and Himalayan balsam. Like all the other species that benefit from over-fertilisation, they will not be eradicated. Raccoons and grey squirrels are also too clever for complete elimination; insects evade control in any case through periodic scarcity. This applies equally to the western corn rootworm as to oriental or American cockroaches. The solution to the malaria problem will in future likewise not lie in the eradication of the carrier mosquitoes — which, incidentally, have always been present here, even during the cold centuries of the Little Ice Age through to the late 18th century — because Anopheles, the fever mosquito, is distributed as far as the Arctic Circle, but rather in combating the pathogens, that is, in the medical treatment of people. One could therefore leave those with an interest in it their minor battlefields, so that they may celebrate victories in battles that cannot be won in the medium and long term. Were it not for something more dangerous lurking in the background.The pseudo-biological, unecological condemnation of foreign species promotes, through its modes of expression and argumentation, general xenophobia.All too easily, 'ecology' can be invoked and misused to provide seemingly natural justifications for the rejection of the foreign. Biology has already been misused far too often for us to risk following its stance toward non-native species without objection. Even less than with peoples and humans can one specify and determine what is 'European' and what is not 'for nature.' Purely political entities, such as the European countries, which emerged from contemporary history, are entirely unsuitable for this purpose. Not a single one has natural borders in the biological sense — not even the British Isles. For they were part of continental Europe until the incursion of the North Sea, several millennia after the end of the last ice age. The true, the 'permanent' islands in the Mediterranean lost their distinctiveness in animals and plants already in early historical times. The current state of Europe (and of the entire Earth) will not be permanent.

Far more important than combating the new, the unknown, would be an intensive engagement with that truly forward-looking task characterized at the Earth Summit in Rio in 1992 by the concept of 'sustainable development' (sustainable development). Its core idea does not entail rigid adherence to a particular state favored for whatever reasons, but rather a reasonable, because sustainable, transformation. Sustainable means the creation and maintenance of imbalances that are productive enough to meet demand, yet sufficiently stable so as not to spiral out of control. Sustainable development means that the world of tomorrow will be different from that of today — also for the plants and animals that live with and around us.All of them are worth preserving for the future. None is 'evil' simply because it is foreign or because it responds to what has been prepared for them by humans. For even in the world of plants and animals, the principle holds that supply determines demand. And that one gathers where abundance prevails.

Josef H. Reichholf

Josef Helmut Reichholf (* 17 April 1945 in Aigen am Inn) is a German zoologist, evolutionary biologist and ecologist who has repeatedly caused a stir as a book author with provocative theses. For Reichholf, science thrives on critical dialogue; it must constantly re-examine itself and, where necessary, rethink and correct even long-held supposedly incontrovertible theses. He views apparent alliances between science and politics or industry — for example in climate protection or third-party-funded research — with scepticism, as they endanger the independence of science.