Conservation at a crossroads
Conservation in New Zealand is at a crossroads. Threatened species continue to face extinction. There are also serious social issues around poison drops in forests. A new approach is needed to resolve these conundrums.
Recently, in the New Zealand Journal of Ecology, I discussed possible paths we could take to preserve our biological treasures. Only one of these can realistically lead to a future in which some native bird species are able to thrive, with little or no further help from us. So what are the paths?
Path 1: Continue the status quo
Ongoing predator control by trapping or bait stations, or at a landscape scale by repeated aerial drops of 1080. There is no end-point for the next 10 to 10,000 years.
Advocates argue that predator control is akin to maintaining a road to protect the gains made for native species survival. It is an endless arms race to develop new tools to stay ahead of predators as they evolve behavioural and genetic resistance.
However, there is little awareness that some native birds can also evolve, reflecting a mistaken view that all native species are incapable of coping with predators.
Path 2: Complete predator eradication
Predator-Free NZ (PFNZ) argues that speciesdestroying pathogens and poisons will be ultimately developed. Advocates point to significant advances in control methods, and the promise of gene-editing and gene-drives to defeat natural selection.
However, there are insurmountable social, economic and ecological obstacles. For example, if stoats are eradicated but not mice or rats, then expect plagues.
Pathogen releases, and laying of poisons and traps, will be needed around each home, school, office, and park. Repeated attempts may be needed. This could result in civil disobedience.
There is already a black market for ferrets, and others could eventuate for pet rats and possums.
All large ships will need to be quarantined offshore, and international flights systematically searched, to prevent reinvasion.
Path 3: Assisted adaptation
As hard as it is, we may have to accept predators are here to stay. This does not mean that all is lost. International research shows micro-evolution can occur much more rapidly than expected. Some species can adapt within several hundred generations, provided populations have enough behavioural flexibility or genetic variability.
For our native birds, this flexibility can be understood as the ability to change nesting behaviour to avoid attracting the attention of predators, choosing inaccessible sites to nest, or being ‘‘skittish’’.
Adaptation can be actively assisted by reducing predation pressure, enough so that natural selection favours flexible individuals.
This means more predator fences, with predator control outside in a halo. As these safe areas fill up, young birds will look outside for territories and food. Exposing these individuals to reduced predation pressure should favour the selection of ‘‘predator-savvy’’ birds.
Why has this not occurred already? There are intriguing hints that bellbirds and tu¯ ı¯ are already adapting. So we may not have been looking for it.
Natural selection cannot effectively be expressed when many of our species face unrelenting attacks from different predators with which they have not co-evolved. Clearly some species, such as the ka¯ ka¯ po¯ , are in evolutionary traps, and require ongoing protection on offshore islands and behind fences, as they are unlikely ever to be able to cope with predators.
Conservation has become polarised around a method of control, which will likely be detrimental to public support for biodiversity in the long term. It is vital that we, as scientists, do not fall into the intellectual trap that there are no alternatives to current management. Science investment must be broadened to investigate how, and which, native species can adapt.
Meanwhile, we need to protect hard-won gains. That means continuing to use 1080 until we have many more fenced areas. But 1080 should be phased out over much of the landscape when these fences are built.
All the good conservation work that community groups do will hopefully continue, as it reduces predation pressure so that natural selection has a chance to be expressed.
Conservation itself must also evolve beyond the unsustainable sense of crisis it has been in for the past 50 years, to achieve a more widely shared vision and outcome for our precious biodiversity.
A royal commission is urgently needed to elucidate that, and to help quell growing public unease and tension about the seemingly neverending use of current predator control methods.
As hard as it is, we may have to accept predators are here to stay. This does not mean that all is lost.