By Hannah Graham-Cox
The ever-increasing human population is pushing more and more species towards the brink of extinction. With over 600 endangered species, New Zealand is struggling to prioritise ever decreasing funds from a stretched Department of Conservation (Kirk, 2015). So, how are these tough decisions reached? Many empirical methods have been used to assess whether a species is ‘worth’ conservation intervention. Some are simple and straightforward equations, while some are very convoluted involving many different variables. A novel term coming to the forefront as we realise that not all species can be saved, is triage. Triage in this sense, is the process of prioritising conservation activities; allocating scant resources to achieve maximum conservation returns (Bottrill et al., 2008).
Kakapo are an example of a species that may be designated a ‘lost cause’ if the triage approach were implemented by DOC. This nocturnal, flightless, extremely vulnerable bird was decimated by the combined efforts of human and invasive mammal predation, helped along by habitat loss. Now listed as ‘extinct in the wild’ by the IUCN red list, the only known kakapo are managed on pest free islands (Clout & Merton, 1998).
The history of kakapo is a sad and altogether too familiar one. Once, you could supposedly, “shake six from a single tutu bush” (Langton, 2000, p. 250). But following the arrival of humans and our mammalian co-invaders, the entire species was reduced to 51 individuals by 1995 (Ratley, 2014; Harrison & Moorhouse, n.d.). Helped along by modern technology and intensive management, the population has gradually climbed to just under 160 (News and updates from the Kākāpō Recovery Team, 2016). Kakapo have a limited role in ecosystem functioning mainly through vegetation, root and rhizome removal as well as contributing to seed dispersal through frugivory – mostly of rimu fruit (Clout & Hay, 1989; Gibbs, 2007; Atkinson & Merton, 2006). I have evaluated the general considerations when discussing the value of conserving a critically endangered species using kakapo as an example.
Role as flagship species
Flagship species are enigmatic or charismatic species which act as an ambassador for conservation in a given area or globally. Additional funds raised in the protection of this species may be allocated to other causes or conservation action, thus flagship species are often crucial for conservation (Simberloff, 1998; Bennett, Maloney, & Possingham, 2015). kakapo are what may be termed ‘high risk attention grabbers’ – they are a high profile species at great risk of extinction without immediate intervention. In order for species such as this to maintain public sympathy, results of conservation need to be rapid and tangible; for example, the positive response of kakapo to supplementary feeding in 1990-1991 which resulted in a significant population increase (Towns & Williams, 1993). Thus, it has been relatively straightforward to encourage funding from the general public and large corporations for Kakapo. The run-off effects of kakapo recovery include pest eradication and habitat restoration which benefits other species (Axed fund raises questions, 2012). Fortunately for kakapo, they are also charming and cheeky. A prime example of this is the ambassador for kakapo, Sirocco. Sirocco travels the country raising awareness and funds for the conservation of his species. Due to intensive hand rearing (he was the first male to be hand raised and they had not yet perfected avoiding human imprinting), it was realised that Sirocco had imprinted on humans and would not be a successful breeding bird but could make an excellent ‘public face’ for kakapo conservation (Sirocco, n.d.). After a botched attempt at mating with zoologist Mark Carwardine’s head was filmed and put on youtube, Sirocco shot to international fame. In 2011, two years after the infamous incident, 2000 people pre-ordered tickets to see Sirocco in Zealandia, raising funds for the sanctuary (Sirocco, n.d.).
Simply searching for ‘kakapo crowdfunding’ in Google brings up several campaigns raising funds for kakapo conservation. One example of this successfully raised the full goal of $45,400 which will go towards the kakapo 125 project which is described in the ‘Genetic Considerations’ section (Iorns, et al., 2016).
Endemism and phylogenetic uniqueness
An endemic species is found nowhere else on earth, kakapo are an example of such a species. They are described as ‘phylogenetically unique’ as they have been evolving in isolation from other related species for millions of years. Much value is placed upon those species which are rare or unique, and an increasing number of management programs prioritise these species. An example of this is the EDGE programme, launched by the Zoological Society of London, which stands for ‘Evolutionarily Distinct and Globally Endangered’ and prioritises conservation efforts on those species which are phylogenetically distinct as well as rare. As the only member of the subfamily Strigopinae, and being one of the world’s most endangered birds, kakapo rate very highly in the EDGE ranking system (EDGE : Bird Species Information – Kakapo, (n.d.).
The concept of the inherent value of nature can be traced back to Soulé who states that: ‘biotic diversity has intrinsic value irrespective of its instrumental or utilitarian value’ (Soulé, 1985). Thus in themselves, kakapo, evolving in seclusion for millennia, have value. Humans are also sentimental creatures whose dualism of being a part of nature, yet remaining distinct from it has resulted in feelings of guardianship towards nature (Bromley, 2013). The Māori term for this is kaitiakitanga which, through the partnership with Ngai Tahu and honoring Treaty of Waitangi responsibilities, is a core component of the The Conservation Act 1987 (Kawharu, 2000; Treaty of Waitangi Responsibilities, n.d.). Described as a unique, amusing, and beautiful, kakapo are not a difficult species to love either. In the words of Douglas Adams: “The kakapo is a bird out of time. If you look one in its large, round, greeny-brown face, it has a look of serenely innocent incomprehension that makes you want to hug it and tell it that everything will be alright” (Adams & Carwardine, 2009).
All known kakapo are heavily monitored on three offshore islands: Whenua Hou (Codfish Island), Anchor Island and Hauturu o Toi (Little Barrier Island). Listed in Table 1. are tasks the Kakapo Recovery team, made up of ten full-time Department of Conservation staff, perform in order to help boost the kakapo population.
What this involves
Food supplied to the ‘wild’ kakapo must be expertly adjusted: too little food and the kakapo may not breed at all or the female may lay few eggs, too much food and the females may produce too many male offspring.
Ongoing predator control
|All pests (mostly kiore or Pacific rat) exterminated from the three islands which kakapo have been removed to. Anchor island is still prone to stoat invasions as it is within swimming distance of the mainland, so maintenance must be ongoing on this island.|
|It was found that females who have mated more than once in a breeding cycle produce more fertile eggs than those that only mate once. The team remove sperm from selected males (often those with rare genes or who haven’t had many offspring) and using it to simulate a mating event with a female who has already been mated with in that breeding cycle.|
Incubation and hand rearing of chicks
|41% of the current kakapo population have been hand raised. This is an intensive process as the egg requires constant, specialised care. Chicks are returned to the wild at 4 months and have a survival rate of 91%.|
|Each kakapo has a smart transmitter attached to it, sending out data about the health of the bird as well as nesting and mating information. If a nest is established, the kakapo team have rostered ‘night-shifts’ where they guard the eggs or chicks for several months while the female is feeding.|
|Full check-up of the bird is performed including: weighing, taking blood samples, checking the transmitter and removing parasites. This occurs yearly for adult birds, daily for nestlings and every 2-6 weeks for chicks under two years old.|
Table 1. Shows the methods through which the Kakapo Recovery Team is attempting to grow the current kakapo population. Adapted from “In the wild” (n.d.).
Kakapo conservation carries a hefty price tag. While finding exact figures of funds raised and tracing their use in kakapo conservation is difficult, in 1990 DOC entered into a partnership with Rio Tinto, New Zealand Aluminium Smelters Ltd and Forest & Bird. This partnership had raised $3.5 million as of 2010 before Rio Tinto dropped out in 2012 (Guyton & Deal, 2010; Axed fund raises questions, 2012). Due to the very ‘hands on’ approach of their recovery detailed above, every cent of that $3.5 million is vital. Much of the rest of the Kakapo Recovery Team’s funding comes from companies such as Meridian Energy, who have recently agreed to a three year partnership assisting the kakapo recovery fund (A Plan for the Future, n.d.). But three years in the grand scheme of kakapo conservation is not long at all – the long term goal of kakapo conservation is “To restore the mauri (life-force) of kākāpō by having at least 150 adult females” (A Plan for the Future, n.d.). With the current population of less than 160 individuals in total, and incredibly slow and irregular breeding cycles, this could take several decades. As described in the ‘Role as Flagship Species’ section above, crowdfunding is a more recent method for the Kakapo Recovery Group to raise funds for conservation. As is their ‘Adopt a Kakapo’ concept where members of the public can pay $100-500 to ‘adopt’ one of 13 birds currently available on their website (http://kakaporecovery.org.nz/adopt-a-kakapo/).
A species can be described as ‘genetically depauperate’ if it has low genetic diversity compromising its longevity as a species. Genetic diversity in the kakapo population is extremely low after experiencing such a severe bottleneck when the population was reduced to only 51 individuals. All but one of the population’s founders (Richard Henry: the only male from the Fiordland population to produce offspring) came from the same population. Described as a ‘ticking time bomb’, inbreeding depression is the increased likelihood of extinction and results when there is a sustained level of inbreeding due to low population numbers for several generations (Jamieson, Wallis, & Briskie, 2006). Further loss of genetic diversity is being actively managed by DOC through preventing closely related individuals from mating and via a programme termed the kakapo 125 project which aims to sequence the genome of all known living kakapo (Projects – Genome Sequencing – Kakapo, n.d.). Kuia (pictured below), the only daughter of Richard Henry, will be crucial for maintaining diversity in the population. This is because all other kakapo are from a Stuart Island population which had already been isolated prior to human settlement of New Zealand (White et al., 2015a). Despite the efforts already taken, the effects of inbreeding depression are already visible in the current kakapo population and are listed in Table 2.
Kuia, Richard Henry’s daughter, nesting (Thompson, 2016).
Symptom of inbreeding depression
Effect on a population
Evidence of this occurring in the kakapo population
|Low fertility||High number of infertile eggs or high risk of miscarriage (in mammal populations)||
40% of all eggs laid since 1985 have been infertile (average parrot infertility is around 10-15%) (Clout & Merton, 1998; Artificial insemination, n.d.).
Low hatch or chick survival rates
High chick mortality, low recruitment (chicks surviving to adulthood and supplementing the population)
|20% of embryos dying early in development (Artificial insemination, n.d.)|
|Reduced resistance to disease, predation, environmental stress||Increased risk of extinction through predation, disease, parasite infection, environmental stress or events (earthquakes, floods etc.)||
There are currently fears that exudative cloacitis, a bacterial disease which results in infected birds being unable to breed, may become a serious issue in kakapo populations due to reduced fitness (evolutionary longevity) through low genetic diversity (White, et al., 2015b).
Table 2. Showing the symptoms of inbreeding depression, their effects on populations (or species) and the evidence of this observed in the kakapo population.
It is well documented that humans value rarity, but has conservation reached the stage where we no longer have the luxury of conserving species just because we find them charming and charismatic? Or are species such as kakapo still contributing to conservation funding enough as flagship species that it outweighs their lack of ecosystem functioning? Although often seen as pernicious and fatalistic, the triage approach to conservation has its groundings in prioritisation of increasingly limited resources (Towns & Williams, 1993). With budget cuts to the Department of Conservation occurring almost yearly, we need to have systems in place which will mean that these species not only have funding now, but ongoing – and a department to ensure habitat enrichment & pest control persists. I am of the opinion that species such as the kakapo deserve to be protected purely for their own sake. They represent millennia of evolution and their naivety and fragility despite this are endearing factors alone. Perhaps none could sum this up as well as the legendary Don Merton (pictured below) who has been instrumental in their rescue: “They are our national monuments. They are our Tower of London, our Arc de Triomphe, our pyramids. We don’t have this ancient architecture that we can be proud of and swoon over in wonder but what we do have is something that is far, far older. No-one else has kiwi, no-one else has kakapo. They have been around for millions of years, if not thousands of millions of years. And once they are gone, they are gone forever. And it’s up to us to make sure they never die out.” Sentimental reasons aside, kakapo populations have increased by more than 200% since the 51 recorded in 1995 (Plumb, 2016). If this trajectory is maintained, funds will continue to be raised and the future of kakapo will be more secure.
Chris Smuts-Kennedy, John Cheyne and Don Merton with Mandy the dog. The kakapo is Jill, the second male captured in the Esperance Valley, Fiordland, 1974 (Department of Conservation, 1974).
A Plan for the Future. (n.d.). Retrieved March 27, 2017, from http://kakaporecovery.org.nz/a-plan-for-the-future/
Adams, D., & Carwardine, M. (2009). Last chance to see. London: Arrow Books.
Artificial insemination. (n.d.). Retrieved April 21, 2017, from http://kakaporecovery.org.nz/artificial-insemination/
Atkinson, I. A. E., Merton, D.V. (2006). Habitat and diet of kakapo (Strigops habroptilis) in the Esperance Valley, Fiordland, New Zealand. Notornis. 53;37–54.
Axed fund raises questions. (2012, September). Retrieved March 25, 2017, from http://www.stuff.co.nz/dominion-post/news/7716027/The-commercialisation-of-conservation
Bennett, J. R., Maloney, R., & Possingham, H. P. (2015). Biodiversity gains from efficient use of private sponsorship for flagship species conservation. Proceedings of the Royal Society of London B: Biological Sciences, 282(1805), 20142693.
Bottrill, M. C., Joseph, L. N., Carwardine, J., Bode, M., Cook, C., Game, E. T., … & Pressey, R. L. (2008). Is conservation triage just smart decision making?. Trends in Ecology & Evolution, 23(12), 649-654.
Bromley, A. (2013). A Part of Nature or Apart from Nature? New Professors Explore Human Responses to the Environment. Retrieved April 27, 2017, from https://news.virginia.edu/content/part-nature-or-apart-nature-new-professors-explore-human-responses-environment
Clout, M. N., & Hay, J. R. (1989). The importance of birds as browsers, pollinators and seed dispersers in New Zealand forests. New Zealand journal of ecology, 27-33.
Clout, M. N., & Merton, D. V. (1998). Saving the Kakapo: the conservation of the world’s most peculiar parrot. Bird Conservation International, 8(03), 281-296.
EDGE : Bird Species Information – Kakapo. (n.d.). Retrieved April 24, 2017, from http://www.edgeofexistence.org/birds/species_info.php?id=1946
Gibbs, G. (2007). Ghosts of Gondwana; The history of life in New Zealand. Nelson: Craig Potton Publishing.
Guyton, S., & Deal, J. (2010). Christmas comes early for kakapo. Retrieved April 27, 2017, from http://www.tbfree.org.nz/christmas-comes-early-for-kakapo.aspx
Harrison, M., & Moorhouse, R. (n.d.). Kakapo (Strigops habroptila). Retrieved March 26, 2017, from http://www.edgeofexistence.org/birds/species_info.php?id=1946
In the wild. (n.d.). Retrieved April 23, 2017, from http://kakaporecovery.org.nz/in-the-wild/
Iorns, D., Digby, A., Robertson, B., & Howard, J. (2016). Sequencing the genomes of all known kākāpō. Retrieved April 24, 2017, from https://experiment.com/projects/sequencing-the-genomes-of-all-known-kakapo?s=discover
Jamieson, I. G., Wallis, G. P., & Briskie, J. V. (2006). Inbreeding and endangered species management: is New Zealand out of step with the rest of the world?. Conservation Biology, 20(1), 38-47.
Kawharu, M. (2000). Kaitiakitanga: a Maori anthropological perspective of the Maori socio-environmental ethic of resource management. The Journal of the Polynesian Society, 109(4), 349-370.
Kirk, S. (2015). No recovery plan to bring 600 native species back from brink of extinction. Retrieved March 26, 2017, from http://www.stuff.co.nz/national/politics/69920422/no-recovery-plan-to-bring-600-native-species-back-from-brink-of-extinction
Langton, G. (2000). Mr Explorer Douglas John Pascoe’s New Zealand Classic [Revised by Langton, G.]. Christchurch, New Zealand: Canterbury University Press, p. 250.
News and updates from the Kākāpō Recovery Team. (2016, November). Retrieved March 25, 2017, from http://createsend.com/t/i-35D4E98116C3A980
Plumb, S. (2016). Critically endangered kakapo on the increase – National – NZ Herald News. Retrieved April 27, 2017, from http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=11754390
Projects – Genome Sequencing – Kakapo. (n.d.). Retrieved March 24, 2017, from https://www.geneticrescue.science/projects/genome-sequencing/kakapo
Ratley, N. (2014, July). Back from the brink of extinction. Retrieved March 25, 2017, from http://www.stuff.co.nz/southland-times/news/features/10313116/Boom-A-kakapo-in-the-night
Sirocco. (n.d.). Retrieved April 24, 2017, from http://kakaporecovery.org.nz/sirocco/
Simberloff, D. (1998). Flagships, umbrellas, and keystones: is single-species management passé in the landscape era?. Biological conservation, 83(3), 247-257.
Soulé, M.E. (1985). What is conservation biology? Bioscience, 35, pp. 727–734
Towns, D. R., & Williams, M. (1993). Single species conservation in New Zealand: towards a redefined conceptual approach. Journal of the Royal Society of New Zealand, 23(2), 61-78.
Treaty of Waitangi Responsibilities. (n.d.). Retrieved April 27, 2017, from http://www.doc.govt.nz/about-us/our-policies-and-plans/conservation-general-policy/2-treaty-of-waitangi-responsibilities/
White, D. J., Hall, R. J., Jakob-Hoff, R., Wang, J., Jackson, B., & Tompkins, D. M. (2015a). Exudative cloacitis in the kakapo (Strigops habroptilus) potentially linked to Escherichia coli infection. New Zealand veterinary journal, 63(3), 167-170.
White, K. L., Eason, D. K., Jamieson, I. G., & Robertson, B. C. (2015b). Evidence of inbreeding depression in the critically endangered parrot, the kakapo. Animal Conservation, 18(4), 341-347.
Title image: De Roy, T. (n.d.). Kakapo [Photograph]. Retrieved April 27, 2017, from https://www.islandconservation.org/kakapo-population-gets-a-much-needed-boost/
Department of Conservation (1974). Chris Smuts-Kennedy, John Cheyne and Don Merton with Mandy the dog and Jill the kakapo [Photograph]. Retrieved April 24, 2017, from http://www.doc.govt.nz/news/newsletters/behind-the-scenes/archived-newsletters/spring-2014/
Thompson, T. (2016). Kuia, Richard Henry’s daughter, nesting [Photograph]. Retrieved April 27, 2017, from https://www.islandconservation.org/kakapo-population-gets-a-much-needed-boost/
Author: Olivia Carson
In New Zealand, conservation is a crucial tool used to maintain our unique ecosystem. But are our beloved feline friends undoing conservation’s hard work? Cats enjoy preying on some of New Zealand’s endemic species, such as birds like the kiwi, kererū and tui, reptiles like skinks, geckos and tuatara or invertebrates like weta. Statistics show that cats are having an impact on our native fauna, so is it time to revise programs which enable this behaviour to continue?
Trap-Neuter-Return (TNR) is a management technique used in New Zealand (NZ) by participating SPCA clinics whereby wild free-roaming cats, of all ages, are being humanely captured, spayed, and health checked. Upon completion, they are returned to their original habitat where their presence is approved, or they are put up for adoption if they are seen fit for domestication (Levy, et al., 2013). Former SPCA National President, Bob Kerridge, and the majority of NZ’s SPCAs support TNR as it aids in the welfare of, “sick, injured, lost, abused or simply abandoned cats” and it leads to an eventual decrease in the wild cat population (Auckland SPCA, 2016). However, this support is rivalled with opposition from The Department of Conservation (DOC) and conservation minister, Maggie Barry, who in 2015 called for the SPCA to stop the programme altogether, claiming it was destructive to native birds (Smith, 2015). Throughout this article the positive and negative implications of TNR will be explored, arguing that from a conservationist’s perspective, this program, along with feral and stray cats need to go.
Cats are categorised by their behavioural differences, whether they are domestic, stray or feral. Domestic cats are those who live with an owner and depend on humans for their care and welfare. A stray cat is one who was once a domesticated animal but has become lost or abandoned and has their needs indirectly supplied to them by humans or their environment. Feral cats are born and raised in the wild and have few of their needs provided by people and tend to live away from centres of human habitation (Farnworth, et al., 2010). One behaviour which these cats share is their instinct to kill, with studies nationwide showing that many of NZ’s endangered species have targets on their backs.
The debate on whether cats should be classified as pests is strongly controversial. 48% of households in NZ accommodate at least one cat, showing that us Kiwis have a real love for these furry creatures (Mckay, et al., 2009). DOC, on the other hand, consider cats as pests, due to their negative impacts on our native species (Abbott, 2008). This begs the question, why are programmes such as TNR supporting the release of these homeless and undomesticated cats back into the wild?
There are many reasons to support the use of TNR. In Rome, Italy, a study on a long-term TNR programme showed that cat colonies decreased by up to 24% over a 6-year period, demonstrating that loss of reproductive ability has a marked effect on the reduction of the number of unwanted kittens (Natoli, et al., 2006). Furthermore, by returning the cat to the environment after veterinary attention, it allowed them to continue using their hunting instincts towards decreasing mammalian pest populations. The same methodology can be applied to NZ as mammalian pests, such as mice and rats are also known to feast on New Zealand’s native species (Towns & Broome, 2003). Therefore, it could be reasoned that if cats were removed altogether from the ecosystem, it might experience a decline in native wildlife due to a rise in the rodent population.
The introduction of cats to NZ has seen some unfortunate outcomes for native species, which underwent evolution during a period where mammalian predators were non-existent (Norbury, et al., 2014). Domestic, stray and feral cats have all contributed to the extinction of 40% of NZ endemic birds (Sijbranda, et al., 2016). In 1894, a single cat was able to completely wipe out an entire species of Stephen’s Island Wren, who were thought to be taking refuge from mammalian pests on Stephen’s Island (Galbreath & Brown, 2004). This reinforces how destructive one cat, who may be from a TNR programme can be.
The average cat kills approximately 65 creatures a year (van Heezik, et al., 2010). Rats, one of NZ’s most devastating pests, arguably contribute just as much damage, along with ferrets, stoats, weasels and possums. Both government and territorial authorities use alternatives to TNR to control these predators which meet humane standards for example poison and traps. It could be debated that although a less favourable outcome for cats, instead of the SPCA spending money on neutering and providing medical attention, it could be considered more humane to euthanise. Recognising this will stop cats from having an unloved life on the street and ensures that no native animals will come to their demise in the future.
If TNR was terminated, then continued pest management would be essential. Instead of neutering and releasing trapped stray and feral cats, they would need to be humanely euthanised. Continued management would also benefit the eradication of the other pests which cats may prey on. New Zealand aims to have a pest-free ecosystem by 2050 and the Government, iwis, and regional councils are showing their support to this cause by providing approximately $70 million annually towards predator control (The Department of Conservation, 2014). This sum would continue to benefit pest management if TNR was stopped. There are humane pest control options which could be better advertised to the public (Goodnature and Victor professional traps), which may increase support, reinforcing that we don’t need cat input to sort our pest problem, just people’s support.
The negative consequences of having stray and feral cats in our environment far outweigh the positives. Most cat owners are reasonable people, agreeing that measures such as mandatory microchipping, registration and compulsory neutering, would allow for better care of future stray cats. If people complied with these rules, then stray cats could be returned to their owners. We don’t need to remove our much-loved pets altogether, but our native fauna needs protection too, the ones that define us as a nation, and for this to be achievable, TNR must go. TNR currently undermines conservation practices by allowing destructive animals to continue to roam freely. If it weren’t for cats “most-loved” status, it wouldn’t be an issue, as we don’t see rats being neutered and returned to the wild, do we?
Abbott, I. (2008). The spread of the cat (Felis catus) in Australia: Re-examination of the current conceptual model with additional information. Conservation Science Western Australia, 7, 1-17.
Auckland SPCA (2016). What We Do. Retrieved from Auckland SPCA: https://www.spcaauckland.org.nz/what-we-do/
Farnworth, M., Dye, N., & Keown, N. (2010). The legal status of cats in New Zealand: A perspective on the welfare of companion, stray and feral domestic cats (Felis catus). Journal of Applied Animal Welfare Science, 13, 180-188.
Galbreath, R., & Brown, D. (2004). The tale of the lighthouse-keeper’s cat: Discovery and extinction of the Stephens Island wren (Traversia lyalli). The Ornithological Society of New Zealand, Inc, 51, 193-200.
Levy, J., Gale, D., & Gale, L. (2013). Levy, J. K., Gale, D. W. Evaluation of the effect of a long-term trap-neuter-return and adoption program on a free-roaming cat population. Journal of the American Veterinary Medical Association, 222, 42–46.
Mckay, S., Farnworth, M., & Waran, N. (2009). Current attitudes toward, and incidence of, sterilization of cats and dogs by caregivers (owners) in Auckland, New Zealand. Journal of applied animal welfare science, 12, 331-344.
Natoli, E., Maragliano, L., Cariola, G., Faini, A., Bonanni, R., Cafazzo, S., & Fantini, C. (2006). Management of feral domestic cats in the urban environment of Rome (Italy). Preventive Veterinary Medicine, 77, 180-185.
Norbury, G., Hutcheon, A., Reardon, J., & Daigneault, A. (2014). Pest fencing or pest trapping: A bio-economic analysis of cost-effectiveness. Austral Ecology, 39, 795-807.
Sijbranda, D., Campbell, J., Gartrell, B., & Howe, L. (2016). Avian malaria in introduced, native and endemic New Zealand bird species in a mixed ecosystem. New Zealand Journal of Ecology,, 40(1), 72-79.
Smith, O. (2015). Express. Retrieved from Feral politics: New Zealand’s two-cat policy sparks FUR-ious row. http://www.express.co.uk/news/world/582420/New-Zealand-s-Prime-Minister-John-Key-two-cat-policy-controversy
The Department of Conservation. (2014). Predator Free 2050 [Brochure]. New Zealand. Retrieved from http://www.doc.govt.nz/Documents/our-work/predator-free-2050.pdf
Towns, D., & Broome, K. (2003). From small Maria to massive Campbell: Forty years of rat eradications from New Zealand islands. New Zealand Journal of Zoology, 30(4), 377-398.
van Heezik, Y., Smyth, A., Adams, A., & Gordon, J. (2010). Do domestic cats impose an unsustainable harvest on urban bird populations? Biological Conservation, 143(1), 121-130.
Monitoring selected forest bird species through aerial application of 1080 baits, Waitutu, New Zealand- Synopsis by Sarah BezerediPosted: May 20, 2014
Going native – The role of native vegetation in managing wastewater
Public opinion is increasingly indicating that it is unacceptable to discharge wastewater directly into waterways. In determining how to manage this paradigm shift, several District Councils are examining the potential for irrigating wastewater to land. While this approach offers benefits, nutrients from wastewater are difficult to remove and can enter waterways via ground and surface flows. Given the pathogens and contaminants present in untreated wastewater there may also be a perception of risk to public health. Native vegetation potentially has a role to play. Native vegetation can provide a barrier to odours and aerial dispersal and in riparian areas act as a buffer to nutrients while improving connectivity with other habitats. Native planting can also engage the community in wastewater planning. Key challenges with this approach are change in nutrient removal as buffers age and ensuring effective community engagement. Carterton District Council’s (CDC) purchase of land to discharge wastewater from the Carterton Wastewater Treatment Plant (CWTP) is presented as a case study to consider these issues.
Casestudy: Carterton Wastewater Treatment Plant
Water quality monitoring has identified discharges from the CWTP as impacting the health of the Mangatarere Stream (GWRC, 1999). In 2012, CDC purchased Daleton Farm, a 66 hectare site adjacent to the CWTP as a first step towards no longer discharging wastewater into the Stream (CDC, 2013).
|Figure 1: Aerial photograph of Daleton Farm (not to scale) (Source: Googlemaps)|
|Figure 2:Piezometric surface and velocity vectors for the Wairarapa Valley (Source: GWRC, 2010).|
The Mangatarere runs through the north corner and along the north the farm. A residential area is to the north-east and rural properties are dotted around the perimeter. An ephemeral stream drains the area and land between here and the stream is poorly drained (see Figure 1). The existing land treatment system includes sixteen wetland plots. Excess water that could be irrigated to land is discharged into the stream during high rainfall (Clark, 2010). Groundwater flow at the site is in a south-west direction (Figure 2).
Wastewater irrigation and risk
As NZWWA (2003) notes, irrigating wastewater to land requires management of environmental, social and economic matters.
Nutrients are difficult to remove from wastewater and irrigation can accumulate in waterways, impacting organisms through toxicity and triggering excessive growth of oxygen depleting plants (PCE, 2012). Sub-surface flow can transport soluble nutrients rapidly, sometimes even directly into streams. Surface runoff can transport both particulate and soluble nutrients (Tanner et al, 2005). Nutrients are a key issue for irrigating to land at the CWTP. There is significant interaction between surface and groundwater in the area (GWRC, 2009).
Pathogens and contaminants are usually removed prior to irrigation and odour generation and aerial dispersal can be effectively managed by application design and screening (Magesan and Wang, 2003). Nonetheless, convincing the public that these processes are appropriate can be difficult. There is usually goodwill if the community is well informed but public support can be challenging when bureaucratic structures are perceived as untrustworthy (Mermet et al, 2007).
CDC’s vision for wastewater treatment, highlights the constraints surrounding rate increases and that CDC will partner with farmers rather than purchase the remaining 150 Hectares needed to manage all municipal wastewater. Opportunities to offset water and fertiliser costs of agriculture and forestry and allow an economic return are highly regarded and are also options that can assist nutrient removal (Personal communication: Greg Boyle, 26/3/2014). Crop production and forestry instead of grazing will avoid urine inputs and stock removal increases infiltration as trampling compacts soils (Parkyn et al, 2004). Taupo District Council grows and sells a cut and carry haylage crop (Treeweek et al, 2010). Rotorua irrigates commercial stands of Pinus radiata (Magesan and Wang, 2003).
What role can native vegetation play?
While commercial opportunities will be a priority focus at CWTP, a role for native vegetation should still be considered. Vegetation stands along borders will shield neighbouring properties (USDA, 2007) and in riparian areas will improve stream health. Quinn et al (1997) compared stream health in riparian areas of pasture, pine plantation and native forest. Nutrient levels were more favourable in native forest. Connectivity between native vegetation patches is also improved. Ultimately, native planting activities can attract community participation in wastewater planning.
Nutrient removal differs according to hydrology, soils and vegetation. Surface pollutant transport of soluble nutrients is reduced by increased infiltration caused by root channels and soil structure changes. Particulate nutrients are filtered and slowed by dense vegetation. Soluble nutrients transported through sub-surface flows can be removed by vegetation uptake and denitrification. Denitrification, whereby nitrate is removed as N₂ gas, is common in wetlands with anoxic soils rich in organic matter. Cooper (1990) in Parkyn et al (2004) found nitrate loss was concentrated in wetland areas that occupied only 12% of the border of a stream. Planning at the CWTP will need to consider the ephemeral stream and the poorly drained soils to the west as well as the banks of the stream. As Gillian (1994) notes, these area receive runoff and have shallow groundwater seeps.
Stream health and connectivity
Effects of native vegetation on streams include increased shade and terrestrial food sources and reduced water and air temperature in areas where native fish lay eggs (Parkyn et al, 2004). Death and Collier (2010) emphasise restoration of segments is optimised in areas with significant catchment cover suggesting that connectivity between patches is important. As Akçakaya et al (2007) notes increased connectivity aids in the dispersal of biodiversity but needs to be managed as pest species can also benefit. The local streamcare group in Carterton, the Mangatarere Restoration Society (MRS), is supported by both the District and Regional Councils and has released an action plan based on community consultation. The action plan outlines a strategy to links restored areas to the Tararua Forest Park. Opportunity exists for the CDC to work at the CWTP to support this vision, though a pest management strategy will be needed to ensure biodiversity values at the Tararua Forest Park are protected.
Public participation in ecological restoration is common place in New Zealand (Galbraith, 2013). Native planting offers an opportunity to engage the public on wastewater options. In Carterton, for example, wastewater consultation and native planting could be held at the same time. Community consultation has already indicated native planting as an activity the community wants to participate in and the MRS can harness this interest (personal communication: Jill Greathead, 15/6/2012). As Mermet et al (2008) notes replacing management by government with management by community can assist in resolving contentious issues and could assure the community on public health and odour generation issues. Galbraith (2013) notes a role for community participation in changing attitudes, suggesting that environmental education on household and farming inputs to wastewater could also be a useful focus of planting days.
|Plate 1: MRS members participating in native planting at a local landowners property. Photograph by A.J. Hunter|
Challenges with this approach
In advocating for a role for native vegetation, a number of challenges should be considered. The effectiveness of nutrient removal of native vegetation changes as buffers age. Engaging with communities is challenging.
Nutrient response as buffers age
Howard-Williams and Pickmere (1994) studied a native riparian vegetation stretch for 17 years and found that after twelve years nutrient response decreased but wildlife capacity increased. Pores of soils can become blocked and shading limits the role of aquatic and smaller terrestrial plants in nutrient removal. Parkyn et al (2003) suggest maintenance to allow light entry and grass filter strips to remove more particulate nutrients before they enters riparian areas. Howard-Williams and Pickmere (1994) takes a longer view advocating wildlife values to be embraced and that riparian retirement should be accompanied by improved landuse. Implementing such an approach in Carterton, for example, will require working with downstream landusers to improve their impacts. To some extent this is occurring through Greater Wellington Regional Council’s work with local farmers implementing Land and Environment Plans (personal communication: Richard Parkes, 6/2/2014).
Silvertown et al (2007) notes recruiting broad volunteer participation in conservation as challenging. Attitudes towards environmental issues vary and many organisations report age and gender bias in the small portions of the population they manage to engage. While the participation of MRS members will be a useful addition to wastewater consultation, CDC will need to ensure this occurs as part of a broader strategy or the approach may be perceived as being hijacked to appease a conservation orientated elite. As Mermet et al (2007) emphasise governance and coordination approaches to conservation, while useful in bringing together stakeholders can also be seen as reinforcing defacto power balances and be vulnerable to political manipulation.
Native vegetation has a role to play in managing the environmental, social and economic issues involved with irrigating wastewater to land. Native riparian vegetation can assist in removing nutrients while improving stream health and connectivity. Perhaps more importantly, native vegetation planting can also act as a focal point for attracting community participation in wastewater planning. CDC’s plan to irrigate wastewater to land is an opportunity to implement such an approach. Wastewater management will benefit from native vegetation stands along border areas between neighbouring properties, in riparian areas and along the ephemeral stream. Planting activities will need maintenance as buffers age and should be part of a wider strategy to work with householders and neighbouring landowners in reducing nutrient inputs to the stream. Involving the public in native planting activities as part of the wastewater consultation process, provides an opportunity to discuss and resolve contentious planning issues providing it is part of a package of activities involving the wider community.
Akçakaya, H.R., Mills, G. and Doncaster, C.P (2007) The role of metapopulations in conservation. In Macdonald, D. W. and Service, K. (eds), Key topics in conservation biology, Chichester, Blackwell Publishing, pp. 64-84.
Boyer, S (2011, December) Carterton council to pay $20k for leak, Wairarapa Times Age, Retrieved from: http://www.nzherald.co.nz/wairarapatimesage/news/article.cfm?c_id=1503414&objectid=11048605
Clark, S (2010) Carterton District Council Carterton sewage treatment plant discharge to land and water assessment of effects on the environment. Retrieved from
Carterton District Council (CDC) (2013) 2013 Pre-election Report. Retrieved from: http://www.cdc.govt.nz/sites/default/files/Pre-election%20Report%202013.pdf.
Couper, S., Ewart, J., Anderson, T. and Wallace, I. (2009) Natural Nutrient Removal, Taupo District Land Disposal Scheme. Retrieved from: http://www.awtwater.com/docs/weftec/natural_nutrient_removal_weftec.pdf
Death, R. G. and Collier, K. J. (2010) Measuring stream macroinvertebrate responses to gradients of vegetation cover: when is enough enough? Freshwater Biology,55, 1447–1464.
EQONZ (2012) Wairarapa Water Use Project – Discussion of the potential for incorporation of treated municipal wastewater. Retrieved from:
Galbraith, M. (2013) Public and ecology – the role of volunteers on Tiritiri Island. New Zealand Journal of Ecology 37 (3) 266 – 271.
Greater Wellington Regional Council (GWRC) (2010) Mangatarere Stream catchment water quality investigation. Retrieved from:
Greater Wellington Regional Council (GWRC) (2010) Wairarapa Valley groundwater resource investigation Middle Valley catchment hydrogeology and modelling. Retrieved from: http://www.gw.govt.nz/assets/council-publications/Wairarapa%20Valley%20Groundwater%20Resource%20Investigation%20Middle%20Valley%20Catchment%20Report%20updated.pdf.
Greater Wellington Regional Council (GWRC) (2012) Regional Freshwater Plan for the Wellington Region. Retrieved from: http://www.gw.govt.nz/assets/Plans–Publications/Regional-Freshwater-Plan/Regional-Freshwater-Plan-incorporating-plan-changes-1234-and-5-updated-April-2012.pdf.
Guggenmos, M. R., Jackson, B. M. and Daughney, C. J. (2011) Investigation of groundwater-surface water interaction using hydrochemical sampling with high temporal resolution, Mangatarere catchment, New Zealand. Hydrology and earth system science, 8, 10225 – 10273.
Howard-Williams, C (1991) Dynamic process in New Zealand Land-Water Ecotones. New Zealand Journal of Ecology, 15 (1), 87 – 98.
Howard-Williams, C and Pickmere, S (1994) Long-term vegetation and water quality changes associated with the restoration of a pasture stream. In Colliers, K. J. (Ed) Restoration of Aquatic Habitats. Selected papers from the second day of the New Zealand Limnological Society 1993 Annual Conference (pp. 93 – 109), New Zealand, Department of Conservation.
Howard-Williams, C and Pickmere, S (1999) Nutrient and vegetation changes in a retired pasture stream. Recent monitoring in the context of a long-term dataset. Retrieved from: http://conservation.govt.nz/Documents/science-and-technical/Sfc114.pdf.
Laurenson, S., Bolan, N., Horne, D., Vogeler, I. and Lowe, H. (2007) The sustainable management of sewage wastewater irrigation to pasture – New Zealand Land Treatment Collective: Proceedings for the 2007 Annual Conference. Retrieved from: http://www.lei.co.nz/images/custom/2007_sewage_wastewater_irrigation.pdf.
Magesan, G. N. and Wang, H. (2003) Application of municipal and industrial residuals in New Zealand forests: and overview. Australian Journal of Soil Research, 41, 557 – 567.
Mermet, L., Homewood, K., Dobson, A. and Billé, R. (2008) Five paradigms of collective action underlying the human dimension of conservation. In Macdonald, D. W. and Service, K. (eds), Key topics in conservation biology, Chichester, Blackwell Publishing, pp. 42-58.
New Zealand Water and Waste Association (NZWWA) (2003) Guidelines for the safe application of biosolids to land in New Zealand. Retrieved from:
Parkyn, S. M., Davies-Colley, R. J., Halliday, J. N., Costley, K. J. and Croker, G. F. (2003) Planted Riparian Buffer Zones in New Zealand: Do They Live Up to Expectations? Restoration Ecology, 11, 4, 436–447.
Parkyn, S (2004) Review of riparian buffer zone effectiveness, MAF Technical Paper,No: 2004/05.
Parliamentary Commission for the Environment (2013) Water quality in New Zealand: Land use and nutrient pollution, Wellington, Parliamentary Commission for the Environment.
Quinn, J.M., Bryce Cooper, A., Davies‐Colley, R. J., Rutherford, J.C., and Williamson, R.B. (1997) Land use effects on habitat, water quality, periphyton, and benthic invertebrates in Waikato, New Zealand, hill‐country streams. New Zealand Journal of Marine and Freshwater Research, 31 (5) 579-597.
Schipper, L. A. and McGill, A (2008) Nitrogen transformation in a denitrification layer irrigated with dairy factory effluent. Water Research, 42, 2457 – 2464.
Silvertown, J. Buesching, C.D., Jacobson, S.K. and Rebelo, T. (2007) Citizen science and nature conservation. In Macdonald, D. W. and Service, K. (eds), Key topics in conservation biology, Chichester, Blackwell Publishing, pp. 127-141.
Tanner, C. C., Nguyen, M. L. and Sukias, J. P. S. (2005) Nutrient removal by a constructed wetland treating subsurface drainage from grazed dairy pasture. Agriculture, Ecosystems and Environment, 105, 145 – 162.
Treweek, G., Balks, M. R. and Schipper, L. A. (2010) Nitrogen leaching from effluent irrigated pasture, on a vitrand (pumice soil), Taupo, New Zealand – initial results, 2010 19th World Congress of Soil Science, Soil Solutions for a Changing World, Brisbane, Australia, Published on DVD.
Stuart McKay has over 15 years experience working for governments in Australia, the UK and New Zealand across health, agriculture, housing and environment portfolios. His experiences range from representing Australia at Commission on Sustainable Development meetings at the UN headquarters in New York to providing project management expertise to health, housing and social care projects in the UK. With the New Zealand government at the Ministry for Primary Industries Stuart was responsible for the 2011 independent audit of the Dairying and Clean Streams Accord, the Natural Resource Sector Briefing for Incoming Ministers and part of the cross portfolio team that implemented the National Policy Statement on Freshwater Management. Stuart was also pivotal in securing funding for the establishment of the Mangatarere Restoration Society a community restoration group in the Wairarapa. Stuart is sustainable development consultant at Sustainable Communities and is currently completing a post graduate certificate in ecological restoration at Victoria University, Wellington to supplement and specialise his expertise. He currently holds a Bachelor of Science in Environmental Science and Social Ecology with Honours in Sustainable Development from Murdoch University in Perth, Western Australia.