Category: wildlife ecology

  • I see you: Sauron and the panda

    “I wish we could get away from these hills! I hate them. I feel all naked on the east side, stuck up here with nothing but the dead flats between me and that Shadow yonder. There’s an Eye in it. Come on! We’ve got to get down today somehow.” JRR Tolkien, The Lord of the Rings

    We’ve all had that feeling of being watched, of something that has taken an interest in what we are doing, and not perhaps with our best interests. It makes us fell uncomfortable, awkward, and we often change our behaviour in response, become more cautious, less spontaneous.

    Tolkien knew the power of the watching individual. Sauron, the chief antagonist in The Lord of the Rings, is literally portrayed as the Great Eye – “The Eye was rimmed with fire, but was itself glazed, yellow as a cat’s, watchful and intent, and the black slit of its pupil opened on a pit, a window into nothing. Then the Eye began to rove, searching this way and that; and Frodo knew with certainty and horror that among the many things that it sought he himself was one.” Knowing that someone can see you wherever you are is about as big a threat as we can imagine, whether it is Sauron, your boss, or your mother! We generally hate the concept that someone is watching us.

    Tolkien loved the word ‘watch’ (he used it over 330 times in the Lord of the Rings!). The watch-tower of Weathertop is the site of Frodo’s wounding, a Watcher-in-the-water nearly ends the journey at the entrance to Moria, there are Silent Watchers at the gates of Cirith Ungol, the menace of the Old Forest, Fangorn (known as the Watchwood to the Ents). Threats are usually described in the language around the feeling of being watched. And it works, it quickens the pulse of the reader. We know the feeling and respond.

    Ever get that feeling that something was looking for you?

    The problem with knowing that you are observed (or can be observed) is that you behave in ways that are different to your normal behaviour. Many species will respond to observation by not performing rarer sorts of behaviour, like play or reproduction, or by moving away from the observer.

    Gollum knows all about the watching eye and this makes him much more cautious in his movements. “His Eye watches that way all the time. It caught Smeagol there, long ago.’ Gollum shuddered. ‘But Smeagol has used his eyes since then, yes, yes: I’ve used eyes and feet and nose since then. I know other ways. More difficult, not so quick; but better, if we don’t want Him to see. Follow Smeagol! He can take you through the marshes, through the mists, nice thick mists. Follow Smeagol very carefully, and you may go a long way, quite a long way, before He catches you, yes perhaps.’ Gollum scuttles about because he does not want to be observed.

    Frodo, under the wearying influence of the ring as he stumbles through Mordor, almost completely changes his normal behaviour under the threat of constant detection. “Anxiously Sam had noted how his master’s left hand would often be raised as if to ward off a blow, or to screen his shrinking eyes from a dreadful Eye that sought to look in them. And sometimes his right hand would creep to his breast, clutching, and then slowly, as the will recovered mastery, it would be withdrawn.” If not for Sam, who does not have this anxiety, Frodo would not make it to Mt Doom.

    In animal behaviour we have a similar problem. We usually want to observe an animal’s ‘normal’ behaviour but they will often change their behaviour if they can see a human watching them. Today, technology can come to our aid.

    Yes, yes we realise you are the cutest species… Red Panda resting. Image from Kat Bugler.

    One of the more powerful new-ish tools available to those that study animal behaviour are trail cameras. These devices allow us to observe animals in the field 24/7 (just as long as they wander past the unsleeping gaze of the lens and trigger the image capture). This is a huge improvement for behavioural studies, as we can watch without the actual presence of human observers. We have used cameras in many studies here at Lincoln, mostly in understanding the life history and behaviour of nocturnal mammalian pest species..

    Recently, we used trail cameras to find out more about red panda in Nepal. Cameras were placed on red panda latrine trees (which are exactly what you are imagining). We were able to record activity patterns of wild red panda in their natural environment. Such data is useful in working out management plans to help with their conservation. We were also able to record other wild species that share their habitat.

    In some of these captured images, it appeared that the red pandas were looking at the trail cameras. If they are aware of the cameras then this might alter their behaviour. Maybe they are curious and spend more time loitering in the areas? Maybe they are frightened and don’t behave in their normal way?

    Kat Bugler, as part of her MSc at Lincoln University (with supervisors Adrian Paterson and James Ross), decided to examine whether red pandas were camera shy. Kat was able to get permission from zoos in New Zealand and Australia to observe their captive red panda in their enclosures. Each habitat was different but Kat was able to set up trail cameras to record behaviour around the main activity areas and platforms. She had a more powerful camera set up out of the enclosure to record behaviour of the pandas in these areas and around the trail cameras. Kat also spent time recording her own observations.

    Trail camera setup in a zoo enclosure. Image from Kat Bugler.

    In a paper published in Animals, Kat was able to show that there was a difference in red panda behaviour when a human observer was watching them, compared to a camera. When red panda were being watched by an individual they defecated less, ate less, moved less, played less, rested less, and slept more than when they were only being ‘watched’ by the trail cameras. Red panda were much slower to change behaviours when being observed. Interestingly, there were similar differences, if not as large, when comparing behaviour recorded by the outside camera compared to the enclosure trail cameras. The presence of people changes red panda behaviour, but so does the presence of a trail camera.

    These are subtle changes. Trail cameras are hardly the eye of Sauron: “And suddenly he felt the Eye. There was an eye in the Dark Tower that did not sleep. He knew that it had become aware of his gaze. A fierce eager will was there. It leaped towards him; almost like a finger he felt it, searching for him.” Are trail cameras useful for monitoring red panda behaviour if they can cause changes in behaviour? Absolutely, they do record all of the behaviour that red pandas exhibit, they just may alter the duration and frequency of occurrence. As long as we bear that in mind then we have a great tool to use in the wilds of the Himalayas and in understanding more about the red panda.

    “He did not feel invisible at all, but horribly and uniquely visible; and he knew that somewhere an Eye was searching for him” Maybe Sauron would have been better off putting trail cameras on all of the paths into Mordor!

  • The big, bold, redbacks of Buckland

    “No, Mr Baggins has gone away. Went this morning, and my Sam went with him: anyway, all his stuff went. Yes, sold out and gone, I teller. Why? Why’s none of my business, or yours. Where to? That ain’t no secret. He’s moved to Bucklebury or some such place, way done yonder. Yes it is – a tidy way. I’ve never been so far myself; they’re queer folks in Buckland. No, I can’t give no message. Good night to you!” JRR Tolkien – The Fellowship of the Ring

    One of the greatest illustrations of Tolkien’s work, IMHO, The Gaffer and the Black Rider by Stephen Hickman.

    I’ve always liked this passage where old Gaffer Gamgee is talking, unbeknown, to a nazghul. It is an important story point but delivered in the type of conversation that you could hear all over the world. ‘Those people that live 20 – 30 km away are just so different and weird!‘ Are the people of Buckland really so different to the good, honest folk of the Shire? If so, how did this happen by simply crossing a river?

    There is a question around invasive species whether the individuals that arrive in a new area are just a random selection of the individuals (and their traits) that live in their home area or whether they represent a group of individuals with consistent and particular traits that make them more likely to have successfully invaded the new area.

    For example, all humans in Aotearoa/New Zealand have arrived from outside these shores over the last 1000 years. Were the people that made their way here more bold and explorative than the rest who stayed behind? Or were they no different than their neighbours who stayed at home? Maybe they just simply had the opportunity to go?

    These ideas are important in thinking about why invasive species are successful at establishing or not. If any old random subset of the population can turn up then they are less often going to successful at establishing (they may not be fit-for-purpose!) compared to if they arrive with skills that allow them to survive better in a new environment (or even to survive the journey).

    Being large might help give invasive individuals an advantage over native species. Likewise, producing more offspring, growing faster, being bold, exploring more, dispersing sooner, having a broader diet, could all help with invading and establishing.

    What about our Bucklanders?

    “Long ago Gorhendad Oldbuck, head of the Oldbuck family, one of the oldest in the Marish or indeed in the Shire [has had high evolutionary fitness over many generations], had crossed the river [successfully able to disperse relative to other hobbits and to explore more], which was the original boundary of the land eastwards. He built (and excavated) Brandy Hall, changed his name to Brandybuck, and settled down to become master of what was virtually a small independent country. His family grew and grew [high fecundity in offspring production], and after his days, continued to grow, until Brandy Hall occupied the whole of the low hill, and had three large front-doors, many side-doors, and about a hundred windows. The Brandybucks and their numerous dependants then began to burrow, and later to build, all round about … The people in the Marish were friendly with the Bucklanders … But most of the folk of the old Shire regarded the Bucklanders as peculiar, half foreigners as it were [suggests a slightly different distribution of traits compared to the parent population].Though, as a matter of fact, they were not very different from the other hobbits of the Four Farthings. Except in one point: they were fond of boats, and some of them could swim [bold and innovative behaviours].” JRR Tolkien- The Fellowship of the Ring

    Captive redback with web. Image by Adrian Paterson.

    We are also told elsewhere that the Brandybucks and Tooks (another bold lineage of hobbits) are generally taller than average Shire hobbits. Tolkien, as I have said in many other places (taxonomy of orcs and hobbits, evolutionary biology ideas, burrow architecture, mammal pest management, fire and ecosystems), was rather accurate when it came to integrating biology into his writing. Did he get it right here?

    To test this invasion idea you need a species that is well-studied in it’s native range as well as in its colonising range. You also need to be able to measure all of those traits. Spiders fit the bill nicely. They’re small and have short generations, are easy to fit into small experimental set ups, and some are venomous and, therefore, well studied. Enter the redback spider (Latrodectus hasselti), invasive in Japan and New Zealand and well studied in its Australian homeland.

    Cor Vink, New Zealand’s leading arachnologist, joined a group based in Toronto, Canada headed by Monica Mowery, to look at individuals from these three areas. They measured the size of individuals (bigger is usually better in interactions with competitors), their egg sac production (producing more young may give you more opportunities for at least some surviving), and length of generation times in captive populations (shorter allows for faster replacement, longer allows for larger more long-lived individuals).

    A redback – amazing photo from the talented Bryce McQuillan

    They measured the behaviour of the redbacks, such as frequency of cannibalism (you never know when a snack might come in handy!). Also, individual spiders were placed in a new environment and the speeds at which they started spinning webs (exploration) or moving after being exposed to a puff of wind (boldness) were measured. Spiders were also placed into a warm arena with a small simulated breeze to see whether they would balloon (effectively float away in the wind) or rappel (climb using their web silk) away from the start point (dispersal).

    The outcomes from this work were published in Biological Invasions. Redbacks from the invasive populations showed more dispersal behaviour than the home populations. They also tended to be larger in size, more cannibalistic, and produced more offspring. Interestingly, the redbacks in Japan and New Zealand did not seem to be more bold or explorative than in Aussie. Overall though, the invasive populations looked and acted differently to the source population.

    It appears that populations that successfully disperse and establish in new areas might do so because they are settled by individuals with useful traits that differ a little from the source population. This may help us to figure out which species potentially pose the most invasive threats.

    What about those strange Bucklanders? The Gaffer was mostly right. They are a bit different. Bucklanders are a population that managed to successfully disperse to an isolated area. Bucklanders are larger and more fecund. Tolkien does not record whether the Bucklanders tended to be more cannibalistic than hobbits in the Shire, but that would be a prediction!

    We can certainly sympathise with the Gaffer’s concerns about his Sam going to live among them.

  • Mātauranga Māori: the way of the past and future?

    During my time studying at Lincoln University I have noticed that there is a lack of Mātauranga Māori in our research and study methods. This lack of recognition for the value of Māori methods is concerning, although this could be related to the high demand for Māori academics throughout the country.

    New Zealand’s culture is unique. Understanding and participating in the Māori culture is a unique experience that is not replicated anywhere else around the world. Incorporating Mātauranga Māori research methods holds the potential to be beneficial for all research projects. There needs to be a clear understanding of Mātauranga Māori and how colonisation has affected Māori connections to their land. Mātauranga Māori is a modern term for the combined knowledge of Polynesian ancestors and the experiences of Māori living in the environment of New Zealand.

    Understanding how to incorporate cultural methods into research holds the potential to generate a greater understanding of unique ecosystems in New Zealand. There are many different methods and systems from Māori culture that can be used within research to help describe and understand the data being collected. Mātauranga Māori is a knowledge system that incorporates a Māori philosophical thought, world view and practice. Kaitiakitanga is described as a place-based customary responsibilities and practices of Māori who have a genealogical history that connects them to the land and it embeds a vital link between Māori and Papatuanuku (Earth Mother).

    Science knowledge underpins a large part of our day-to-day lives, and it’s questions encourage us to learn about the world we live in. Indigenous cultures have an advantage (to some degree of course) with their understanding of the land they inhabit, as their ancestors have spent centuries gathering information from medicine, food and historic events that directly relate to the land. Unfortunately, due to the dominance of traditional and classic research methods in science, much of this information has been disregarded and suppressed.

    Amanda Black from Lincoln University, along with lead author Tara McAllister and others, co-wrote a paper (published in 2020) deciphering Mātauranga Māori in New Zealand ecology. Her article discusses the benefits of understanding and incorporating Māori knowledge and practices in research cases. Indigenous knowledge and connections to the land and marine environments offer deep temporal and spatial insights that can reshape our understanding of biodiversity. Such knowledge can also help us to create new pathways to halt or slow the rate of biodiversity loss.

    The use of Mātauranga Māori within research allows us to re-shape our current understanding of the environment and provides improvements to address pressing environmental issues. ‘Two-eyed seeing’ is a metaphor that is used to assist people in conceptualising indigenous and western knowledge systems and to combine them in various ways that provide important insight for research.

    Using this system can enhance ecosystem management throughout New Zealand. For example, assigning legal personhood status to a natural ecosystem (such as when the New Zealand Parliament assigned the Whanganui River legal personhood) aligns with how Māori view themselves – an integral part of the ecosystem. Legal personhood provides a framework where activities of exploitation need to be evaluated against the impacts on the ecological health of the system as a whole.

    The Whanganui River, Kathrin & Stefan Marks

    Ecosystems as legal identities could provide a flexible and durable alternative to the current approach of regarding ecosystems and their natural services as ‘free’, which has led to their gradual decline. This is where the Kaitiakitanga system is important. It is the responsibility of everybody residing within New Zealand to understand how the speed and scale of urban and agricultural landscape change disrupts the relationship between people and their lands. The loss of links to nature has the possibility to damage the health and well-being of urban Māori (and all New Zealanders).

    The recurrent theme of the paper is the importance of co-development and co-creation of research through effective partnerships with Māori. The paper recognises that there is a lack of interaction with Māori regarding research. It also illustrates the need for scientists to move beyond a research process that involves either no or one-off consultation with Māori to a process that acknowledges Māori as Treaty partners.

    Being able to incorporate understandings from multiple knowledge systems is vital for a thorough understanding of the natural world, which is crucial in advancing the science of ecology within New Zealand. Understanding the indigenous knowledge systems/Mātauranga Māori of New Zealand and incorporating it into research priorities will improve the overall findings for researchers as they will have a more informed background of their area of study.

    The author Janie Kersten is a postgraduate student in the Postgraduate Diploma in Applied Science taught at Lincoln University. This article was written as an assessment for ECOL 608 Research Methods in Ecology.

  • 1080 reasons for optimism

    Photo overlooking Mount Summers (Jan 2022). Image by Chida Chapagain.

    It’s good to be optimistic. I have always been hopeful about the future. I lived the first 11 years of my life in a refugee camp. Times were tough, but I knew things could only get better. Even as a child, I knew there was more to this world than what I had experienced.

    Fast forwards a couple of years, and my family and I are living in New Zealand, happier than ever. The first 11 years in Nepal, compared to my last 11 years here in New Zealand, have been extremely different. My life changed for the better.

    Sometimes I wonder what would have happened if my family had moved to America or Australia instead of New Zealand. I often catch myself saying, “maybe my life would have been even better?” Optimism combined with curiosity can be a powerful motivator, leading us to explore the unknown. But we must be realistic with our expectations. Just because we are optimistic about the unknown doesn’t mean it must be true. There will always be challenges and limitations. Nothing is, or will ever be, perfect. 

    The same applies to alternative pest control methods being developed in New Zealand. The pest control toxin 1080 has its concerns, as do alternative methods that have been or are being developed. 1080 is a fully developed method that has been repeatedly shown to control introduced pest mammal populations on a large scale.

    The common brushtail possum (Sept 2010). Photo by Daniela Parra from Flickr.

    While it may not be perfect, it is widely recognised among scientists and conservationists that 1080 is currently the best tool we have for pest control. The use of 1080 is essential in protecting our native flora and fauna. However, we should always be looking to make improvements, but until such progress is made, the use of 1080 must continue. Perhaps you’ve read other things about 1080 and don’t agree. Allow me to explain.

    Bruce Warburton, Penny Fisher, Brian Hopkins, Graham Nugent, and Phil E. Cowan of Manakai Whenua Lanacare Reserach, along with James Ross of Lincoln University, outline the major areas of concern raised by 1080 and summarise the changes that have been made to the use of 1080 to address these concerns.

    The main four concerns related to the use of 1080 have been:

    1. the potential environmental and human health risks,
    2. the limited control over where the bait lands when applied aerially,
    3. the lack of species selectivity, and
    4. the animal welfare impact on target and non-target species.

    They explore the impacts of 1080 use for conservation and bovine tuberculosis (TB) control. They then summarise alternative toxicants and methods for mammal pest control being investigated in New Zealand. Then they address to what extent these alternative methods might be able to address the concerns raised by 1080 opponents. This article may alter your views on 1080.

    1080 is the current best tool we have for our unique fauna!

    Sodium fluoroacetate (1080) has been a recognised pesticide since the early 1940s. 1080 is most frequently mixed into cereal baits for possum and ship rat control. New Zealand is the world’s largest user of 1080. The extensive use of 1080 in New Zealand is made possible by our unique fauna, where we have 35 introduced mammal species and only two native terrestrial mammals (both bats).

    Introduced mammals, such as rats, possums, and stoats, are widespread and have significant impacts on native biodiversity and/or agricultural production. They continue to damage and threaten native and endemic species at unacceptably high rates.

    Māori believe ‘failure to act falls short of our responsibilities to our ancestors, and future generations’. Fortunately, 1080 is a very efficient method for pest control. Monitoring by the Department of Conservation (DOC) before and after aerial 1080 operations targeting possums, rodents, and stoats has repeatedly shown consistent benefits for nesting success in kiwi, kea, kaka, whio, pīwauwau, mohua, and tītitipounamu. O’Donnell and Hoare in 2012 found native bird populations to have doubled after more than 20 years of sustained predator control. 

    North Island Saddleback (Oct 2021). Photo by Geoff Mckay from Flickr.

    Are the ‘concerns’ about 1080 fact or evidence-based?

    There are concerns and opposition to the use of 1080. Some are evidence-based. 1080 does kill non-target species. According to Dave Hansford, about 12% of radio-tagged kea died after aerial 1080 operations. In 1970, there was a ministerial review of the properties, effectiveness, and regulatory control of 1080. The review supported the use of 1080 but also recommended areas for improvement. Most of these recommendations were implemented, but opposition to its use remained.

    In 2006, there was another formal assessment of 1080. Once again, the use of 1080 was permitted. 1080 opponents were still outraged. This triggered another investigation by the Parliamentary Commissioner for the Environment (PCE), who is tasked with providing independent advice to the government. The PCE concluded that “not only should the use of 1080 continue, but that we should use more of it.” Justified concerns about 1080 have been thoroughly reviewed many times, and these reviews have refined the ways in which 1080 is used safely to benefit the NZ environment. The remaining strong opposition to 1080 use by some New Zealanders has required that a lot of time and money being spent on developing, testing, and registering alternatives to 1080. 

    What are these alternative pest control methods?

    There are many alternative methods for pest control. However, many of these are not feasible for our unique situation. For example, shooting is not a viable method for small mammals like mice and rats, and it is too expensive to apply on a large scale. Trapping, similarly is not cost-effective for large-scale operations, especially in the more remote, mountainous parts of New Zealand. Although these methods can complement 1080, they cannot achieve the levels required for effective large-scale conservation. New toxins, including zinc phosphide, sodium nitrate, coumatetrayl, and diphacinone, have also been registered for use. However, none have been developed for aerial use.

    Genetic methods have the potential to drastically reduce the population of mammalian pests. There is a lot of attention on “gene drives”, which are engineered using the CRISPR/Cas9 genome editing technology. The gene drive DNA sequence, typically for reduced fertility, is then interwoven into the genome of an individual organism of the pest species, and every offspring of that individual inherits this modified DNA. One individual with this deleterious gene could potentially lead to complete eradication. This is the most promising alternative to 1080 in terms of cost and efficacy. There is, however, be significant scientific and public scrutiny to be done on this method.

    In the meantime, our birds are continuing to be eaten by pest mammals.

    My final thoughts

    Having lived in both Nepal and New Zealand, I have been able to witness many beautiful birds. Nepal is home to the Himalayan Monal, which is my favourite. I vividly remember chasing this colourful bird around as a child. New Zealand is also home to many beautiful birds. We cherish these birds; they are part of us. However, today, many of them face the risk of extinction.

    I am not an expert in pest control, but, I understand that without pest control, conservation programmes would fail. Reviews after reviews have shown that 1080 is the best current pest control method we have for introduced predatory mammals (possums, mice, rats, stoats, weasels) in New Zealand. Until we have better options, we need to continue using the best tools because our endangered endemic species cannot wait. We are lucky to have a pest control method that has proven to be so effective. It’s good to be optimistic.

    The author Chida Chapagain is a postgraduate student in the Postgraduate Diploma in Applied Science taught at Lincoln University. This article was written as an assessment for ECOL 608 Research Methods in Ecology.

  • Fishing for possum DNA

    When I was a child, I was fixated on animals. In fact, 5-year-old me would go around telling all the primary school mums that I wanted to be a Palaeontologist. This was often met with some strange looks, quite possibly because they didn’t even know what a Palaeontologist was themselves. Since then, I have been less focused on digging up dead animals and more interested in protecting the ones that are still alive.

    In New Zealand, tourism and agriculture are arguably the biggest money-maker industries. People flood from overseas to check out the clean green image being advertised in their home countries for themselves. The ‘Great Walks’ lead tourists through the rugged bush that New Zealand has to offer. Along the way they might even see some of our diverse flora and fauna, of which most can not be found elsewhere on Earth.

    On the other hand, the dairy, sheep and beef industries in New Zealand, earn large amounts of overseas revenue. This all started when Samuel Marsden introduced shorthorn dairy cattle to New Zealand from New South Wales and the rest is history.

    https://www.australiangeographic.com.au/topics/wildlife/2017/04/killer-possums/

    This brings me to the devious, but very cute looking, Brushtail Possum, Trichosurus vulpecula. In Australia, the Brushtail Possum is a protected species. In New Zealand they are a serious threat to our homegrown species. Possums compete with our native bird species for food and inhabit the same areas. These fluff balls are omnivores. In addition to eating the leaves off trees, they rob the nests of birds and eat the chicks and eggs.

    Bovine tuberculosis is a disease that affects many farm animal species. Possums are the biggest carriers of tuberculosis and can infect herds of dairy cows, causing serious illness to the animals and a large vet bill for the farmer. Due to these factors, New Zealand tries incredibly hard to get rid of these furry mammals. One important thing that we need to know is where these possums are present and and in what numbers. For a nocturnal and relatively cryptid species, this is a lot harder to do than simply call a roll!

    The use of trace DNA to monitor animals, such as possums, is a relatively new concept. However, a trial was held in Canterbury where researchers collected DNA from saliva left on WaxTags and Chewcards to determine the number of possums in an area and check whether these individuals were Tuberculosis carriers. From the initial field study, it was found that multiple possums would bite the WaxTag and Chew cards which made it difficult for the lab team to isolate certain animals. A new device to collect data was needed.

    A mechanical collection device was created which would remove the bait after one animal had bitten into it, which protected the saliva and therefore the individual DNA could be distinguished. The device was a bit like a fishing line, catching its prey and then reeling in the DNA! Researchers found that the mechanical device allowed the DNA to be collected and more easily sequenced. They also found that the genetic material was more easily recovered from covered WaxTags than on the uncovered WaxTags.

    Mechanical device created to protect DNA sample on the WaxTag.
Image from: A New Non-Invasive Method for Collecting DNA From Small Mammals in the Field, and Its Application in Simultaneous Vector and Disease Monitoring in Brushtail Possums
    Mechanical device created to protect DNA sample on the WaxTag.
    Image from: A New Non-Invasive Method for Collecting DNA From Small Mammals in the Field, and Its Application in Simultaneous Vector and Disease Monitoring in Brushtail Possums

    Cameras used in the field trials picked up that the possums interacted with the new WaxTags, and 87% of the devices were triggered after the first interaction. This is a positive point because in order for a monitoring device to be useful, the target has to interact with it.

    This new way of collecting trace DNA samples was a success. DNA from Brushtail Possums was able to be amplified for genetic identification and was able to detect if diseases were present. The combination of the device being interesting enough for the targets to interact with, and the subsequent DNA extracted being protected until collection, means that it is ever more likely that technology like this can be used for other pest species to determine their disease risk.

    The current study is the first to collect trace amounts of possum DNA and keep it protected from the elements until genetic analysis has taken place. This is a pretty big step for DNA collection methods. However, transmission of infectious diseases by vectors, such as possums, is density dependant. More collection devices need to be installed in these areas being studied to create ‘encounter’ history for individuals to determine population density and to calculate the likeliness for for transmission of these vector carried diseases.

    This research suggests that there are new ways for non-invasive monitoring pest populations. The road to New Zealand being predator free by 2050 is a long one, but is shortened by the impressive new technologies being developed in the pest management space. This technology is key for determining the populations of pests in their area and how likely their livestock are to contracting devastating diseases such as Bovine Tuberculosis.

    Dealing with pests may not be the most fun thing to do week to week, however, determining where populations are and where the risks lie can help experienced personal to more effectively manage pest populations and get New Zealand back to where we should be, mammal predator free.

    This article was prepared by postgraduate student Rebecca Anderson as part of the ECOL608 Research Methods in Ecology course.

    Emami-Khoyi A, Agnew TW, Adair MG, Murphy EC, Benmazouz I, Monsanto DM, Parbhu SP, Main DC, Le Roux R, Golla TR, Schnelle C, Alizadeh H, Csányi S, Heltai M, Jansen van Vuuren B, Paterson AM, Teske PR and Ross JG (2021) A New Non-invasive Method for Collecting DNA From Small Mammals in the Field, and Its Application in Simultaneous Vector and Disease Monitoring in Brushtail Possums. Front. Environ. Sci. 9:701033. https://doi.org/10.3389/fenvs.2021.701033

  • Nosy predators check out the competition

    Growing up in New Zealand, I had a great passion for animals. Viewing everything through a child’s eyes, I believed that all wildlife should be free to thrive anywhere they wanted. Today I see the realities of the world were all animals are cherished, but some are out of place and others are vulnerable. I am not alone in realising the endangerment and damage that pest species can cause to our native species. This awareness has me seeking to understand the appropriateness of eliminating certain species from particular locations in order to protect others.

    The flora and fauna within New Zealand are some of the most remarkable in the world. A large majority of the animals and plants (and fungi) are endemic, or unique, to New Zealand. Over the years, many species have been introduced to New Zealand, such as ferrets, stoats, hedgehogs and ship rats, that have put these unique animals and plants at risk. It has become vital that monitoring and control of these predators is implemented to allow our native species a greater chance of survival.

    Research to improve strategies and techniques to monitor and remove these predator species has been underway for many years now. One method used to monitor these predators is through deploying food-based lures that attract the target animals to traps or cameras. This allows for observations to be made in order to determine the density of these species in the surrounding area, as well as to increase the chances of trapping and removing these animals.

    One way to attract these predators is to use odours from more dominant predators to attract the target species to the traps or cameras. This technique is based on the observation that mammals, like stoats and rats, use scent as their primary sense to forage for food and detect dominant species (higher ranking species than themselves). Dominant species directly influence the behaviour of mesopredators (mid ranking predators) by either attracting them or repelling them away from the odour. A dominant predator’s odour may provoke the subordinate (lower ranking predator) into preforming eavesdropping behaviour. This behaviour is used by species to inspect the location where the dominant predator has roamed. If the location is good enough for the big, tough predator then maybe it is a good place for the subordinate as well.

    Researchers from Lincoln University, University of Auckland and Landcare Research chose to test ferret odour verses fresh rabbit meat (a traditional lure) for stoats, hedgehogs and ship rats. This study took place at Toronui station, a 1500 hectare sheep and beef farm located in Northern Hawkes Bay. It lasted for 64 days trial.

    From left to right; Stoat (Mustela erminea), Hedgehog (Erinaceus europaeus), Ship Rat (Rattus rattus) and Ferret (Mustela putorius furo), all mammalian predators introduced to New Zealand. Charlie Marshall, (CC BY 2.0), https://www.flickr.com/photos/100915417@N07/49407663736; Jesus Duarte, (CC BY-NC-ND 2.0), https://www.flickr.com/photos/26795194@N00/8897432606; Amanda and William Explore, (CC BY-NC 4.0), https://www.inaturalist.org/observations/120567285; Max Moreau, (CC BY 2.0), https://www.flickr.com/photos/9426349@N07/6085681724.

    The results from this trial confirmed that the ferret odour was the best for attraction, at least for stoats and hedgehogs, while rats avoided the ferret odour. Other studies have also found that rats avoid fresh odours. Stoats showed the strongest attraction to the ferret odour, with double the number of stoats being observed at the monitoring stations compared to fresh rabbit meat. These results can lead to exciting new possibilities to improve the monitoring and management of these species, especially in places where they are predicted to be rare.

    One surprising result that was found was that the population of stoats at Toronui station before the study began was estimated to be rare. After the study was completed, the stoat population was predicted to be widespread. This makes you wonder just how underestimated the population of stoats in New Zealand really is.

    Studies like this are important as New Zealand. With very limited native mammals, the native species, such as birds and insects, within New Zealand have had no need to adapt to mammalian predators. As a consequence when predator mammals were introduced into New Zealand they caused devastating damage to the endemic species.

    Ferret odour lures were found to last longer than the fresh rabbit meat lures. This means that the ferret odour lures can be left out in the field for a longer period of time and still work just as well. Rabbit meat lures become ineffective faster leading to underestimates of pest populations.

    The finding of the effectiveness of ferret odour as an attractant, especially in stoats, introduces a new tool and opportunity for pest management and conservation. It opens up many paths for future research to develop and learn more about this type of monitoring and the positive effects that it could have on our native species. More recent work has reported similar outcomes.

    Mammalian predators are a major threat to the unique biodiversity that we have in New Zealand. New discoveries, such as the use of dominant predator odour in predator removal, gives me hope that there is a future for our taonga, native species.

    The author Stacey Lewthwaite is a postgraduate student in the Master of International Nature Conservation taught at Lincoln University. This article was written as an assessment for ECOL 608 Research Methods in Ecology.

    Garvey, P. M., Glen, A. S., Clout, M. N., Wyse, S. V., Nichols, M., & Pech, R. P. (2017). Exploiting interspecific olfactory communication to monitor predators. Ecological Applications, 27(2), 389-402.

  • Is your house cat a ‘super-predator’?

    A bell on a collar is commonly used by cat owners to try to protect local wildlife. Or at least to avoid dead carcasses being presented inside the home. A study of domestic cat behaviour at the Ōruapaeroa/Travis Wetland, Christchurch, suggests that this approach may not be as effective as you might expect.

    Collar-bell warning devices are likely to be largely ineffective at reducing hunting success. This conclusion was drawn after a 12-month study of 88 domestic cats living close to the 119 ha wetland reserve. This is consistent with most (but not all) similar New Zealand and overseas studies. An explanation for such a confounding outcome may be due to a cat’s tenacity and ability to easily learn to compensate for the bell. Couple this also with the likelihood that birds don’t necessarily associate a bell warning with danger.

    Photo credit: CC BY-SA 2.0 Brandon O’Connor, Flickr

    Cat night curfew, another wildlife protection strategy required of responsible owners in Australia and promoted in New Zealand, may even be counterproductive. Many of our native species of birds and reptiles are mostly active during daylight. They hunker down and hide during night hours.

    Mice and rats prefer the evening for their foraging explorations. These rodents are invasive pests that do immeasurable damage to New Zealand natives species, including birds. Since cats, by cultural convention and scientific study, are known to prey on rodents, it might seem detrimental to lock them inside at night.

    Travis Wetland, is the last large freshwater wetland in Christchurch and is home to 53 species of birds. It has an estimated diversity of 700-900 invertebrate (mainly insect) species, many endemic to New Zealand. The urban cat research project at the wetland site was conducted by masters student Shelley Morgan, from Lincoln University. The study concluded that house cats in urban settings, bordering sensitive nature reserves like Travis Wetlands, do roam and incorporate these wildlands into their home ranges. There they target mostly rodent pests, but sometimes more precious native animals, like lizards and birds. Cats with bells were not any less effective in bringing home prey!

    On balance, you might think that domestic cats provide beneficial services to bird populations by controlling mice and rats. This view is widely debated, with some recent studies arguing that cat predation has an overwhelming negative impact on native wildlife especially in wetlands, braided rivers and along shorelines. Furthermore, it seems likely that just a few of the moggies are particularly troublesome. Some cats are ’super-predators’, exhibiting a high tendency towards hunting, often focusing on a favoured prey. It appears that this little clowder of cats may have a disproportionate impact on threatened native species. As confronting as these uncomfortable facts are, they need to be acknowledged and solutions sought. 

    Photo credit: CC BY-SA 2.0 Niels Hartvig, Flickr

    New Zealand has one of the highest levels of cat ownership in the world, with over half of households supporting at least a single cat. The social benefit of pet ownership, and the passion that we hold for our cats, should not be underestimated. A social licence to restrict ownership or cat movements will be difficult to achieve. Nevertheless, almost certainly within the community of cat lovers will be a myriad of ideas for limiting the danger to treasured native species.

    One option is to seek agreement for a suitably sized cat-free buffer zone between urban and nature reserves. Although a risk remains that the absence of domestic cats in a halo around a wetland reserve might just encourage remaining cats in the district to prowl further and expand their hunting range.

    The Royal New Zealand Society for the Prevention of Cruelty to Animals (RSPCA NZ) classifies cats into companion, stray and feral types in a recently published white paper. The organisation acknowledges the impact of free roaming cats on native biodiversity, but stresses the need to protect cat welfare and manage them humanely. The RSPCS promotes the need for cat owner self reflection, community debate and appropriate council bylaws. In the meantime, if you suspect that your beloved companion is a ‘super-predator’, perhaps consider a ‘Birdsbesafe‘ collar cover. Unlike a bell, the ‘birdsbesafe’ collar offers a colourful warning of a cat’s presence and alerts prey with good colour vision (birds and lizards).

    Morgan, S. A., Hansen, C. M., Ross, J. G., Hickling, G. J., Ogilvie, S. C., & Paterson, A. M. (2009). Urban cat (Felis catus) movement and predation activity associated with a wetland reserve in New Zealand. Wildlife Research, 36(7), 574-580. https://doi.org/10.1071/WR09023

    This article was prepared by postgraduate student Andrew Wells as part of the ECOL 608 Research Methods in Ecology course in his Master of Pest Management degree.

  • Seduced by the Stoat Stench

    As a child who was raised next to the ocean, I suppose it’s only fitting that the beach is my attractant. Something about the sand between my toes takes me back to when I was 6. My talents were at a peak as I managed to take the win in multiple sandcastle competitions. The sea gives me a sense of security and allows my mind to reset, clearing all worrying thoughts. And of course, it is the foundation behind most of my hobbies; fishing, diving, swimming (and sandcastle building). The beach has always been a part of my upbringing, a place where I enjoy the company of family and friends.

    This image has an empty alt attribute; its file name is Screen-Shot-2022-04-28-at-12.16.58-PM-1024x692.png
    Beach Day – CC BY-NC-ND Image by Anna Meban

    One of the things I found most interesting after a trip down to the beach was how my little jack russell paid far more interest in me when I returned home. Now maybe this had something to do with us neglecting to take him with us, but he would always sidle up to me, frantically sniffing and then stare at me longingly, as though I had betrayed him. He knew I’d made friends with a passing puppy on the beach and he knew that whoever had left these hairs entwined in my clothing was not him.

    It’s important to remember that these attractants differ, especially when they include scents such as urine, scats and bedding odours. Yes, you read that right, these are the types of odours that Lincoln University’s Elaine Murphy and James Ross, along with their fellow colleagues, investigated in terms of the power of attraction in stoats (Mustela erminea). More specifically their study discussed whether body odours of reproductively fertile (oestrous) stoats have the potential to be used as lures for pest trapping.

    Their study, published in the journal Animals, tested these lures in a series of lab and field trials. Lab trials were undertaken at Lincoln University and involved wild-caught stoats. The experiment was set out in a way where each odour sample was placed in a metal mesh tea ball, allowing stoats to smell but not interact. As well as this, a control sample was used, consisting of unscented Dacron, allowing stoats to choose between scented and unscented chambers.

    The field trials differed slightly, with the lure stations providing a menu selection of stoat odours and more traditional lures consisting of hens eggs and dried rabbit meat. The field trials took place in a range of New Zealand’s well-known locations, Abel Tasman, Lake Rotoiti (Tasman) and the Coromandel.

    Exploratory Stoat - By Charlie Marshall - https://flic.kr/p/2igZc6j
    Exploratory Stoat – CC BY 2.0  Charlie Marshall (Flickr) 

    This got me thinking about how important scents are as an attraction method for animals, even for humans themselves. It may be the scent of home-cooked meals in the kitchen. The strong scent of cologne as your crush walks by. The smell of salty air drawing me to the ocean and reminding me of home. Everyone has something they are attracted to but these things differ depending on the person… or species.

    In Abel Tasman and Lake Rotoiti, the trials compared fertile female stoat bedding odours to a dried rabbit meat block formulation. In the Lake Rotoiti trials, they also tested a combination of both lures together. It was the Coromandel trial that grabbed my attention, as this focused on whether male odours had the same charm as females. The trial was divided into two stages, first the male stoat bedding odour was partnered with either dried rabbit or hen eggs, and second, the male bedding odour was trialled on its own.

    The lab and field trials both showed very promising outcomes for the control of stoats. In the captive animal trials, stoats had greater interaction times with stoat odours than with the control dacron. Stoat odours were just as much preferred by stoats as the hen eggs and dried rabbit meat. Male odours were also equally effective attractants for both males and females showing interest in the scent of the opposite sex.

    So what can we do with these alluring aromas?

    Well, it is becoming increasingly more evident that food lures in the wild are not always the most effective way of targeting stoats when using kill traps and bait stations. Although these are the best techniques at the moment, conservation workers still struggle to catch stoats in many locations. Elaine and her colleagues mention how this is likely due to every individual having different preferences (basically a personality), as well as stoats being spoilt for choice in terms of food sources in certain areas.

    With all pest control there will be some animals that manage to dodge the bullet. The use of odour as a lure adds another technique into the mix. This new tool may be just what we need to increase chances of stoat capture rates in areas where food is abundant.

    Stoat - RSPB Sandy
    Stinky Stoat – CC BY-SA 2.0 Airwolfhound (Flickr) 

    What’s even better is that, as stoat populations begin to decline, this scent lures method will only become more effective! As desperation sets in and survivors scramble to find mating opportunities, they will lead themselves right into their own funky smelling fate.

    But wait, there’s more…

    From the results gathered within this study, it is thought that these stinky stoat odours may have even more potential than just capturing stoats. In conjunction with traditional lures, these odours also captured the attention of ferrets and rats. With the looming deadline of ‘Predator free 2050‘, this research could be the next step in trying to reduce these sneaky (and stinky!) pests.

    More research is now needed to figure out which chemicals are driving the attraction and how to produce these lures in a form that can be utilised nationwide, Elaine, James and their colleagues are on the trail of a breakthrough scent that has the potential to revolutionise predator trapping methods. Something to think about next time I’m at the beach.

    The author Anna Meban is a postgraduate student in the Master of Science – Conservation and Ecology taught at Lincoln University. This article was written for an assessment for ECOL 608 Research Methods in Ecology.