EcoLincNZ

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  • New Zealand’s most stubborn weed

    New Zealand’s most stubborn weed

    Cirsium arvense is commonly known as the Canada thistle in USA and Californian thistle in Canada. No one wants to take responsibility for these prickly things. They actually come from Europe where they are called creeping thistles.

    This thistle is a small weedy plant that can be a potential nightmare for New Zealand farmers. According to the NZ Ministry for Primary Industries, (2021), it cost the country $722 million in lost revenue in the year 2020 alone, up from $31 million in 2009.

    Photo by Make It Old (Flickr User)

    Given the disruptive nature of this weed, Wendy Kentjens, a budding weed ecologist with the passion for gardening, along with her supervisors, Seona Casonato and Clive Kaiser, decided to learn more about controlling the Californian thistle population on New Zealand pastures.

    To understand why Californian thistles are so weedy, Wendy decided to study the interesting microscopic world of the endophytes living inside, and how they may help or hinder the plant.

    Sounds straight forward! Well, it was far from that.

    Here is a summary of the challenges Wendy faced while carrying out research on Californian thistles.

    ‘Ah the prickly little devils…’ – Working with the thistles meant cuts and scratches all through the research.

    ‘Miss Unpopular, conducting pot trials at the nursery.’ – Turns out, planting weeds that no one likes is a fast way to make some frenemies.

    ‘The sheep ate my data!’ – Wendy found that the sheep initially didn’t eat thistles on pastures, but when they got infected with a rust fungus (Puccinia punctiformis), it made it very tasty for the sheep. She talks more about using rust fungas as a biocontrol agent in her paper “Californian thistle (Cirsium arvense):endophytes and Puccinia punctiformis” (Kentjens et al., 2024).

    ‘Hard to photograph the entire plant.’ – It can be really hard to see all the features of a plant from a single photo; Wendy’s mum made her a pencil drawing of the weed for her thesis.

    Figure drawn by Marion van Cruchten

    How do you find the microscopic endophytes within the thistle?

    To find all the endophytes present in these thistles, the bottom, the middle, and the top leaf of the plant were all cut into small 5 mm2 pieces and placed in a petri dish over a growing medium. Then, spore by spore, each different looking fungus was isolated into new growing dishes and incubated.

    Voila! Now Wendy had pure cultures of all the fungi she had found and was all ready for the next step.

    DNA from these pure fungal cultures was collected and identified.

    What did they find inside?

    A total of 88 genera of fungi were cultured from the plant tissue, of which 65 were not previously associated with Californian Thistles.

    The diversity found was a significant increase in our understanding of this infamous weed and what lives within its structure that makes it supposedly invincible.

    Fungal biocontrol can be an effective tool against these weeds. However, Endophytes can alter outcomes of a host–pathogen interaction. A recent study published by Manaaki Whenua (Landcare Research), found that 60% of all rust fungus released as biocontrol had a medium effect on the weed host or a variable effect. Around 15% of all rusts released as biocontrols have failed to become established at all.

    There could be a number of reasons for the variable or unsucessful results. In the case of the invasive Japanese knotweed (Fallopia japonica), two of the endophytes accociated with the weed (Alternaria sp. and Phoma sp.) hindered the establishment of fungal biocontrol by suppressing the production of rust pustules (raised masses of coloured spores that rupture epidermal leaf tissue). (Den Breeyen et al., 2022).

    Understanding these organisms living within the thistle will help future studies on the effective use of fungal biocontrol in fighting these “lovely” weeds. Looking at the endophytes and how they are helping these weed propogate so sucessfully will help us get one step ahead of it and hopefully find biocontrol agents that can circumnavigate these endophyte-host relationships.

    Note that the figure drawn by Marion van Cruchten is currently under review by the European Journal of Plant Pathology titled ENDOPHYTIC DIVERSITY AND COMMUNITY COMPOSITION OF CIRSIUM ARVENSE TISSUES OVER A GROWING SEASON. Authors Wendy Kentjens, Seona Casonato, and Clive Kaiser

    This article was prepared by Master of Science student Dee Patel as part of the ECOL608 Research Methods in Ecology course.

    References:

    Den Breeyen, A., Lange, C., & Fowler, S. V. (2022). Plant pathogens as introduced weed biological control agents: Could antagonistic fungi be important factors determining agent success or failure? In Frontiers in Fungal Biology (Vol. 3). Frontiers Media S.A. https://doi.org/10.3389/ffunb.2022.959753

    Kentjens, W., Casonato, S., & Kaiser, C. (2024). Californian thistle (Cirsium arvense): endophytes and Puccinia punctiformis. In Pest Management Science (Vol. 80, Issue 1, pp. 115–121). John Wiley and Sons Ltd. https://doi.org/10.1002/ps.7387

    Kentjens, W., Casonato, S., & Kaiser, C. (2024). Endophytic genera in californian thistle (Cirsium arvense (L.) Scop.). Australasian Plant Pathology, 53(2), 199–210. https://doi.org/10.1007/s13313-024-00972-w

    Ministry for Primary Industries. (2021). Economic costs of pests to New Zealand (Nimmo-Bell & Associates, Ed.; Paper No: 2021/29). Ministry for Primary Industries. https://www.mpi.govt.nz/dmsdocument/48496-Economic-costs-of-pests-to-New-Zealand-Technical-report

    – figure drawn by Marion van Cruchten is currently under review by the European Journal of Plant Pathology titled ENDOPHYTIC DIVERSITY AND COMMUNITY COMPOSITION OF CIRSIUM ARVENSE TISSUES OVER A GROWING SEASON. Authors Wendy Kentjens, Seona Casonato, and Clive Kaiser

  • Under Cover of Darkness: Moon Brightness and Mammalian Predator Activity

    Under Cover of Darkness: Moon Brightness and Mammalian Predator Activity

    Written by Kate McDowell

    Last June, I found myself several hours into what would end up being a sixteen-hour run, in the middle of the night, on the coldest weekend of the year. As the ground visibly started to freeze in front of me, I realised that my head torch was struggling in the negative temperatures. Its battery couldn’t cope with the cold exposure. But you know what, I had a trick up my sleeve; it was a full moon.

    I was guided by the incredible illumination of the moon on a clear winter night, and by how few animals I saw apart from the sheep and cattle of Lake Taylor station. As I left the station and entered Lake Sumner Forest Park, my headtorch flickered in the biting sub-zero temps of mid-winter New Zealand near the Southern Alps. I had barely heard a sound since nightfall, apart from my own crunching footfalls on freshly frozen tussock.

    There were no pest animals dancing in the moonlight that chilly midwinter run, and I found myself wondering if our mammalian pests changed their activity based on how bright that big ball of cheese in the sky was. In 2016, Shannon Gilmore did a neat study on the effects of moon phase and illumination on activity of five introduced NZ mammals (cats, rats, mustelids, possums, hedgehogs) for her thesis at Lincoln University. 

    A trail runner foolishly runs 16 hours over an alpine pass, whilst being watched by introduced predators who may or may not be contemplating consuming the body of said runner. [Source: Chat GPT AI, Kate McDowell]

    I seemed to be one of the few introduced mammals blatantly puffing my way up the North Branch Hurunui riverbed. I have this strong memory of looking down and watching myself be followed by my own moon shadow. It made me question – how many eyes were following me in the dark canopy of the nearby beech forest?

    Gilmore found that increased vegetation cover and rain were contributing factors to pest detection. Sites with dense canopies had higher detection rates, potentially because they provide better shelter and reduced exposure from threats like light. While rainfall was not a statistically significant factor, pest activity generally decreased with rainfall. Gilmore suggested this may be because it is cold or the rain might be disrupting the animal’s sense of smell.

    So maybe my paranoia about forest animals staring me down wasn’t so crazy after all. It was certainly interesting to think back on the run and how many introduced predators there could have been in the nearby beech forests. The conservation implications for understanding where predators are and why they might change their activities also gave me some things to mull over the next day.

    Detecting these introduced predators is essential for informing control efforts; we need to know where predators are and how many of them are in a given area. Environmental conditions may be obscuring the predator’s true activity levels. Gilmore added to previous studies of moon phase effects on mammals by accounting for interaction effects of weather and vegetation. Whether these effects were caused by the lower light levels or by something else not explored in this study is yet to be answered.

    Many studies have looked at the role of moon phase and animal activity, but in 2016 few studies had investigated the additional factor of the moon’s brightness. Gilmore was the first to measure hourly light levels through the night and looked at how it affected the activity level of the nocturnal pest species. A highly sensitive light meter (Sky Quality Meter, or SQM) to measure illumination levels between moon phases in the Blue Mountains (Otago), Banks Peninsula (Canterbury) and Hawkes Bay.

    Gilmore found that while moon phase could not explain pest activity, moon illumination did. As the dark side of the moon grew larger, pests seemed to thrive under cover of darkness and became far more active. When the moon hits a mammal’s eyes, Gilmore theorised that they may be spurred to hide. Most introduced mammals in NZ are prey in their native countries and it is hard to say whether a single century of living without their native predators has changed their behaviour.

    SQM successfully managed to detect differences in illumination between moon phases and under different canopy cover levels. Canopy cover was found to have a larger impact on illumination than moon phase. SQM findings on Banks Peninsula suggested that on darker nights a pest is more likely to be active.

    Building on earlier research, Farnworth, Innes and Waas (2016) released a paper looking at the effect of light on mouse foraging behaviour. This study agreed with Gilmore’s results, finding that mice displayed strong preferences for foraging in unlit areas. Farnworth et al. further built on Gilmore’s conclusions by contemplating that artificial light could provide protection from predators in ecologically sensitive areas – for instance, in areas where predator proof fences have been breached by a tree limb dropping on it.

    Predator proof fence study by ZIP scientists showing a rat trying to escape. [Source: ZIP (Zero Invasive Predators Ltd), used with permission]

    The innovative organisation Zero Invasive Predators (ZIP) completed an interesting follow up study in 2018, focusing on whether or not light could deter rats from entering an area. They found that although light did not limit rats passing through, they were less likely to linger in lit zones. Their conclusion: illumination could be used in a layered deterrent system, where light is used to slow down pests.

    Conservation in NZ is generally hamstrung by lack of funding. Efficiency is key to making the most of the meagre dollars on offer, so studies like Gilmore’s can help optimise monitoring and control operations. So when that bad moon comes a-rising, you can bet that pest control and monitoring will be less effective, and it would be more useful to focus efforts during darker nights.

    I definitely felt exposed running through a riverbed under a full moon, so I can appreciate how light can serve as a useful predator deterrent. It’s another tool we should add to the belt as we work toward a predator-free country.

    We’ve reached the end of our illuminating lunar article, but the real question now is how many song references did you pick up on? 😉

    This article was prepared by Master of Science student Kate Morrison as part of the ECOL608 Research Methods in Ecology course.

    Paper: Gilmore, S. (2016). The influence of illumination and moon phase on activity levels of nocturnal mammalian pests in New Zealand (Master’s thesis, Lincoln University).

  • The Magical World of Grass and Clover

    The Magical World of Grass and Clover

    *Disclaimer: This article contains Harry Potter references

    After four years of living and studying together, you would think you know someone pretty well. Alas, last week it turned out one of my flat mates had never seen (or read) Harry Potter… shocked, heartbroken, and outraged – the only way to solve this flat feud was to start from the beginning and watch Harry Potter and the Philosopher’s Stone.

    The next day, it was back to study. However, I couldn’t get the wizarding world out of my mind, especially knowing that the second movie, the Chamber of Secrets, was scheduled for that night. It got me thinking. Every hero has a sidekick. Batman and Robin, Frodo and Sam, Harry and Ron. But what if these iconic heroes don’t only exist in the worlds of Gotham City, Middle-earth, or Hogwarts. What if the heroes on this earth have sidekicks too?

    Legumes (like clovers) are heroes. Destined for greatness and capable of incredible things, they can capture nitrogen (N) from the atmosphere and convert it into ammonia, a biological form of nitrogen that fuels the ecosystem. Farmers often incorporate clovers into their pastures to provide nitrogen into the system. Because of their magic-like nitrogen capturing abilities, clovers boost the growth of neighbouring grasses and create an increase in food quality and quantity for grazing animals.

    White Clover (Trifolium repens). CC BY 2.0. Harry Rose

    It is generally understood that this is a one-way relationship, meaning clovers are humble heroes that provide N to the grasses and plants surrounding them. However, through my muggle research, I came across a recent study titled “Grasses procure key soil nutrients for clovers” by PhD student Zhang Wei.

    Could it be? A sidekick to our green three-leaf (sometimes four if you’re lucky) hero?

    Wei and his team questioned whether we properly understand the relationship between clovers and grasses. For the purpose of this article, let’s think of clovers and grasses as characters to understand better their relationship and how they work together.

    Perennial Ryegrass (Lolium perenne). CC BY-SA 4.0. Michel Langeveld

    Different plant species have various magic-like abilities to acquire nutrients. Grasses, for example, are potion makers and can release chemical substances into the soil to make elements such as iron (Fe), zinc (Zn), copper (Cu), and manganese(Mn) more available in the soil. Other plants call on the Room of Requirement and collaborate with fungi to increase access to nutrients through the fungal networks. Like how the Room of Requirement appears for those who need it most, fungi create symbiotic relationships with plants, enabling more nutrients to ‘appear’ and become more accessible in the soil. And clovers, as you now know, use their spellwork to fix atmospheric nitrogen (N).

    However, just like the spell “Wing-gar-dium Levi-o-sa” requires a certain pronunciation, N fixation requires a certain nutrient – phosphorus. Phosphorus is a nutrient constantly in high demand for clovers due to N fixation being such a taxing process.

    Zhang Wei and his research team carried out experiments to better understand how grasses influence the nutrient availability for clovers. Clovers and grasses were grown separately in individual pots, much like Harry living alone in the cupboard under the stairs. They were also grown together in shared pots, similar to Harry and Ron bunking together at Hogwarts. Measurements were then taken from the soil and leaves in all the pots to understand how the clovers and grasses influence each other’s growth.

    The researchers found that grasses promoted the growth of clovers when grown together. This was evident when higher amounts of nutrients such as nitrogen (N), phosphorus (P), potassium (K), and sulphur (S) were found in clover leaves growing with grasses compared to clovers that grew alone. Grasses give clovers a boost in accessing essential nutrients, much like how Ron supports Harry, offering the strength and loyalty he needs to face He-Who-Must-Not-Be-Named.

    Mixed sward of White Clover (Trifolium repens) and pasture grasses growing together. Nicole Parnell. 2025.

    Additionally, more biomass was achieved when both clovers and grasses were grown together compared to when they were grown apart. How would Harry have gotten through his years at Hogwarts without his friends by his side? They achieve more when they work together. By sharing their resources, the plants could increase their biomass, which boosts livestock feed while lowering fertiliser demand.

    The muggle authors acknowledge that more research is needed to fully understand the complexities of how nutrients move through the soil in plant communities like this, especially under field conditions. In 2023, Zhang Wei and his supervisors took the study into the field and, once again, saw enhanced legume growth when grown alongside a diverse range of pasture grass species. Think of Harry’s resilience and leadership, Ron’s loyalty and humour, and Hermione’s intelligence and discipline, all of which work together to create a strong, unbeatable partnership. Similarly, there is an enhancement of nutrient uptake in diverse pastures with legumes (including native legumes) and grasses. This suggests a possible reduction in fertiliser requirements in pastures with increased plant diversity.

    A study that referenced Zhang Wei’s work similarly found that plant mixtures with various legume and grass species reduced intraspecific competition, a term that explains competition between individuals of the same species (think Gryffindor vs Slytherin). This means that the growth and productivity of both legumes and grasses were further enhanced when grown together.

    Zhang Wei’s PhD study provided further insights into the flow of nutrients within plant communities, demonstrating that grasses also play a vital role in nutrient availability and enhancement. This study builds on the argument that pasture diversity can reduce reliance on artificial fertilisers and promote sustainable farming methods. These methods can increase the ecosystem’s stability, making it more resilient to disturbances such as droughts and/or floods. Like any partnership, growing together makes them stronger.

    That’s where the magic happens.

    This article was prepared by Master of Science student Nicole Parnell as part of the ECOL608 Research Methods in Ecology course.

  • Detecting red panda, dancing with Kate Bush

    Detecting red panda, dancing with Kate Bush

    I’ve been a fan of Kate Bush since she released ‘Wuthering Heights’ when I was 10 years old. She famously does not tour or give shows and so I have never had the chance to see her live. A couple of weeks ago a tribute act ‘An evening without Kate Bush’ came through Christchurch. Great! I booked tickets and dragged Julie along.

    My wife is a long suffering SOKF (spouse of Kate fan), but she was happy to indulge me. Little did she know what was in store. It was a great show. Sarah-Louise Young danced and sang very well and was quite funny. Kate Bush always walks a fine line between quirky and bonkers. The Piano audience had a good time.

    The show was quite interactive. At one point Sarah-Louise asked what our favourite Kate song was. I stuck up my hand and she came over. In addition to the song (Get out of my house), she was interested in whether Julie was a fan (not particularly) and how long we had been married (30 years).

    As she turned to go, Julie added “Oh and Adrian proposed to me in a Kate Bush way.” Well that was that. Julie was then explaining The Dreaming album cover, the ring, the kiss and so on. Much hilarity ensued.

    The show continued on. We got to ‘Don’t give up‘, the song sung by Peter Gabriel with Kate. Sarah-Louise wanted a couple to come onstage and of course that was us. We had to slow dance for the song (much as happens in the video). That’s 6.5 minutes, or an eternity on the stage.

    So, there we were, literally, in the spot light, in front of 325 people. I didn’t find it too bad. I focused in the dancing and not tripping over. Julie was very uncomfortable and most definitely not herself. We reflected later that I am more used to ‘performing’ as a lecturer in front of crowds. Julie is a teacher but only has much smaller groups to perform to.

    I think that we did OK. It turned out that there were a couple of people in the audience who new us and messaged that we did some good dancing (probably they were just happy that they hadn’t been picked to do it).

    As we quietly swayed and turned on stage I did reflect on how the knowledge of being observed really does affect the behaviour of individuals. This links through to my research where I am often making observations of individual birds and mammals.

    A gaggle of red panda! Image from Sonam Tashi Lama

    Recently, we have been using trail cameras to get a better understanding of red panda, and other mammals, in their habitat of eastern Nepal. In these areas red panda are relatively cryptic and declining. Grids of cameras offer a way of observing red panda over long periods of time without humans needing to be nearby.

    Cameras can tell us about the distribution of species over daily and seasonal cycles (Collecting mammals: camera traps in eastern Nepal). We also observed that panda do notice the cameras and that this can lead to subtle changes in their behaviour (I see you: Sauron and the panda).

    In this work with Sonam Tashi Lama (Red Panda Network), and published in the Wildlife Society Bulletin, we set up 19 sites in the alpine forests of eastern Nepal. At each site we had two cameras, one set up in a typical manner at ground level and the other in the tree canopy 5 m above. The cameras collected data over several months.

    We found that red panda were active over the whole day (gotta eat a lot of bamboo and other vegetation!) but activity peaked around dawn and again at midday.

    Arboreal cameras took four times as many photos as ground cameras. These were mostly of leaves blowing in the wind but they were eight times more effective at capturing red panda images. These behaviours included action activities (e.g. tree climbing), clear images of faces, and motion‐lite activities, like sleeping and grooming.

    Image from Sonam Tashi Lama

    So, now we know that cameras can affect the behaviour of red panda being observed and that the placement of the cameras can affect how successful our observations are. Is this a problem? Perhaps, but it is better to know there is a problem when we conduct future research. Also, the information that we are gathering, even if there is some biases, is still way better than not knowing anything.

    We will take the net gain in what we now know about red panda and that can help us with managing them and their habitat.

    It was nice to be reminded about how it feels to be observed. Whether it is 300 Kate Bush fans or a trail camera, there is a physical reaction to knowing that something is out there and perhaps it is watching you. It’s something to keep in mind when designing these studies.

    Oh and don’t put your hand up when you are in the audience of these kinds of interactive shows!

    Adrian Paterson is in the Department of Pest-management and Conservation at Lincoln University. Now that he thinks about it, he has spent a lot of his research prying into the private lives of animals.

  • How to help lizards in your back yard/paddock

    How to help lizards in your back yard/paddock

    Has your cat ever brought in a nice present only for you to find it’s a lizard? Have you seen a lizard scutling away on a nice sunny summer’s day while walking around the garden? Well, you may have lizards residing in your back yard!

    In New Zealand we have over 125 different lizard species, 76 are skinks and 48 are geckos, all but one one skink species is native. Of these 126 species, 49 (~36%) are Threatened and a further 67 (~50%) are At Risk (Hitchmough et al., 2021). Therefore 86% of our lizard species are threatened by various factors, such as predation, urbanisation, habitat fragmentation, and agricultural intensification.

    We all need to play our part to ensure that lizards do not continue to decline.

    There are simple tools we can use that can help the lizards in our back yard. Skinks love to hide under rocks and in small gaps when startled. Geckos love to live in tight crevices, like spaces in wood, stone and even in various human-made structures (e.g. power boxes and garages).

    We can create structures called Artificial Retreats (ARs) that mimic these natural retreats that lizards love so much. Artificial Retreats are a tool that we can easily implement that can support vulnerable lizards.

    Currently, artificial retreats have been designed for scientific monitoring and are commonly constructed from roof-cladding Onduline sheets, which isn’t an easily accessible or cheap material. My thesis investigated two other alternative designs that are constructed in a manner that is easily accessible to landowners and public members keen to do their part in lizard conservation.

    One AR type was constructed from a stack of three bricks (Figure 1) that have a 10 mm wooden dowel stuck between each layer so that the lizards can easily move between them.

    The second was constructed from two plywood sheets (Figure 2), bolted together, with the 10mm dowel in between the sheets.

    The third was the common Onduline design (Figure 3). I tested these ARs across Canterbury farms located at Cleardale Station in the Rakaia Gorge, as well as Flea Bay and Goughs Bay on Banks Peninsula.

    I captured 26 lizards to test in the three AR designs and there was no preference among the three. However, the geckos at Cleardale Station preferred some designs more than the Flea Bay lizards. At Flea Bay, the lizards were more commonly found in the brick (46%  of all geckos) whereas at Cleardale they didn’t use the brick ARs. At Cleardale Station, a equal number (17%) were found in both Onduline and wooden ARs. At Flea Bay, 17% lizards were captured and only 4% of lizards were found in the Onduline design at Flea Bay.

    Depending on the location of the property and the species of lizards present, there will be differences in which AR they prefer. Having an option of several different AR designs is preferable. 

    During the field trials I found that the ARs did not withstand heavy stock (cattle)interactions and were frequently interfered with. However, I did not have any problems with ARs placed in sheep paddocks.

    Landholders can implement any or all three of the designs into their property and all have a chance of lizard occupation. A variety of designs means that landholders can choose which AR design to use based on what available materials they have.

    Having a choice of AR designs make it accessible to whomever wants to conserve lizard species on their properties without having to spend large amounts of money or spending valuable time having to source the materials to construct the AR.

    Key design components and considerations when planning and building lizard ARs.

    • The ARs need to have at least one gap that has a 10mm gap.
    • Placed in an area where lizards or their poo have been seen.
    • Recommended not to be placed in a paddock in cattle.

    Acknowledgements: A massive thank you to the financial support for this project from The Brian Mason Trust and the North Canterbury Forest and Bird Trust.

    Reference

    Hitchmough, R., Barr, B., Knox, C., Lettink, M., Monks, J., Patterson, G., Reardon, J., van Winkel, D., Rolfe, J., & Michel, P. (2021). Conservation status of New Zealand reptiles, 2021.  

    Written by Sam Fitzgerald, a MSc student in the Department of Pest-management and Conservation at Lincoln University.

  • PAPP: A humane toxin for feral cats in New Zealand?

    Can a cute-looking animal turn into a fierce demon? Yes, when cat moves from a snoring heap on your couch to hunting birds and reptile species. Cats have been silent killers in New Zealand for decades. It is estimated that 100 million of birds are killed by cats every year in New Zealand. As the sun sets, here comes the giant, big-eyed bully— FERAL CATS.

    At night, birds and other native species seek shelter in their homes, shutting their doors, but feral cats can break the lock and drag them out of their houses, feasting on them. That sounds demonic!

    Justice may be on the horizon. A charming, dashing, handsome saviour of the birds is coming. Ladies and gentlemen, of the bird world, and reptiles as well, let me introduce to you your saviour. Para-aminopropiophenone! That’s a big name for a saviour; let’s shorten this to PAPP (say it like ”pap”).

    PAPP being developed as a new, humane poison for feral cats by Connovation NZ Ltd. Importantly, mammals are more susceptible to PAPP than birds are. PAPP kills feral cats more humanely than previous toxins, as it acts faster and is less aversive.

    Two fierce demons hunting a poor little bird (Image by- Gilbert Mercier, Flickr user)

    News of the introduction of a new toxin on the market is spreading like wildfire in the wildlife world. “But we should never celebrate too early,” an old Kea is saying, and Old Ben Kokako adds “We must be cautious“.

    To measure PAPP’s effectiveness, a two-phase trial was conducted by researchers Murphy, Shapiro, Hix, MacMorran, and Eason. The first trial was undertaken at two sites in North Canterbury. The second trial was undertaken on the central plateau in the North Island. Cats were trapped in Havahart live capture traps and were radio-collared to monitor their activities. Submarine bait stations, which are designed to target cats only, were stationed in the field. Three infrared monitoring cameras were also placed to monitor cats’ activities in the field area.

    And the hunt begins… (Image by- Pinke, Flickr user)

    The cats were first pre-fed so that they got used to the bait. Toxic baiting was then carried out by placing meat baits (minced beef and minced rabbit) containing 80 mg of PAPP at bait stations. The birds were eagerly waiting for the results of the trials. “Patience is a virtue” is an old saying in the reptile family.

    Five out of eight radio-collared cats and six other cats were poisoned found dead at the site. That was a huge success for the team, as the trial results showed the efficiency of PAPP. Another result from the North Island was just as promising. 13 cats out of sixteen radio-collared were found dead, and there were three more without the radio collar. So, a total of 27 cats from both islands were found dead. The remaining radio-collared cats appear to have left the area before the poison-baiting trial started.

    The result was great news for the bird and reptile world. Some of the birds were still suspicious about PAPP’s effectiveness. The matter was solved when the researchers showed the results of an earlier cage trial in which 18 out of 20 cats died and suggested that PAPP is an effective new tool for feral cat control in the field. During this trial, the cats who partly ate the bait also died, which shows PAPP’s overall effectiveness.

    Another question raised by an old Canterbury gecko was "what about the susceptibility of birds and reptiles to PAPP?". As in Australia, studies suggested that bandicoots (small marsupial mammals) and varanid lizards were highly susceptible to PAPP. It was a matter of great concern for both researchers and the native animal world. But it was also resolved as there was no evidence that some non-target species were also eating PAPP in the NZ trials, as the submarine bait stations used in the trials helped ensure targeted delivery.
    cute but alert… (Image by- patrickkanavagh, Flickr user)

    The researchers concluded their findings by addressing the non-target delivery of PAPP by developing efficient delivery systems, like bait stations, tunnel systems, or specific bait presentations that exploit the cats’ foraging behaviour. They also found that PAPP is the most humane way to kill feral cats among all the toxins found on the market as cats died within one to two hours. It acts fast and is less aversive.

    It was a sigh of relief for birds and reptiles because they had found a saviour. PAPP is a great solution to eradicating feral cats more efficiently. It is a true silent killer and a good alternative to sodium monofluoroacetate 1080 (another toxin used for poisoning). 1080 also affects non-target species, when delivered aerially, whereas no such effects were seen in the case of PAPP when delivered through submarine bait station for targeted delivery. So, PAPP isn’t just a funny name, it’s a glimmer of hope for New Zealand’s wildlife, and a demon-slayer!

    This article was prepared by postgraduate student Sikander Nagal as part of the ECOL 608 Research Methods in Ecology course in his Postgraduate Diploma in Applied Science degree.

    Original Article- Control and eradication of feral cats: field trials of a new toxin

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  • Why don’t restored streams bounce back?

    In New Zealand, many would agree that fresh water is one of our most loved natural resources. We drink it, we swim in it, we use it to farm and to make a living, we even use it to generate our power! Unfortunately, especially in Canterbury after some major earthquakes, many of our streams and rivers are struggling. They look something like this:

    Kowhai River, Kaikōura. From Environment Canterbury, ND.

    In stream restoration, we want to return the features of a stream back to their original state, before things like urban development or introduced species affected the quality. This includes adding native plants, allowing fish to make their way out to sea or further upstream, and making sure farm animals can’t walk straight into the stream. All of these things and more can help us to make healthier waterways.

    It does not always go to plan, with some hardy introduced species putting a spanner in the works and refusing to co-operate with careful scientific methods. Imagine a beautiful stream that’s been through tough times—pollution, habitat destruction, earthquakes you name it. People step in – scientists, council members, developers, maybe the general public, and they work hard to restore it, but here’s the kicker: sometimes, things just don’t bounce back like they should. Why? That’s exactly what a recent study by Issie Barrett and her team set out to uncover.

    To understand why streams struggle to recover even after the most thorough restoration efforts, we need to understand a few key factors.

    1. Species Interactions: In a healthy stream, different plants and animals interact in specific ways, such as some animals eating others or different plants competing for space. When a stream is damaged and then restored, these interactions might not work the same way anymore. This can make it harder for the original species to come back and thrive.

    A particular species of snail, the New Zealand mud snail (P. antipodarum) is particularly good at living in these degraded streams, they thrive under pressure and limited food sources. These snails are perfect species to take over a degraded environment and reduce the recovery ability! So even when original species are introduced, such as the mayfly, the same food source now has double the competition, meaning a negative reaction – that habitat can’t provide that much food even in a restored state.

    New Zealand mud snail Potamopyrgus antipodarum. Photo Credit Michal Maňas 2014

    2. Negative Resistance: This is a big concept, which in essence means that even when the physical conditions of a stream improve (like cleaning up pollution or adding new habitats), the plants and animals in the stream don’t always come back as quickly or fully as hoped.

    During the stream’s degradation years, new species like the mud snails might move in – kind of like uninvited guests crashing a party. Even after things are cleaned up, these newbies can stick around and hog resources, making it harder for the original gang to make a comeback. This is what they call “negative resistance.” This can happen because the habitat is too degraded for the ideal species to thrive even if they did before.

    3. Resilience Mechanisms: This means the ability of a system to absorb and adapt to change, ultimately returning to the restored ideal. This is where our negative resistance comes into play. If the species or the system is already not functioning as it should, we are going to have a hard time creating a resilient system that can adapt to a changing environment and overcome any future issues.

    For example, a high level of nitrogen could change the make-up of the riverbed so drastically that a species sensitive to nitrates may never repopulate that system. Understanding the relationship between negative resistance and resilience is important for predicting and enhancing any successful restoration efforts.

    What can we do?

    Look at the Big Picture: When restoring a stream, it’s not just about fixing what we can see. We need to think about how all the different plants and animals interact with each other. This includes what nutrients are in the water and what microscopic invertebrates might be living in that water.

    Keep Checking In: It’s important to keep watching restored streams over time to make sure they’re getting better and to fix any problems that come up. If we don’t see an improvement in 5 or 10 years, there must be something else we can do.

    Be Flexible: Sometimes, we might need to change our restoration plans based on what we learn from watching how the stream responds. As scientists we have to be okay with admitting our first idea didn’t work, and then be willing to help come up with a better solution for the future.

    Vegetated drain in Canterbury with optimum riparian planting. Photo credit Jon Sullivan, ND.

    Why it matters

    Overall, there are some pretty complex systems that are at play in stream restoration projects. It is not as simple as putting in some better plants and some bigger, cooler rocks and hoping it will all work out in 10 years. By paying attention to how plants, animals, and the environment all work together, perhaps we can work towards a deeper understanding of the best ways to help our New Zealand streams thrive for many more generations to come.

    I think it would be pretty cool to keep swimming in our rivers and looking for fish in the summer, but next time you go to your local river, have a look and see what plants and other animals would really love to keep living there too.

    This article was prepared by Postgraduate Diploma in Environmental Management student Tayla Cross as part of the ECOL608 Research Methods in Ecology course.

  • Echoes of misunderstanding: Invasive species or welcome guests?

    In a new age of ‘fake news’, the exponentially growing ChatGPT, and being talked at by your climate change-denier uncle at the dinner table, how do we know who to trust? Well, the scientists obviously. But what happens when the scientists get it wrong?

    An article released in January of 2024 “Systematic and persistent bias against introduced species” by Patricio Pereyra and colleagues, ruthlessly called out conservation biologists for demonstrating a bias against introduced species. Researchers were accused of shedding a negative light on introduced species no matter their taxonomy, habitat, time of introduction, and regardless of their attributed harm.

    Photo: Amelia Geary / Design: Archi Banal

    Pereyra speculated that the invasion of zebra mussels in North America had a strong impact on the establishment of the bias. Most cases of negative framing in publications were from North America.

    A month later, a counterargument article, led by Dan Simberloff and including Phil Hulme from Lincoln University, was submitted to the same journal. This response tore Pereyra’s article to shreds. For example, there is so much more published material labelling invasive species as harmful simply because most research is driven by funding to deal with harmful species.

    The “guilty until proven innocent” was seen by Pereyra as a bias, whereas Simberloff argued that it was the safest approach. Better to prevent outbreaks first rather than assume innocence and scramble to clean up the mess later.

    The validity of Pereyra’s research methods was also called into question. In their assessment of 300 publications, Pereyra and colleagues based their assessments on only the introduction of each paper, the section where no current research is reported. Pereyra stated that no non-native species have caused any type of extinction, by citing a study that only assessed their impact on native plants. This would be news to those in New Zealand dealing with the impacts of introduced mammalian predators. In addition, all of the assessments made in this article were made by two authors, with a third brought in when those two disagreed.

    Photo: Author

    Pereyra and colleagues continued to selectively use evidence that matched their hypothesis by making continual reference to the ‘tens rule’. This states that only 1% of non-native species will become pests. As more research on more diverse taxa was undertaken, this rule became a misleadingly low estimate. In fact, it is estimated that 50% of invasive vertebrates lead to harm. So while modern conservationists are able to recognise that the tens rule is outdated, the average person reading at home will not.

    This is just a tiny example of a much larger problem science is facing right now; the power of a harmful narrative in science and its implications for the general public. The science world has been struggling for a while now with issues like P-hacking (selecting data analyses that produce results aligning with their hypothesis), fraudulent scientific papers making it to publication (fabricating research that has not taken place to boost career accolades and experience in industry), and like the mentioned article, lack of rigorous scientific procedure.

    False science can turn certain areas of science into a debate to be had by those who are not fully equipped enough to have it. By now I believe just about everyone in the Western World knows about the reports that vaccines cause autism, an idea that originated from two academic physicians in the 1950s.

    Image: outtacontext

    Over 70 years later there is a massive group of people who still believe this to be true, despite countless modern scientists disproving this idea. Not only do scientists have to conduct research to further the field, they now have to spend countless years using countless resources trying to prove to the public that the beliefs they are so desperately holding on to are, in fact, not accurate.

    While the article accusing scientists of holding a bias against non-native species may not have such a wide reach as the vaccine debacle, it does have the ability to change the minds of people. It can change the environmental beliefs they hold, the way they look at conservation, and the future research they conduct, as well as aligning with their personal beliefs outside the world of science. It creates issues that would otherwise not have arisen; spreading misinformation, fostering unwarranted skepticism, and contributing to the polarisation of environmental issues.

    For example, the Pereyra paper could cause shifts in perception, such as questioning established ecological principles, potentially undermining conservation efforts aimed at preserving native biodiversity. This can have a ripple effect, influencing policy decisions, funding allocations, and public support for important conservation initiatives. While openness and debate in the scientific community is important and should be encouraged, you simply have to get your facts right.

    So again I ask, what happens when even the scientists get it wrong? Actually, it happens all the time. Trial and error are the engine of science! Scientific theories are tested to be disproven to ensure we actually have a full understanding of whatever it is we are studying.

    People at home can also look to disprove scientific theories. Pay attention to the transparency of the method and study size, credibility of sources, and citations from reputable journals and research institutions. It may not save your life, but it will save you from a lifetime of ill-informed conversation around the dinner table. You don’t want to be that relative.

    This article was prepared by Master of International Nature Conservation student Alexandra Paish as part of the ECOL608 Research Methods in Ecology course.

  • Wild hunters: Unveiling the hidden leopards of northern Pakistan’s borderlands 

    Our adventure begins in the breathtaking north of Pakistan, where the majestic peaks of the Himalayas, and their foothills, stand as one of the last sanctuaries, a place where the sky meets the earth. Here, clouds drift over rough mountains and lush valleys, into dense forests. Glistening lakes and spectacular waterfalls shape this natural paradise.

    In this wilderness, the air echoes to the calls of rhesus monkeys, while wild boars wander through the underbrush. The Himalayan red fox prowls the mountains, on the hunt for colourful pheasants, a tale as old as time. 

    But the fox is not the only hungry predator in these forests. A top predator, larger and stronger, with a powerful bite and covered in unique dots, reigns in the mountainous range. The majestic leopard (Panthera pardus), a mysterious and shy creature, expert at camouflage, is prowling these forests.

    Leopards are amongst the most iconic big cats. Just like other big cats, leopards are endangered. Human activity and landscape alteration pose significant threats to their survival. When leopards and humans cross paths, conflicts arise, turning this top predator from hunter to hunted. 

    Panthera pardus fusca is described as larger subspecies, with brighter
    coloration and smaller rosettes (Bellani, 2019).

    Photo Credit: CC BY 2.0 DEED, taken by Rupal Vaidya in October 2016

    Leopards are generally cryptic and shy, much remains unknown about these ferocious hunters. 

    Muhammad Asad, a PhD student at Lincoln University, started his dangerous journey to this wild region in the north of Pakistan. The dangers of the landscape were not limited to wildlife; humans also posed a significant risk in this troubled region. Undeterred, Asad was ready for the challenge that lay ahead. 

    Leopards are amongst the world’s most widespread carnivores, ranging from Africa to Asia. Prowling over such a vast distribution has led to the recognition of several subspecies, most of which are endangered. The forests in the north of Pakistan are known to be home to leopards, but their subspecies status has not been assessed.  

    Contrary to the legend of water-shy cats, leopards are excellent swimmers. Still, the mighty Indus River was believed to act as a barrier between populations, maybe even keeping subspecies apart.

    To unravel this mystery, Asad and his team collected and analysed tissue samples from leopards. Modern techniques have created a genetic tool as powerful as its name: mitochondrial DNA (mtDNA). Mitochondria, the powerhouses of our cells, have long been known for their role in providing power for our cells. These powerhouses also carry their own DNA, passed down maternally, making mtDNA incredible useful for studying population dynamics and subspecies differentiation.

    A key protein encoded on the mtDNA, NADH 5, is essential for energy production and is highly variable among big cats, making it an excellent candidate gene for subspecies identification.

    Through their research, Asad and his team found two distinct subspecies of leopard in the north of Pakistan, P. p. saxicolor and P. p. fusca, both belonging to the Asian group of leopards.   

    Panthera pardus saxicolor is commonly a bigger subspecies and is often
    more pale coloration, with bigger rosettes (Kiabi et al., 2002).

    Photo Credit: CC BY 2.0 DEED, taken by Guido Konrad in July 2021

    These findings mark the first subspecies identification in this region and hold significant implications for conservation efforts. The coexistence of both subspecies in the same region suggests an interesting natural corridor that connects leopard habitats, offering hope for their conservation in the face of habitat fragmentation.

    At the same time, discovering two subspecies living in the same area opens up the possibility of them interbreeding. This can create some challenges for conservation. We might wonder: could one or both of these subspecies disappear over time? Or will they blend together and create a new subspecies? Hybridisation is very unpredictable, which is why it’s important to work on conserving both subspecies. They each have unique evolutionary histories, which are the product of thousands of years of adaptation and survival, and could potentially be lost due to this phenomenon called hybridisation.

    These findings not only help leopard conservation in the paradise of the Himalayan belt in the north of Pakistan, but also contribute to global conservation efforts to protect this amazing species. By identifying subspecies and unveiling their genetic patterns, we can better protect them. It is important to protect both subspecies, which helps protect the overall species Panthera pardus.

    This article was prepared by Master of International Nature Conservation student Eric Tscherbatko as part of the ECOL608 Research Methods in Ecology course.

    Thank you to all scientist who contributed to these amazing results, namely Muhammad Asad, Francesco Martoni, James G. Ross, Muhammad Waseem, Fakhar I- Abbas and Adrian M. Paterson for your important work!

    Asad M, Martoni F, Ross JG, Waseem M, Abbas F, Paterson AM. 2019. Assessing subspecies status of leopards (Panthera pardus) of northern Pakistan using mitochondrial DNA. PeerJ 7:e7243 https://doi.org/10.7717/peerj.7243

  • Microbes matter in breaking down nitrogen in dairy pastures

    Our eyes are captivated by the breathtaking diversity of the living world, where billions of plants and animals enchant us with their variety and richness, thriving above ground or in water. But we often overlook the organisms beneath our feet, in the hidden world of soil, where an equally mesmerizing realm teems with life.

    E. R. Ingham: “Just one spoonful of soil can be home to millions of microbes“- the astonishing dynamic of these tiny, unseen organisms would blow our minds, if we only knew their story.

    I am fascinated by the biodiversity of the massive underground community. Countless small living things, such as microbes, insects, and earthworms, are tirelessly at work, busily breaking down organic matter and waste like leaf litter, faeces, and other dead organisms.

    Soil sample under the microscope, Image credit: © William Edge
    from Dreamstime.com CC BY-NC 2.0

    These organisms play fundamental roles in decomposition and also contribute to unlocking essential nutrients, like nitrogen and phosphorus, making these nutrients more available to plants. However, some microbial species can degrade useful substances, primarily affecting the cropping system and leading to lower crop yields in agriculture.

    In New Zealand, our grazing pastures face a significant challenge of soil microbes depleting essential nitrogen (N) in the soil. The NZ dairy industry has a substantial economic impact. A report by Sense Partners highlights that DairyNZ accounted for a quarter of New Zealand’s total export earnings (26 million) in 2023, making it a crucial contributor to national prosperity. For dairy farmers, “grass is green gold” because high-quality pasture is the key to their success, supporting healthy and productive livestock.

    Nitrogen boosts pasture supply, especially when N fertilizer is applied in mid to late spring. In most regions, this application results in an optimal and reliable grass response of around 10 to 15 kg DM/kg N. Why the need to apply synthetic fertiliser when nitrogen is abundant in the atmosphere, which contains 78% nitrogen. The catch is that atmospheric nitrogen is not directly available to most plants (except for legumes) due to its highly stable form (N2).

    Given the necessity of nitrogen fertilisers in grazing pasture systems, a go-to choice is urea. It’s most cost-effective and the most widely applied nitrogen fertiliser in NZ dairy pastures. The scale of its usage is staggering, with over 400,000 tonnes of urea being used annually in dairy farm systems since 2013.

    Two Cows by Martin Gommel | Flickr | CC BY-NC 2.0

    There is a downside. Ammonia-oxidizing soil microbes release an enzyme called urease that can break down over 80-90% of urea fertiliser when soil moisture is high. This leads to significant economic losses for farmers and contributes to environmental pollution through nitrate leaching.

    Note: Urea is the substance of solid nitrogen fertilizer, while urease is an enzyme found in plant tissues, fungi, bacteria, and some invertebrates, but not in animals.

    Dr. Hossein Alizadeh, a senior researcher in the Department of Agricultural Sciences at Lincoln University, leads a team focused on addressing the problem of nitrogen loss in soil. They have identified key culprits of rapid nitrogen loss in the soil – urease-producing microbes.

    By understanding these microbes better, the team can develop solutions to enhance the uptake of nitrogen nutrients by pastures and reduce greenhouse gas emissions. This is crucial because nitrogen from livestock urine and agricultural fertilisers converts to nitrous oxide (N2O), contributing to about one-sixth of New Zealand’s CO2 equivalent greenhouse gas emissions.

    To detect the nationwide urea degradation levels in dairy farm pastures, Dr. Alizadeh and his research team collected soil samples from various regions, including Auckland, Canterbury, Manawatu, Marlborough, Nelson, Otago, Taranaki, Waikato, Wairarapa, and the West Coast. The sampled pastures primarily consisted of ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.). Some grazing lands were relatively young, only nine months old, while others had 60 years of usage.

    To determine whether urease-producing microbes are present in different soil samples, researchers measured ammonium production. Urease breaks down urea and nitrogen in the soil converts to ammonia gas (NH3) and nitrate (NO3-) leaching. In the lab, if the urease producer actively breaks down urea and releases ammonia, the Petri dish with cultured microbes will show a pink colour (see Figure below). Additionally, to identify microbial bacteria and fungi, they applied the PCR (polymerase chain reaction) technique, morphological identification methods.

    Urease detection medium for isolation of soil urease producing microorganisms (left) and a purified urease (right). Own work CC BY-NC 2.0

    Hossein found some novel microbial species, such as Pochonia bulbillosa, Mariannaea elegans, and Gliomastixsp., which were reported for the first time for their urease production. The study also revealed variations in urease activity among the isolates and a diverse microbial community composition across different locations. For instance, in Nelson, bacteria were the dominant urease producers in the soil, while in Oxford, it was fungi, marking a significant discovery in soil microbiology.

    The groundbreaking research by Dr. Hossein and his team on identifying urease-producing microbes not only provides fundamental knowledge but also opens up possibilities for practical applications. The findings suggest the potential of manipulating these microbial populations in soil to reduce urease activity, a concept that is being further explored in the N-Bio Boost program led by Professor John Hampton of Seed Technology at Lincoln University. This project, funded by the New Zealand government and the fertilizer co-op Ravensdown, aims to harness a naturally occurring fungal species in the soil to enhance the nitrogen efficiency of plants, promising both environmental and economic benefits for New Zealand.

    So next time you are walking on pasture, pause and appreciate the busy world that is found under your feet!

    This article was prepared by Master of Pest Management postgraduate student Danyu Li as part of the ECOL608 Research Methods in Ecology course.

    Alizadeh, H., Kandula, D. R. W., Hampton, J. G., Stewart, A., Leung, D. W. M., Edwards, Y., & Smith, C. (2017). Urease producing microorganisms under dairy pasture management in soils across New Zealand. Geoderma Regional, 11, 78–85. https://doi.org/10.1016/j.geodrs.2017.10.003