EcoLincNZ

Category: wildlife ecology

  • Finding a needle in a haystack: locating the short-tailed bat

    Most of us have been in the position where we’ve struggled to find something, be it your car keys, phone, or favourite pair of sunglasses. No matter how hard or long you search it just seems to elude you. One minute it’s there and the next it’s gone. You know it’s there, but where!! It’s an extremely frustrating feeling.

    This feeling is all too familiar to those scientists trying to monitor one of New Zealand’s bat species, the lesser short-tailed bat. These scientists would probably argue that finding small bats in a large forest has a few more challenges than searching for your car keys at home.

    Lesser short-tailed bat, Photo credit: CC-BY-4.0 Department of Conservation (NZ), via Wikimedia Commons

    To make monitoring the lesser short-tailed bat a bit easier it would be useful to know which parts of the forest they prefer to visit. Jessica Scrimgeour, Laura Molles, and Joseph Was looked into which forest structure lesser short-tailed bats are most likely to be found in. The scientists pondered over whether these elusive bats are in the forest they’re monitoring but they just can’t find them, or are they not in the forest at all.

    Most lesser short-tailed bat monitoring in New Zealand has occurred at ground level. However, scientists were aware that these bats can and do fly in all levels of the forest, from way down low to way up high. Bats may be hard to find when you are repeatedly looking in the same spot in the forest.

    Hard beech forest (Fuscospora truncata) in Ecclesfield Reserve, Upper Hutt, New Zealand, Photo credit: Rudolph89, Public domain, via Wikimedia Commons

    Back in 2013 Scrimgeour (Department of Conservation), Molles (Lincoln University), and Was (University of Waikato) used automatic bat monitors (ABMs) in the North Island to investigate this. ABMs are sound activated recorders that collect bat echolocation calls. ABMs can be set at different heights in beech and podocarp forests. Generally speaking podocarp forests are made up of trees of varying heights with a thick understorey. Beech forests on the other hand are made up of different beech tree species of a similar height, with a more open understorey.

    Lesser short-tailed bats prefer to fly through forests that have minimal clutter, or are the most open. ‘Clutter’ refers to, among other things, the amount of branches, leaves, and tree trunks that hinder the bats flight and echolocation.

    Echolocation is the bats way of navigating. It works by bats sending out sound waves that hit surrounding objects and then bounce back to the bat allowing the bat to orientate itself. In a cluttered forest the objects are very close together, which means that the bats are still sending out sound waves at the same time sound waves are bouncing back. Returning sound waves become challenging to interpret and can interfere with tasks such as orientating and finding food.

    Initially the group thought that a more cluttered forest would attract more bats, as clutter might mean an increase in biodiversity, with better quality food available. Even if the cluttered forest had the most food, which for bats is insects, they preferred to take the path of least resistance. Navigating through dense forest is just hard yakka, requiring too much energy. No surprises there, who doesn’t take the path of least resistance?

    Podocarp forest west of MacKay hut on the Heaphy Track, South Island, New Zealand, Photo credit: Pierre Lavaura, Public domain, via Wikimedia Commons

    Lesser short-tailed bats are very committed to taking the path of least resistance and even change the height they fly at depending on the type of forest they’re in. In the beech forest, bats spent the most time flying in the bottom tier of the forest, as this part was the least cluttered. In podocarp forest, bats spent most of their time flying in the least cluttered middle tier of the forest.

    As New Zealander’s we like to think that we are different to the Aussies across the ditch, but our bat species don’t quite think the same. The trans-Tasman bats are actually very similar to each other. Other research on bats in Tasmania found that bat flying activity is greater when the forest is more open. So I suppose you could say that the Tasmanian bats are a bit lazy like our bats, or they behave optimally!

    The results from this 2013 study have also been backed up in subsequent research in New Zealand. This research found that in urban and rural settings long-tailed bat activity was also effected by vertical airspace and horizontal microhabitats.

    For those on the lookout for bats this study has helped with deciding where to place monitoring devices for more robust monitoring programmes. Finding that needle in the haystack has just a little bit easier.

    Lesser short-tailed bat, Photo credit: CC-BY-4.0 Department of Conservation (NZ), via Wikimedia Commons

    What’s been happening with monitoring programmes for bats since 2013? Well, it turns out quite a lot. Acoustic monitors are now used instead of ABM’s. These monitors are basically microphones that record bat echolocation calls as they fly past the monitors. More research has gone into where bat activity is likely to be the highest to further help in the placement of acoustic monitors.

    This new knowledge has definitely paid off with the exciting recent discovery of a population of the lesser short-tailed bats in the lower North Island. It was thought that the lesser short-tailed bat was extinct from the Pākuratahi forest, Upper Hutt, because bats had not been detected there for a very long time. It just goes to show that just because you haven’t detected something doesn’t mean it’s not there. Sometimes you just need to look a bit harder or, at least, a bit smarter.

    Scrimgeour, J. Molles, L., & Waas, J. R. (2013). Vertical variation in flight activity of the lesser short-tailed bat in podocarp and beech forest, Central North Island, New Zealand. https://researchcommons.waikato.ac.nz/server/api/core/bitstreams/fe6c95f0-a86d-408b-a6b4-cbc112a24865/content

    This article was prepared by Postgraduate Diploma in Applied Science student Anna Gardiner as part of the ECOL608 Research Methods in Ecology course.

  • Repelling New Zealand’s deer: keeping the target on predators

    Imagine walking through the lush forests of New Zealand, where native birds sing and the ecosystem thrives. For many, the thrill of hunting deer adds to the adventure, as these animals are both prized game and an integral part of the environment. However, lurking within this paradise are predators, like possums and rats, which threaten the very fabric of this delicate ecosystem.

    To combat these problem predators, New Zealand has employed a controversial yet effective method: aerial 1080 poison drops. These toxins are effective against pests but can inadvertently harm other wildlife, including the beloved white-tailed deer (Odocoileus virginianus).

    White Tailed Buck.
    Brad Smith. July 3rd 2006

    White-tailed deer are not native to New Zealand; they were introduced for hunting in the early 20th century. Despite being an introduced species, they have established a stable population and have become an important part of New Zealand’s hunting culture, especially the population on Stewart Island. Protecting them is crucial not only for maintaining biodiversity but also for supporting the recreational and economic benefits associated with deer hunting.

    Recent studies have shed light on how we can minimise this collateral damage by using deer repellents. Let’s dive into the findings and their implications for both wildlife management and conservation.

    New Zealand’s unique biodiversity is under constant threat from invasive species. Possums, rats, and stoats prey on native birds, insects, and plants, disrupting natural ecosystems. To protect these vulnerable species, aerial drops of sodium fluoroacetate, commonly known as 1080, are used. This toxin is highly effective at reducing predator populations, but it’s not without its drawbacks. One significant concern is the unintended by-kill of non-target species, such as the white-tailed deer.

    Intensive ground-based searches for white-tailed deer carcasses were conducted in the Dart Valley/Routeburn catchments following the aerial application of 1080 cereal pellets as part of the ‘Battle for the Birds’/Tiakina Ngā Manu predator control program in August 2014. Lincoln University PhD student Kaylyn Pinney, with her supervisors James Ross and Adrian Paterson, organised this search. Four areas, each 100 hectares in size, were searched over four days. The results were published in NZ Journal of Zoology.

    To estimate the effectiveness of their search, simulated deer carcasses were used. The success rate for finding these simulated carcasses was 78%. All actual white-tailed deer carcasses found contained traces of 1080 in their muscle tissue (ranging from 0.41 to 1.06 mg/kg). Based on these findings, researchers estimated that approximately 3.85 deer per 400 hectares died from 1080 poisoning. This translates to a potential mortality of about 146 white-tailed deer across the entire 15,215-hectare predator control area. These results suggest that recurrent predator control operations could impact the sustainability of white-tailed deer hunting. (For more on this see ‘Is it fair, for orcs and deer?’)

    Repellents are substances designed to deter animals from consuming certain items without causing them harm. In the context of predator control, deer repellents can be coated on 1080 baits to reduce the likelihood of deer ingesting the poison.

    Kaylyn Pinney then tested a deer repellent-coated 1080 bait to see if it could reduce the mortality of white-tailed deer during predator control operations. She tested two types of repellents: Epro Deer Repellent (EDR) and Pestex-DR. The study was divided into two parts: trials in a captive herd on the West Coast and monitoring of wild deer fitted with GPS collars in the Dart/Routeburn Valley in Otago, New Zealand.

    Routeburn Valley.
    yiwenjiang26, Routeburn vally closer up. March 10 2007.

    In the captive trials, five deer were presented with three types of cereal baits: non-repellent (NR), EDR-coated, and Pestex-DR-coated. The baits were placed in a controlled environment where deer could freely choose among them. The results were promising. The deer showed a clear aversion to the repellent-coated baits, with significantly less consumption compared to the non-repellent baits. The repellents appeared to be effective, though not infallible. One older buck did consume a single EDR-coated bait initially but avoided it afterward.

    The second part of the study involved monitoring ten wild deer equipped with GPS collars during a 1080 drop. To fit the deer with GPS collars, Kaylyn and crew captured the animals by tranquilising them and then attached the devices. Kaylyn could now track their movements and monitor their survival. The results were mixed. One deer, the youngest in the study, died from 1080 poisoning, suggesting that body size may play a role in susceptibility to the poison. Importantly, the study confirmed, however, that using EDR significantly reduced deer mortality compared to previous operations without repellents.

    While the study shows that repellents can reduce by-kill, there are challenges. Ensuring that every bait is adequately coated with repellent is crucial. Additionally, different deer may react differently to repellents, as observed with the older buck in the captive trial. Kaylyn suggests that using a lower concentration of 1080, such as 0.08%, could further reduce deer mortality, especially for smaller deer.

    The study also highlights the importance of understanding deer habitat use. The GPS collars allowed researchers to identify how much time the deer spent in different types of habitats. The varied exposure of the collared deer to the 1080 baits was influenced by their movement patterns and habitat preferences. Future studies should consider these factors to optimise bait distribution and minimize non-target impacts.

    1080 Warning Sign.
    Shaddon Waldie, 1080. July 30th 2009.

    These findings have significant implications for wildlife management and conservation in New Zealand. By using deer repellents like EDR and Pestex-DR, we can make predator control operations more targeted and reduce the unintended consequences for non-target species. This approach not only helps protect the native ecosystem but also addresses public concerns about the humane treatment of wildlife.

    The study underscores the need for continuous innovation and adaptation in conservation strategies. As we gain more insights into the behaviour and ecology of both target and non-target species, we can develop more effective and sustainable methods to preserve New Zealand’s unique biodiversity.

    The journey to protect New Zealand’s native species is complex and challenging. This study offers a glimmer of hope by demonstrating that deer repellents can significantly reduce the by-kill of white-tailed deer during aerial 1080 operations. While not perfect, these findings pave the way for more refined and humane conservation practices. As we continue to balance the needs of predator control with the protection of non-target wildlife, studies like this guide us toward a more sustainable and harmonious coexistence with nature.

    Imagine once again walking through those lush forests, now knowing that both the native birds and the majestic deer can thrive in a balanced ecosystem.

    This article was prepared by Master of Science postgraduate student Ella Gordon as part of the ECOL608 Research Methods in Ecology course.

    Link to the main article

    Pinney, K. A., Ross, J. G., & Paterson, A. M. (2022). Assessing EDR and a novel deer repellent for reducing by-kill of white-tailed deer (Odocoileus virginianus), during aerial 1080 operations. New Zealand Journal of Zoology, 49(3), 199–214. https://doi.org/10.1080/03014223.2021.1978510

    Additional Links and Further Reading

    New Zealand Department of Conservation

    The New Zealand Department of Conservation (DOC) website provides comprehensive information about New Zealand’s natural heritage, conservation efforts, and recreational opportunities. Key sections include:

    Parks & Recreation: Information on places to visit, activities, camping, and hiking.
    Nature: Details on native plants and animals, pest management, and habitats.
    Get Involved: Volunteering, funding opportunities, and educational resources.
    Our Work: Conservation projects, research, and monitoring programs.

    Manaaki Whenua – Landcare Research

    The Manaaki Whenua – Landcare Research website provides a wide range of information on New Zealand’s land environment and biodiversity. It covers research areas such as soil health, water management, biodiversity conservation, and climate change. Additionally, it offers resources for educators, data and mapping tools, and information on various conservation projects. The site also features sections for news, events, and opportunities for public involvement in environmental efforts.

    1080: An Overview

    The “1080: An Overview” page on the Predator Free NZ Trust website provides comprehensive information about the use of 1080 (sodium fluoroacetate) in New Zealand for predator control. It details what 1080 is, why it is used, its application methods, and its effectiveness. The page also covers the benefits and risks associated with 1080, including its impact on native species, non-target species, and the environment. Additionally, it includes examples of successful 1080 applications and addresses common concerns such as its impact on drinking water.

    Nugent, G., & Yockney, I. (2004). “Feral deer in New Zealand: current status and potential management.” New Zealand Journal of Zoology.
    This article discusses the status and management of feral deer populations in New Zealand.

    Morriss, G. (2007). “Epro Deer Repellent reduces by-kill of deer during aerial 1080 operations.” Landcare Research Report.
    This report provides detailed findings on the effectiveness of EDR in reducing non-target by-kill.

    Frampton, C. M., et al. (1999). “Efficacy of 1080 carrot baits in controlling possums.” New Zealand Journal of Ecology.
    This study examines the effectiveness of 1080 in controlling possum populations.

    Spalinger, D. E., et al. (1997). “Influence of learning and experience on foraging behavior of white-tailed deer.” Journal of Wildlife Management.
    This research explores how learning and experience affect deer foraging behavior.

    Bowen, L. H., et al. (1995). “Leaching rates of 1080 from RS5 cereal baits under simulated rainfall.” New Zealand Journal of Ecology.
    This paper discusses how environmental conditions affect the concentration of 1080 in baits.

    Pinney, M., et al. (2020). “Effectiveness of deer repellents in reducing non-target by-kill during predator control operations.” Journal of Wildlife Management.
    This study delves into the specific effects of deer repellents on non-target species during 1080 operations.

  • PredatorFreeNZ 2050: fantasy into reality

    High in the treetops of a lush forest, a group of native birds gathered together, their vibrant feathers glinting in the dappled sunlight. Excited chirps and melodic trills filled the air as they engaged in a lively conversation. Their voices carried the hopes and dreams of a restored ecosystem.

    Koru, a charismatic Tūī with iridescent feathers, fluttered his wings and cleared his throat. “Have you all heard the latest? The Humans are determined to make New Zealand predator-free by 2050!”

    The cheeky Kākāriki, a lively parakeet, interjected. “Can we truly reclaim our forests from the claws and jaws of those invaders?” A wise and observant Morepork owl, Ruru blinked his large, round eyes. “Is that so? Quite a lofty goal, but can they really do it?”

    Photo credit: CC BY-NC-ND 2.0 Simeon W Flickr
    Red-crowned Kakariki, Photo credit: CC BY-NC-ND 2.0 Simeon W, Flickr

    With its unique biodiversity, New Zealand is home to a huge array of species found nowhere else on Earth. However, many of these treasures face an existential threat from invasive predatory mammals, such as rats, stoats, and possums, introduced by human settlers centuries ago. These voracious predators ravage the native bird populations. Many species are now extinct, and more are now on the brink of extinction.

    Predator-Free New Zealand 2050 (PFNZ2050) was initiated in 2016 with an audacious aim of eradicating the most destructive trio of predators: possums, stoats, and rats; from New Zealand. This call for action echoed through the mountains and valleys, inspiring conservationists to make New Zealand, once again, a land of breathtaking beauty and thriving unique biodiversity. The ambitious aim of Predator Free 2050 is not without precedent. To date, New Zealand has successfully eradicated invasive mammals from 105 (admittedly much smaller) islands.

    In 2020, a journal article was published that assesses the feasibility and steps needed to achieve Predator Free 2050. it was written by James Ross, from the Centre for Wildlife Management and Conservation (CWMC) at Lincoln University, Grant Ryan from The Cacophony Project, Merel Jansen from the Department of Applied Biology, HAS University of Applied Sciences, Hertogenbosch, The Netherlands, and Tim Sjoberg, from the Taranaki Mounga Project. Together, these researchers have decades of experience controlling and monitoring pest mammals in New Zealand.

    The first step, removing predators with aerial 1080 poisoning and ground-based resetting traps, will help remove the majority of predators. A modified aerial 1080 approach, developed by Zero Invasive Predators (ZIP), can result in localised eradication. This was first tried in a 400-ha area at Mt. Taranaki in 2016, then at a 2,300-ha site in South Westland, using ground-based resetting traps. Regular servicing of resetting traps also gives better ground-based control results.

    Once pests have been eradicated from an area, the next big challenge is to defend the area from invasion. ZIP demonstrated how to defend predators from re-invasion in two sites using a “virtual barrier” of traps. A 2 km wide barrier of traps protected a 400-ha peninsula at Bottle Rock in the Marlborough Sounds. Using this virtual barrier of traps, ZIP prevented predators from re-invading at two sites, in the short term.

    Australian brushtail possums, initially introduced into New Zealand for the fur trade, and now one of the major pest mammals in New Zealand.
    Photo credit: CC BY-SA 2.0, Gnu Chris, Flickr

    Detecting the survivors is the next crucial phase for eradication, as any survivors can build a new population. The CWMC and Cacophony Project found that thermal cameras are 3.6 times more sensitive than trial cameras in detecting possums. Whilst trail cameras appear to improve detection rates, they do not always trigger when a small, fast-moving animal moves in front of them. These cameras also use infrared illumination at night, which may deter some animals.

    Thermal cameras are a new advanced technology that shows high sensitivity in detecting both small and large pest mammals. Because the motion detection is done using software, the sensitivity can easily be adjusted. Unlike trail cameras, thermal cameras do not require infrared illumination to operate at night.

    Videos collected by the thermal cameras are classified using AI technology (machine learning) trained on a library with more than 50,000 tagged videos. The AI can identify the animal species and only keep recordings for the target pests, which can be stored on-board the device or sent out using the cellular network.

    To achieve the PFNZ 2050 goal, detecting the last few individual pest mammals is complex and expensive. As a technical improvement in detection, ZIP has made an AI network of over 500 cameras across the Predator-free South Westland project area. The AI cameras use LoRa (low-powered radio technology) to send the information to solar-powered mini-satellites. The information is transferred to a web server that checks the information the next day. The AI cameras only need to be serviced twice a year to change the batteries. The AI cameras have reduced the time to detect one predator from around six weeks to just one day and have reduced the cost significantly.

    PFNZ2050 will require more innovative strategies, control tools, and wider public support to be successful in its ambitious challenge. Future control work will increasingly take place in and around urban areas. As such, the next most important advancement needs to be construct control tools that community groups can use. There should be a bottom-up-driven approach to community engagement in conservation so that as new technologies become available, the number and size of invasive mammal-free publicly and privately managed reserves can increase. In a recent study, people showed high support for species-specific toxins, but there is a shortage of funding for registration of these toxins.

    NZ has a 60-year history of eradicating pest mammals, from tiny 1-ha Maria Island to more than 11,000 ha Campbell Island, with suitable techniques and public support. This is an example of how the impossible becomes possible when passion, science, and community unite.

    With a final chorus of their harmonious calls, the native birds took flight, their wings carrying their hopes and aspirations to the corners of the land. From forests to cities, their songs echoed, touching the hearts of all who listened.


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

  • Remove one NZ invasive mammal predator and another steps into its place

    Invasive species are a major concern for ecosystems worldwide, causing significant disruptions to native flora and fauna. Some mammals can have particularly devastating effects on local ecosystems due to their predatory nature. In the Hawke’s Bay, New Zealand, a recent study titled “Niche Partitioning in a Guild of Invasive Mammalian Predators” sheds light on the dynamics of invasive mammalian predators and their impact on the region’s native biodiversity.

    I’ll walk you through the key discoveries and explain why they hold immense importance in our understanding of niche partitioning and its implications for ecosystem management.

    Niche partitioning refers to the process by which species with similar ecological requirements coexist within an ecosystem by utilizing different resources or occupying different ecological niches. Niche partitioning reduces direct competition, promoting the coexistence of species that would otherwise struggle to survive in the same habitat.

    In Hawke’s Bay, a guild of invasive mammalian predators has established, comprising three key species: stoats(Mustela erminea), ferrets (Mustela furo), and feral cats (Felis catus). 

    These predators were introduced to New Zealand and have since wreaked havoc on many native bird populations. Recent studies have revealed an intriguing pattern of niche partitioning among these invaders, suggesting a potential balance within the guild.

    Camera traps were deployed in three seasons. Credit by Albert Salemgareyev/ACBK

    Researchers have observed distinct differences in the dietary preferences and hunting strategies among these invasive predators in Hawke’s Bay. These variations have allowed the species to exploit food, reducing direct competition and encouraging the peaceful coexistence of individuals.

    Stoats, being the smallest and most agile of the three predators, specialize in hunting rats, mice, and birds. Their slender bodies and keen sense of hearing enable them to pursue their prey with stealth and precision. Ferrets, on the other hand, are larger and more versatile, adapting to different types of prey or using various hunting techniques. Ferrets tend to target larger prey, such as rabbits and small hares, which they capture using their strength and speed. Feral cats, similar to stoats and ferrets, are solitary hunters, exhibiting a broader dietary range, preying on both small and medium-sized mammals, birds, and reptiles.

    While the predators may occasionally target overlapping prey species, they generally exhibit distinct foraging preferences and occupy different microhabitats. Stoats predominantly inhabit forested areas, where their excellent climbing abilities give them an advantage in pursuing prey in trees.  Ferrets, with their larger size and ground-based hunting strategies, are often found in open grasslands and shrublands. Feral cats, being highly adaptable, can exploit a range of habitats, from dense forests to human settlements.

    The phenomenon of niche partitioning among invasive predators in Hawke’s Bay has important implications for native species conservation. By occupying different ecological niches, these predators help reduce the burden on specific native animals in an indirect manner, allowing them to persist despite the presence of invaders.

    Bird species, in particular, have been heavily impacted by the invasion of mammalian predators. Native birds, such as kiwi, weka, and tui, have experienced population declines due to predation. However, the niche partitioning observed among invasive predators offers a glimmer of hope for the survival of some native bird species. For example, stoats target ground-dwelling birds, while ferrets focus on larger prey, like rabbits. This division of labour reduces the overall predation pressure on specific bird species and allows them to maintain a foothold in their respective habitats.

    Stoats are tricky to study. They are hard to find in the field and difficult to keep in captivity. Image from Adrian Paterson.

    Understanding the dynamics of niche partitioning among invasive mammalian predators can inform targeted conservation strategies. By recognizing the specific resources and habitats favored by each predator species, conservationists can create plans for managing natural areas that utilize the division of habitats to safeguard endangered native animals.
    Implementing effective trapping and removal programs, focused on the specific predators posing the greatest threat to certain bird species, can help alleviate their population declines.

    Habitat restoration initiatives aimed at enhancing native bird habitats, while creating barriers for invasive predators, can further support the survival and recovery of endangered species. For instance, Wellington, Zealandia is a 225-hectare fenced sanctuary dedicated to protecting and restoring native wildlife. The sanctuary is predator-free and provides a safe haven for endangered bird species like the tīeke (saddleback), kākā, and hihi (stitchbird). Zealandia also conducts active predator control outside the sanctuary to create a buffer zone for native birds.

    The study on niche partitioning among invasive mammalian predators in Hawke’s Bay offers valuable insights into the complex interactions within ecosystems and the potential consequences of invasive species on native biodiversity. These findings provide a foundation for conservation efforts and ecosystem management strategies aimed at mitigating the negative impacts of invasive predators on native flora and fauna. By understanding the dynamics of invasive species, we can work towards restoring and preserving the delicate balance of ecosystems, ultimately fostering a more sustainable future for our planet.

    Removing cats and ferrets from an ecosystem often has unforeseen consequences, as evidenced by the subsequent increase in site use by stoats. Stoats, cunning predators known for their ability to adapt to changing circumstances, have exploited the absence of cats and ferrets to their advantage. In the absence of these competitors, stoats have become more active during the day, closely following diurnal bird activity. This behavioral shift has raised concerns among conservationists, as it highlights the need for predator control measures to account for the specific hunting patterns and preferences of different predators.

    Failing to address this issue adequately could lead to a worse outcome for daylight birds, whose vulnerability to stoat predation may increase if their activities are not considered in predator control strategies. Therefore, it is crucial for ongoing conservation efforts to not only focus on removing invasive predators but also to consider the complex interactions among species and the potential cascading effects that may arise.

    This article was prepared by Master of International Nature Conservation student Albert Salemgareyev as part of the ECOL608 Research Methods in Ecology course. Albert won a prestigious Whitley Award for Conservation in 2023.

    Garvey, Patrick M., Alistair S. Glen, Mick N. Clout, Margaret Nichols, and Roger P. Pech. 2022. “Niche Partitioning in a Guild of Invasive Mammalian Predators.” Ecological Applications 32(4): e2566. https://doi.org/10.1002/eap.2566 

  • Island life, saviour of the wrybill

    I’ve never been so pleased to see the braids of a river than when I finally escaped the jaws of the Waimakariri Gorge in my kayak, as part of the Coast to Coast race. A braided river brings not just relief from roaring bluff corners, and the threat of capsizing my kayak, but a peaceful place that unusual birds decide to call home.

    Rakaia River, NZ (Geoff Leeming, 2006, CC BY-NC 2.0, via flickr)

    One such creature is the Wrybill or Ngutu parore. It’s the only bird in the world with a laterally curved beak (bending to the side)! Sadly, this little bird faces many threats. In 2008 some optimism was found in the research of Duncan, Hughey, Cochrane and Bind (River Modelling to better manage mammalian predator access to islands in braided rivers). The paper explained how particular characteristics of braided rivers could be used to support successful breeding of braided river birds, including our wee friend, the Wrybill.

    Braided rivers are made up of multiple threads of flowing water, with islands found between the threads. The researchers knew that these islands provided a safe place for endangered breeding birds, with the water flowing around them providing a partial barrier to a major threat –

    Wrybill
    (57Andrew, 2007, CC BY-NC-ND 2.0, via flickr)

    introduced mammalian predators, such as hedgehogs, rats, mice, stoats, weasels, ferrets and cats.

    It was already known that water extraction, narrowing and stop-banking of rivers impacted the flow of water in the braids, but little was known about the optimal flow of water or the required characteristics of the islands to support breeding birds. Models were used to determine the number and area of islands needed for successful breeding. The researchers found that certain levels of water flow preserve islands large enough for nesting (larger than 2 hectares) and protect the area from mammalian predators or weed invasion. This information was used to recommend abstraction rates on braided rivers during peak breeding season. They did conclude that using photos in the research would increase understanding of how islands change in different flows.

    One of the authors, Ken Hughey, was from Lincoln University and his PhD, back in 1985, looked at factors impacting the breeding of braided river birds in Canterbury. He studied five different birds: Wrybill, Banded dotterel, Black-fronted tern, Pied stilt, and the South Island pied oystercatcher. Among other things, Ken found that higher levels of predation on birds occur where there were lower flows of water and lower numbers of channels or threads in the river. He recommended that minimum flow levels should be higher during the breeding season to protect the nesting birds. The 2008 study builds on this understanding and provides information not just about the flow of water needed, but also the size of the islands required to protect the nesting birds.

    This study has been used in subsequent research in New Zealand around maintaining river flows in braided rivers. This is unsurprising given braided rivers are rare around the world and Canterbury is known as New Zealand’s braided river hotspot. The themes within the research were around maintaining river flow levels, predator and weed control, maintaining river islands, and water abstraction. Advances since this work seems to be focussed on weed control and the impacts of hydropower to braided river systems.

    It appears that the messages about the importance of minimum flows and island size in braided rivers for breeding birds are getting through. The Regional Council in Canterbury (ECAN) refers to the importance of flows in preserving the ecology of the river for breeding river birds in the Canterbury Water Management Strategy and the Canterbury Land and Water Regional plan. The knowledge that came from the research by Duncan, Hughey, Cochrane and Bind, and subsequent research, has clearly shown how local communities think about braided rivers and informed how they care for them. This is demonstrated by the Ashley Rakahuri River Care Group in 2022, when they made a submission to the ECAN to raise concerns about gravel extraction on the Ashley Rakahuri River and how this will impact the islands needed by birds to breed safely.

    This approach also appears to complement work by the Predator Free 2050 campaign regarding pest control within braided river environments. I was intrigued as to how the authors felt the research was received and asked one of them, Ken Hughey, about the impact. He said it ultimately led to high flows being recommended and resourcing for predator control on the islands. Sounds like a great result!

    New Zealand Map (mhx, 2010, CC BY-NC-ND 2.0, via Flickr)

    Undertaking research consumes your life while you are doing it. It is fascinating to see the journey from conception to the completed work and then how it informs environmental work moving forward.

    The Wrybill is still classed as vulnerable and there is work to be done, but this research has added valuable insight into flow regimes for braided rivers. It has highlighted the importance not just preserving islands for breeding birds, but ensuring they are above a certain size. It has prompted further research, and informed councils and charitable groups on how to best support endangered braided river birds, like our wee friend the Wrybill. I’m sure there shall be some grateful kayakers out there too! I shall sign off this blog with an image of the Wrybill making the most of his unique laterally curved beak.

    This article was prepared by Master of Environmental Policy and Management student Katherine Manning as part of the ECOL608 Research Methods in Ecology course.

    Wrybill/Ngutuparore (Shellie, 2016, CC BY-NC-ND 2.0, via Flickr)

    Here is a full citation for the article:

    Duncan, M.J., Hughey, K.F.D., Cochrane, C.H., Bind, J. (2008) River modelling to better manage mammalian predator access to islands in braided rivers. Exeter, UK: British Hydrological Society 10th National Hydrology Symposium: Sustainable Hydrology for the 21st Century, 15-17 Sep 2008. 487-492

  • Neighbourhood disputes, models, and a harmonious coexistence with elephants

    In my home country, Germany, we have cut down every bit of primeval forest. We hunted aurochs, brown bears, wolves, lynx and even beavers to extinction between the 17th and 19th centuries. After messing it all up like that, we now dare to tell other countries, that still hold on to their forests and wildlife, what to do with their nature.

    “Don’t hunt those animals you used to hunt sustainably for centuries; we think they are so charismatic”. Currently, wolves are slowly coming back to Germany, and immediately people (successfully) changed laws to permit their shooting if they prey on sheep because it is “not bearable” to live in close coexistence with wild animals like that. Apparently, wolves don’t belong to Germany anymore because…yeah, because what? Because humans live here?

    Now close your eyes and imagine you are a subsistence farmer. Oops, don’t close them, rather, continue reading! You can still imagine, though! Every day you’re working hard taking care of all the veggies and crops you planted to feed your family. One day you look up, and what you see is a massive giant, almost as tall as your house. That giant has destroyed everything you ever planted.

    African elephant (Loxodonta africana) drinking. Picture © Severin Racky (used with permission).

    Happily munching on the last corn cob, the elephant greets you with an intimidating “HEI!”. Sounds absurd? Well, this scenario is much more realistic than our Western culture’s perception of African savannas as a vast untouched wilderness with Simba and all his large mammal friends living their best lives, without humans in the picture and without “HEI”, Human-Elephant-Interactions.

    This perception of wild Africa has influenced our approach to mitigating HEI. A common attempt is to build physical barriers, such as fences, to separate humans and elephants, believing they could protect both parties. However, elephants are unbelievably strong and intelligent creatures, and they easily overcome these obstacles, leaving farmers caught in a perpetual battle to safeguard their livelihoods.

    I have personally witnessed elephants knocking over trees onto “elephant-proof” electric fences to get to the other side. No fence can hold back a herd of determined elephants. Fences, therefore, cannot be the only solution when both humans and elephants need to get their food from the same land. It doesn’t stop with crop and infrastructure damage, though; Humans and elephants die through HEI. Elephants are killing around 500 humans per year and humans return the favour.

    After bothering you with way too much bad news, at least I can tell you that science offers a glimmer of hope! Picture a team of brilliant minds huddled around computer screens, armed with data and determination. With powerful tools with mystical names like Agent-based modelling (ABM) and Geographic Information Systems (GIS), ecologists are unravelling the complexities of HEI to help us understand human-elephant interactions better. With these tools, the researchers can simulate scenarios and explore the factors determining conflict incidents, to develop effective measures to reduce the conflicts and to mitigate poaching. The models are needed because, due to plenty of ethical problems, these kinds of experiments could not be conducted in real life.

    In their study from 2021, Abel Mamboleo, Crile Doscher, and Adrian Paterson, from Lincoln University, simulated 18 scenarios, considering things like human population, elephant population, rivers, conservation corridors, and protected areas. They evaluated their impact on different HEI incidents, such as crop damage, human deaths, elephant deaths, and hidden impacts. The term “hidden impacts” refers to indirect consequences of HEI and includes fear restricting movements, missing school, or resulting health issues. For example, their “elephant-effects scenario (ES)” evaluated the effects of varying elephant populations on HEI, the “human-effects scenario (HES)” evaluated the effects of varying human populations on HEI, and the “environment-effects scenario” evaluated the effect of varying environmental parameters (distances to rivers, protected areas and corridors) on HEI.

    Using their models, the scientists identified hidden impacts of HEI (e.g. fear and resulting health issues or restricted movements depending on elephants) as the most challenging incidents to mitigate. Interestingly, maintaining a greater distance from rivers seemed to effectively reduce those hidden impacts. Now who would have thought that?

    Their model also indicated that most incidents of elephant crop damage occur within 1 km from rivers. Therefore, according to the model, it is possible to lower the risk of your crops being eaten and trampled by a grey giant by planting them further away from rivers (Yeah, good news!). Among the incidents studied, human deaths were found to be the easiest to reduce (more good news!). Fifteen out of the 18 scenarios lead to significantly fewer human deaths.

    African elephants drinking and playing at a waterhole. Picture © Severin Racky (used with permission).

    Distancing human activities from rivers, and creating conservation corridors and protected areas, seem to be an effective mitigation strategy. However, challenges remain. Reducing the deaths of elephants seems to be one of the most difficult tasks, with only six out of the 18 scenarios showing significantly fewer dead elephants. The number of elephant deaths was reduced in some scenarios, such as a so-called “ENS-River-Protect-Corridor”, in which the scientists modelled farms to be 7000 m away from rivers, protected areas and wildlife corridors.


    While no single scenario that the scientists played through was able to completely eliminate all incidents, their modelling provided valuable insights and recommendations for potential strategies to reduce HEI. With their models, the researchers showed that HEI is influenced by many different factors beyond the pure numbers of humans and elephants. Geographical and environmental features, such as rivers, protected areas, and corridors, and socioeconomic activities, also play crucial roles. With the approach of creating safe distances between human activities and critical areas, the researchers found practical strategies to minimize the deaths of both humans and elephants.

    The study’s findings, therefore, highlight the need to address the spatial relationship between humans and elephants and promote responsible settlement planning. Successful strategies for mitigating HEI require a holistic approach that balances the needs of both humans and elephants and prioritizes a healthy elephant population as well as the well-being of affected human communities.

    It is important to emphasize that models are just a tool, implementing solutions still needs to be done by our big, juicy human brains. For example, in all scenarios, the model suggested to just lower the population size of humans and/or elephants to mitigate HEI. Fewer humans, fewer elephants: fewer human-elephant interactions. Of course, both options are far away from an ethical or recommendable solution. If the elephant density is extremely high, relocating them to other areas could be a (very complicated and expensive) option.

    Wait a minute! Hey, German politicians, how come you haven’t thought about reducing the population size of humans in areas where the wolves are coming back? I heard many of us would love to live in New Zealand anyway. What about providing a free one-way ticket to New Zealand for every revengeful German sheep farmer who wants to kill wolves as a compensation measure?

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

    Mamboleo, A. A., Doscher, C., & Paterson, A. (2021). A computational modelling approach to human-elephant interactions in the Bunda District, Tanzania. Ecological Modelling, 443, 109449. (https://doi.org/10.1016/j.ecolmodel.2021.109449)

  • The secret life of elephants: ecological engineers and agricultural pests

    As a Kiwi, when I hear the word ‘pest’ my mind instantly goes to possums, stoats, rats and cats. These are some of the invasive mammals which are killing so many of our native species, most of which cannot be found anywhere else in the world. These lethal pests have turned us into killers as well; we promote and stand by numerous lethal methods for pest management, without batting an eyelid. Whilst some are made uneasy by the thought of trapping, poisoning or hunting these creatures, we still employ these measures as second nature.

    When talking about pest management in the past, I never quite understood the shock or disapproval from visitors from overseas. They get a certain look on their faces when they hear what we do to these mammals, many of which they are trying to protect at home. It seems to them that we have become somewhat apathetic to the lives of these creatures and accustomed to having blood on our hands in the name of pest management.

    Dead stoat, trapped in Fiordland National Park/ Avenue

    The way that I look at it, along with many other New Zealanders, is that I feel a strong sense of responsibility for protecting our native birds, lizards and plants. I do accept that these pests are simply trying to survive, on an island archipelago that they didn’t choose to live on.

    Some parts of the world, have a much larger agricultural pest issue: elephants. Hearing this, helped me to understand what others feel when we talk about pests in New Zealand. How can an elephant, such a majestic creature, be considered a pest?

    Of course, an agricultural pest differs in definition to the introduced conservation pests that we have in New Zealand, although reactions to these pests seem to be the same. In retaliation to the damage caused to local livelihoods or personal safety, some people have been reported to purposefully remove native elephant habitats or even employ lethal methods to control the “problem elephants”. I am now the one in shock, although in the grand scheme of things it’s not so dissimilar to our pest control strategies.

    Abel Mamboleo, as part of his PhD research at Lincoln University, asked the question, published in the Journal of Biodiversity & Endangered Species, of whether elephants were really the most disastrous agricultural pest animals or are they actually the agents of ecological restoration. He reviewed multiple studies and publications to obtain crucial information about elephants, agricultural pests and ecological restoration. All of this helped guide him towards the answer to this big question: are elephants a pest or an ecological blessing? He also wanted to summarise the existing knowledge to help both conservationists and local people create appropriate plans for sustainable management.

    Indian elephant bull in musth in Bandipur National Park/ CC-BY-SA 3.0 Yathin S Krishnappa.

    Human-elephant conflicts arise through any interactions between our two species that have negative impacts on social, economic or cultural life, on elephants, or on the environment. The most common feature of these interactions is crop-raiding. As human populations increase, our demand for land, water and food also increases. Consequently, historical elephant habitat is being infiltrated by human activities through agricultural development, limiting elephant habitats to small “ecological islands”. This means their usual dispersal routes are restricted and the competition for resources with humans increases.

    So, what happens when the natural habitat and resources of elephants are taken away? They search for food elsewhere, with the most abundant source being crops on surrounding farms. Elephants actually prefer agricultural crops to wild plants because they are more palatable, nutritious and readily available. For this reason, local people have labelled elephants as the most disastrous agricultural pests, because of the damage from elephants that they sustain. But is this a fair statement?

    Elephants were compared to the criteria an animal must fit to be considered a pest. These criteria include any animal that feeds on crops, damages buildings or stored food, injures people and kills livestock. When looking at it this way, yes, elephants by definition are pests. They damage stored and field crops, which ultimately affects human food security during drought seasons. However, to be labelled the most disastrous agricultural pest seems a bit extreme. In fact, for this to be the reality they must be causing massive economic damage to crops and property; more than other pests.

    While they do cause some local damage, Mamboleo found that they only cause moderate damage when compared to other pests. The damage inflicted by wild pigs actually far outweighs that of elephants and puts them in first place for the most disastrous agricultural pests. Elephants even sit behind rodents, European starlings, red billed quelea and desert locusts when looking at the line-up for the worst pest offenders in these areas. While it is true that elephants can inflict extensive damage, it is still significantly less than other pests. For local people, it is hard to see it this way as they have entire fields of crops decimated by these giants.

    People are seeing persistent crop damage and associating this with pest behaviour. Because their farms often closely border protected elephant habitats, it means people are seeing more severe crop-raiding and they’re seeing it more frequently. While on the other hand, the elephants just see more food. Naturally, the elephants are getting the blame and inheriting this new title; from a local perspective it is an obvious response.

    On the other hand, elephants are considered as agents of ecological restoration. Much like secret agents, they work inconspicuously to repair and re-establish ecosystem services that may have been damaged by human activities. A successful act of ecological restoration must be effective, efficient and engaging. This is otherwise known as the “triple E” principle, which serves as the guidelines for evaluating environmental restoration processes.

    Elephant in India/ CC-BY 4.0 Sanghavisrini

    Elephants are effective because their natural and physical abilities provide all sorts of environmental benefits to humans and other wildlife. They also have the ability to restructure their environments, sometimes opening up thick vegetation and helping their herbivore neighbours in the process.

    Elephants are also efficient because of their high level of intelligence and behaviours; they are able to perform productive ecosystem rehabilitation activities in a consistent and timely manner. Usually this is without the support of human intervention. Elephants have been branded “ecosystem engineers” or “mega-gardeners” because of their role in dispersing seeds, helping both wildlife and humans. Through ecological restoration, these elephants are replenishing cultural resources and socioeconomic conditions for humans and allowing re-connection with nature. Some would call that engaging. This ecosystem restoration allows humans and other wildlife to reuse otherwise damaged ecosystems.

    So what is the answer to whether elephants are the most disastrous agricultural pests or actually the agents of ecological restoration? This needs to be looked at from two separate viewpoints. Yes, they are pests, but they are not the most disastrous. And, yes, they are agents of ecological restoration. But they are both occurring simultaneously, depending on the perspective you view it. Can’t they be both?

    This article was prepared by Master of International Nature Conservation student Quinn O’Halloran as part of the ECOL608 Research Methods in Ecology course.

    Mamboleo, A.A., Doscher, C., & Paterson, A. (2017). Are elephants the most disastrous agricultural pests or the agents of ecological restorations? Journal of Biodiversity & Endangered Species, 5(185). doi:10.4172/2332-2543.1000185 .

  • When grapes lead to war

    Would you steal a loaf of bread to feed your hungry family? Fair enough. What about a couple of grapes to save yourself the misery of wasting nine dollars on sour fruit?

    Grapes, waiting to be sampled.
    © Colin Jensen

    “Try ‘em before I buy ‘em,” is my dad’s usual response to that question, as he pops grapes from three different bags one-by-one into his mouth. A red one here, a green one there, maybe even a dark purple if the season is right. In spite of earnest pleadings from embarrassed children and grocery store placards, there would be no purchase of grapes unless a thorough investigation of both quality and taste had been completed. 

    As weird as it may sound, it turns out my dad is not alone in his grocery store grape grabbing. A quick google search yields numerous articles, blogs, polls and debates on the topic. A more recent article used an extensively rigorous survey of 40 people on Facebook to tackle the question, with results showing that half of respondents advocated for, and actively participated in, grape sampling while shopping. As for the other half? Some seemed to side with this NZ Herald article which refers to grape samplers as both thieves and stealers, while others suggested that this type of behaviour is a “hanging offense”. As a conservation biologist, I am not typically one for philosophical debates, so I’ll leave the ethics of grape sampling and capital punishment up for you to decide. 

    Unfortunately, a jump back into the conservation sphere does not make me immune to grape stealing dramatics. As it turns out, nature, just like the produce aisle of my parent’s local grocery store, is home to its own collection of fruity felons. Among those felons is the European starling. You may know starlings for their incredible vocal range, beautiful coloration, or the massive flocks (or mumurations) they sometimes form (check them out if you haven’t). But to winemakers in New Zealand, starlings may be more well-known for being “vicious” and “wasters of fruit.” Unfortunately the problem that starlings cause in vineyards is nothing new, and in fact, it was this very problem that was the inspiration for research at Lincoln University over 20 years ago. 

    European Starling CC courtesy of Eric Ellingson on Flickr

    Flashback to 1999 – Napster is in its heyday, Brittney Spears’ “Baby One More Time” is on the radio, and, besides a little bit of Y2K hysteria, life is good. Amidst the excitement of a new millennia, researchers Yuki Fukuda, Graham Hickling, and Chris Frampton from Lincoln University were hard at work trying to solve the problem of the grape stealing starlings. To do so, they tested out two devices designed specifically for scaring birds away from agriculture areas – the Peaceful Pyramid and eye-spot balloons. The Peaceful Pyramid, as the name suggests, was meant to be a “peaceful” alternative to other more aggressive bird deterrents like “noisy gas guns”. It featured a rotating pyramid with mirrored sides, which would reflect rays of sunlight towards incoming birds. The goal was to overload the birds vision to the point that they would no longer have the desire to land and feed. The eyespot balloon was a large balloon with yellow and black patterning designed to mimic the eyes of a large predator. 

    Peaceful Pyramid
    © Great Expectations

    Both devices were tested at a vineyard in Dunsandel, and at the University vineyard here in Lincoln. Although both were found to scare starlings away from the grapes initially, within a few days almost all the birds had become habituated to both scarers, and they quickly became ineffective. Ultimately, it was determined that both the eyespot balloon and the Peaceful Pyramid were not practical methods for protecting vineyards. Although these researchers did not find a solution to counteract the stealing starlings, they at least helped re-affirm the idea that anti-bird measures need to be thoroughly tested before they are trusted for protection. 

    In the 24 years since the research at Lincoln was done, there has been no shortage of innovation and testing of bird scaring devices. There has also been some work (here and here) on what birds are doing in the vine-yards. Among the myriad of devices tested, we have seen air cannons, chemical repellents, introduced falcons, large-scale netting, and a few of my favourites, the sci-fi sounding laser scarecrow (unfortunately, this doesn’t look as cool as it sounds), and the RobotFalcon (fortunately, this does look as cool as it sounds). 

    All of these projects have had the same goal: deter birds from pillaging in agricultural settings. Unfortunately, despite each of these ideas producing some level of protection, they all come with limitations. One is too expensive, another is too time and labour intensive, and some only work in good weather. For many, it seems as if finding a fix-all solution to the crop stealing problem is a fruitless endeavour. If it’s not the Peaceful Pyramid, and it’s not the laser scarecrow, then really what more can we do? 

    Well, researchers from the University of Sydney think that they have finally found the answer. (If you have been surprised by any of the bird scaring techniques already described, you may want to sit down for what comes next). Like something out of a Stanley Kubrick film, these researchers have employed techniques that they can only describe as “psychological warfare.” 

    The weapons of war used in this study consist of a stuffed bird attached to a drone (UAV), which is flown through the vineyard whilst playing recorded distress calls of pest birds from a loudspeaker (see image below). The idea is that visual and auditory stimuli on their own are not effective long-term. By tapping into the birds psychology through visual (dead bird) and audio (distress call) cues, they might be able to trigger the birds anti-predator behaviour, and keep them away for good.

    Early results show that crop damage in areas patrolled by this flying fearmongerer are up to four times less than areas which used visual scarers alone. It also appears that this system is just as effective as large-scale netting (currently the most effective way to protect grapes), but is much more cost effective. While these results are preliminary, and further testing is still needed, it seems that hope may be flying (and screaming) in on the horizon. 

    © Zihao Wong – UAV bird scarer as used in: Psychological warfare in vineyard: Using drones and bird psychology to control bird damage to wine grapes

    So there you have it. Starting with a couple of grapes at the grocery store, we end with a weapon of war designed to create fear and confusion. While we may not be any closer to answering the debate about grocery store grape sampling, we at least seem closer to solving the grape stealing starling situation. Will psychological warfare finally be the fix-all solution? Perhaps, but only time (and research) will tell. 

    As for me, I still don’t quite understand what it is about grapes that causes both the starlings and my dad to lose all sense of self-control. Maybe with 24 more years of research, innovation and whatever military tactic comes after psychological warfare, we will finally find that out. I am sure it will be a wild ride. 

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

    Citation: Y. Fukuda , C. M. Frampton & G. J. Hickling (2008) Evaluation of two visual birdscarers, the Peaceful Pyramid® and an eye‐spot balloon, in two vineyards, New Zealand Journal of Zoology, 35:3, 217-224, DOI: 10.1080/03014220809510117

  • Kea pine for a new home?

    Kea, our smart alpine parrots, are sometimes a little too clever for their own good. They are a species struggling to maintain large and healthy populations. Part of their problem is that they are very curious and seem to be fascinated by what humans do, and more importantly, often live in human-influenced habitat. This is not such a good trait when it leads them to interact with hazards like lead or toxins, nor is it useful if they find human ‘junk’ food.

    This curiosity is also not helpful when we want to study kea. Many of the approaches that work with other bird species just fail for kea. Instead of going about their business they come and see what you are doing, and that’s not great for understanding key aspects of their life histories.

    Spot the kea at the top of the tree! Image by Adrian Paterson.

    I has some first-hand experience with researching kea about twenty five years ago, when I was a newly minted Lincoln University lecturer. I was helping Kerry-Jayne Wilson to supervise a masters student, Mark Jarratt. Mark was interested in how much lead, and other nasty waste, the kea were finding in the local Arthur’s Pass area, and consuming, in their habitat. For example, lead was present in paints, shotgun pellets and rubbish in the tips and kea were often observed eating it.

    Mark had to catch kea to take blood samples to check for lead contamination. Catching kea can be fairly challenging. They are not easily fooled and they can learn by observing others. Adding to the difficulty was that we had to keep the birds in captivity for an hour or so as part of the procedure. And this was a problem.

    We initially used a cage. We would capture a kea, put it in a holding cage, and then go and try and capture the next one. However, each kea would often figure out how to escape the cage. We would return to find a cage open and our patient free (and not likely to be so easily caught again). So then we took the cage with a kea into a small hut nearby, thinking that if the bird got out of the cage then they would at least be in the hut. Unfortunately, some of the kea managed to figure out how to open the windows in the hut. Moral: don’t work with animals smarter than you are!

    So, when PhD student Jodanne Aitken came to James Ross and me and wanted to do a project on kea, I was a little hesitant. However, Jodanne is nothing if not persistent, passionate and persuasive, and a project on kea was begun.

    Early morning in the plantation. The native forest in the distance was often commuted to and from by kea. Image by Adrian Paterson.

    Jodanne was interested in how kea move about and utilise the landscape. Much of her PhD work is in the Southern Alps around Arthur’s Pass, where she is using transmitters to figure out just how mobile kea can be. Is that kea you see gnawing your car wiper blades from the local valley or could it be from several mountain ranges away? More on that in future EcoLincNZ articles!

    Jodanne’s initial work was in looking at how kea might be using plantations of introduced pine and Douglas fir in the Nelson region. Forestry has become a dominant part of many regional landscapes, often hilly and where native forests once grew (and kea once flew). This is especially the case in the Nelson region. The question that Jodanne wanted to answer was whether these forestry plantations, typically monocultures with a lot of human activity, provide a net gain or loss for kea.

    Jodanne filming kea foraging behaviour. Image by Adrian Paterson.

    Are plantations the equivalent of barren wastes for kea, where there is little food and high densities of mammalian predators (not to mention hazards that humans introduce into an area)? Alternatively, do plantations offer new food resources and places to roost and nest? Of course there could be a range of outcomes from positive to negative.

    Jodanne was able to work in forestry blocks run by Nelson Forestry Limited. Local workers were key to providing Jodanne with almost real-time information on kea presence within blocks that were being actively harvested. One advantage of working in plantations were the forestry roads that gave rapid, if a little hair-raising, access to most of these areas.

    Jodanne was able to capture three kea and mount GPS trackers in fancy backpacks to collect movement data. She also observed kea during the morning and late afternoon-early evening periods for several months, mostly to record their feeding. Jodanne used direct and video observations to observe their foraging. Kea poo was also collected when available to get some physical information about diet.

    The kea with transmitters spread their time between the plantation areas and neighbouring native forest. The majority of time was spent in the pines where they foraged, roosted and nested. Kea were observed eating pine seed, as well as tissue stripped off newly harvested Douglas fir logs. The faecal samples, well the bits that could be identified, contained lots of invertebrates.

    Kea have discovered that they can strip the bark of newly harvested logs, scrape off the cambion tissue, chew this and get something nice out of it. (Maybe a bit like eating sweets?) This may be one of the attractions of being in plantations. Image by Adrian Paterson.

    In short, as summarised in a NZ Journal of Zoology paper, kea seemed to be using the pine plantations in similar ways to more natural areas. Good news! However, one of three kea that carried a GPS recorder was killed by a cat. So, there may be some significant risks for kea spending a lot of their time in these areas. ‘Swings and roundabouts’ as they say.

    Despite this being a relatively small scale study, it does indicate that we could learn a lot more about kea in these highly modified landscapes. Jodanne has taken this training and shifted her sights to a much larger scale project on kea movement in the Southern Alps and southern Westland.

    Kea are one of the smartest bird species on the planet but they still need our help to let them survive the arrival of the smartest mammal species and the changes that we have made. Understanding this clever species is fundamental to helping them. This tricky challenge has been accepted by Jodanne and her research colleagues.

    Article by Adrian Paterson, an Associate Professor in the Department of Pest-management and Conservation at Lincoln University.

  • Kiwi calling: when listening is not enough

    I don’t know about your’s, but my mum gets worried when I don’t respond to her phone calls for a few hours. Once, I can’t remember what I was doing, but I didn’t hear the phone ringing. When I finally checked my phone I saw about 17483 missed calls, oops. I can only wonder what went through her mind when I wasn’t responding: she was probably picturing me skydiving, in an ambulance, or lost in the woods during a hike.

    But what if she’d had a more statistical mindset and thought about why I hadn’t responded? Or even better: what if she’d thought about reasons why she could not detect me?

    Ecologists and conservationists consider something similar when analysing data obtained from searching an area for a certain animal species. An animal could be present at a certain site, but still go undetected. First, they have to consider what ecological reasons might have determined where the species was present or absent (for instance, where is there suitable habitat within the considered area). Second, they have to take into account what factors might have influenced the likelihood of actually observing the species (such as the distance from the observer, or the fact that the surveyor may not be skilled enough to recognise the species). These are defined, respectively, as occupancy (which is the same as saying “presence”) and detection probabilities, and can be estimated by using statistical models.

    Occupancy probability and detection probability are described by two different models and both of them will influence what will be observed during a survey. Taking into account that not all the animals will be observed is very important when attempting to accurately assess a species’ presence, which could otherwise be underestimated.

    A young roroa being released as part of the Operation Nest Egg programme. Image by Jon Sullivan on Flickr.

    Peter Jahn, James Ross, Darryl MacKenzie and Laura Molles, in a study published in 2022, wanted to know how accurate acoustic surveys of roroa-great spotted kiwi (Apteryx maxima) were between 2011-2015. During this time, 18 birds were translocated from the Hawdon Valley, in Arthur’s Pass National Park, to the Nina Valley, in Lake Sumner Forest Park, representing one of the initial efforts of the Operation Nest Egg programme. The researchers also wanted to compare kiwi presence before and after 2015, and between the two areas.

    They gathered data from a survey conducted in 2012-2013 by DOC in both the valleys and then repeated the methodology in 2017-2018. The technique they used was passive acoustic monitoring (PAM). PAM is effective when studying elusive species such as kiwi. Automatic recorders were deployed in the two study areas and left there for up to three weeks, activating just before sunset and switching off shortly after sunrise.

    The team analysed the kiwi calls recorded in each of the valleys. The goal was to find a model that would best describe the obtained data, and use it as a base to estimate occupancy and detection probability. Peter Jahn and colleagues wanted to know which factors were important in detecting the kiwi and looked at the study area (Nina and Hawdon Valleys), year, length of the survey night, breeding/non-breeding season, precipitation, wind speed, night length, varying recorder battery capacity.

    Similarly, my mum could have considered the fact that my phone may have been in silent mode, or had no service, or estimated the actual likelihood of me being in an ambulance. All of these factors could have influenced her imperfect detection of me.

    In both the study areas, the detection probability was found to be higher during the breeding season, to increase with longer survey nights and to be influenced by wind speed, rain accumulation and recorder sensitivity. Also, as expected, kiwi presence in the Nina Valley increased after the translocation, as it did in the Hawdon Valley. Moreover, it was found that the number of sites where kiwi calls were recorded increased in 2017-2018 in both the areas and that, in total, many more calls were detected in the Hawdon Valley than in the Nina Valley.

    The Hawdon Valley in Arthur’s Pass National Park. Image CC-BY-NC by Jon Sullivan on Flickr.

    Wait, the number of sites where calls were recorded and the presence of kiwi increased in the Hawdon Valley after kiwi were removed from there? How is that possible? Yeah, that was one surprising finding of the study. In fact, the researchers were expecting that occupancy would decrease after the birds’ removal, but what they found actually suggests that new pairs re-occupied the territories left inhabited by the translocated individuals.

    This is a promising result, because it means that such conservation strategy doesn’t necessarily negatively influence the population from which the individuals are taken. Also, the ongoing pest mammal control in the Hawdon Valley could have balanced the negative effect of the translocation. I guess the only thing left to do now is find out what makes kiwi desire those territories so much that they can’t stay away: maybe they have the most delicious earthworms of New Zealand?

    To conclude, these findings demonstrate that the species is reacting well to this reintroduction programme, considered that kiwi presence increased in the Nina Valley too. Furthermore, this study showed that combining occupancy estimates through statistical models with acoustic monitoring is very useful when studying the outcomes of kiwi’s translocations. However, if you, reader, can’t wait to know more about what happens to our dear kiwi when we move them around, sit back and read Peter Jahn’s PhD thesis: never stop learning.

    Finally, going back to my mum trying to “detect” me: I suggest the probability would increase a lot if she learned to call outside of my usual napping times!

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

    Jahn, P., Ross, J. G., MacKenzie, D. I., & Molles, L. E. (2022). Acoustic monitoring and occupancy analysis: Cost-effective tools in reintroduction programmes for roroa-great spotted kiwi. New Zealand Journal of Ecology, 46(1), 3466.