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.
Collecting things seems to have deep roots in the human brain. There are few things more satisfying than finding something unexpected that you really need for your collection. The shock (woah!), the excitement (at last!), the surprise (how did this get here?), the urgency (I better grab this before someone else does), even though anyone standing close to you probably won’t care about this!
My youngest son had a few years of thrifting where he would scour second-hand stores for ‘cool clothes’ that he could buy and then sell on for a reasonable profit to people who wanted that retro look but didn’t want to spend time searching. Edgar trained me up to spot certain brands, labels, styles and so on. For about five or six years I spent a lot of time browsing ‘dead peoples’ clothes’ as my middle son Arthur called them. I still remember a great trip with Edgar as I took him to a university semester in Dunedin. We struck gold in Waimate (a little off the beaten track) and found 30+ items!
A small selection of Tanith Lee.Active from the 1970s till the 2010s – prolific and great for collecting! The Winter Players and Companions on the Road are two of my favourite (short) books ever. Image from Adrian.
What do I collect? I guess there is a distinction between hobbies and collecting? I have a lot of small plastic figures that I love painting but I am not searching for some elusive or rare halfling commando. I buy a lot of boardgames and there are some older games that I might keep an eye out for, but I would count these as hobbies not collecting.
Books, I have a lot of books…. Some of that is hobby – reading the latest books by Tad Williams or Lindsey Davis, for example. But I definitely collect some authors (Tanith Lee, Robert Howard) and spend time in second hand book shops with a list…. I still remember the day that I found the original D&D colouring book in absolutely mint, uncoloured condition! So rare! So elusive! All mine! (Sadly it has somehow gone missing from my collection in recent years!).
Collected on camera – a red panda. Image by Sonam Lama
As a zoologist interested in natural history, you are also dealing with collecting. Typically you want to collect the types of species found in an area. This tells us a lot about species diversity and richness, conservation, ecological interactions, evolutionary adaptations and so much more! This collection could be physical (like the hundreds of thousands of insect specimens found in our LU Entomology Research Museum) or it could be observational, where spotting an individual from a species can be logged (like with iNaturalist). But it certainly scratches the collecting itch.
Observations can be direct (e.g. I saw that animal) or indirect (e.g. I found a footprint of that animal). Either way these are data that tell us that a species is found in the area. We are increasingly relying on indirect methods to collect observations – in fact much of our wildlife research here in Pest-management and Conservation is around developing better ways to monitor our mammal pests.
Sonam Lama was a Master of International Nature Conservation student at Lincoln University. He had spent a lot of time working for the Red Panda Network back in Nepal. As part of his research, with Adrian Paterson and James Ross, he was interested in being better able to monitor red panda in the wild (but that will be another story!). Sonam was also keen to find what other species share the red panda habitat in far eastern Nepal. Were there many predators? Were there many competitors?
Sonam in the forest of eastern Nepal. Image by Sonam Lama
Sonam worked within the high altitude (between 2-4000 m abs) forests of Ilam, Panchthar and Taplejung, which provide a corridor between the rest of Nepal and India. Over this large area Sonam identified sites where he could put his 60 cameras. Typically the cameras were attached to the base of a tree. Observations from these camera traps were made through winter and spring. Results have now been published in the European Journal of Wildlife Research.
So what did Sonam collect? Over 3000 camera trap days about 90000 images were recorded. Two thirds were false triggers (vegetation moving in the wind, sudden changes in temperature with sunrise and sunset) – such is the bane of the camera approach. About 11000 were of local people moving through the forest. Amongst all of this were over 5000 images of mammals, including 23 different species, and 3600 images of birds, including 37 species.
Seventeen of these mammals were medium to large and could be identified. Red panda were observed. The commonly seen species were a deer – northern red muntjac, wild boar and leopard cats. The rarest were other cats: marbled cat (first record in Nepal), Asiatic golden cat and common leopard. The spotted lingsang was also collected for the first time, as was the first melanic (black) leopard.
Collecting images and video also allows us to look at behaviour. We can get a sense of when species are active. We can see which species move around in groups. Wild boar foraged for tubers in front of the camera, red panda marked their territory, two porcupines mated! Red panda and macaques were active during the day, red foxes and porcupines were nocturnal.
Collected on camera, a melanic form of leopard. A first for the region. Image by Sonam Lama.
All of these collected images and videos provide little snapshots of natural history for these species, many of which are difficult to find any other way. Our understanding of potential threats for red panda has also increased. They definitely share their habitat with several potential predator species (and we found a few that were not even known from Nepal). Perhaps more importantly we were able to show that people are common in these habitats and that they are often accompanied by dogs. Good to know from a conservation point of view!
Collecting images of different species using trail cameras is an increasingly common tool around the globe. It is becoming an essential tool for monitoring species. It doesn’t hurt that there is that thrill of the collector when you find an image of something surprising in amongst all of those misfires.
This article was written by Adrian Paterson (Pest-management and Conservation at Lincoln University). Yes he is a collector ( I guess you could argue that he collects EcoLincNZ articles!).
We often put up with bad situations because they stop something worse happening. This can be as big as having nuclear weapons to stop major wars occurring. Paying taxes is a burden but it keeps a society healthy and connected. Not eating so much chocolate seems wrong but will give you better long-term health.
And then we have plastic. Plastic must rank as one of the most successful of human inventions. It can be used in myriads of applications, keeps foods hygienic for longer, and allows more people to have the luxuries of the modern world. Plastic also causes incredible waste and we are still learning about the ongoing and long-lasting impacts that occur from the breakdown of plastics into smaller and smaller molecules.
One of the biggest shifts in day to day life over the last decade or so is the movement away from plastic where possible. Many countries have banned (or are banning) single use plastics. I would doubt that there is anyone unaware of plastics as an issue for our sustainable future.
Plastic figures from Cthulhu: Death May Die! A great game with great plastic figures (but some guilt comes with it!). Image from Adrian Paterson.
One of my hobbies is in collecting and playing board games. Historically there has been a lot of plastic in games. Lately, there has been a real effort by gaming companies to make as much as possible from cardboard and wood and to remove stuff like shrink-wrap. (Although I do love me some great detailed plastic miniatures some of the time. I try to add use by painting them. Unfortunately, there is still nothing quite as good for sculpting as plastic. Hopefully that will change (see this approach using mostly wood shavings as a building matrix called re-wood).)
As we have mentioned many times on EcoLincNZ, we do a lot of research on vertebrate pest management, especially in monitoring and detecting mammals, like stoats, deer, possums, hedgehogs (even elephants and leopards). Controlling these pests is vital for conserving New Zealand’s endemic biodiversity. We are very good at doing this and improving all of the time. Unfortunately, we use a lot of plastic.
Our tracking tunnels, chew cards and wax tags all have significant plastic components. Some of these are single use, some can be used a few times, but there are always some that get left in the environment. Also, many of the places that we are interested in monitoring are, by definition, in areas that have low human impacts and very little exposure to plastic. And here we are bringing the plastic there.
Tracking tunnels are made of plastic. Typically they can be used multiple times but many are left in the monitoring areas. Image from Adrian Paterson.
Now, you could argue that a few negatives of using a relatively small amount of plastic is far outweighed by the good that using these devices does. And you would be correct. But what if we could have our cake and eat it too?
Katie looked at how much plastic is munched up by species, like rats and mice, when they interact with chew cards placed in various habitats. These bits of plastic remain in the rats and then the environment even if the cards are retrieved. The plastic fragments are also much reduced in size by the nibbling and can move around much easier, through wind, rain and rodent stomachs. The removed chew card will also end up in landfills.
Katie found that chew cards in Canterbury and Taranaki typically left 15% of their volume behind in the environment as nibbled bits. Given the scale of monitoring throughout New Zealand this can quickly add up to a lot of plastic in areas that typically have no plastics.
A well nibbled chew-card. All that missing plastic is now on the forest floor or in the faeces of rodents. Image from Katie Pitt.
There may be an alternative. Katie tested some new chew cards made from wood pulp, and so fully biodegradable. Of course we don’t want to use a product that is inferior to what we already use, especially for something as important as protecting our biodiversity. Katie tested the use of wood pulp chew cards alongside plastic models. She consistently found that they performed just as well in a range of conditions (including with a lot of rain!). Katie also found that prices per chew card were similar with scope for the wood pulp cards to eventually become cheaper.
Is this a problem that people want to solve? Katie asked individuals from 30 organisations that work in pest monitoring and found that 97% were keen to move away from single-use plastics, as long as there was no major reduction in functionality and cost.
So we have a problem, people want to solve this problem, we have an alternative, and this alternative seems to work as well as what we already have. Eat that cake and have it as well!
There is still a bit of work to do to scale this up to the levels that we need if this is to replace the status quo. Katie is also looking at how we would replace tracking tunnels. But the future is looking bright. And plastic-free.
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.
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.
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.
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.
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. saxicolorandP. 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.
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
Helpful gardeners or destructive beasts? Hedgehogs could be the last thing standing in the way of restoring native wildlife.
Most New Zealanders are aware of the current predator problem, with possums, rats and stoats taking the cake for the biggest pains, but what about cute little hedgehogs? Are they really as innocent as they look or are they discretely unravelling the very fabric of our treasured native wilderness? Some scientists went on a hedgehog hunt to find out.
Now imagine the magnificent Ōtamahua: an 80 hectare island smack in the middle of the flooded volcanic crater of Lyttleton Harbour, completely uninhabited by people, but instead populated by some weird mini chickens with fancy hairdos. Back in the day, European explorers hadn’t decimated local wildlife populations yet, and the island was teeming with now extinct koreke New Zealand quails, inspiring them to call this place Quail Island.
Quail Island is a recreation reserve run by the Department of Conservation (DOC) and is being restored to a natural landscape after being formerly farmed. In this programme, the Quail Island Trust and DOC teamed up with a plan to eradicate all exotic pest mammals from the island. Scientists were ready to restore the island to its original splendour by bringing back native insects, lizards and birds, but one thing could be standing in the way of this; the island is dominated by European hedgehogs, and they’re not going down without a fight.
So what’s the deal with hedgehogs? Everyone seems on board with killing every invasive pest mammal out there like it’s a glorified action movie. Oddly, people tend to feel very differently about these freaky little spike balls. Unlike other mammals that were introduced in New Zealand, people love them. This is because they can be seen helping around the garden, happily munching on slugs and snails, which are considered pests. But it’s difficult to understand exactly how these slug-munchers are impacting native wildlife, all we know is that we have gravely underestimated them.
What else is on the dinner menu for these hedgehogs? Aside from the snails and slugs in your garden, they enjoy eating native beetles of all sizes, with a side of millipedes, and then moth larvae and earthworms for dessert. Some have even developed a taste for weta. Hedgehogs also snack on lizards and the eggs and chicks of ground-nesting birds. The hedgehogs are hungry and this is a bad situation for these vulnerable species.
In the distant future, the year 2000, researchers from Lincoln University decided to go to war with the hedgehogs. They did so using their most powerful weapon of all: science and the pursuit of knowledge. They tested their techniques on local hedgehogs before heading into battle on Ōtamahua Quail island. The scientists discovered that they could entice the hedgehogs with a feast of their favourite foods. They tested baits like “kitekat chunky fish cat food” and quail eggs.
(It is worth noting that while the original quail island quails went extinct, they were replaced by introduced California quails, which is convenient because the island didn’t have to renamed.)
Once the scientists got to Quail Island and came face to face with these adorable monsters, they realized that unlike other invasive mammals, hedgehogs were pretty chilled out. They didn’t mind being caught and released again, which meant that it would be possible to remove them from the island without bloodshed. At this point, the animal rights activists may be cheering and the conservationists may be booing. Not killing them means putting them somewhere else. Instead of removing the problem, we are just relocating it.
Photo of Ōtamahua Quail Island by Jon Sullivan CC BY-NC 2.0
So the Lincoln researchers got to work running around the island, setting up 53 hedgehog traps. Since there was actually no such thing as a hedgehog trap at this point, they used their smart brains and decided to use traps for other pests which were known to catch hedgehogs by accident. The systematic trials led the scientists to the conclusion that one of the most effective baits for catching hedgehogs was something called “Chunks of Tasti Dinner Dog Roll”. You just can’t make this stuff up. Cat food and peanut butter were similarly popular among hedgehog audiences but surprisingly, quail eggs were not!
Here’s the bad news: hedgehogs had made themselves at home across every kind of habitat on the island. Also, the number of hedgehogs being caught each night didn’t decrease over the course of the 11-day study, leading the scientists to conclude that there were far more hedgehogs on the island than they had previously thought.
The baited traps were placed across all habitat types on the islands, but had much less success around pine and macrocarpa forests. The traps had the most success in catching hedgehogs in grassy and scrubby areas. Could this be the hedgehog headquarters?
This research provided some important insights into the possibilities of eradicating hedgehogs. They figured out which food is preferred and which types of cages work best. They found that the hedgehogs didn’t hang out in pine and macrocarpa forests as much because there weren’t as many insect snacks for them in there.
Quail Island in the centre. Image from Adrian Paterson.
This study found that live trapping hedgehogs is possible but it is inefficient. The project took 75 hours of work and only managed to remove 24 hedgehogs, that’s 3 hours per hedgehog! The scientists suggested switching to lethal traps because these Houdinis are clever masterminds and they could be escaping from the live traps.
Are there other options? Some have suggested recruiting the help of our best friends, dogs. On another island, dogs were used to find and kill possums. Hedgehogs are smelly and hunting dogs can find them easily without even being trained. The only caveat is that dogs do have to be trained to ignore other species, especially native birds like the precious little white-flippered penguin, another resident of Quail Island.
On the mainland of Aotearoa New Zealand, hedgehogs were found in densities of 5 hedgehogs per 1 hectare of land (which is the size of 2 rugby fields). This is probably not the case on Quail Island because it is so dry, but nonetheless it will take a lot of effort to remove these destructive little creatures.
This is one case study for the eradication of hedgehogs. While the current focus is on eradicating other predator species, may this serve as a warning that we can’t forget about the humble hedgehogwhen we talk about predator control.
Researchers compared two populations of kakaruai/South Island robins in similar forest habitats, one from the predator free island of Motuara and one from the main island, where introduced predators are present.
In the experiment, robins from the main island were more shy and less bold when they could pick up presented food items close to the researchers.
This suggests that a selection pressure from introduced predators favours individuals that are less bold and more cautious, potentially shifting personality traits of individuals in populations under predation pressure in the long term.
Petroica australis in the Hawdon Valley (Arthur’s Pass). (C) Copyright Maximilian Hanschmann – all rights reserved.
The small birds only weigh 35g and can survive up to 17 years – given that they are safe from invasive predators.
While still occurring on the main islands and doing better than many other species endemic to New Zealand, that evolved in the absence of any mammalian predators, the robins struggle to survive since several predatory mammal species have been introduced to New Zealand by humans.
During their evolutionary history in New Zealand, the birds never needed to coexist with these predators and as such act in a naive way towards them, making them an easy prey for ship rats, possums, stoats, weasels and feral cats.
Introduced predators are a big problem for robins, even if populations survived until now, they are struggling where predators are present, a fate they share with almost all remaining native bird species. Predators will prey on eggs, nestlings, fledglings and adult females in the nest, leading to skewed sex ratios, where there are many more males than females in the population. The risk of nest predation is seven times higher where mammalian predators are present, and the life expectancy of adult birds is reduced by roughly 75% compared with areas free of predatory mammals.
Petroica australis on the West Coast of South Island. (C) Copyright Maximilian Hanschmann – all rights reserved.
Individuals in two different populations, living in a similar native (kanuka Kunzea ericoides dominated) forest habitat but with a different exposure to introduced mammalian predators, were studied. One population lives on the predator free island sanctuary of Motuara and originates from a population that was never under the influence of mammalian predators, except for rats. The other population lives in two connected patches on mainland New Zealand, close to Kaikoura and is exposed to mammalian predators present at the site, including feral cats, stoats, ferrets, weasels, rats, mice and possums.
The aim was to assess the boldness of the robins or the willingness to take risks, which can vary among individuals within a species and can be influenced by environmental factors.
A robin in Nina Valley. Image from Adrian Paterson
To assess the propensity to take risks (known as the ‘shyness-boldness’ continuum) of the birds, mealworms were presented as food items at different distances to the researchers (proximity as a risk). It was then noted how long a bird took to pick the first item up (approach time) and how long a bird took to pick up all the food items (handling time). The quicker the bird approached and the more time it spent close to humans, the bolder it was considered.
The results showed that robins not under influence of predators had a significantly bolder personality. They were much more likely to quickly come as close as 30cm to the researchers and spent more time handling the food as robins that live on the mainland, under the predation pressure of various introduced mammals.
The findings highlight the big impact of introduced predators, influencing the behaviour and possibly evolutionary outcomes. Individuals that are more cautious around predators are less likely to get killed and have a greater chance to have more offspring, promoting their personality traits in the next generations. These effects are likely not limited to robins, but likely also apply to other struggling native bird species that survived until now.
Robin and trail camera in Nina Valley. Image from Adrian Paterson.
What you can do:
Spread the word! Talk with other people about biodiversity issues and how to solve them.
Value the unique native ecosystem of New Zealand and its vulnerable species.
Promote no-go areas where birds breed and in core areas of vulnerable ecosystems.
Lobby for better regulations and environmental standards.
Use your vote in elections to support the effort to safe New Zealand’s unique, but highly endangered biodiversity.
Control predators on your property. Help others controlling predators.
Plant native plants from your region. Remove non-native plants, even if they are “pretty”.
Participate in citizen science (e.g. iNaturalist) and help to detect various species.
Be a responsible cat owner: cats should be microchipped, registered and unable to reproduce uncontrolled. Consider walking your cat on a leash or ensure it can’t leave your property. New Zealand’s native species are exceptionally vulnerable to predation! Feral populations are not only a huge issue for non-adapted, vulnerable species, but also an animal welfare problem for the feral cats.
Be a responsible dog owner: dogs should be microchipped, registered and unable to reproduce uncontrolled. Walking your dog on a leash reduces the negative impact on wildlife. Dogs are among the gravest threats for adult kiwi, as they can kill a kiwi by just giving it a playful push (kiwis don’t have a sternum and are incredibly vulnerable). Ensure the dog can’t leave your presence.
Read the full study here: White, R., Rossignaud, L., & Briskie, J. V. (2023). The bold bird gets the worm? Behavioural differences of South Island robins (Petroica australis) in relation to differing predation risk. New Zealand Journal of Zoology, 51(2), 334–349. https://doi.org/10.1080/03014223.2023.2255165
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.
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.
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.
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.
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?”
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.
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.
