Unearthed Gems – EcoLincNZ articles from the last two decades see the light again! From 2008…
The blue penguin (Eudyptula minor) is found around New Zealand’s coastlines and in many parts of south-eastern and western Australia (where they are sometimes known as fairy penguins). Over the years there have been many different suggestions put forward to explain the regional variations seen throughout the range of this species.
Early researchers hypothesised that each geographical region of New Zealand contained a subspecies of blue penguin. Molecular data from gene regions is often ideal for examining these kinds of hypotheses. A study in 2002 found only a little support for regional differences but a lot more support for major differences between blue penguins in New Zealand and Australia.
Image by Julie Paterson.
In a follow-up to this study Adrian Paterson, Rob Cruickshank, Gabby Drayton (Lincoln University) with Jonathan Banks (then University of Waikato) examined the regional genetic variation of blue penguins across Australia. Samples were taken from a western Australian and Victorian populations (which are thousands of kilometres apart).
The team examined the fast evolving control region and the slower evolving cytochrome B gene regions of the mitochondrial DNA from each penguin sample.
The western Australian individuals were found to be the same as the Victorian samples implying that there is a high level of gene flow between east and west Australia (more than from the east and west coasts of New Zealand, for example).
The study also confirmed that Australian and New. Zealand blue penguins are very different genetically and may warrant becoming recognised as separate species in the future.
Curiously, this study also agrees with the earlier study by placing the birds from Otago, New Zealand with the Australian birds rather than the other New Zealand populations. This result is hard to explain at present and will provide impetus for further studies.
This was the second EcoLincNZ article uploaded and was written by Adrian Paterson. In upgrading to a new site it was lost. I am uploading some of these old articles to let new readers access them. Adrian is currently working on little penguins for the first time since this time in 2008!
Unearthed Gems – EcoLincNZ articles from the last two decades see the light again! From 2008…
Tuatara, leiopelmatid frogs, weta (Orthoptera), peripatus (Onychophora), southern beech (Nothofagus) and kauri (Agathis australis) and other New Zealand species are often referred to as Gondwanan taxa. What does this mean? Gondwanaland was a large landmass made up of the southern continents that slowly broke apart through Jurassic and Cretaceous time. The New Zealand area began to break away from Eastern Australia and Antarctica around 83 million years ago in a large chunk of land the size of India, called Zealandia. Slowly this landmass sank. All that remains of this small continent are New Zealand, New Caledonia, Norfolk, Chatham Islands and the subantarctic islands. The term ‘Gondwanan’ is given to species whose distribution recalls this ancient history.
The living species of penguins. Art by Julie Paterson.
First, a taxon is Gondwanan if its lineage has been continuously present in New Zealand since Zealandia broke away from Gondwanaland.
Second, a taxon is Gondwanan if it is descended from a lineage that was present in Gondwanaland prior to break-up but arrived in New Zealand after Zealandia broke away from Gondwanaland and sank (dispersed and colonised).
Third, a taxon is Gondwanan if species are currently found in former Gonwanaland landmasses – but with no expectation of a common historical process to explain different instances of this pattern (which could be because of either of the two meanings above).
For example, penguins are found in New Zealand, Australia, southern Africa, South America and Antarctica and certainly demonstrate a Gondwanan distribution (third meaning).
Penguins have a fossil history to at least 62 Myr ago and molecular analyses suggest a much earlier origin in the Gondwanaland landmass, implying that they are found in the New Zealand region by virtue of having been in Gondwanaland when Zealandia rifted away (first meaning).
Fossil and molecular data all suggest that modern living penguin species all share a recent ancestor from about 25-30 million years ago. Living penguin genera of Eudyptes, Eudyptula and Megadyptes may have colonised New Zealand from other former Gondwanan landmasses since that time (second meaning).
Indeed, Eudyptula, the blue penguin, is found in Australia and New Zealand with molecular evidence for recent contact between these populations. Thus, the modern distribution of penguins could be described as Gondwanan in all three senses.
Does it really matter; it’s all Gondwanan isn’t it? Science is about being precise, removing ambiguity and these three meanings suggest different things. Meaning three simply acknowledges that there is a group of species that share a certain southern hemisphere pattern. Meanings one and two provide different explanations for the origin of this pattern with meaning one implying species have been continuously in New Zealand for 80 million years and meaning two implying that the species could have arrived at any time over the last 80 million years.
Understanding the difference will allow biogeographers (scientists that study where species are found) to be better able to tell the complicated story of the history of the New Zealand’s biota.
This was the very first EcoLincNZ article from 2008, written by Adrian Paterson. In upgrading to a new site it was lost. I am uploading some of these old articles to let new readers access them. Adrian is still bothered by how we use Gondwana.
Being a born and bred southern man from South Otago, crying is not something that I do much (or was encouraged to do).
There are some things that make the eyes prickle, though. Movies can certainly do it. Aragorn telling the hobbits “My friends, you bow to no one” in The Return of the Kingis certainly is up there. The last “That’ll do pig” from Farmer Hoggett in Babehas always gotten me. The final soaring ending of The Last of the Mohicans as Hawkeye and Cora gaze out over the forest clad hills brings the shiny eyes. The speech from young Paikea about her grandfather in Whale Riderwas emotional enough in 2002, now that I am a koro myself with a granddaughter, I can only imagine it would be even more devastating.
In reading books I am a lot more immune to tears. There are, however, a few passages in The Lord of the Rings that will make the eyes water. One of them is in my most favourite section in the trilogy.
Tucked in towards the end of The Two Towers is the chapter Journey to the Crossroads. The last section, just over a page long, tells how Frodo, Sam and Gollum finally arrive at the crossroads. They have been sneaking through the gloom of Ithilien for the whole day, in an absolute unnatural quiet, broken occasionally by distant thunder or drums. They are scared and dejected. They arrive at the crossroads where, once they pass them, they will be committed to walking past Minas Morgul and into Mordor.
An old statue and surrounding walls have been vandalised by orcs at some point and all is in disrepair. Everything is sombre and Frodo is filled with dread.
The King at the cross-roads (Darrell Sweet)
At that moment the sun drops below the ash-cloud cover and shines a light on the scene, picking out the fallen head of the statue and the pretty flowers encircling it like a crown.
“They cannot conquer for ever!” said Frodo. And then suddenly the brief glimpse was gone. The Sun dipped and vanished, and as if at the shuttering of a lamp, black night fell.”
Cue the lump in the throat. It’s the hope that gets you.
There is another reason why I like this chapter so much. The hobbits are travelling through Ithilien, a beautifully lightly wooded region next to the Mountains of Shadow. Mostly the malign influence of Sauron has been kept to a minimum. There are always signs that Orcs have been up to mischief and that the local environment is beginning to suffer from Orc impacts. As the trio move closer to Minas Morgul, a source of orcs, pollution of the local rivers, and general environmental callousness, we start to see greater impacts on nature.
In my humble opinion, one of the best and most moving passages in the Lord of the Rings.
And then the sun shines for that brief moment and the Hobbits see that there are still beautiful plants growing and flowering, even in these areas of high impacts. Nature can persist in the face of ongoing Orcanisation.
Over the last few years, much of my research has involved looking at the impacts of anthropogenic (human) impacts. These impacts are often through urbanisation – building suburbs everywhere -and on local species in the environment. Research has ranged from how blackbird behaviour changes from the town to the country, to how kea and black-fronted terns respond to farming-use changes in the environment.
While we have a focus on impacts on birds in New Zealand, bats are a group that are often looked at in other parts of the world. Bats move around the landscape and will almost always come into contact with anthropogenic impacts in their travels. Bats are often a good indicator species for any local problems caused by humans.
Much of the work on bats has been done in Europe and often around major cities, typically in low altitude flat areas. Lincoln University Master of International Nature Conservation student Quinn O’Halloran had the opportunity of collecting data on bats in the South Tyrol landscape of the northern Italian Alps. Quinn joined a long term data collection project in the EURAC Institute for Alpine Research.
After a summer spent surveying for bats (using bat detectors that can record their calls) Quinn was given access to six years of data from 320 sites, focussing on 32 urban settlement sites and spent her thesis time analysing this information. Quinn wanted to find out how bats responded to urbanisation of these alpine valleys where the human population has grown over a large area in the last few decades.
Image from Valentin Heimer (EURAC Research)
Quinn was interested in how variables impacted the activity and diversity of bats in these areas. She looked at the influence of factors like the amount of hard surfaces and woodlands, distance to woody patches and rivers, access to old buildings and so on.
Typically, urbanisation has a big impact on bat diversity and numbers. There are a few bats that do well with human changes but most don’t and so there is a clear signal that cities are not great for bats.
Image from Andrea De Giovanni (EURAC Research)
In the South Tyrol this was not the case. Quinn found that bat diversity and activity was much higher than expected, even with bats that typically don’t do as well in urbanised environments in other parts of Europe. It seemed that there was enough access to woody patches, water and green areas in these alpine environments for the bats to be less impacted than in other places.
It is likely because of the three dimensional landscape of the alpine environment. The South Tyrol has a landscape of deep glacial-cut valleys (flatfish bottoms and steep sides). People live and build in the valley bottoms but they don’t make it far up the sides (even to farm) as they are very steep.
For a flying bat this is not such a problem and so they have access to somewhat wild areas not too far way up the valley walls. This access is enough to counter some of the urban impacts that are problems for bats living in cities on open plains where there are few wild areas. Quinn was able to show that bats and human changes in the environment respond in different ways depending on the landscape.
Image from Harriet Taylor.
So, much like Frodo and Sam at the crossroads, there is always hope. Urbanisation can seem like an overwhelming problem for our native diversity, and it often is. But we also need to remember that not everywhere is the same and that species are often more resilient than we think (or at least better at finding and using resources in the local environment than we expect).
Nature is robust, and, sure, it will accept help where we give it. But nature is not just a victim, it can also help itself as well. And that’s a hopeful message.
Now, if that doesn’t bring a tear to your eye then I don’t know what will.
When Adrian isn’t choking back the tears he is a lecturer at Lincoln University.
I think most of us at some point in our lives experience loneliness. Even we as a species are alone, having separated from our closest relatives, chimps, several million years ago. We are also alone in our genus with the last of our Homo siblings species having gone extinct roughly 10 – 40 thousand years ago. Now, there is only us, Homo sapiens.
For the Gradungulidae family of New Zealand’s spiders shared the same story until recently.
Gradungulidae, the large clawed or odd-clawed spiders, is a family of spiders endemic to New Zealand and Australia. Gradungulids are identified by their asymmetrically large claws on the 1st and 2nd legs that they use to capture prey(giving rise to their ‘odd-clawed’ name).
Until recently there were only three species of Gradungulidae found in New Zealand; Gradungula sorenseni, Pianoa isolata, and Spelungula cavernicola.
Gradungula sorenseni has the widest distribution across NZ, in forests stretching from Nelson and Marlborough in the north, to western Southland and across the Foveaux Strait into Stewart Island in the south.
Pianoa isolata is found only within the native beech (Nothofagaceae) forest of Waikaia Forest in central north Southland, where it gets its common name Piano Flat spider, named for a series of flats along the Waikaia River.
Spelungula cavernicola, has a more limited distribution, and is one of only two legally protected spiders, the other being the Katipo spider (Latrodectus katipo). Spelungula cavernicola is found, as its name implies, primarily in caverns or cave systems. It is present in the Oparara cave system north of Karamea on the upper west coast of the South Island, caves along the Heaphy River, and in the Motupipi cave region of Golden Bay.
One of New Zealand’s two legally protected spiders, the Nelson Cave Spider, Spelungula cavernicola, Forster, 1987. Photo: Mark Anderson. Photo taken 15 July 2017, sourced from Wikimedia Commons. Cc-by-4.0 license. https://commons.wikimedia.org/wiki/File:P1150023-001.jpg
All of these species of New Zealand’s Gradungulids were described by New Zealand’s most accomplished arachnologist, Dr Ray Forster. While describing these species Dr Forster suspected that the actual diversity of the Gradungulids was much greater but he could not gather sufficient samples to captures this within his lifetime.
This extra diversity has continued amongst New Zealand’s subsequent arachnologists. Over the last 20 years Gradungulids specimens have been diligently collected across their distributions to fill this gap within Grandungulid taxonomy (including The following people collected specimens over 20 years: Peter Michalik , Cor Vink , Martin Ramírez , Danilo Harms and Stephen Pawson).
In 2015 a photo was uploaded by Andy MacDonald to iNaturalist of an unidentified species of Pianoa found in Mount Richmond Forest Park, Marlborough. This site is 600 km away from the known population of Pianoa isolata in Waikaia Forest! This find led to the discovery of another population of a different Pianoa species near Rarangi, Marlborough by Patrick Miller. Both of these discoveries were made by amateur naturalists, making this an amazing win for citizen science!
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Unidentified Pianoasp. (sp. means an unidentified species in the Pianoa genus) in Mount Richmond Forest Park. Photo: Andy MacDonald. Photo taken 17 October 2015, sourced from INaturalist. Creative Commons copyright. https://www.inaturalist.org/observations/2148126
All of this research and specimen collection over the last 20 years has resulted in the discovery of two new species of Gradungulidae, with there likely being more!
Specimens from Spelungula, Pianoa, and Gradungula were analysed using both DNA and traditional taxonomic methods and confirmed that there was enough difference in populations of Pianoa, and Gradungula to constitute different species!
These two new species have been named Gradungula kahurangi sp. nov. (sp. nov. means new species) and Pianoa civis sp. nov. There are also likely to be another species of Pianoa and another two species of Gradungula, but these were unable to be confirmed due to a lack of adult specimens (where species differences are most obvious).
The populations of Spelungula cavernicola found in the Oparara and Takaka cave systems were not found to be different enough to be two separate species, despite these two cave systems not being connected and roughly 70 km apart!
Piano civis, sp. nov. male raised from a subadult by Cor Vink for taxonomic description. Photo: John Marris. Obtained with permission from John Marris and Cor Vink for use in this blog.
This suggests that historically, and even currently, there may be travel of Spelungula cavernicola between cave systems, likely using the isolated caves of the Heaphy Valley. This is a rather impressive feat for a cave spider!
This lines up with present research on Spelungula cavernicola being troglophiles (species that can live both in cave, but also on the surface) rather than troglobites (species that live exclusively in the permanent darkness of underground habitats, such as caves).
Pianoaisolata, and Gradungulasorenseni now have new siblings, likely with more on the way! However, Spelungula cavernicola is still alone, an impressive testament to their ability to travel outside their cave systems which they depend on!
Diversity of New Zealand Gradungulids appears to be concentrated in the northern part of the South Island. Research is ongoing, with potentially three more species to be described. Citizen science has played a crucial part in the discovery of these new species! So, get out there and get involved.
Who knows there may be a new species out there waiting for you to find it!
Bellbirds love to sing; they sing for everything that they do. Communicating, courtship, foraging, defending their homes, it’s almost like they’re living in a musical. I’ve always been captivated by the song of bellbirds. Whether I’m on a walk in the Port Hills, or at Willowbank Wildlife Reserve looking at the capybara and otters, I hear bellbirds singing in the background.
The New Zealand Bellbird, or Anthornis melanura, is a honeyeater species and a close relative of New Zealand’s Tūī (Prosthemadera novaeseelandiae). They have a variable diet, feeding primarily on nectar, but also fruits, insects, and scale insect honeydew. In Christchurch, bellbirds spend their summers in the Port Hills, feeding from the large nectar supplies that come from flowering native vegetation. Then, in the winter, some move to the city, where urbanisation creates a warmer environment, and sugar feeders and exotic plantings provide food.
In 2019, PhD student Jennifer Dent studied foraging and migratory patterns of bellbirds in Christchurch for her thesis, using their calls to determine where different groups were. Bellbirds in different areas make different calls, basically a different accent, language, or singing a song in a different key, and this is referred to as dialect.
For this, Jennifer placed DOC AR4 audio recorders at 59 locations. 29 locations were in the Port Hills, where recording took place in autumn. Sites were everywhere from Rapanui Bush in the east to Ahuriri Reserve in the west, totalling 15 km around the Port Hills. The other 30 recording locations were in Christchurch city during winter, from as far north as the Groynes, as far east as Sumner, and as far west and south as Lincoln. From this, Jennifer matched dialects in the Port Hills in autumn to those recorded in Christchurch city in winter.
Christchurch dialects
Jennifer found four different bellbird dialects in Christchurch.
Dialect A was the most common dialect. It was spread across the northern region of the Port Hills, as well as in more central areas, such as the Botanic Gardens.
Dialect B was the next most common. In the Port Hills, it was found in Kennedy’s Bush, and in the city, it was in south-western areas, such as Halswell and Hoon Hay.
Dialect C was the least common dialect that Jennifer observed. In the Port Hills, it was found in Omahu Bush, and in Christchurch, it was found outside of the city, but only as far as Tai Tapu and Lincoln.
Dialect D was the last dialect. This pattern is unusual because it was not found in the autumn Port Hills recordings, but was found in the winter Christchurch recordings around the eastern and northern parts of Christchurch, such as Sumner, the Groynes, and Riccarton Bush, but because it was not found in the autumn recordings, it is not known where they went after winter.
It’s surprising that four different dialects were found both so close together and with very little overlap, especially since there are no geographic barriers stopping members of one group from flying to another. Jenny suggested that there could be two main reasons for this: limited dispersal and vocal imitation.
Limited dispersal, or philopatry, is the theory that states that birds remain in the areas where they were born and raised perhaps because it is harder to survive outside their own groups. A second theory is that vocal imitation by bellbirds occurs when birds move between groups, but we don’t notice it because they are so quick to pick up on the new dialect. It is possible that both of these theories are occurring simultaneously.
Following bellbirds into the city
The presence of all Port Hills dialects in the Christchurch recordings suggests that seasonal dispersal from the Port Hills to Christchurch is a shared behaviour among all populations. Furthermore, as shown by the map, dispersing to the nearest suitable location rather than spreading across all of Christchurch also seems to be a shared behaviour.
Bellbirds in Christchurch likely remember foraging areas for different times of the year, but rather than remembering many locations across Christchurch, they remember only a few patches that are close together. This is referred to as patch-scale resource tracking, and it has been shown to be a low-work, high-reward technique for foraging by bellbirds.
Next time you hear a bellbird singing, you aren’t just hearing background noise, you’re hearing a local neighbour. That bellbird might be a Cashmere regular or a member of the Tai Tapu community. It makes Christchurch a more lively city, as it’s not only just a place for us, but for birds following their own routines, singing their songs as they go about their day.
This article was prepared by Master of Science student Max Mulvihill as part of the ECOL608 Research Methods in Ecology course.
For myself, a plastic decoy is first, and foremost, synonymous with hunting. Perhaps to some this hobby seems counterintuitive coming from an ecologist, but rest assured, we pride ourselves on habitat protection and pest population management (with the added benefit of free-range tucker).
Over years of game-bird chasing, I have put out dozens of decoys. Never once did it cross my mind that a tool like them could be used for conservation.
But when you think about it critically, why would decoys not be useful? Decoys and callers are first and foremost attractants, playing on the target species’ keen senses and basic behavioural responses. As ecologists, we already familiar with attractants. The tried and true Pics peanut butter bait in tracking tunnels, enticing awiry old possum to investigate, or the sprinkling of icing sugar in front of a wax tag, are very common in our conservation landscape.
Black-fronted terns (Chlidonias albostriatus)- credit Carey Knox (CC0 no rights reserved)
Species of birds that live within colonies use cues from peers to gauge habitat quality. To put it plainly, think of it like a review on a hotel. You’re probably more likely to go to one that your mate rated higher, right? So if your bird mates hang out in an area then this is probably a sign that it is a great place for a nest. These cues have the added benefit for colony birds of improved breeding success and survival.
Historically, conservation for colony-forming birds, such as the Kororā and Black-fronted tern in New Zealand, has underused this behaviour, relying heavily on predator control and habitat enhancement instead. These techniques are both particularly costly and need extensive upkeep for continued positive results. How about instead of focusing on getting the number of living birds up, we focus first on increasing the number of their plastic alternatives? … Have conservationists lost their minds? Quite the opposite.
Benefits of social attractants
Social attractants, such as decoys and audio players, can work effectively to encourage threatened species to inhabit more desirable areas. Decoys can mimick the cues that gauge habitat quality by colony-forming birds.
By actively encouraging individuals to inhabit these areas, this may reduce the number of birds attempting to nest in more dangerous locations. Those dangerous places could include a particularly low-lying section of coast where nests would be swept away during severe weather events, or an area without predator control.
Attractants could be used in combination with predator-proof fences, weeding and predator control, to create nesting sanctuaries. This is particularly useful for our more aeronautically inclined natives that are not confined by fencing, as opposed to their flightless counterparts. Nests and attractants would give them a reason to stay within these safe havens, which would improve survival and breeding success.
For our rarer species, social attractants may further aid breeding success by encouraging a higher number of individuals into a particular area. This would help boost reproduction rates due to more breeding-age adults being close together.
Illustration by Author (CC0 no rights reserved)
Trialing social attractants for black-fronted tern conservation
Social attractants were used in a Lincoln University study to identify their effects on black-fronted terns (Chlidonias albostriatus). This study was completed by Courtney Hamblin in 2019.
The types of social attractants that Courtney used included a sound anchor system, which played a variety of black-fronted tern calls, includingfishing, begging, and kit calls, on a looped playback. Her study also used plastic decoys as visual attractants.
Courtney’s experiment used nine braided rivers within the Canterbury region, with ten locations each for both untreated (without attractants) and treated (with attractants) sites.
First up, Courtney needed to pick her sites on these braided rivers. She selected sites that best fit tern nesting, but without terns having nested there before. She also wanted the sites to be safe for terns to nest at if they chose to do so. It wouldn’t have been a good look if nests had started floating away!
Courtney then compared tern behaviour between sites with and without attractants. To do this, patience had to be a virtue. Over fortnightly 1-hour sessions for each site, she looked for interactions, particularly terns circling/hovering over these areas, landing within plots (land-in) and landing close by (land-out).
Diagram of the audio playback setup (Above) and example of a decoy used in the project (Below). Photo credits – Courtney Hamblin (CC BY – NC 4.0)
When the study had concluded, Courtney, and her supervisors Adrian Paterson (LU), James Ross (LU) and Richard Maloney (DoC), found that there was over nine times more activity recorded within plots with attractants than within plots that lacked any attractants.
Black-fronted tern nesting was also found to have occurred near eight out of ten treated sites. Of these, five sites had terns nesting within 300 m, which was significantly closer than distances from the untreated sites.
Unfortunately for me, as they were used together, there was no speculation on whether the decoys or the audio playback setup had the greater effect. So for now, I won’t be trading in my trusty wooden duck caller for a fancy electronic apparatus.
These results show that black-fronted terns do interact with social attractants. They could be useful for black-fronted tern conservation by helping to attract individuals into desirable areas to nest.
So social attractants could provide us with huge gains for black-fronted tern conservation, now that we understand all their neat uses!
Diagram of the treated plot – note there would be an equally sized area used for the untreated plots without decoys and speakers. Credit – Courtney Hamblin (CC BY – NC 4.0)
So what are the opportunities for social attractants? Endless!
Social attractants already have success stories. A notable win was their use in helping to restore the iconic Atlantic puffin to Eastern Egg Rock in Maine. But let’s ponder the future.
Think about the possibilities, such as their use in protecting species against climate change effects. Social attractants could readily be employed to move nesting locations away from at-risk coastal areas or encourage nesting within predator-proof sanctuaries to avoid exotic threats that are likely to arrive in New Zealand ecosystems.
Final thoughts
Even with all the prospective benefits, the study also made me think about issues that may arise with social attractants. Sure, they encourage some native colony birds to interact with them, but would this not be the same for native/exotic predators? They too key off cues from their target species, such as sounds and visuals.
This sparks memories of harriers circling over my decoys, ready to pounce on any shot birds, as if they were using my decoys as a marker for a prospective feast.
To me, this was a particularly poignant thought, which I would love to see investigated.
This article was prepared by Master’s of Bio protection student, Jonathan Morriss, as part of the ECOL608 Research Methods in Ecology course.
Hamblin, C., Paterson, A., Ross, J., Maloney, R. (2019). Social Attractants, a Conservation Tool for Black‐Fronted Terns. Wildlife SocietyBulletin. 1-8. https://doi.org/10.1002/wsb.989
Additional Information:
Bonbaci, S., Pejchar, L., Innes, J. (2018). Fenced sanctuaries deliver conservation benefits for most common and threatened native island birds In New Zealand. Ecosphere. 9(11). https://doi.org/10.1002/ecs2.2497
Buxton, V., Enos, J., Sperry, J., Ward, M. (2020). A review of conspecific attraction for habitat selection across taxa. Ecology and Evolution. 10(23). 12690–12699. 10.1002/ece3.6922
Herrera-Giraldo, J., Figuerola-Hernández, C., Wolf, C., Colón-Merced, R., Ventosa-Febles, E., Silander, S., Holmes, N. (2021). The use of social attraction techniques to restore seabird colonies on Desecheo Island, Puerto Rico. Ecological Solutions and Evidence. 2(2). https://doi.org/10.1002/2688-8319.12058
Dating is hard and confusing for most… but especially for these guys.
A recent study on two native semi aquatic spiders, Dolomedes aquaticus and Dolomedes minor, revealed that spider dating is dramatic, but beneficial for their evolution. These spider species spend a lot of time diving for their prey in rivers and streams.
Male fishing spiders (Dolomedes species) perform complex courtship displays for their partners, which include vibratory, visual, and chemical signals, all just to avoid being killed by the female they are trying to impress, and just so he gets the opportunity to copulate.
D. aquaticus at Boyle River. Photo by Nicky Lowther (CC BY-NC)
These fishing spider species are found throughout New Zealand. In a particular area in the lower South Island, something interesting is going on… they are hybridising!… but only in one direction.
These species are closely related and have been observed to interbreed. This causes genes from one species to pass to the other; this process is called introgression. Introgression between these species has only been observed in one direction between female D. aquaticus and male D. minor. Introgression has also only been seen in one location, in the south of the South Island, the “introgression zone.”
Distribution of Dolomedes aquaticus and D. minor within New Zealand, with introgressed D. minor specimens shown. Data from Vink and Dupérré 2010 and Lattimore et al 2011. Also shows collection locations of spiders for laboratory experiments, and Waipara field monitoring site. The introgression zone is shown by the square box. (Content subject to copyright: please see the study image notes for details)
The purpose of this study was to investigate life history traits and mating behaviour that promoted and limited introgression that occurs only one way and is limited to one area.
Spiders were collected from within and outside the introgression zone and mating behaviour was tested in a lab.
From these experiments, it was found that males from outside the introgression zone were less willing to continue courtship once realising the female was of a different species from themselves, often ghosting halfway through, an experience familiar to those of us in the dating pool. On the other hand, D. minor males within the introgression zone were happy to flirt with any female. This unfussy selection seems familiar. Whether this is a spider phenomenon or a southern cultural trait remains unclear.
Another interesting find was that female D. minor were more short tempered when it comes to D. aquaticus males, having much higher attack and rejection rates towards D. aquaticus males than the opposite pairing. When a D. aquaticus male attempted courtship, the females often attacked and ate him. This suggests the differences in female behaviour between the two species may have just as much influence on gene flow as mate choice.
Female receptiveness to male courtship is key for introgression to occur, including female ability to recognise male courtship, female choice, and premating aggressive behaviour, these could all prevent interbreeding in ways that could vary throughout the species’ range.
Pairings were more successful if the pairings were similar in size. Females in both species are much larger than males, although D. aquaticus is larger overall. It was suggested that one way introgression could be because a female D. aquaticus assumes that a smaller male would be an easier snack, not a great mate!
D. aquaticus at Boyle River. Photo by Nicky Lowther (CC BY-NC)
Other potential factors could include that partners in the south could be less choosy in their mate selection as their breeding seasons may be shorter due to natural conditions. D. aquaticus females may think males of their species are rarer, or D. aquaticus male and D. minor female genitalia may not be compatible.
In summary, it is likely that mating behaviour has a strong influence on the dynamics of introgression gene transfer between these species within the introgression zone.
Male behaviour may limit introgression one way, preventing mating between D. minor females and D. aquaticus males. Also, female behaviour and choice may limit introgression because of a preference: mate or meal?
In the end, these spiders prove one thing: rejection is natural selection, and preference is important in evolution. So, next time you have a bad date, consider yourself grateful that your rejection did not end in sexual cannibalism. 🕷️
This article was prepared by Master of Bioprotection student Nicky Lowther as part of the ECOL608 Research Methods in Ecology course
Connolly, S. J., Hunt, J., Curtis, K. M., Painting, C. J., Cooney, C., & Vink, C. (2025). Mating behaviour influences the direction and geographic extent of introgression in New Zealand fishing spiders (Dolomedes). Journal of Evolutionary Biology, 38(3), 291–304. https://doi.org/10.1093/jeb/voae147
Plant communities dominated by mānuka/kāhikatoa (Leptospermum species)or kānuka (Kunzea species) are an extremely common feature of New Zealand’s native biodiversity. They are found in all manner of shapes, sizes, and habitats – dry and wet, high and low, warm and cold. We’ll call these communities ‘shrublands‘ throughout this text. Reality is much more complex with other types of native shrublands made up of different plant species as well as kānuka and mānuka also forming forests or scrub. There’s a great piece here if you want some more details.
If you’ve ever bashed through young, dense, mānuka/kānuka shrublands whilst out tramping you might have noticed they aren’t very diverse. That’s because during this young phase they form such a thick canopy and dense shade that other plants find it difficult to establish. Once these stands age the canopy opens up and lets light in allowing other species to take off.
The weed Spanish heath (Erica lusitanica), the lighter yellow-brown plants near the ground, invading gaps in mānuka (Leptospermum scoparium var. scoparium) shrubland on Bealey Spur. Photo Will Todhunter
These shrublands are important for our native biodiversity. Some are remnants from before humans arrived. Others have expanded following human induced forest clearance and subsequent regeneration. These regenerating shrublands are what we call seral, an intermediate stage in ecological succession.
Banks Peninsula has many classic examples of this phenomenon, and if you go for a walk up Bowenvale Valley, in Christchurch, you should be able to spot large areas of planted kānuka where Christchurch City Council is trying to jumpstart this process.
In many cases introduced plants can establish in the wild and invade natural ecosystems, including native shrublands. We will call these invasive introduced species weeds. These exotic weeds can negatively impact our biodiversity, displacing native plants and changing the ways our ecosystems function. Weed invasion has been well studied in forest and grassland ecosystems in New Zealand, but less so in shrublands. It is important to understand what drives weeds to invade shrublands, as this can help guide us when considering actions to protect these habitats.
Both the number of different species (species richness) and the size of the area covered by a species (its cover) play a role, but they don’t always align. Some shrublands had high numbers of species with low cover, whilst others had low numbers of exotic species but these were high in cover. This second example can be seen when a few aggressive weeds dominate.
Shrubland on Banks Peninsula. Photo by Will Todhunter CC BY
Low species richness, high species cover. The above image captures this, showing vegetation in a mature kānuka stand on Banks Peninsula. An open canopy of kānuka sits above a lower tier of native saplings of māhoe (Melicytus ramiflorus subsp. ramiflorus), poroporo (Solanum laciniatum) and kawakawa (Piper excelsum subsp. excelsum), and a dense ground cover of the highly invasive exotic veldt grass (Ehrharta erecta). The veldt grass forms such dense mats that it limits the establishment of most other plants and was once voted NZ’s worst weed!
A clear takeaway from the study was that the physical structure of shrublands plays a big role in determining how susceptible they are to exotic plants. Shrublands with dense canopies and multiple layers of vegetation act like a shield, limiting open ground and leaving less space for weeds. Shrublands with open areas let in more sunlight and have more available options for weeds to gain a foothold.
The surrounding land cover and land use heavily influenced weed invasions. Where shrublands were close to human modified landscapes ,weed invasion increased, and the same when shrublands were close to rivers. Modified landscapes typically had a higher number of weed species, providing a seed source that can then move into more natural areas.
Size and shape of shrublands matters. Shrublands with long edges experienced higher levels of weed invasion, with edges often having more disturbance and being more accessible to invaders. This is known as an “edge effect“. Topography is another contributor, with lower and flatter areas more invaded than those that are steep and/or at higher elevation
Unsurprisingly, climate also played a major role. Warmer temperatures were shown to increase weed invasion, and many introduced plants thrived in mild conditions. The expansion of suitable habitat ranges of weeds through a warming climate is yet another reason to be concerned about climate change!
Scrubland on Onawe Peninsula, Banks Peninsula. Photo by Adrian Paterson
Lastly, these researchers found that no single factor could fully explain weed invasion, it’s all about a combination of various factors. Something that readers might have expected.
Through my work in conservation I’ve been lucky enough to spend time in a range of shrublands. Some of the most special are the fragmented remains of the once extensive kanuka drylands of the Canterbury Plains, such as Motukānuka Scientific Reserve. Research has found that intensive land use change adjacent to these remnants has strongly contributed to increased weed invasion on the edges. Irrigation changing water availability and increased nitrogen availability from surrounding farms were attributed as two of the main drivers here.
There’s a couple things we can learn from these studies when thinking about protecting shrublands. To reduce the impacts of exotic plant invasion, the larger the area of shrubland the better. Dense, structurally rich vegetation is going to be more resilient to invasion. However, often small fragments of biodiversity are all that are left to work with, so factoring in a buffer from surrounding land use then becomes important.
In many situations active management of weeds, such as physical control using herbicide, is essential to protect native species and ecosystem function’s from their impacts.
So now that you know a bit more about shrublands, keep an eye out for some of the features discussed here. Keep learning about the native and introduced plants of New Zealand, and get out there with the right people and deal to some weeds!
This article was prepared by Will Todhunter, Postgraduate Diploma in Applied Science student, for an assignment in ECOL608 Research Methods in Ecology.
Rossignaud, L., & Hulme, P. E. (2023). Native vegetation structure, landscape features and climate shape non-native plant richness and cover in New Zealand native shrublands. Diversity and Distributions, 29(8), 1009–1020. https://doi.org/10.1111/ddi.13713
‘Coming soon in 3D!’ Periodically throughout my life movie-makers have dabbled with making films that we can watch in three dimensions. You would get your special glasses before the movie session and then sit there wondering when to put them on until the action got going.
To be honest I don’t remember many of the movies that I saw like this. The Avatar movies have always had the option and I watched at least the second movie this way. Spears and monsters would lunge out of the screen at you.
Other than that I am drawing a blank. This is not to say that every 3D movie is bad but just that 3D on its own doesn’t make a film more memorable.
Avatar Adrian! Look out for the arrow!
I don’t even dislike the experience despite having to wear the 3D glasses over my own glasses. There is something immersive about dodging things ‘coming out of the screen’. However, I seldom choose this option if 2D is available. It all seems a bit too much like work perhaps?
Adding a third dimension can help with appreciating scale and movement though. It can also help with identifying who’s who in the screen – there’s just a bit more information that your brain can use.
Identifying individuals is a big deal in biology, especially conservation. When you have a small population you are interested in individuals. How are they doing? Are they breeding? Who do they hang out with?
Of course, for many species there are not a lot of features to differentiate between individuals. They are similar in height, uniform in coloration, and have similar behaviours.
To make them more distinctive we could always band our target with bright colours or paint an obvious mark on them but this involves capturing and interacting with the individual. This causes a great deal of stress and catching individuals is not always simple.
Ideally we could use cameras to take pictures that we could measure features in that are unique to an individual. Two dimensional pictures require an individual to be in an exact place with an exact orientation for this to work. So this is not a reliable method.
Bit wait! … Coming soon in 3D!
It turns out that if you take pictures with different devices from slightly different angles at the same moment then you can much more accurately calculate measurements on individuals. At least in theory.
Jane Tansell with her trusty kiwi dog. Picture from Jane Tansell.
Jane Tansell, a recently completed PhD student at Lincoln University, and her supervisors, Adrian Paterson and James Ross, set out to see if we could use this idea to identify kiwi. Kiwi populations and individuals are difficult to measure. They are nocturnal, usually found in scrubby terrain, are reasonably featureless, and spend a lot of time in burrows. We can use trained dogs to find them but this is quite stressful for kiwi. We can listen to their calls during the night but this is difficult to split into different individuals and certain parts of the population don’t call anyway.
Trail cameras have been used to successfully locate kiwi. Jane wondered if she could pair cameras 12-25 cm apart, taking images that could be used to essentially create a 3D image of features on each bird. Jane knew that kiwi bills vary between individuals and can be used as an ID.
Jane worked with the more technically literate Maurice Kasprowsky and Tom Gray to cobble together the cameras and get them to work together.
Jane, as reported in NZ Journal of Zoology, first tried the setup on a taxidermied kiwi in good light conditions. She found that the cameras could be used to measure the bills to within 1.5% of their actual length. This was a great achievement and would certainly be able to determine individuals.
In theory we should be able to photograph kiwi and recognise them by measuring their bills. Image from Adrian Paterson.
Jane then set up field trials with live kiwi. In the real world, with low light and moving birds the cameras were less efficient. At worst they were terrible but often they were within 3-4% of the actual bill length. This is not good enough to replace current field identification methods but it was still quite impressive given the relatively jury-rigged setup.
Improvements in cameras, especially 3D cameras, are happening quite quickly. With some more trial and error Jane should be able to start reducing the error enough for this to be a viable noninvasive method for following kiwi in the field.
While this is not as exciting as an arrow flying at you from an Avatar movie, this use of 3D does have real world uses that will help with understanding a national icon!
The author, Adrian Paterson, is a lecturer in the Department of Pest-management and Conservation at Te Whare Wānaka o Aoraki Lincoln University. Adrian is a kiwi but unfortunately has no bill to measure.
My time at Lincoln University has taught me that when it comes to bird monitoring, the most common practice is the 5 minute bird count (5MBC). This method is a simple and effective way of counting birds within a specific area by recording sightings and calls. Much of the time, using 5BMC, it is likely that you will not see the bird you are hearing, which is why being able to identify New Zealand birds just by sound is a very good skill.
Lincoln University legend Jon Sullivan did a study on different bird data collection methods that could also mahi together to build a more accurate picture of birds in an area. The study focused on wider Christchurch, beginning in 2003, and recorded patterns in bird species within the area.
One method that was used was the stationary method , which is pretty much the same as the 5MBC but is extended to 20 minutes. The other method used was the ‘mobile method’, also known as the ‘line-transect method’, where you collect data while moving at a fast pace, perhaps by bike, car, or running.
The grey warbler (Gerygone igata, riroriro) are found throughout New Zealand. They are small, grey/brown with a more pale shade of grey for the face to throat. They weigh approximately 6.5 g (lighter than a mouse) and their diet consists of insects and spiders.
Fantails are one of my many favourite bird species, as they love to follow humans around when you are on bush walks. Fantails are able to adapt to environments that have been changed by humans, which is not very common for New Zealand native birds. Fantails (Rhipidura fuliginosa, piwakawaka) are often found in open native bush, exotic plantation forests, orchards and gardens. Their diet consists of insects, especially small species. Fantails are a small bird about the size of a house sparrow, but what makes them so distinctive? Well the answer is in their name…. Yes their tails, like their name suggests they have a long tail that fans out like a well a fan.
Fantail. Photo CC By Chris S, Flickr
Bellbird/ Korimako
Bellbirds(Anthornis melanura, koromiko)are commonly found in the South Island. These birds have a short, curved beak and are green with a slightly forked tail. Bellbirds, similar to Tūī’, have a distinctive song, it is like a high ringing that’s also kind of smooth, and the repeat the same tune. Bellbirds reside throughout native and exotic forest, scrubs and shelter belts of New Zealand. Their diet is nectar from native and exotic plants, although they do consume fruit in late summer and autumn. Also their diet consists of honeydew that’s found on beech trees.
Bellbird. Photo CC By Glenda Rees, Flickr
Back to the study
Jon Sullivan wanted to understand how nature responds to a forever changing world. He collected distribution and abundance information for many species with these three species being the focus. This is where the methods came into play as a standardised method and a repeatable one is needed to accurately tell us if a species is present or not. The methods talked about above were to work alongside each other.
Around 100,000 bird counts were collected. The approach used helped to summarise data that was from one location, a certain time each week, and one daily route. The results showed that this approach was effective and just as effective as the 5 minute bird count. Counting birds while riding your bike along a road was just as effective at estimating and following trends as more traditional methods.
Fantails, grey warblers, and bellbirds (but not to the same extent as the other 2) are majorly restricted to their forest biotopes and native plantings, particularly in spring.
Like any good study, more data are needed to get a better and clearer understanding. This could create a good opportunity at Lincoln University to teach students doing ecology to learn how to use different techniques besides just the 5MBC methods. Then we too can collect decades long information on our favourite birds.
This article was prepared by postgraduate student Caitlan Christmas, Masters of Science in Ecology and Conservation, for an assignment in ECOL608 Research Methods in Ecology.
