How many native bees fit into six car parking spaces?

Two-fifths of a tennis court. About six car park spaces. Three-tenths of an IMAX screen.

That’s the size of my front yard. Yet despite its limited expanse, and its densely urban situation 10 km north of Melbourne CBD, my yard is habitat for at least five species of native bees.

I began watching the bees closely last year in lockdown. The tiny, faintly metallic Sweat Bees (Homalictus) are most common. They appear first in Spring, visiting the Wahlenbergia, the Oxalis weed in the lawn, the strawberry, and rocket flowers; anywhere there’s pollen.

Later, the bold and stripey Lipotriches turn up. Like rock-climbers gripping an overhang, they lock themselves upside down to the anthers of dangling Dianella flowers, emitting short zip-like buzzes as they work with methodical focus.

Then when Summer days begin to blaze, the hyperactive Resin Bees (Megachile) arrive, with that distinctive ember thumb print on their behinds. They fire around the yard like deranged bullets, collecting pollen and scouting for cracks to nest in.

That such biodiversity endures in this landscape—once grassy woodland, now houses, roads, and light industrial—is a testament to these species’ resilience. But their persistence also begs the question of which species might now be absent, less tolerant of such drastic change.

The White-headed Digger Bee (Amegilla albiceps) is one such bee. Large, rotund, and covered in a pelt of golden and white fuzz, one has not been recorded in Melbourne for at least 70 years, perhaps longer. In a Summer free of travel restrictions, I’ll leave town to seek the White-headed Digger. But for now, I’ll keep discovering the delightful locals. It’s Homalictus season now.

This mini essay was originally written for the Urban Field Naturalist Project

The native bees of Moreland City

Bees are an effective treatment for depression. Well, my depression. And specifically the kind of malaise that comes from being locked out of our national parks and wild places for a second Spring running.

After monitoring my small front yard last Spring-Summer, I knew there was a set of small but diverse native bees that revealed themselves when the weather was warm and the yard was blooming. This year, I’ve decided to go deep and get to know them a whole lot better.

Getting even a basic knowledge of the 2000 native bees of Australia is a very big task. Getting to know the native bees of a single 50 km2 local government area (where I live) is much easier. So I set out to reconcile all the official and unofficial records for native bees within Moreland City LGA (just north of Melbourne CBD), to build a species list. And after going to that effort, I figured the local community would probably also like to have that information. So here is version one of the ‘Native Bees of Moreland‘ infographic (PDF link):

Building the inventory of Moreland’s bees

I started by pulling all of the records for bees in Moreland LGA from Atlas of Living Australia. After taking out the two introduced species, there were 12 species-level identifications plus 52 records for bees identified only to genus or subgenus. I then validated the species identified against their geographic ranges to exclude any obviously erroneous records. After that I reviewed iNaturalist records for bees in Moreland to see if I could identify any species that did not appear in the Atlas records.

My summary from this process is in the table below:

SpeciesStatusNotes
Amegilla (Zonamegilla) assertaReliably presentA. chlorocyanea also possible given distribution, observations in nearby LGAs, and iNaturalist records
Lasioglossum (Homalictus) sp.Reliably presentNo species-level identifications confirmed. But the genus is very common. At least two species are in Moreland. Possibly L. punctatus, L. brisbanensis, L.urbanus, L. sphecodoides
Hylaeus (Prosopisteron) littleriReliably presentUnlikely to be the only Hylaeus species in the area
Hyleoides concinnaRare and presentNo record since 1946, however one record from neighbouring LGA, Mooney Valley, 2017
Lasioglossum (Chilalictus) calophyllaeReliably presentCommon and recent records
Lasioglossum (Parasphecodes) hiltacusHistoricalNo record in the LGA since 1956
Lasioglossum (Chilalictus) lanariumHistoricalNo record since specimen from 1894
Lipotriches (Austronomia)Reliably presentNo identified specimens, but iNaturalist observations confirm the genus is present
Megachile (Eutricharaea) obtusaHistoricalNo record since specimen from 1906
Megachile erythropygaReliably presentPinned specimen from 1987. iNaturalist observations since
Megachile (Rhodomegachile) deaniiDoubtful recordFar outside known distribution. Must be erroneous.
Braunsapis sp.Doubtful recordB. unicolor and B. plebeia specimens from 1958. Very far from known distribution. Must be erroneous records.

Clearly, for a very populous area, there are very few records. This is the case for not only bees, but insects in general. An added challenge is that it is often difficult to diagnose bees to species level. Together, that means it has been very easy to find bees that have never been recorded in the area.

For example, the most common small bee in my yard is a tiny, dark Homalictus with a faint green wash on the thorax. It most closely resembles Lasioglossum (Homalictus) sphecodoides, but this species has never been recorded in the area – presumably because no one with the right taxonomic expertise has collected bees, or examined Homalictus specimens from Moreland. Indeed, no species-level identification for a Homalictus has been made for Moreland at all.

In the first-bee hunting trip I took outside my yard this Spring, I even recorded a new genus for the area. I caught both male and female reed bees – Brevineura sp., flitting around a flowering Diosma in the cemetary.

Then there are those historical records – bee specimens collected 60 – 100 years ago and not seen since. How tantalising! Perhaps they are extinct in the area? Or maybe they are just so rare and scarcely recorded. Well not long after finalising the infographic, I rendered it instantly out of date by finding a Lasioglossum (Parasphecodes) hiltacus for the first time in Moreland since 1956.

In just two short trips outside the house I’ve recorded a new genus to the area and made the first local observation of a species since 1956. While I’m aware that our small, arbitrary local government boundaries bear no influence on ecology, it does make a useful context for illustrating just how under-studied is our urban bee biodiversity.

Pollinators of Slender mint bush (Prostanthera saxicola var. bracteolata)

With Melbourne in lockdown and my change in career, time in the bush has been scarce for me this year. So it was with some relish that I recently headed out to Pyrete Range for a therapeutic communion with some native plants and pollinators. Most of Spring flowering had passed already, but I found a large population of Prostanthera saxicola var. bracteolata in peak flower. It’s a pretty restricted and uncommon shrub, so there are not likely to be many other floral visitor observations that have been made on this species.

The Slender Mint Bush (Prsotanthera saxicola var. bracteolata)

I spent a relaxed hour or two on a warm day wandering between plants, making informal observations of flower visitors, and photographing interactions. The most frequent floral visitor was a native reed Bee (Exoneura sp.) which was in high numbers and reliably visiting flowers. I must have observed around 50 or more foraging bouts by reed bees, crawling deep into the flowers for nectar and collecting pollen from the anthers in the upper corolla.

I have known reed bees to nest in fern fronds (in wet forest) and in rushes and sedges (in the high country). Quite where they are nesting in this dry sclerophyll habitat, I do not know. But there is obviously a very large population of them.

Exoneura native bee covered in pollen from Prostanthera saxicola var. bracteolata

Honey bees were also somewhat common visitors, as were some striking iridescent blue-green forester moths (family Zygaenidae). I saw six forester moth visits, but am not convinced they could be effective pollinators. They usually perch on the outside of the flowers, extending their proboscis into the base of the corolla for nectar, scarcely contacting the anthers.

One surprise was a single visit observed by this jewel beetle (Castiarina sp.), which was enjoying a feed on Prostanthera pollen.

Reed bee (Exoneura sp.) in flight

Project update: Contrasting bird and insect pollination through use of novel camera and genetic technologies.

I recently put together some material on my work for the University of Melbourne open day. As a teaser for the papers in current preparation, here’s an abstract and some visuals on the project.

While we simply do not know what pollinates many of Australia’s plants, there is good evidence emerging showing Australia to be a global hotspot for bird-pollination. This raises questions about what ecological and evolutionary factors might encourage plant lineages to adapt to use birds as couriers for their pollen. As well, we might ask what the outcomes are when a plant species ties its reproductive fortunes to a bird, rather than an insect.

My project employs custom cameras designed for motion-capture data capture of insect visitors to flowers, in order to demonstrate contrasting bird versus insect visitation in pairs of closely related native shrubs. Fine-scale population genetic analysis in these plants is revealing evidence for systemic differences in the movement of pollen under these different pollinator regimes.

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Styphelia stomarrhena is pollinated exclusively by birds.

The video below shows bird visitation by a number of honeyeater species, as well as the way in which floral morphology excludes bee pollinators from accessing pollen or nectar in Styphelia stomarrhena.

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Styphelia xerophylla is the sister species to S. stomarrhena and has evolved a tight relationship with a single species of native bee: Leioproctus macmillanii.

 

The videos below show motion-captured footage of the native pollinator of Styphelia xerophyllum, a female native bee (Leioproctus macmillani).

However the flowers are also visited by introduced honeybees (Apis mellifera).

 

A quick note on plant names: These species recently underwent taxonomic revision, moving them from genus Astroloma to Styphelia. It is rather new, hence the confusion over these shrubs apparently having two names.

Photos from the field: The Great Western Woodlands.

The Great Western Woodlands (GWW) form the largest tracts of temperate woodlands left on Earth. They hold approximately 30% of Australia’s Eucalypt species, and close to 20% of Australia’s plant species overall. This is truly an overlooked gem of Australian biodiversity. Last Spring I was lucky enough to visit for my work on pollination in our native plants.

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My target there was Eremophila, a genus of approximately 250 species largely confined to arid and semi-arid Australia. The GWW represents one of the centres of diversity for the genus, and so I chose it as a likely spot to set up a new study contrasting bird and insect pollination.

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Eremophila alternifolia was one of about 15 Eremophilas I saw flowering despite the drier than average conditions.

I was joined by perhaps the best kind of field assistant: a trained and accomplished professional ecologist who also happens to be my beautiful wife. After driving 2800km from Melbourne to field sites near Norseman, Western Australia, we spent a little under two weeks observing pollinators, surveying and mapping populations of plants, and collecting samples for population genetics.

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One of the many viewpoints south of the Nullarbor Plain.

I left in awe of the scale of these woodlands, in love with the peace and isolation they offer, and a bit concerned over their insecure future. Fully 60% of the GWW is tenured “unallocated Crown land”, unmanaged and open access. With more visitors, and more appreciation of the value of these vast woodlands, I hope we can find a way to secure more of it into ongoing reserve for future generations.

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The bluebush understory contrasts dramatically with red sand in many areas. Front left is one of my study species Eremophila scoparia.

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The whole region is dotted with salt-pans.

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As predicted from the small, violet flowers, Eremophila scoparia was visited by a host of native bees.

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Eremophila decipiens has characteristic bird-adapted flowers.

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Camera traps being expertly arranged by Samantha. Footage revealed that E. decipiens was being visited by a range of honeyeater species.

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Eremophila calorhabdos

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This spectacular Grevillea hid a massive bloom of flowers underneath it

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The inflorescences are held on stems that grow along the ground underneath the shrub. The very long style with pollen-presenter is suggestive of adaptation to birds, but mammals might not be out of the question.

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Eucalyptus loxophleba with daggy botanist for scale

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Majestic Salmon gum (Eucalyptus salmonophloia) with Samantha for scale.

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The serenity of wandering amongst giant Salmon gums at dusk was magic.

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Gleaming bark on Eucalyptus salubris

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Elevating on Lake Cowan. Photo: S. Vertucci.

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For the second half of the trip I was joined by collaborator and all-round legend Dr. Renee Catullo. I made us walk 10km to collect camp gear following a single poor decision.

Stay tuned as research results emerge. The study should tell us about the way pollen moves under bee and bird pollination, and how those fine scale patterns play out on a grand landscape level.

Photos from the field: Northern Sand-plains, WA

Peaceful woodlands of widely spaced gnarled Eucalypts lie in mosaic with spiny, scratchy, shrubby heath on the sand-plains north of Perth. They form one of the most floristically diverse regions on earth, with estimates of over 60 species of plant per 0.01 ha (an area smaller than half an an IMAX screen).

With so many species packed on top of one another, it is perhaps not surprising that in the effort to co-exist, some plants have been forced to flower outside the traditional Spring-flowering window. Winter in the sand-plains, while often wet and cloudy, is therefore anything but dull. While daily insect activity is very low, resident birds and honey possums must still feed, and so there are a comparatively high number of vertebrate-pollinated species in full flower at this time of year.

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Omphalina chromacea in its diminutive but sulphureous glory

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Bird-pollinated Astroloma glaucenscens excludes insect visitors with a tiny corolla-tube opening

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Pterostylis sanguinea: a sexually-deceptive trap-pollination orchid

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Astroloma stomarrhena, bird-pollinated. This individual has curiously short corolla tubes.

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Calothamnus sanguineus mixed in with Conostephium

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Calothamnus sanguineus

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An early-flowering Caladenia latifolia

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Diuris corymbosa

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Tiny pgymy Drosera

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One of the most common orchids in the area, but I’ve never seen it flower. Pyrorchis leaf.

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Very rare, and while this specimen is a little tired late in the season, the winter-flowering Cleopatra’s Needles (Thelymitra apiculata) is a stunning contrast of hues.

First video of bird pollination in Astroloma stomarrhena

I’m thrilled to share this never-before seen sequence of birds feeding on Astroloma stomarrhena, a winter-flowering shrub endemic to Western Australia.

Earlier this year, I decided A. stomarrhena looked like a perfect candidate for my new study on pollinators and gene flow. What I needed was a bird-pollinated species of plant, closely related to an insect-pollinated species. This one seemed to match all the criteria I needed, except there was no evidence that it was bird-pollinated. But with those long, tapered corolla tubes, and that pink-red coloration, I believed that birds absolutely had to be the pollinator.

The danger was, that while birds might be visitors, the plant could be somewhat “generalized”, and also use insects. This is pretty common, especially in places like Australia where European Honeybees (Apis mellifera) have invaded ecosystems that evolved in their absence, and honeybees will visit absolutely everything whether the plants are adapted to bees or not.

By deploying a new camera-trapping method that I am developing to record insect visitation, I was able to gather several days of pollinator observations, despite some very bad weather. After initially being baffled as to what honeyeater might visit such a low ground-hugging shrub, I got my answer after day one, when I captured video of my new favourite bird: the Tawny-crowned Honeyeater (Gliciphila melanops) feeding on the flowers. Furthermore, the recordings of honeybee fly-bys are sufficient to rule them out as pollinators.

This little result is a win on two fronts: a successful trial of new pollinator-monitoring cameras, and vindication of predicting pollinators from flower morphology.

Click here for the full HD video.

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Bumping into old floral friends, and pollination with a hug.

Rare plants nurseries are like second hand bookshops. It’s always so tempting to browse on the off chance you find that little treasure. I recently visited a charming rare plants nursery in Mt Macedon (boutique-y town outside Melbourne, Australia) where I discovered these for sale:

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Hello old friend! (Hesperantha coccinea)

The last time I saw this elegant iris, it was flowering on stream banks 10,000 km away in the Drakensberg Mountain range in South Africa. There in its natural habitat, it is pollinated in some areas by a very special butterfly: the Mountain Pride (Aeropetes tulbhagia). In other places, it is pollinated by the amazing long-tongue fly (Prosoeca ganglbaueri). The two forms are a wonderful example of “pollination ecotypes”, where different populations are undergoing adaptation to their unique pollinators. The fly-serviced ones are a pink hue with narrow petals, while the butterfly-pollinated ones are much redder with broader petals.

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Hesperantha coccinea at home in South Africa with its pollinator (Prosoeca ganglbaueri).

Fast forward two weeks, and I’m home walking the dog in my quite unremarkable Melbourne suburb, when who should I see?

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Hello old friend! (Diascia sp.)

It’s winter here, with very little in flower, but these brilliant little pink blooms volunteering themselves from underneath a fence in suburban Melbourne really made my day. The last time I saw a Diascia, it was growing amongst the boulders on creek beds and on cliffs in the Drakensberg Mountains. These are Diascia, or “twinspur” and its this common name that alludes to their fascinating pollination story.

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Hug-pollination by oil-collecting bee (Rediviva sp.) in Diascia.

Diascia have two spurs on the back of the flower, which is distinct from the usual arrangement of a single nectar-spur. The difference is that these flowers don’t reward pollinators with sugary secretions, instead they provide oil to specialised oil-collecting bees in the genus Rediviva. The bees use this oil to line their nests and provision their young. In order to collect the nectar, they must reach deep into the twin spurs with their lanky forelimbs, and comb it out. In so doing, they effectively hug the reproductive parts of the Diascia flower and effect pollination.

In Spring, I plan to take some cuttings from this little Diascia. Keeping species with special personal significance is a deeply satisfying part of cultivating plants. A plant can be kept like a souvenir or memento marking a time in one’s life, just like a photo or trinket. But plants have an advantage over these inanimate reminders. Because biological reproduction requires the physical donation of part of the mother’s cells to the daughter cells, my keepsake plant can be viewed as a physical part of the plant that appears in my fond memory. If I could see in four dimensions, I could literally look down the line of cell-divisions all the way back to where the Hesperantha in the nursery physically intersects as the same individual with the Hesperantha I observed flowering in the Autumn sun of the Drakensberg Mountains in South Africa.

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The Drakensberg Mountains, South Africa, Autumn 2014.

 

Photos from the field: East Gippsland, Victoria

I recently began a brand new project with the University of Melbourne. The beginning of a new project is filled with equal parts excitement and trepidation—excitement at the novelty, the blank canvas, the potential, and trepidation at not wanting to put a foot wrong in critical early decisions that will affect the outcome of a career-defining opportunity.

Here the photos from a first foray into East Gippsland, surveying sites for bird-pollinated Prostanthera walteri.

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Mt. Elizabeth

 

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Snowy River National Park

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Prostanthera walteri

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Prostanthera hirtula

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McKillops Bridge

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The Snowy River

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The Snowy River

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Prostanthera walteri

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Snowy River National Park

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Gippsland waratah – Telopea oreades

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Floral diversity in Prostanthera

 

The Toadlet Diaries 2: Gulf country.

In 2010 I was fortunate to accompany herpetologist Dr. Renee Catullo on a trip through Australia’s Top End collecting little brown frogs. Here are some of my field notes along with photography. While my photography has vastly improved, I’m not sure I’ve felt so inspired to write since that trip. I hope this series of vignettes communicate some of the flavour and excitement of the wet season in Australia’s monsoon tropics.

(Part one here)

31 January 2010

I was relieving myself a stone’s throw from the inundated Carpentaria Highway when I saw my first Brolga. Its lanky form drifted indolently against a pastel sky as the tropical sun poured out late afternoon’s final slanting blaze. I finished my business, picked up my binoculars and shovel, tucked the bog roll under my arm, snatched a nearby burrowing frog with my free hand and wandered back to where Steve had left our hired Landcruiser: bogged up to the axles in the soft roadside sludge.

We had been following a map to the “Lost City”, scrawled on a take-away order pad by a gnarly-toothed cook at Cape Crawford’s “Heartbreak Hotel”. (This sentence is entirely true and gives me great pleasure to write). I had hoped to see the exceedingly elusive Carpentarian Grass-wren there, but like Grass-wrens, Lost Cities are difficult to find. Renee planned to make a 200 km push down and back the Tablelands Highway that night so our search for the Lost City was truncated in favour of beginning the evening’s driving. Our U-turn was truncated on the shoulder of the highway, which had been under floodwater for the last 3 or 4 days and needed little persuasion to engulf the hired Landcruiser.

We had been stalking 300 kms of the Carpentaria Hwy for the last two nights and had seen one car in that time. It was 5.30pm on Sunday and we had enough food and water in the car to last us a few nights should it come to that, but in a great fluke of variance the next 30 minutes sent us three different cars. Our eventual saviour rocked up in a big old Landcruiser. As a spry indigenous woman jumped out of the passenger seat to retrieve a rope from the tray, a man as weathered, wide and red as our fair country hopped out of the driver’s seat. Our saviour was in a hurry, the rope quickly linked our cars back to back and he barked some instructions to an unsure Steve behind the wheel of our stricken vehicle. Soon wheels were spinning as his truck revved and squealed, switching about like a hooked barramundi. Steve eventually found 4WD, low range, reverse and our steed was yanked backwards from the muck.

Impeded on the Carpentaria Hwy

Impeded on the Carpentaria Hwy

That was the beginning of one of the most eventful evenings of the trip. We were now running a bit late, but counted ourselves lucky to have gotten away with an hour delay. The drive ahead saw us traveling south down the Tablelands Highway, a road that splits rocky cliffs of rust red upon which the ivory white bark of eucalypts is thrown into dramatic contrast by the light from the setting sun. We stopped on a vast flat grass plain after dark and watched the moon rise, a giant languid yellow disc that was to light the rest of our evening.

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It is worth mentioning that I only refer to the roads by name because there are so damn few of them here in the Top End. Each road takes on a character through its interaction with the elements, the lansdscape, and the idiosyncrasies of the disparate roadhouses, towns and remote communities it links across vast distance. These bitumen ribbons of country and the hours spent on them forms a large part of the Top End experience for residents and visitors alike.

Soon after dark the animals started throwing themselves in front of the car. A remote wet season highway at night is chaos. I’ve never seen so much wildlife ever, and you’ll be pleased to know most of it survived. Bustards, nightjars, owls and curlews appear in the headlights, I brake and they make a flapping flash in my periphery as they fly within centimetres of the windscreen. Agile wallabies bound in groups across the road ahead, or sometimes they just stand on the road shoulder, waiting for us to drive closer before darting out into our path. The road is littered with frogs, only discernable as the car drives on over them. But one can’t look out for them as it is much more important to spot the groups of Brahman cattle from a distance safe enough to slow down. At several points we’re slowed to sub 10 km/h as dozens of cows slowly bumble down the road in front of you for hundreds of meters. There is nothing to do but travel along behind until they find a spot to vacate the bitumen. In addition to the fauna there’s water to watch for, the road is flooded in some points up close to a meter, and the floods have dragged onto the road a flotsam of logs, branches and general crap to drive around.

Tablelands Hwy denizen with biologist for scale - Black-headed python

Tablelands Hwy denizen with biologist for scale – Black-headed python

When we swapped drivers I had run over what I was horrified to hear Renee later estimate as a total of 30 burrowing frogs. At the wheel, Steve the frog lover perhaps avoided a few more than I did, but unfortunately he was unable to avoid a nail tail wallaby. The nail tails are beautiful creatures up close, covered in soft, fine light caramel fur with faint white markings. A dark dorsal line runs from the back of their neck down their spine to the nail protruding from a spray of thick black bristles at the end of the tail.

That was one day in gulf country, out near Boroloola.