Onkaparinga River NP (10th Sept, 2022)

Context: 15.4km2 of steep river valley, remnant Eucalyptus woodland, degraded ex-farmland infested with introduced European Olive, and revegetation sites. Numerous recreational walking tracks and lookouts over the valley and down to the river. Includes Hardy’s Scrub on the the south side of Chapel Hill Road.


iNaturalist Projects

Onkaparinga River National Park, South Australia

Ferals in South Australian Reserves – Onkaparinga River NP


See the full list of 83 observations covering 55 species on iNaturalist


After somewhat of a Winter hiatus, I’ve returned to regular biodiversity hiking now the weather is improving. A good place to start was a short loop around a section of Hardy’s Scrub in the Onkaparinga River National Park. Following Old Quarry Track for approx. 150m, I took a left turn and followed a narrow track that ran through the scrub, down to Blewitt Springs Road, then back up to Old Quarry Track.



The introduced Freesias that are a significant invasive species in parts of Hardy’s Scrub were appearing near the Chapel Hill Rd gate. Although not in the great numbers as other sections of the park. A patch of Geraniums and the all too common Bridal Creeper had their place near the gate too.



The track slopes gently to the right side. This time of year the high side of the track is populated by three, perhaps four, native carnivorous Sundew species. The most prominent is Drosera gunniana. One of the tall growing species, its mucin droplets produced by the stalked glands on the leaves glisten in the sunlight. The species has the inflorescence close to the final leaves, with hairy sepals. The similar Drosera auriculata has the inflorescence held well above the leaves, with glabrous sepals. The other two are the common in the region Drosera whittakeri with its rosette of leaves a few inches in diameter, and the much smaller Drosera glanduligera.



On that first section of track, we spotted one of my favourite local Ant species on a Grass Tree, a Dolichoderus scabridus, with its golden gaster and red legs. Their nests can sometimes be found in rotting logs.

Along the narrow side track we startled a couple of Western Grey Kangaroos (Macropus fuliginosus). They are always about this park, but are often hidden during the day, relaxing amongst the dense undergrowth. One paused to strike a pose resulting an a few quality photos.

There are numerous large patches of Red Beaks / Fire Orchids (Pyrorchis nigricans) throughout Hardy’s Scrub. Typically they do not flower unless a fire has come through recently. Some have leaves reaching 10cm across. Occasionally some will flower without fire, perhaps fewer than 1 in 200. However flowering can also occur due to disturbance, so those near the edge of a walking track may present flowers more frequently. We didn’t spot any flowering or in bud this time around.



This time of year, if you know where to look, certain Insect species are quite easy to locate. The Leaf Beetle Callidemum hypochalceum, a species we might call the Metallic Dodonaea Leaf Beetle, can be frequently found on the Sticky Hop-Bush (Dodonaea viscosa). These Plants are quite easy to identify themselves as the female plants this time of year are covered in winged fruit ranging from lime green through to dark maroon. So if you’re out in nature and spot such a Hop-Bush, pause to take a closer look and you might find a few of these iridescent Beetles.



That invasive pest, Bridal Creeper (Asparagus asparagoides), is present in this park as well as so many others. To combat the spread a Rust Fungi known as Bridal Creeper Rust (Puccinia myrsiphylli) was introduced in 2000. It infects the plants, absorbing the nutrients from the leaves resulting in visible yellow spots and leaf shedding. It is most prominent during Spring. I’ve typically ignored this in the past, but creating an iNaturalist record to show its presence in an area has value, and I’ll look to do that more frequently.



On the return section of the track back up the hill from Blewitt Springs Road there is a large patch of Heath Teatrees (Leptospermum myrsinoides) that while flowering from late September through November play host to a wide range of Insects, in particular some spectacular Jewel Beetles. We were too early this visit with none of the Teatrees yet flowering. Over a few visits I’ve recorded 13 Insects on or around these Teatrees, including 4 Jewel beetles in the Genus Castiarina. This is a spot I try to visit each year.

Lastly, while recording one of the flowering Gorse Bitter Peas (Daviesia ulicifolia) I unintentionally recorded my second ever sighting of a native Trichocolletes Bee. I’d really like to take some quality photos of this Genus, but I expect I’ll need a good macro lens before I can get them.

A few additional highlights from the day below.



Onkaparinga River NP (1st May, 2022)

Context: 15.4km2 of steep river valley, remnant Eucalyptus woodland, degraded ex-farmland infested with introduced European Olive, and revegetation sites. Numerous recreational walking tracks and lookouts over the valley and down to the river. Includes Hardy’s Scrub on the the south side of Chapel Hill Road.


iNaturalist Projects

Onkaparinga River National Park, South Australia

Ferals in South Australian Reserves – Onkaparinga River NP


See the full list of 58 observations covering 37 species on iNaturalist


With a few hours left on day three of the City Nature Challenge I stopped in at Onkaparinga River National Park to search along the start of the Echidna Hike. The section of the hike that runs parallel to Piggott Range Road seems relatively undisturbed, with quite a high number of species in a small area.

First record was an abnormal growth on a Sticky Hop-Bush (Dodonaea viscosa). These growths are quite common with many plants showing at least one patch, and some with dozens. The growth is potentially caused by a Phytoplasma (Genus Phytoplasma). These small genome Bacteria are obligate intracellular parasites of plant phloem tissue, transmitted by sap-sucking Insects. I’ve never noticed any particular Hemiptera associated with these Dodonaeas, but it might be worth taking a closer look. The literature suggests that multiple Hemiptera species are involved, but it seems likely there is a primary transmitter in each area or region. If that’s the case I should be able to find a particular species of Bug on multiple Hop-Bushes.



This time of year identifying some species requires knowledge of either what dried seed pods look like, or be able to recognise the first shoots emerging now the rainy season is beginning. The finished flower stalk and empty fruit capsules of Milkmaids (Burchardia umbellata) are easy to ID, due to the way the stalk branches. The tall flower stalk of the Nodding Chocolate Lily (Arthropodium fimbriatum) is also quite distinct. It can be separated from the stalk of the Common Chocolate-lily (Arthropodium strictum) in that the flowers occur in groups of 2 to 4 emerging from the same axil.



The emerging Fringe-Lilies are easy to recognise from their twining branches, with the Twining Fringe-Lily (Thysanotus patersonii) most common at this location. Also emerging are the leaves of the Blue Stars (Chamaescilla corymbosa), which I used to mistake for Orchids, and can be separated in that they have multiple emerging leaves, whereas the local similar looking Orchids have a single leaf at this stage.



I didn’t really walk slow enough to find many Insect species but did record my second Australian Painted Lady (Vanessa kershawi) for the CNC, and a Mud-nesting Spider Wasps (Genus Fabriogenia) on the hunt.



Onkaparinga River NP (29th Apr, 2022)

Context: 15.4km2 of steep river valley, remnant Eucalyptus woodland, degraded ex-farmland infested with introduced European Olive, and revegetation sites. Numerous recreational walking tracks and lookouts over the valley and down to the river. Includes Hardy’s Scrub on the the south side of Chapel Hill Road.


iNaturalist Projects

Onkaparinga River National Park, South Australia

Ferals in South Australian Reserves – Onkaparinga River NP


See the full list of 119 observations covering 68 species on iNaturalist


Final stop on the first City Nature Challenge day was a loop through Onkaparinga River National Park, starting at Gate 11 on Piggott Range Rd, following the fire track along the ridge and back along Sundew Ridge Hike.



Finding Bird species during the CNC is very much dependent on luck. I missed out on the Black Swan at Onkaparinga River Recreation Park, but added four species within the first few minutes on this hike. A female Crescent Honeyeater (Phylidonyris pyrrhopterus), which is quite common, a Yellow-faced Honeyeater (Caligavis chrysops), far less common, a Striated Thornbill (Acanthiza lineata), common but hard to get clear enough photos to ID on an overcast day, and finally an unexpected Collared Sparrowhawk (Accipiter cirrocephalus).

Through this section of the park there are few understory Plant species. Considering the density of vegetation higher up the river along the Echidna Hike, it seems likely this is due to historic farming usage, or an excess of Western Grey Kangaroos. Aside from the Eucalypts, the area is a repeating patchwork of Varnish Wattle (Acacia verniciflua), Sticky Hop-Bush (Dodonaea viscosa), Rock Wattle (Acacia rupicola), Kangaroo Thorn (Acacia paradoxa). A few Prickly Guinea-Flowers (Hibbertia exutiacies) are still present. The absence of understory allows large numbers of Bridal Creeper (Asparagus asparagoides) to proliferate. The occasional flowering Twiggy Daisy-Bush (Olearia ramulosa) adds some colour this time of year.



Even in this section of the park the Mosses cover much of the ground this time of year giving it a yellow-green colour. Like the other Plant species, these are mostly a few common species, repeating. I found at least 8 species without much effort on this hike, including Barbula calycina, Leptodontium paradoxum, Triquetrella papillata, Polytrichum juniperinum, and a Rosulabryum sp.



Breaking from the fire track and heading back along the Sundew Ridge Hike, the track runs along the side of a denuded hillside with views directly down to the Onkaparinga River.



Further along this track the vegetation density increases. On the high side of the track I spotted a Koala (Phascolarctos cinereus). These don’t seem particularly common in this park. This is only the 2nd one I’ve located over the last few years. Under the trees near the track I found a large patch of Slender Velvet-Bush (Lasiopetalum baueri). These only seem to grow in the area between this track and down to the river, always is large patches rather than individuals.



Along the track I found a great example showing the size range of two local Ant species. A relatively large Pony Ant (Genus Rhytidoponera) with a tiny Big-headed Ant (Genus Pheidole) chewing on its antenna.



Last of all, a species I was hoping to find, a small cluster of Early Sundews (Drosera praefolia). This particular carnivorous Plant puts up its flowers in April, which then senesce before its leaves emerge. It’s possible this is an adaptation that helps to prevent pollinators becoming ensnared.