Onkaparinga River NP (10th Sept, 2022)

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.

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