With a few hours to spare on Sunday I took the chance to walk a familiar section of Echidna Hike in Onkaparinga River National Park. This flat section hosts an abundance of Plant species and is easily accessible from one of the main entrances. I wandered for almost two hours, but as I was searching for Invertebrates, I barely covered a few hundred meters.
This was a good chance to practice using the 100mm macro lens in the field. Although I’ve had it more than a year, I’ve not had much opportunity to practice choosing my settings in an uncontrolled environment. Very glad I took it out though as it proved its worth.
Not many Plant species are in flower at the moment, but a yellow flowering variant of the Harlequin Mistletoe (Lysiana exocarpi) was on full display. This hemiparasite was attached to a Cherry Ballart (Exocarpos cupressiformis). The Mistletoe draws water and nutrients from the host species, but still has green leaves that photosynthesise.
This area of the park has a population of Oyster Bay Cypress-Pines (Callitris rhomboidea) running along both sides of the track. These have a quite appealing form that makes me wonder why we don’t cultivate them and use them as native Christmas trees. This species is monoecious, having both male and female cones on the same plant. The male cones are only a couple of millimeters. It’s the larger female cones up to 2cm wide that are long lasting and used to help determine which Callitris species it is.
The camera lens proved its worth on a Golden Wattle (Acacia pycnantha) seed and pod. Most of the pods had dried and dropped their seeds, but this one remained. Each of the more than 100 species of Wattle in South Australia has a distinct seed morphology. It’s worth pausing to open any pods you come across just to see the variation in structure from species to species. Being Legumes, Wattles are nitrogen-fixing, forming symbiotic associations with various strains of root-nodule bacteria (rhizobia).
Inevitably, when you stops to look closely at any Plant you’ll start to spot all the invertebrate species utilising the Plant. In this case it was a single larva of the Omnivorous Tussock Moth (Acyphas semiochrea).
This part of Onkaparinga River NP has quite dense undergrowth, and few obvious Western Grey Kangaroo (Macropus fuliginosus) tracks passing through it, so I had figured the spot wasn’t too popular with the Kangaroos. This morning however there was a couple of females and a juvenile trying to make their way through it. They are probably there often but I don’t see them. I’m hoping this park doesn’t go the way of some others where the Kangaroo population is getting out of hand due to lack of predators and causing significant damage to the park ecosystems.
A side project I’m working on at the moment requires photographs of a wide range of tree trunks, especially Eucalypts, showing their distinctive bark and a range of natural ground covers, such as leaf litter. The value of having a camera in hand is that wherever you point it, it draws your focus, and as much time as I spend out hiking, I found I’ve never really stopped to see that amazing variety of patterns in the bark and leaf litter. I’ve shown just a few below. I didn’t think to determine which species they were, but that’s something I’ll do next time. Most are Eucalypts, and the darker one with yellow Lichen spots is a Cherry Ballart.
It’s easy to overlook certain native Plants that don’t immediately draw the eye with interesting patterns, flowers, or fruit. However this bias doesn’t affect the Invertebrate species that rely on these Plants. Allocasuarina species are one such group I tend to overlook, being a little bland at first glance. But get up close with a camera and it’s amazing what you can find.
Below is a closeup shot of branches on an Slaty Sheoak (Allocasuarina muelleriana). The leaves are reduced to scale-like teeth arranged in whorls around ribbed, jointed branchlets. Each branchlet is around 10mm long.
Upon these branches were a gathering of Dolichoderus scabridus Ants with their stunning red legs and golden gaster (abdomen). Such gatherings are often Ants seeking honeydew from an Insect feeding on the plant sap. In this case it appears to be a species of Giant Scale Insects (Family Monophlebidae) secreting the honeydew. The Ants get a feed and in return may function as protection from predators for the Scale.
It’s worth to pay attention when out hiking, especially if the path is narrow and requires brushing past overhanging vegetation. It’s easy to walk past some fascinating critters, some of which may not appreciate the disturbance.
While photographing Psylloids on a Eucalypt I spotted a Four-spotted Cup Moth (Doratifera quadriguttata) larva in a defensive posture, no doubt trigger by my disturbance. These brightly coloured caterpillars are best left unhandled as the thorax hosts 4 sets of retractable venomous spines that are displayed when disturbed (See below). The sting sensation is said to be akin to a Honey Bee sting. I’ve brushed past many hanging from Eucalypt leaves but not yet been a victim. One species in the same Genus was found to have 151 toxins with the peptide cecropin being responsible for the pain sensation.
The above is just a small selection of the species I was able to find in a less than 2 hours. When out in nature, walk slow and look closely. There’s much more going on than appears at first glance.
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 45 observations covering 29 species on iNaturalist
Epistemic Curiosity 