Location three on the second day of the City Nature Challenge was Lady Bay Beach. When the tide is out, the beach south of the HMAS Hobart lookout has quite a variety of seashells. I hiked a few kilometers down the beach along the rocks, then looped back above the high tide line, all the while keeping an eye out for birds of prey on the coastal cliffs.
The section of beach just South of the HMAS Hobart lookout is sandy and frequently covered in sea wrack. This spot seems to be a favourite for a few Bird species. This time it was the Masked Lapwings (Vanellus miles), Magpies (Gymnorhina tibicen) and a Raven (Corvus sp.).
The sea wrack is a mixture of species which I should put some effort into learning to differentiate. Specifically differentiating the green, red and brown algae from the vascular marine Plants, from the Kelp and the Sponges. Amongst the abundant Seagrass (Posidonia sp.) I found a some Codium species (Genus Codium), some Sea Nymph (Amphibolis antarctica) and Warty Twig Seaweed (Scaberia agardhii). All quite common along Greater Adelaide coastline.
Past the sandy section of the beach is the rocky coastline. It is here that the seashells wash up beyond the rocks and get caught behind them. One of the keys to recording a large number of species during a bioblitz is Molluscs. A good shell filled beach may have a more than 100 species. Within the Greater Adelaide area, the Lady Bay Beach is the best I’ve located so far. On this hike I managed to record 29 Mollusc species. I’m sure there are more here, if only I could differentiate them and recognise them from smaller shell fragments. Very common are the Australian Black Nerite (Nerita atramentosa) and Wavy Top (Diloma concameratum). Perhaps less common were the Striped-mouth Conniwink (Bembicium nanum) and Painted-lady Pheasant Shell (Phasianella australis). I don’t know enough about Molluscs to say which species are rarely sighted in this area, however Phasianotrochus irisodontes seems to have few records on iNat. The gallery below shows some of these and a few others recorded on the day.
As far as Molluscs go the highlight of the day was a Fimbriate Helmet Snail (Cassis fimbriata). These are reasonably common, and I found three on this day, but it’s uncommon to find an intact shell with much of its colour remaining. As you can see by my hand, these are quite a bit larger than most other shells found.
Along the beach it’s always worth lifting your head occasionally to look beyond the sand. Interesting marine Birds often fly past and if the timing is right you can get some reasonable photos. Keep an eye on the rocky shoreline as well. Today I was lucky to spot a Pacific Reef-Heron (Egretta sacra) hunting near the water. Only the second time I’ve spotted this species, the first at Hallett Cove.
Reaching a far point and heading back, a Pacific Gull (Larus pacificus) flying into a strong headwind flew directly overhead. I managed to capture a few photos of it slowly making headway into the wind. With the sun behind, the different rows of feathers are highlighted.
On the walk back I tracked through the weedy dune above the hightide line. Almost every species growing here is an introduced weed. Sweet Scabious (Sixalix atropurpurea), Searockets (Genus Cakile), Sea Spurge (Euphorbia paralias), Wild Cotton (Gomphocarpus cancellatus), and False Sow-Thistle (Reichardia tingitana). All of these were in flower, providing a great source of nectar for the Bees and coastal Butterflies. Meadow Argus (Junonia villida) seem to be fond of the Sweet Scabious, Cabbage Whites (Pieris rapae), a few Monarchs (Danaus plexippus) including one with a damaged wing, struggling against the strong wind that repeatedly found me to be a suitable windbreak. And the highlight of the CNC BioBlitz so far, a Small Grass-Yellow (Eurema smilax). The first time I’ve seen this species, which breeds up North with the larvae feeding on Cassia and Senna species.
One final interesting find was a species of Meshweaver Spider (Family Dictynidae). A chance encounter with one running across a rock, which I wish I’d stopped to take more detailed photos of this uncommonly sighted Family.
Lady Bay Beach
Rocky reef beach extending from Normanville Beach down to Wirrina Cove, HMAS Hobart wreck offshore, and a seashell filled beach south of the lookout.
iNaturalist Projects
Lady Bay to Wirrina Cove, South Australia
See the full list of 129 observations covering 82 species on iNaturalist
Epistemic Curiosity 