Northern Suburbs Branch 23 November 2022
A group of seven explored the natural history of the coastal dunes alongside Challenger Parade, City Beach. Weather conditions (fresh breeze, Beaufort scale 5) were not ideal for recording bird species. We failed to see or hear any fairy-wrens. Nevertheless, we recorded seventeen land bird species and three marine bird species.
We entered the dunes via the CMB 41 sandy path. Then we zigzagged from beach/path/Challenger Parade etc., until we emerged at the highest point near the Swanbourne meteorological station, positioned within the Department of Defence lands. This provided a fine prospect of the extensive wattle scrub extant in land inaccessible to the public and reminded us of how much coastal dune vegetation has been destroyed in Cottesloe and elsewhere along the metropolitan coastline.
The width of the dune system is narrowest in the north (c. 100 m, where we began the excursion) and widest in the south (c. 600 m, where we finished). Tuart is present only in the south and then only in small patches. The dunes closest to the beach have sparse vegetation of Spinifex (mostly S. longifolius) and, in places, much Marram Grass (introduced) and some Euphorbia paralias (introduced). On the dunes inland Scaevola crassifolia, Olearia axillaris, and Rhagodia baccata predominate. Wattle scrub becomes prevalent farther inland, comprised of Acacia rostellifera and A. cyclops, with occasional arborescent groves of Moonah (Melaleuca lanceolata) and Coastal Peppermint. Some swales have dense thickets of Lepidosperma gladiatum. Along the CMB 49 path, groves of 3-metre-tall ‘old growth’ Quandong occur.
A few species were in flower: Carpobrotus virescens, Calothamnus quadrifidus, Clematis linearifolia, Melaleuca systena, Scaevola crassifolia, Arctotis stoechadifolia (a weed), Oenothera drummondii (a weed), Acacia cyclops, and Agonis flexuosa. We observed the seed encircled by the red aril of Acacia cyclops and could distinguish the legumes of this species from A. rostellifera by their shape. Ripe fruits of Asparagus asparagoides were also seen. We found quandong in bud and were surprised to see no fruits.
Although most of the annual weeds were dead, we could see the recent extent of White Flower Fumitory, Veldt Grass, and other exotic grass species. There is still much work to be done by the Town of Cambridge and the Botanical Parks and Parks Authority in ridding these dunes of these and other introduced plant species.