Waldegrave Islands is an island group located about northwest by west of Cape Finniss and about northwest by west of the town of Elliston on the west coast of Eyre Peninsula in South Australia. The group consist of the following islands: Waldegrave Island, Little Waldegrave Island and according to some sources, a pair of rocks known as the Watchers. Both islands can be accessed via the rocky coast on their northern sides which is sheltered from southerly swells.
Waldegrave Island
Waldegrave Island is a flat topped island with steep sides having a length of about , a maximum height in the range of and an area of. Its east coast which is about long is terminated at the north east with a point named McLachlan Point and the south by a point named Point Watson. It overlaps the seaward boundary of Anxious Bay as proclaimed by the Australian government in 1987 and again in 2006 under the Seas and Submerged Lands Act 1973.
Little Waldegrave Island
Little Waldegrave Island is located about west of Waldegrave Island. It is a flat topped island with steep sides having a length of about , a maximum height in the range of and an area of.
The Watchers are a pair of rocks that are spaced about apart and which are located about west of Little Waldegrave Island. The western rock has a charted height of and is reported in another source as being. The eastern rock is charted chart as an intertidal reef.
Formation, geology and oceanography
The Waldegrave Islands were formed about 6000 years ago following the rise of sea levels at the start of the Holocene. The Waldegrave Islands consists of a ‘crystalline basement ’ which outcrops to a height of on Little Waldegrave Island and which exists as a submerged reef connecting both islands. The Waldegrave Islands are considered to be ‘remnants of a once more prominent Cape Finnis’ with the ‘remains of the bridging isthmus lie as a submerged reef connecting Cape Finnis’ to Waldegrave Island at its north-eastern tip. The Watchers are reported geologically as being ‘two isolated outcrops of crystalline rocks’. Waters around Waldegrave and Little Waldegrave Islands drop to depths of within about of its north, west and south coasts. Its east coast drops into water of depths between due to the presence of the submerged reef structure between it and Cape Finniss. The Watchers are associated with a submerged reef system independent of that underlying the Waldegrave and Little Waldegrave Islands. Waters adjoining the Watchers drop to depths of within about immediately south and west of the western rock and about to its north east.
Flora and fauna
Flora
A survey carried out during 1979 on Waldegrave Island found 26 species of plant that occurred in the following ‘five distinctive groupings’: introduced pasture, ‘heavy infestations of African Boxthorn and native shrublands of native juniper and coast daisy-bush and saltbush. A survey carried out in 1980 on Little Waldegrave Island found southern seaheath, sea celery and nine other species of plant including ‘colonising weeds such as African boxthorn and common iceplant’.
Little Waldegrave Island is the site of a breeding colony of Australian sea lion. As of 1999, the population was reported as being 38. On the larger island, Flinders' expedition killed "a few" Australian sea lions.
Cape Barren geese
As of 1996, the Waldegrave Islands were considered to be the ’second most important breeding area’ for Cape Barren geese in South Australia and as having a breeding population of 20 pairs. As of 1999, the geese were reported as having a population of 350 and as staying ‘in the Elliston area for the summer, feeding in swamps around the margins of Lake Newland and on grain in wheat paddocks’.
Little penguin
The Waldegrave Islands have been reported as the site of a little penguin breeding colony. As of 1999, 300 pairs were reported in 1996 as being present on Waldegrave Island. As of 2006, the populations on Waldegrave and Little Waldegrave Islands were estimated as being respectively 600 in 2006 and as being ‘common’ in 1979.
