On 21 October 1980, the conservation park was placed (i.e. "registered") on the Register of the National Estate. The following is the description and the statement of significance published at the time of placement.
Description A group of approximately twelve oceanic islands and associated submerged rocks from 22km-74km from the coast. Includes the Waldegrave islands , Topgallant islands and Ward islands (but excludes Pearson and Flinders islands). The islands are granite inselbergs up to 100m above sea level, and some are capped with calcarenite, a rock type of aeolian origin as windblown dunes. The islands feature precipitous cliffs to 75m tall, deep overhangs, sea caves, crevasses, talus slopes and summit platforms. The larger islands have some soil development and mostly support low shrubland communities dominated by nitre bush (
Nitraria billardierei), gallweed (
Zygophyllum apiculatum), saltbush (
Atriplex paludosa), grey saltbush (
A. cinerea) and a daisy bush (
Olearia ramulosa)… The islands are largely undisturbed because of the difficulty of access from the sea; Topgallant island contains some infestations of African boxthorn and common ice plant…
Statement of Significance The registered islands in this group, namely Waldegrave Islands , Topgallant Islands, Ward Islands and Pearson Islands, are true inselbergs or island mountains, rising abruptly to a maximum of 240m above sea level from the eastern section of the Great Australian Bight. Other important landforms within the Group are of marine origin, including old coastal foredune deposits and formations indicating a higher sea level than presently exists… The islands of the Group are some of the most scenically spectacular of all South Australia's offshore islands. Many birds utilise the Investigator Group islands, which may be significant as intermediate points for birds migrating from Flinders Island to the Australian mainland, or as extended feeding territories for Flinders Island species… Several rare or threatened bird taxa, or species with disjunct populations, utilise the islands for breeding, including osprey (
Pandion haliaetus), white-breasted sea-eagle (
Haliaeetus leucogaster), cape barren goose (
Cereopsis novaehollandiae), white faced storm-petrel (
Pelagodroma marina) and short-tailed shearwater (
Puffinus tenuirostris)… A small colony of Australian sea-lions (
Neophoca cinerea), one of the world's rarest marine mammals, breeds on Ward Island… Groups of the New Zealand fur seal (
Arctocephalus forsteri) shelter on the rock platforms of several islands and may breed on them… ==See also==