Of these, three—the Swan, Helena, and Canning—flow into the Swan River estuary. The Serpentine, further south, flows into the Murray River just before the latter enters another large estuary, the Peel Inlet. The Gingin Brook, on the northern boundary of the district, flows into the Moore River just before the latter enters the sea. Along the banks of these rivers various trees occur which are not found on the more open plains. The accompanying sketch map (fig. i) indicates the features referred to.
IV.—General Remarks on the Birds.
Up to the present 191 species of birds have been met with in the region described above, and of these 126 are believed to be resident. One former resident, the Ground-Parrot, is now extinct in the district, but three species have been acclimatized —viz., the Laughing Jackass (Dacelo gigas), and the Indian and Senegal Turtle Doves, all of which are firmly established. Other introduced birds which have escaped from confinement, but have not become established, have not been included in the list.
Many of the resident birds receive great accessions to their numbers in the winter, and it is not very easy to decide in every case whether a bird should be regarded as a true resident when it is not known to breed in the district. There seems little doubt that the number of residents is still increasing. The union of south-western Australia with the rest of the continent is still probably recent in a geological sense, and the former island of the south-west is probably still being stocked with birds. Almost certainly the Black-breasted Plover, White-necked Heron, and Straw-necked Ibis are recent arrivals, and it is to be hoped that shortly the White Egret may be added to our list of residents. It is to be hoped that the Starling and Sparrow will not manage to reach the south-west by the overland route now open.
Of the visitors, 40 may be regarded as fairly regular, though a great deal more study will have to be devoted to them before we have a proper understanding of their movements. The Long-billed Cockatoo, which was formerly a regular winter visitor to the district, is now extinct, though still found further north. Six species arrive in the spring and breed in the district—viz., the Australian Bee-eater, four species of Cuckoo, and the White-shouldered Caterpillar-eater. Eight species which breed in the northern hemisphere are also regular summer visitors to the district—viz., Turnstone, Golden Plover, Curlew, Common Sandpiper, Greenshank, Little Stint, Sharp-tailed Stint, and Curlew-Sandpiper—whilst the Wood-Sandpiper and White-rumped Swift, also northern breeders, have each occurred once. Probably further observation will show that other northern waders sometimes visit the district.
The regular winter visitors, like the summer visitors, fall into two classes. Seven sea-birds which breed further south, either on the Australian coast or in the Antarctic regions, are found on
