Page:The Emu volume 4.djvu/16

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4
Milligan, Description of a New Kestrel from W.A.
[Emu 1st July

building their nests under one roof, so to speak. It is said in respect of this latter family that the greater number of their settlements is formed of nests containing merely the chamber for the young and the apartment arranged by the male for his own occupation, and that some males build separate nests for themselves. It is perhaps more than a coincidence that the male ot the species under notice (as also its ally, Acanthiza chrysorrhoa) builds a so-called "cock's nest," and which is generally thought to be for his own occupation. I recorded an instance (see "Notes on a Trip to the Stirling Range," Emu, vol. iii., page 17) where I found the "cock's nest" an independent structure, but in the same bush. The "conglomerate" nest of the local species was not only long, but bulky. The unusual size was due to the great amount of raw wool which had been filched from the sheep enclosure in the vicinity and which had liberally, if not extravagantly, been interwoven into the structure.

Distribution of Species.—The trip afforded the best of opportunities for making observations on that interesting phase of ornithology—namely, the distribution of species. From the results, I have been enabled to fix the northern or southern limits of many Western Australian species, and also the eastern or western limits of many others. Further exploration will doubtless cause alteration in the limits fixed, but I think not very materially, as I have had the advantage of examining as well a collection of bird-skins obtained by one of the Museum collectors at Wurarga and Day Dawn, some 200 miles north of the Wongan Hills, as also another made by Mr. Bruce Leake, of Kellerberrin, in his district (distant some 160 miles south-easterly from the Hills), and donated by him to the Museum. I have also had to aid me our collection from the Stirling Range, distant some 350 miles in a southerly direction from the Hills, and my own personal knowledge of coastal distribution from Lake Yanchep in the north to Cape Leeuwin in the south.

As our starting point was near the northern end of the great coastal mountain chain of Western Australia, the Darling Ranges, I was further enabled to obtain sufficient data upon which to base, or perhaps confirm, the positive existence of, purely coastal forms as contradistinguished from purely inland ones, or, as I prefer to term them, "ultramontane" forms. Doubtless farther north, where the influence of the natural barrier of the coastal range is not felt, and where species are free to come and go without interruption, the fixed limits for eastern and western species will not apply. The natural formations of country over which we passed (and which for the most part ran north and south) were most clearly defined, and thus conduced not only to easy observation of species, but also to positive results in recording them. These well-defined formations might and could be likened to a vertical section of different rock strata placed upon a horizontal plane.