Summary.In an examination of the focusing abilities of 15 species of owls, the North American barn owl, Tyto alba pratincola (Bonaparte 1838), was an outstanding accommodator, having a range of accommodation exceeding 10 diopters . Using comparable methods, we examined the accommodation of 4 specimens of the Australian barn owl, Tyto alba delicatula (Gould 1837). We failed to elicit accommodation greater than two diopters, and most stimuli failed to evoke any discernable accommodation at all. Furthermore, examination of other Australian tytonid owls, the grass owl, T. longimembris, the sooty owl, T. tenebricosa, and both the mainland and Tasmanian subspecies of the masked owl, T. novaehollandiae novaehollandiae and T. novaehollandiae castanops, also failed to reveal anything but very moderate accommodative ranges. We conclude that the outstanding accommodative ability of the American barn owl is truly an exception to the modest accommodative abilities of the tytonid owls generally.
The Cumberland and Northumberland Island Groups, more commonly known as the Whitsunday Islands, form the largest offshore island chain on the east coast of Australia. Between 20ºS and 21ºS latitudes there are 37 large islands ranging in size from 10,931ha (Whitsunday Island) to 100ha and a further 96 islands less than 100ha in size. Combined they cover an area of 35,296ha or 3,529km². Some of these were surveyed for archaeological sites in September, 1982, as part of a continuing investigation of islands off the Queensland coast (Rowland 1980, 1982a and 1984).
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