DEBUS: Diagnostic Characters of AUSTRALIAN 232 some Australian Corvids WATCHER flying over the beach area. After landing, a brief inspection of this area revealed 91 nests with eggs and numerous fresh scrapes. One nest contained three eggs while one or two eggs were about equally spread among the others. The nests were situated on 'mini' sand dunes or ridges about 0.5 m in height. These dunes covered most of the beach area above the normal high water level. The dunes were covered with clumps of Arctotheca populifolia, an introduced plant now widely distributed on beaches, particularly along the south coast of Western . The nests were situated among the clumps. During the previous visit to the island in October 1981, very few of these small dunes were present and no Fairy Terns were seen. There is no previous record of their breeding on this island. Acknowledgements I wish to thank my wife who assisted me with the survey, Derrick and Barry Beale for our boat transport, Ian Abbott for the plant identification, Mike Clarke (Organiser, RAOU Nest Record Scheme) for details of nest records, and Austin Daw for his observations. By S. G. LANE, Lot 6 Fairview Road, Moonee, via Coifs Harbour, NS. W 2450 •

On the Diagnostic Characters of Some Australian Corvids

Despite a major milestone in corvid field identification provided by Rowley (1970), there is still some incorrect information reaching the ordinary bird­ watcher via some of the popular literature. This can only compound the problem of separating a bird group which many observers find difficult; it can also lead to serious errors of identification. This is unfortunate because accurate identification is an important consideration in the very interesting subject of the comparative ecology of these . It is a topic which requires further work, especially on the Torresian orru and the C. bennetti where they occur together, and on the C. tasmanicus and its sympatric congeners. It is also one to which ordinary bird­ watchers can contribute much valuable data, but the value of locality records and other notes is lessened when there is the possibility of birds incorrectly identified. The misinformation in recent books is doubly unfortunate, because the books concerned have appeared since Rowley's definitive papers on the corvids. Pizzey (1980) stated that one of the characters of the C. mellori is the 'extensive loose bare skin on chin between bases of lower mandible'. However, it is the C. coronoides which shows this character and not the Little Raven; the latter has a well-feathered inter-ramal area (Rowley 1970) and this is the very character by which these two ravens may be separated in the hand. Pizzey did state that the Australian Raven has bare inter-ramal skin; it may be useful to point out that this feature is sometimes visible in the field, especially in the case of juveniles which have pink inter­ ramal skin. The only other corvid which shows this feature in the field, but to a lesser extent, is the Forest Raven-juveniles can show narrow pink edges to VOL. 10 (7) DEBUS: Diagnostic Characters of SEPTEMBER 1984 some Australian Corvids 233 the inter-ramal area when viewed at close range. Like the Little Raven, the two have a well-feathered inter-ramal area. Balmford (1980) stated that the Australian Raven's call is deep and harsh, and both she and Kloot & McCulloch (1980) stated that the Little Raven's call is higher pitched. This is also incorrect-the Australian Raven's call is actually the higher-pitched call, sounding rather like a human child. The Little Raven's call is deeper and harsher, and the Forest Raven'& call is deeper and harsher again. To use a musical analogy, the Forest Raven may be thought of as a bass, the Little Raven and Little Crow as baritones, and the Australian Raven and as tenors, although there is of course some overlap in pitch range between the middle group and the others. Some observers are possibly failing to recognise the Forest Raven in southern . Some Victorian observers with whom I have spoken have remarked that the Australian Ravens they heard in Queensland sounded so different from Victorian birds that they were at first taken to be a different species. This has not been my experience-Queensland Australian Ravens sound little different from those in the Riverina of and in northern Victoria. The Forest Raven is now known to occur around coastal Victoria from the Otway Ranges into South Australia, and it is actually the common species in places such as Mortlake (R. Weatherly, pers. comm.). I suggest that some Victorian observers have been wrongly ascribing deep, harsh calls to the Australian Raven because of the misleading published information on corvid calls, as discussed above, and that they are possibly hearing Forest Ravens instead. Pizzey (1980) stated that the Forest Raven's habits are generally like those of the Little Raven. This is rather misleading, since the Forest Raven is more like the Australian Raven in behaviour, social organisation and ecology. Observers should not expect Forest Ravens to behave like Little Ravens. Now that the Little Raven and the northern race of the Forest Raven Ct. boreus are known to occur in the same area (Debus 1980), there is the problem of separating these birds as well. This is somewhat more difficult than in the south where the Forest Raven shows blunt wings and a very short tail. A review of the measurements of male C t. boreus (Debus 1984) has revealed that there is a greater size difference between this race and the Little Raven than previously thought. The size difference is comparable to that between the Torresian and Little Crows, which means that most specimens should be separable on measurements if their sex is known. I have always thought that New South Wales Forest Ravens in the field appear to be particularly large corvids, especially in wing-span.

References Balmford, R. (1980), Learning About Australian Birds, Collins, Sydney. Debus, S. J. S. (1980), 'Little and Forest Ravens in New South Wales', Aust. Birds 15, 7-12. -- (1984). 'A re-appraisal of the dimensions of male Forest Ravens', Corella 8, 19-20. Kloot, T. & McCulloch, E. M. (1980). Birds of Australian Gardens. Rigby, Adelaide. Pizzey. G. (1980), A Field Guide to the Birds of Australia. Collins. Sydney. Rowley. I. (1970). 'The genus Corvus (Aves: ) in Australia'. CSIRO Wildlife Research 15, 27-72.

By STEPHEN 1. S. DEBUS, P.O. Box 1015. Armidale. NS. W 2350 •