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Cumbungi swamps are the most permanent waterfowl habitat in much of the inland of south-eastern Australia and are known to form valuable dry-weather refuges for many waterfowl and to provide favoured habitat at all times for some species. As part of a series of studies of the ecology of waterfowl in inland New South Wales the breeding and food of species found in such a swamp have been studied. This paper describes the general ecology of a cumbungi swamp and provides the introduction to a series of papers on the waterfowl encountered in it.

In inland Australia the erratic semi-arid climate has led to the development of irregular movement patterns and breeding seasons in wild ducks. Whilst some species are sedentary and have quite regular breeding seasons, others are completely nomadic and breed whenever and wherever conditions may be suitable. There is a similar division of habits among individuals of the same species. This paper reviews what is known of the breeding seasons and movement patterns of the different species of wild ducks occurring in the interior of New South Wales.

For five species of morphologically very similar Corvus to occur on one continent and for two or three of these species to frequently coexist in sympatry, effective isolating mechanisms must be active to maintain species integrity. This paper describes and compares the behaviour and social organization of Corvus coronoides and C. mellori in detail; C. tasmanicus, C. orru, and C. bennetti were studied less intensively but are compared wherever possible. Few spectacular or species-specific displays were recorded. Calls are varied and a "vocabulary" for C. coronoides is given; each species has a characteristic territorial advertisement call. Both C. coronoides and C. mellovi form long-lasting pair bonds; probably the other species do so as well. Adults of C. coronoides, C. orru, and C. tasmanicus maintain territories all the year round; immatures and non-breeding adults live in nomadic flocks. C. mellori and C. bennetti occupy a breeding territory only for the minimum time (3 months) necessary to rear young; for the rest of the year they and their non-breeding conspecifics are nomadic. The number and size of C. covolzoides territories varied little over the years of the study; this and the ever-present reservoir of mature but non-breeding adults in the flocks suggest that large mosaic territories for permanently resident species may limit breeding density. The nomadism of non-breeding birds enables transient localized food-gluts to be utilized.

This paper compares the breeding seasons of the five species of Corvus inhabiting Australia. The more sedentary species (C. coronoides, C. orru, and C. tasmanicus) tend to have regular annual breeding seasons. The more nomadic species (C. bennetti and C. mellori) tend to breed in late winter and early spring but if this time is unfavourable they may respond to suitable environmental stimuli (usually rainfall) whenever they occur. All species have an immature period of 2 or 3 years. Adult males actively produce sperm over a 10-week period each year. In females the ovaries rapidly regress after egg-laying but retain the capacity to redevelop. The species of Corvus studied were typically single-brooded and in the event of failure a replacement clutch rarely occurred later than 5 weeks after the first eggs had been laid. Only the female incubates and her brood patch develops when the first egg is laid. In Australian Corvus the colour of the eye changes from brown to white with age, and in each species only birds with white eyes were found breeding. From this observation and records of aviary birds of known age it was concluded that C. orru, C. bennetti, and C. mellori do not breed until they are more than 2 yr old, and C. coronoides and C. tasmanicus more than 3 yr of age. Observations in the field on known-age birds banded as nestlings showed that breeding rarely occurred before a bird of any species was 3-4 yr of age.