Paternity likelihood was tested in a population of splendid fairy-wrens Malurus splendens by allozyme electrophoresis. A total of 91 offspring of 24 dams and 37 putative sires were typed at 10 polymorphic loci. All young were compatible with their dams but at least 65% were not fathered by any of the males in their group. A long-term study of this wren population has shown that the males are sedentary, show little evidence of dispersal and help care for the nestlings and fledglings in their group. Had the senior male sired all the offspring in his group, there would have been a high incidence of close inbreeding. The promiscuous mating system demonstrated here would reduce the level of inbreeding in the population but still allow individuals the security of group-living in a stable year-round territory.

No abstract

A 15-ha plot of salmon gum woodland contained 241 hollows with an entrance diameter and depth exceeding 90 mm, in 173 trees, the majority (95%) in salmon gums. Occupancy of these hollows during the spring of 1978 was 47%; eight species of bird (six Psittaciformes, one Anseriformes and one Falconiformes) were involved. Galahs, corellas, red-tailed black cockatoos and Port Lincoln parrots were the most numerous hollow-nesting birds in the area; there were differences in the sizes of hollows they used, which were separable on entrance size and on inside diameter of the hollow 0.5 m below the entrance. There was a trend for hollow size to decrease in the order: red-tailed black cockatoos, corellas, galahs and Port Lincoln parrots. Red-tailed black cockatoos nested in more dead trees, or trees which were lower and had smaller canopies, than did the other three species. The woodland contained few young trees, trees were dying rapidly and there was no regeneration. This situation is typical for woodland throughout the agricultural area, and future prospects are discussed.

No abstract

The red-winged fairy-wren, Malurus elegans, is endemic to the high-rainfall region of south-western Australia. We studied it in Eucalyptus diversicolor (karri) forest near Manjimup, Western Australia from 1980 to 1995. After a detailed study of breeding biology during 1980–86, we monitored dispersal and survival in known groups during 1987–95. M. elegans bred cooperatively, with 83% of groups (mean size 4.1) including one or more non-breeding males or females that helped to rear young and defend the territory. Survival of breeding adults (78%) and helper males (76%) was high. Territories and groups persisted from year to year, even though one or other of the breeding pair was replaced. Most known dispersals were to a group only 1–2 territories distant. Dispersal was female-biased, mostly in their third or fourth year. A behaviour not recorded in other Malurus spp. was that some birds, chiefly females, joined groups as helpers. The feeding rate of nestlings was not related to group size, but in larger groups the share of work done by the breeding female decreased. Helpers did not enhance the survival of breeding females, and had little overall effect on the production of fledglings. Females produced a mean of 2.4 fledglings, 1.8 independent young and 1.1 yearlings per year; survival of fledglings to the start of the following breeding season was44.2% (31–61%). We argue that the high levels of adult and juvenile survival influence many aspects of the social system in M. elegans, such as large groups, the presence of female helpers, occurrence of immigrant helpers and delayed dispersal. We suggest that an important benefit of delayed dispersal and group living is in promoting the survival of young birds, and increasing their chance of acquiring a territory.