摘要:

SummaryA colour-banded population ofMalurus splendenswas studied from 1973–1988 in up to 34 cooperative-breeding territorial groups in woodland-heath near Perth. The study is considered in three parts: 1973–77, with regular minor patchy fires; 1978–84, with no fires; and 1985–1988, after a major fire in January 1985. Eggs were laid from late August to January, mostly in September-November. Rain in mid- to late August may delay the start of laying. Groups without dependent young may continue breeding into January but most such late attempts fail during periods of extreme heat. Before November, most nests were within 1 m of the ground; later nests were higher. Most clutches were of three eggs (mean = 2.90) and clutch size did not vary during the breeding season or from year to year. Incubation lasted 14–15 days (13–14 d in December), nestlings hatched synchronously and fledged 10–12 days later. Parasitism by cuckoos varied between years, affecting from 0 to 52% of nests (mean = 21%); the most common nest predators were reptiles and cats. Fertility was 93% and over all years 49% of eggs produced fledglings (1973–77: 56%; 1978–84: 58%; 1985–88: 33%); 52% of nests produced at least one fledgling. Replacement clutches were laid soon after a nest failed, often within seven days.M. splendensis multi-brooded; variation in reproductive effort occurs through the number of clutches, not clutch size. Overall, 36% of females renested after successfully rearing a brood; 22% of females reared two broods, with considerable variation between years (63.6% in 1978; 2.8% in 1985). Groups produced a mean of 3.2 fledglings and 2.2 independent young per year; even in years with a high rate of nest failure, 75% of groups produced at least one fledgling. Breeding success did not differ between early and late nests, and fledglings survived equally well. The production of multiple broods is an important feature in the life history ofM. splendensand other resident Australian passerines.

ISSN:0158-4197    

DOI:10.1071/MU9910197

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

SummaryThe distribution and abundance of Emus in the South Australian pastoral zone between 1978 and 1989 was determined by winter aerial surveys. The average number of Emu groups present ranged from a low of 0.02 km−2in 1983 to 0.08 km−2in 1980, 1981 and 1988. Between 1984 and 1989, average size of these groups was found to range from 2.22 to 4.55 Emus. Although the distribution varied from year to year, Emu density was generally highest in the northeast of the pastoral zone and lowest in the more arid northwest. The northeast of the pastoral zone is a relatively productive area, containing a mixture of land systems, particularly‘run-on’areas. The low open woodlands and tall shrublands of the northwest and south of the pastoral zone supported low densities of Emus. Areas of high Emu density were generally dominated by more intensive sheep grazing, by fans and/or hills, by red duplex soils, and by low shrublands of predominantly bluebush. Rainfall during summer and autumn was considered an important determinant of Emu density, with this period being important in terms of egg production.

ISSN:0158-4197    

DOI:10.1071/MU9910222

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

SummaryIntraspecific nest parasitism was recorded in 31% of clutches containing±5 eggs laid by Maned DucksChenonetta jubatain nest boxes near Canberra. This is within the range for other cavity-nesting waterfowl. Frequency of parasitism was higher in 1987 (62% of 13 incubated clutches) than in 1988 (27% of 22 incubated clutches). Less rain fell during the laying period in 1987 (209 mm) than during the same period in 1988 (309 mm). Rain increases the growth of pasture grazed by Maned Ducks. The higher incidence of parasitism in the drier year suggests that individual Maned Ducks used nest parasitism as a salvage strategy, to enhance their chance of reproductive success when food was relatively scarce. Natural and experimental parasitism did not increase nest desertion, nor did they reduce clutch size of hosts, fat levels of incubating females or egg hatchability. Larger broods survived as well as smaller ones. Thus, nest parasitism in Maned Ducks may increase the reproductive success of the parasite, without reducing the reproductive success of the host. The sample sizes in this study were small and more data are required to confirm these tentative conclusions.

ISSN:0158-4197    

DOI:10.1071/MU9910230

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

SummaryA colour-banded population of White-fronted Chats was studied to determine parental roles, the occurrence of multiple breeding, mate and site fidelity, the length of the breeding season, nest-site natural history and parameters of reproductive output. Apart from nocturnal incubation and brooding, which was performed by females, both sexes shared nesting duties equally and remained together throughout the breeding season. The breeding season was long (4.2‘equally good’months) and repeat nesting, up to at least five times, was common after successful and unsuccessful nests. Clutch size was small (2.75 eggs), reproductive success was low (18.5% of eggs laid) and most losses (83%) were due to predation. Nest predation may be an important factor in the evolution of the life histories of White-fronted Chats and other Australian bird species.

ISSN:0158-4197    

DOI:10.1071/MU9910236

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

ISSN:0158-4197    

DOI:10.1071/MU9910250

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

ISSN:0158-4197    

DOI:10.1071/MU9910251

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

ISSN:0158-4197    

DOI:10.1071/MU9910255

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

ISSN:0158-4197    

DOI:10.1071/MU9910257

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

ISSN:0158-4197    

DOI:10.1071/MU9910258

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor