Breeding biology of raptors in the south-west of the Northern Territory, Australia

Aumann, Tom

doi:10.1071/mu00073

Cited by 11 publications

(7 citation statements)

References 22 publications

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“…Some 78.7% of items were obtained during October-December compared with 7.8% during January-June. Only 22.9% of items were obtained during 1996 when raptor densities were low and breeding activity was depressed (Aumann 2001b(Aumann ), compared with 33.9% and 43.1% during 1995(Aumann and 1997 Most prey data (76.6% of items) were obtained from 106 occupied territories on the creek sectors searched intensively. Of the remaining items, c. 6% derived from other riparian nests, c. 4% from nests at bores, soaks, dams or waterholes, c. 12% from nests elsewhere (which included all of the wedge-tailed eagle nests located) and c. 1% from chance observations away from breeding sites.…”

Section: Resultsmentioning

confidence: 99%

“…Diet information was obtained primarily by collecting regurgitated pellets of undigested material and the remains of part-eaten animals from beneath active raptor nests and nearby food-exchange and roost trees during the breeding season: September-December for most raptors in central Australia (Aumann 2001b). Most of the nests were located along 100 km of drainage (a 10-km sector on each of 10 different creeks) searched intensively to determine assemblage composition.…”

Section: Methodsmentioning

confidence: 99%

“…Rabbit populations collapsed in the study area as 1996 progressed, with warrens ploughed in and fumigated in preparation for the arrival of the rabbit calicivirus. The buzzards compensated by increasing their consumption of birds, particularly budgerigars, which were plentiful in the study area in 1997 after near-absence the previous year (Aumann 2001b(Aumann , 2001c. How they would cope in a year of bird scarcity if rabbit numbers remain low is a matter for conjecture.…”

Section: Intraspecific Comparisonsmentioning

confidence: 99%

“…The main purpose of the study was to quantify the food resources of raptors in the south-west of the Northern Territory, Australia, as a pre-requisite to a broader exploration of the importance of resource availability in the structuring of the raptor assemblages there (Aumann 2001a(Aumann , 2001b(Aumann , 2001c. The diets of several raptor species have been determined in the east and south-east of Australia (Marchant and Higgins 1993;Olsen 1995), but in the arid inland only that of the wedge-tailed eagle (Aquila audax) has been a focus of significant research (Leopold and Wolfe 1970;Brooker and Ridpath 1980).…”

Section: Introductionmentioning

confidence: 99%

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An intraspecific and interspecific comparison of raptor diets in the south-west of the Northern Territory, Australia

Aumann¹

2001

Wildl. Res.

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Dietary information, collected during 1995-97 in the south-west of the Northern Territory, is presented for 11 raptor species. Unlike better-studied populations of these species in south-eastern and eastern Australia, most of the raptors in the arid inland were found to depend heavily on reptiles and birds, the budgerigar (Melopsittacus undulatus) being a particularly important food for many species during those periods when it was plentiful. Between-territory, between-year and seasonal differences in diet are quantified for most species.The raptor assemblages in central Australia included specialists on medium-sized to large mammals, small to medium-sized birds, and small reptiles/invertebrates, as well as several generalists. Indices of prey diversity and evenness were calculated for each species, and diet overlap between them was used to investigate aspects of interspecific competition for food. Overall, diet overlap was greatest among the bird specialists and between some of the generalists. It increased in 1997, a year of comparative plenty, possibly because several species exploited an abundance of some prey taxa and competitive pressure eased. R a p t o r d i e t s i n t h e No r t h e r n T e r r i t o r y T . A u m a n n

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Intraspecific Comparisonsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An intraspecific and interspecific comparison of raptor diets in the south-west of the Northern Territory, Australia

Aumann¹

2001

Wildl. Res.

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“…This preference did not limit breeding opportunities, as nests of other species were utilised if raven nests were unavailable. Falcons preferred nests in the tallest trees available, as do most tree-nesting raptors (Cade 1982;Marchant and Higgins 1993;Aumann 2001a;Sharp et al 2001); however, the species of tree chosen was subject to availability. The falcons readily used single, isolated nest trees, allowing them to breed in territories that contained just one large tree.…”

Section: Nest-site Selectivitymentioning

confidence: 99%

Territory fidelity, reproductive success and prey choice in the brown falcon, Falco berigora: a flexible bet-hedger?

McDonald¹,

Olsen²,

Baker-Gabb³

2003

Aust. J. Zool.

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The brown falcon, Falco berigora, is one of Australia's most common and widespread raptors, inhabiting a broad array of habitats and most climatic zones across Australia. We monitored a large, marked population (44-49 pairs) over three annual breeding seasons in southern Victoria. Reproductive parameters such as clutch size and the duration of parental care were constant across years. However, there were marked differences in brood size and the proportion of pairs breeding. Both sexes of falcons were found to have high territory and mate fidelity, with only 10% of members of each sex changing territories during the study. Falcons were flexible in their choice of nest sites, using a variety of tree species and even isolated nest trees. Nest sites and territories were regularly distributed throughout the study area, with the density of the population the highest on record for this species. The diet of the population as a whole was very broad, but each pair predominantly specialised on either lagomorphs, small ground prey, small birds, large birds or reptiles. Individuals that changed territory within the study area also switched their diet according to the predominant land-use within the new territory and thus prey availability. We argue that, at the population level, broad dietary breadth, flexibility in choice of nest site, and a conservative, static breeding strategy allows the species to persist in a broad range of environments, possibly through 'bet-hedging'. At the individual level, changeable dietary specialisation, high territory fidelity, strong year-round territorial defence, confining breeding to years when individual conditions were favourable and adjusting brood sizes when required appear to be the main strategies enabling brown falcons to thrive under a variety of conditions.

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The structure of raptor assemblages in riparian environments in the south-west of the Northern Territory, Australia

Aumann

2001

Emu - Austral Ornithology

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Breeding biology of raptors in the south-west of the Northern Territory, Australia

Cited by 11 publications

References 22 publications

An intraspecific and interspecific comparison of raptor diets in the south-west of the Northern Territory, Australia

An intraspecific and interspecific comparison of raptor diets in the south-west of the Northern Territory, Australia

Territory fidelity, reproductive success and prey choice in the brown falcon, Falco berigora: a flexible bet-hedger?

The structure of raptor assemblages in riparian environments in the south-west of the Northern Territory, Australia

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