Diets of Wedge-tailed Eagles Aquila audax and Little Eagles Hieraaetus morphnoides breeding near Canberra, 2008-2009

Gerald Olsen, Stephen Debus, David JUDGE, A Rose

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    Abstract

    In the Australian Capital Territory during 2008-09, the diet of breeding Wedge-tailed Eagles Aquila audax consisted of 65 per cent mammals, 33 per cent birds and 1 per cent reptiles by number (n = 94 prey items from 10 nests), of which 19 per cent consisted of macropods, 34 per cent rabbits (mostly adults, plus 4% hares), and a range of other large mammals, many probably eaten as carrion. Breeding Little Eagles Hieraaetus morphnoides took 52 per cent mammals, 45 per cent birds and 3 per cent reptiles by number (n = 58 prey items from six nests), of which 2 per cent consisted of macropod (one small joey kangaroo) and 50 per cent rabbits (mostly juveniles). Both eagle species took more rabbits in 2008-2009, compared with two earlier periods in 2002-2003 and 2004?–2007. By biomass Wedge-tailed Eagles took 93 per cent mammals (20% rabbits, 45% macropods); Little Eagles took 73 per cent mammals (almost entirely rabbits) and 24 per cent birds. Geometric Mean Prey Weight for Wedge-tailed Eagle prey was 1650 grams, for Little Eagles 337 grams. Standardised food niche breadth was 0.205 for Wedge-tailed Eagles, and narrower (0.143) for Little Eagles. The Shannon Index for Wedge-tailed Eagles was 2.75, for Little Eagles 2.28. Although a Pianka Index suggests 46 per cent overlap in prey used by the two eagles, the great difference in GMPW and heavy use of rabbits by Little Eagles suggest that there is little interspecic competition for prey. Little Eagles may be declining in the ACT because rabbits, their main prey, are poisoned, and this poisoning may affect Little Eagles more than some other raptors.
    Original languageEnglish
    Pages (from-to)25-29
    Number of pages5
    JournalCorella
    Volume37
    Issue number2
    Publication statusPublished - 2013

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    Aquila
    eagles
    mammal
    breeding
    diet
    bird
    reptile
    rabbits
    nest
    carrion
    niche breadth
    raptor
    mammals
    poisoning
    reptiles
    food
    birds
    biomass
    Australian Capital Territory
    nests

    Cite this

    Olsen, Gerald ; Debus, Stephen ; JUDGE, David ; Rose, A. / Diets of Wedge-tailed Eagles Aquila audax and Little Eagles Hieraaetus morphnoides breeding near Canberra, 2008-2009. In: Corella. 2013 ; Vol. 37, No. 2. pp. 25-29.
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    title = "Diets of Wedge-tailed Eagles Aquila audax and Little Eagles Hieraaetus morphnoides breeding near Canberra, 2008-2009",
    abstract = "In the Australian Capital Territory during 2008-09, the diet of breeding Wedge-tailed Eagles Aquila audax consisted of 65 per cent mammals, 33 per cent birds and 1 per cent reptiles by number (n = 94 prey items from 10 nests), of which 19 per cent consisted of macropods, 34 per cent rabbits (mostly adults, plus 4{\%} hares), and a range of other large mammals, many probably eaten as carrion. Breeding Little Eagles Hieraaetus morphnoides took 52 per cent mammals, 45 per cent birds and 3 per cent reptiles by number (n = 58 prey items from six nests), of which 2 per cent consisted of macropod (one small joey kangaroo) and 50 per cent rabbits (mostly juveniles). Both eagle species took more rabbits in 2008-2009, compared with two earlier periods in 2002-2003 and 2004?–2007. By biomass Wedge-tailed Eagles took 93 per cent mammals (20{\%} rabbits, 45{\%} macropods); Little Eagles took 73 per cent mammals (almost entirely rabbits) and 24 per cent birds. Geometric Mean Prey Weight for Wedge-tailed Eagle prey was 1650 grams, for Little Eagles 337 grams. Standardised food niche breadth was 0.205 for Wedge-tailed Eagles, and narrower (0.143) for Little Eagles. The Shannon Index for Wedge-tailed Eagles was 2.75, for Little Eagles 2.28. Although a Pianka Index suggests 46 per cent overlap in prey used by the two eagles, the great difference in GMPW and heavy use of rabbits by Little Eagles suggest that there is little interspecic competition for prey. Little Eagles may be declining in the ACT because rabbits, their main prey, are poisoned, and this poisoning may affect Little Eagles more than some other raptors.",
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    language = "English",
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    Diets of Wedge-tailed Eagles Aquila audax and Little Eagles Hieraaetus morphnoides breeding near Canberra, 2008-2009. / Olsen, Gerald; Debus, Stephen; JUDGE, David ; Rose, A.

    In: Corella, Vol. 37, No. 2, 2013, p. 25-29.

    Research output: Contribution to journalArticle

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    T1 - Diets of Wedge-tailed Eagles Aquila audax and Little Eagles Hieraaetus morphnoides breeding near Canberra, 2008-2009

    AU - Olsen, Gerald

    AU - Debus, Stephen

    AU - JUDGE, David

    AU - Rose, A

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    N2 - In the Australian Capital Territory during 2008-09, the diet of breeding Wedge-tailed Eagles Aquila audax consisted of 65 per cent mammals, 33 per cent birds and 1 per cent reptiles by number (n = 94 prey items from 10 nests), of which 19 per cent consisted of macropods, 34 per cent rabbits (mostly adults, plus 4% hares), and a range of other large mammals, many probably eaten as carrion. Breeding Little Eagles Hieraaetus morphnoides took 52 per cent mammals, 45 per cent birds and 3 per cent reptiles by number (n = 58 prey items from six nests), of which 2 per cent consisted of macropod (one small joey kangaroo) and 50 per cent rabbits (mostly juveniles). Both eagle species took more rabbits in 2008-2009, compared with two earlier periods in 2002-2003 and 2004?–2007. By biomass Wedge-tailed Eagles took 93 per cent mammals (20% rabbits, 45% macropods); Little Eagles took 73 per cent mammals (almost entirely rabbits) and 24 per cent birds. Geometric Mean Prey Weight for Wedge-tailed Eagle prey was 1650 grams, for Little Eagles 337 grams. Standardised food niche breadth was 0.205 for Wedge-tailed Eagles, and narrower (0.143) for Little Eagles. The Shannon Index for Wedge-tailed Eagles was 2.75, for Little Eagles 2.28. Although a Pianka Index suggests 46 per cent overlap in prey used by the two eagles, the great difference in GMPW and heavy use of rabbits by Little Eagles suggest that there is little interspecic competition for prey. Little Eagles may be declining in the ACT because rabbits, their main prey, are poisoned, and this poisoning may affect Little Eagles more than some other raptors.

    AB - In the Australian Capital Territory during 2008-09, the diet of breeding Wedge-tailed Eagles Aquila audax consisted of 65 per cent mammals, 33 per cent birds and 1 per cent reptiles by number (n = 94 prey items from 10 nests), of which 19 per cent consisted of macropods, 34 per cent rabbits (mostly adults, plus 4% hares), and a range of other large mammals, many probably eaten as carrion. Breeding Little Eagles Hieraaetus morphnoides took 52 per cent mammals, 45 per cent birds and 3 per cent reptiles by number (n = 58 prey items from six nests), of which 2 per cent consisted of macropod (one small joey kangaroo) and 50 per cent rabbits (mostly juveniles). Both eagle species took more rabbits in 2008-2009, compared with two earlier periods in 2002-2003 and 2004?–2007. By biomass Wedge-tailed Eagles took 93 per cent mammals (20% rabbits, 45% macropods); Little Eagles took 73 per cent mammals (almost entirely rabbits) and 24 per cent birds. Geometric Mean Prey Weight for Wedge-tailed Eagle prey was 1650 grams, for Little Eagles 337 grams. Standardised food niche breadth was 0.205 for Wedge-tailed Eagles, and narrower (0.143) for Little Eagles. The Shannon Index for Wedge-tailed Eagles was 2.75, for Little Eagles 2.28. Although a Pianka Index suggests 46 per cent overlap in prey used by the two eagles, the great difference in GMPW and heavy use of rabbits by Little Eagles suggest that there is little interspecic competition for prey. Little Eagles may be declining in the ACT because rabbits, their main prey, are poisoned, and this poisoning may affect Little Eagles more than some other raptors.

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