Review of the management of feral animals and their impact on ...

Impacts
This seed-eating finch has <strong>the</strong> potential to compete with native finches for grass seed.
It has been blamed for declines in <strong>the</strong> chestnut-breasted mannikin, zebra finch,
double-barred finch <strong>and</strong> red-browed finch (Immelmann 1965, Garnett 1988) but
without strong evidence. It has a different feeding ecology from most <strong>of</strong> <strong>the</strong>se species
<strong>and</strong> Frith (1973) discounted an <strong>impact</strong> upon any <strong>of</strong> <strong>the</strong>se birds apart from <strong>the</strong>
mannikin, a closely related finch with similar feeding habitats. Immelman (1965)
describes <strong>the</strong> nutmeg mannikin as a ‘serious competitor with <strong>the</strong> chestnut-breasted
mannikin’, Frith (1973) commenting that ‘This might be so, but <strong>the</strong>re are no
quantitative figures yet to show a decline in this species.’ The two species
occasionally hybridise (Immelman 1965). The nutmeg mannikin is most likely to
displace <strong>the</strong> native mannikin from disturbed environments close to human settlements
(Frith 1973). Even so, <strong>the</strong> chestnut-breasted mannikin remains a common bird with a
very wide distribution.
In recent years <strong>the</strong> nutmeg mannikin has exp<strong>and</strong>ed its range. It was previously
unknown from Cape York Peninsula (Blakers et al. 1984) but in recent years has been
recorded from Weipa <strong>and</strong> from <strong>the</strong> eastern side <strong>of</strong> <strong>the</strong> Peninsula, presumably as a
result <strong>of</strong> new aviary releases or escapes. This raises <strong>the</strong> prospect that <strong>the</strong> nutmeg
mannikin could become established in <strong>the</strong> Top End <strong>of</strong> <strong>the</strong> Nor<strong>the</strong>rn Territory, as a
result <strong>of</strong> fur<strong>the</strong>r aviary releases, where it would probably compete with <strong>the</strong> yellowrumped
mannikin, a species listed by <strong>the</strong> Nor<strong>the</strong>rn Territory government as ‘Near
Threatened’. The two finches have matching habitat preferences. Birdwatchers who
reside in <strong>the</strong> Nor<strong>the</strong>rn Territory should be asked to look out for escapee nutmeg
mannikins, <strong>and</strong> any populations that are noted should be swiftly eradicated.
3.7.33 European Goldfinch (Carduelis carduelis)
Summary
A bird found at <strong>the</strong> edge <strong>of</strong> <strong>the</strong> Rangel<strong>and</strong>s where it has no known <strong>impact</strong>s.
Distribution
This finch is found in south-eastern Australia, mainly outside <strong>the</strong> Rangel<strong>and</strong>s. Its
distribution extends marginally into <strong>the</strong> study area in <strong>the</strong> New South Wales Riverina,
<strong>and</strong> to <strong>the</strong> north <strong>of</strong> <strong>the</strong> Murray River in South Australia (Barrett et al. 2004).
Impacts
The goldfinch feeds mainly upon weed seeds <strong>and</strong> no adverse environmental <strong>impact</strong>
could be expected.
3.7.34 Common Blackbird (Turdus merula)
Summary
A bird that sometimes spreads <strong>the</strong> seeds <strong>of</strong> exotic weeds.
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