As regular CFZ-watchers will know, for some time Corinna has been doing a column for Animals & Men and a regular segment on On The Track... particularly about out-of-place birds and rare vagrants. There seem to be more and more bird stories from all over the world hitting the news these days so, to make room for them all - and to give them all equal and worthy coverage - she has set up this new blog to cover all things feathery and Fortean.

Sunday, 2 December 2012

Myna 'guity of evicting Aussie birds'

Debate has raged for more than a decade about the damage caused by swelling myna populations, both in Australia and other countries around the world, leading the pesky bird to be rated No. 3 on the IUCN's list of the worst invasive species. Now a team of Australian researchers has come up with what is thought to be the world's first clear proof that mynas do indeed have a negative impact on native bird numbers. In a long running study, Kate Grarock and her colleagues of the ARC Centre of Excellence for Environmental Decisions (CEED) and Australian National University investigated 20 birds species round the national capital, Canberra, analysing ornithological records of bird abundance collected by the Canberra Ornithologists Group (COG). COG established the Canberra Garden Bird Survey (GBS) in 1981 in which volunteers surveyed birds in and around the city. Observers survey an area of 3.1 hectares every fortnight for a 120-minute period. A total of 74 492 surveys was undertaken in Canberra over 29 years "We found a negative relationship between the establishment of the Common Myna and the long-term abundance of three Australian cavity-nesting species and eight small bird species," Ms Grarock says. The birds most affected by mynas were cavity nesters like the Sulphur-crested Cockatoo, Crimson Rosella, Laughing Kookaburra, and small birds such as the Superb Fairy-Wren, Striated Pardalote, Rufous Whistler, Willie Wagtail, Grey Fantail, Magpie-lark, House Sparrow, Silvereye and Common Blackbird. Larger birds like magpies, wattlebirds, galahs, ravens and currawongs appeared unaffected. "To the best of our knowledge, this finding has never previously been demonstrated at the population level," she adds. "It is particularly difficult to track the impact of an invasive species on native wildlife when it isn't an actual predator, as this can take place subtly and over a long time and can vary season by season," she says. "Also you need to know whether it is the invader that is causing the damage – or whether it is simply due to habitat change, such as cities expanding."

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