Braidwood Landcare surveys

Sun 05 November 2017 07:30am

Sue Lashko

The Braidwood Landcare group contacted COG in 2011 to see if we would be interested in surveying the birds on five to six properties where some revegetation has been done. These surveys were repeated in 2013 and 2015 and will again be carried out in 2017. We will not only survey the revegetation sites, but also remnants and riverine areas. Ten to 12 surveyors are required, beginning at 7.30am, and must be sufficiently experienced to undertake the survey. Please contact Sue Lashko on 62514485 or if you are interested and to receive further details.

Post event report

Nine COG members carried out the surveys on 5 properties on a cool, still day.  The area was noticeably drier than on previous surveys and this no doubt contributed to lower bird numbers than usual. Nevertheless, 55 species were recorded on Jillamatong where there were many waterbirds, in particular.
Several species were recorded for the first time including Baillon’s CrakesAustralian Shelducks (and 13 offspring) and a Swamp Harrier on Jillamatong, Striated Thornbills on several properties,  Rufous Fantail on Clarevale, and a pair of Eastern Whipbirds on Durham Hall, the latter two species usually being found in wet forests.  Many of the species that migrate north for the winter had returned including White-winged Triller, Dusky Woodswallow, Dollarbird, Australian Reed-Warbler and Rufous Songlark.  Perhaps the dry conditions accounted for the absence of any cuckoos or Sacred Kingfishers which returned to Canberra several weeks ago.

One particularly interesting bird found in the remnant on Durham Hall was a “blue” rosella which showed no crimson; in place of the crimson was pale yellow.  It was with a normal Crimson Rosella and from the attention they were showing in a tree hollow, it seemed that they were a pair intent on breeding.  At lunch, one property owner produced a photo of a “blue” rosella taken in his garden in August 2017  and I have had a report of one on Mt Sunset this year.  Another proeprty owner can recall seeing a “blue” rosella in the area in 1998.  It is possible for rosellas to live for more than 19 years but it is more likely that they have bred with normal Crimson Rosellas and produced several more blue birds. The fact that the Durham Hall bird was more yellow than the bird in the photo supports this theory.  Fellow members of COG have suggested the following explanation:

  • A bird may carry the mutated (recessive) gene but not show it.
  • In this case the “mutant” gene exists at low levels in the population. So most birds do not show or carry the “mutant” gene.
  • The ‘blue’ Rosella must have received the mutant gene from both parents.
  • Where 2 normal parents are both carrying the recessive gene: on average, all other things being equal, 25% of their offspring will show the ‘blue’ character, other 75% normal.
  • Where there is 1 blue rosella parent and the other normal parent carrying the recessive gene: on average, all other things being equal, 50% of their offspring will show the ‘blue’ character, other half normal.
  • Where there is 1 blue rosella and the other normal parent is not carrying the recessive gene, they will only produce normal looking offspring, although all of the offspring will carry the mutant and the normal gene.
  • Where there are 2 blue rosella parents: all of any offspring will show the ‘blue’ character.
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