Hello Birders.
Further to my comments on Russet-tailed/Bassian Thrushes.
I have revisited Julian Ford's paper. My comments require
minor adjustment, but the gist of the argument was correct. In fact, the
minimum difference in tail length was 7 mm (98 mm in a male heinei vs 105
mm in a female lunulata); however the breakdown of means were:
female heinei 92.2 mm n=7
male heinei 94.2 mm n=19
female lunulata 105.7 - 113.2 mm n=3, 10, 13, 13
male lunulata 111.3 - 115.8 mm n=8, 6, 21, 19
NB: lunulata has a range of means as SA, Tas., Vic. and NSW samples were
treated separately.
Anyway the difference, around 13-21 mm in females and 17-22 mm in males
would clearly be a detectable difference in the field, with the caveat that
not many of the lunulata sample were from the overlap zone in n. NSW and
none from se. Qld.
Incidentally, for the statistically inclined, Ford's paper has some neat
scattergrams of principal component analysis.
Reference: Ford, J. 1983. Speciation in the ground-thrush complex Zoothera
dauma in Australia. Emu 83: 141-151.
P.S. Lansley <>
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