Fw: Faulconbridge Gang-gang Cockatoos

[Andrew Taylor <>]

There seems to be little evidence of biased sex ratios in birds so the
observer is likely mistaken when they say their local Gang-gangs usually
have 1 female & 1 male offspring.  Two is apparently the normal Gang-gang
clutch size but only 50% of these clutches should be male-female (and
25% male-male and 25% female-female) unless something quite remarkable
is happening.

Sex-dependant survival rates are known, e.g:
http://galliform.psy.mq.edu.au/Megapode_project/Reprints/goeth&booth.pdf
but given the number of birds involved chance seems by far the most
plausible explanation.

Andrew