Hi Phil,
Seems I ruffled your feathers with this speculation!
To clarify the email:
In Vic MMC's breed between Aug and Nov.
Immature (= sub-adult) All plumages that follow first moult until full
breeding capacity and/or plumage is reached. Birds are usually independent of
adults.
Generally speaking immature female birds can be aged by their eye colour,
general plumage colour and overall build. Females do not reach full breeding
plumage for up to four years. For instance the brick red eye colour is not
complete until about four years of age; although the colour change commences at
about two years. The body plumage colour is duller in younger birds and the
body shape is often slender, giving the overall appearance of a bird with a
thin body and 'boof' head.
Male birds can be similarly aged by eye colour, body shape and crest shape
and colour. Generally speaking they do not reach full breeding plumage until
two years old. The crest feathers of males tend to have more curl than females
and the curl increases with age, often exceeding 90 degrees. The frontal band
of pink above the cere widens with maturity. Colour of frontal band also
changes from pale dull pink to bright deep pink in adults.
My travelling mate conducts training for Vic. and S.A. wildlife agencies with
regards to Major Mitchell ageing and sexing for the purpose of conducting
aviculture inspections to prevent illegal trafficking of wildlife. He knows
his stuff.
I trust this helps you.
Regards,
Scott Falconer.
Philip Veerman <> wrote:
Re this: "My travelling partner has studied MMC's for several decades
in the area and could only identify half a dozen immature birds, which sadly
seems to back the theory that the population is ageing and on the decline."
Is that so? What time of year do they breed there? Would it not be the case
that at this time of year, most young birds are no longer dependant. On that
basis at this time of year there would be expected to be few Dependant Young,
if that is what is meant by immature birds? (How else do you tell them apart?)
Philip
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