Hi Tweets:

Betty Boyd writes:

>I have a question regarding a phrae being used lately. Whatis meant be
>alternate] plumage'?
>
>I know what winter plumage is and eclipse, coming ot of eclipse,
>immature , and breeding plumage. But what is alternate plumage?

Most of the above terms have implicit assumptions about the bird which
sometimes contradict reality.

For example, some 'breeding-plumaged' birds don't breed. Why? because though
they're wearing 'adult' feathering, they're still adolescent birds several
years away from a level of sexual maturity which would allow them to mate;
conversely, some male birds in 'non-breeding' plumage happily help feed the
brood of young they've sired.

In another instance, you may have 'fall-' or 'winter'-plumaged shorebirds
traipsing around your local tidal flats in June and July; or
'summer'-plumaged birds in late October. Or some 'immature'-plumaged birds
which are anything but immature, and so on. The field guides are a total
mishmash of incorrectly-applied ageing terms, showing juvenile-plumaged
birds as 'winter' or 'non-breeding', just as one example, even though most
birds molt out of juvenile plumage quite quickly. Or, as another, birds
which are Basic 2 (2nd Winter) plumage being portrayed as the definitive
subadult bird.

So, a system of terminology which describes the plumage-state alone without
introducing such anti-sense baggage and confusion is of great use in trying
to establish just where a bird actually is in its molt-sequence. Hence the
Humphrey-Parkes terminology.

As Chris Thompson points out, for a complete understanding of it and for a
completely technical application of it, one needs to read the complete
article; *however*, it is possible to use without falling out of
ornithological grace a much-generalised version of this system for many
types of birds such as shorebirds and gulls, as most popular journals now
do. Specialists may sniff superciliously at the amateur's simplifying
adaptations, but that's something specialists usually do anyway when
amateurs co-opt and apply hitherto arcane stuff---it's usually more to do
with turf. I invite them to slug it out in public with the editors of those
journals such as Birding and Birders' World.

Keeping in mind that 'Basic' refers to non-display plumages, and 'Alternate'
to the display plumages---roughly corresponding to 'nonbreeding/fall/winter'
and 'breeding/spring/summer', respectively---here's the generalised sequence:

Down--> Juvenile--> pre-Basic 1 molt--> Basic 1 --> pre-Alternate 1 molt-->
Alternate 1--> pre-Basic 2 molt--> Basic 2--> (as many more years as it
takes to reach Definitive (that is, nonchanging, or 'Adult')-- display and
non-display plumages) pre-Definitive Basic molt--> Definitive Basic-->
pre-Definitive Alternate
molt--> Definitive Alternate, then back and forth between Def Alt and Def
Basic for the rest of its life.

Very useful for ageing, therefore identifying, birds.

Michael Price
Vancouver BC Canada
mprice at mindlink.net