[CT Birds] Pre-adult Bird age and plumage stages

Mntncougar at aol.com Mntncougar at aol.com
Mon Jul 30 08:26:16 EDT 2012

There is a very interesting (to me) discussion on the Michigan bird list  
regarding the terminology used to describe birds which are NOT adults. In 
fact  it addresses some things I have always wondered about when I've read and 
heard  discussions regarding the topic.
This is the original question asked:
What's the difference when one uses the term 'juvenile'  or 'immature' or 
is it just a matter of semantic preference?
But as you will see, the discussion broadened out a  bit. Here is the first 
information given as a  response. It is taken from NYC Birds Wiki:  (Here's 
the actual link in case  it's messed up - 
http://www.nycbirds.com/wiki/index.php?title=ID_Glossary    )
"See the Wikipedia page for _bird anatomy_ 
(http://en.wikipedia.org/wiki/Bird_anatomy)   including feather groups.
Plumages and Molts 
Bird molts occur at different times of the year in response to feather 
wear,  and to change plumages. The terminology for plumages varies. In these  
pages I've used a very simple definition of plumages: 
    *   Juvenile - the first plumage of a young bird with a covering of 
contour  feathers (as opposed to down etc) 
    *   Immature - any that is not in full adult plumage. Technically 
"immature"  also includes "juvenile" but in the descriptions I use it in the 
sense of any  immature plumage distinct from juvenile plumage. 
    *   Adult non-breeding - any adult plumage distinct from the breeding  
    *   Adult breeding - adult in breeding plumage
Birds exhibiting fairly straightforward molt sequences molt out their  
feathers twice a year - once prior to attaining breeding plumage and once to  
replace the worn breeding plumage. Not all feather groups are replaced in all  
molts, and the sequence can depend on age. Molts in migratory birds may 
occur  before, after or during migration so potentially the plumages 
encountered can be  quite complex. Similarly wear and bleaching (most common in gulls) 
can become a  significant factor. 
An excellent discussion of molt and aging terminology can be found at the 
_Ontario Field  Ornithologists_ (http://www.ofo.ca/plumages.htm)  site. 
Notably they define: 
    *   Juvenile (as above) 
    *   Immature - any non-adult plumage including juvenile 
    *   Subadult - largely synonymous with immature 
    *   Adult non-breeding 
    *   Adult breeding 
    *   First winter, first summer, second winter, second summer etc - 
deserves an  explanation. For birds that molt twice a year and have extended 
immature  plumages it is usually possible to observe distinct plumages at each 
stage.  First winter is the first non-breeding immature plumage (the winter  
following the summer the bird was born). First summer is not the  summer 
the bird was born, but the summer following the year the bird  was born. And 
so on and so forth. Large gulls and eagles in particular display  a large 
array of immature plumages 
(up to fourth winter in the case of some large gulls). 
    *   First year, second year etc - for birds that molt once a year this 
plumage  extends from late summer to the following summer. First year is the 
 late summer that the bird was born in through the summer of the following  
    *   Eclipse - this is really the non-breeding plumage of ducks, 
acquired in  late summer or early fall. It is most obvious in males which acquire a 
 female-like plumage. Some ducks adopt eclipse plumage only for a short 
time,  while some take quite a while to come out of it - it's not unusual to 
see  Northern Shovelers with distinct traces of eclipse plumage in early 
winter. By  late winter ducks are usually in their full breeding plumage with no 
trace of  eclipse. 
    *   First calendar year - this works on the Jan 1st to Dec 31st cycle. 
The  first year is the year the bird is born in. This is less frequently 
used, but  has some role in disambiguating the meaning of "first summer" in 
certain  cases. 
It's the definition of first summer that usually gives most people the  
wrong impression (i.e. a lot of people think it's the juvenile plumage and it 
is  not) 
Note that there is an excellent and thorough definition of plumages and 
molts  following the Humprey and Parkes system that is overkill for most 
amateur  discussions of bird plumages. Here non-breeding plumage is "basic", 
breeding  plumage is "alternate", juvenile plumage is "juvenal", the final 
unchanging  plumages for basic and alternate are called "definitive", so 
"definitive basic"  would necessarily be an adult non-breeding plumage. The plumage 
sequence is  juvenal - basic - alternate - basic - alternate - etc ... Molts 
are referred to  in terms of the plumage they become e.g. "first prebasic" 
before first  basic, "definitive prealternate" before definitive alternate." 
However there was a second post that addressed the question somewhat  
differently and answered (or at least shed some light on) my own questions on  
the subject. I Believe this was actually taken from "The Auk":  (The link:  
http://elibrary.unm.edu/sora/Auk/v082n01/p0105-p0105.pdf   ) 
"The use of the terms "juvenal" and "juvenile."--Uncertainty and  confusion
exist as to the use of these terms in regard to birds and their  plumages. 
In larger
dictionaries both words are given synonymous meanings of  young or youthful 
and a youth (noun); but "juvenal" is now very  rare or obsolete in its 
general sense and has become almost  exclusively a technical term 
designating a
specific plumage stage in birds.  The term "juvenal plumage," meaning the 
first covering
of true feathers  following the neossoptile or downy stage, seems to have 
with  Jonathan Dwight (see Ann. New York Acad. Sci., 13: 99, 106, 1900).  
later explained his selection of "juvenal," rather than the more  familiar 
because the latter word "has a less exact meaning" (Auk,  19: 251, 1902), 
being commonly
used to indicate immaturity in general.  Dwight's term "juvenal plumage" has
been adopted almost universally by  American ornithologists, including 
those who,
like Humphrey and Parkes (Auk,  76: 15, 1959), favor abandoning Dwight's 
nomenclature in other  respects. In Great Britain "juvenile plumage" is 
employed in
the same sense  (H. F. Witherby et al., The handbook of British birds, vol. 
1, p.  xxiii;
London, Witherby, 1941.). However much current ornithological  literature, 
both in
the United States and abroad, uses "juvenile" with the  general meaning of 
that is, for any stage prior to the definitive  adult (J. Van Tyne and A. 
J. Berger,
Fundamentals of ornithology, p. 572; New  York, Wiley and Sons, 1959. M. E.
Rawles in A. J. Marshall et al., Biology  and comparative physiology of 
birds, vol. 1,
New York and London, Academic  Press, 1960; see pp. 198-9.). Sometimes--and 
is particularly true of  specimen labels--"juvenile" or "juv." indicates 
only the younger
stages of  immaturity, but without restriction to the first generation of  
feathers. Some American ornithologists insist, nevertheless, on a  fine 
which seems to me both unnecessary and productive of  confusion; they use 
as an adjective for the first feathered  plumage, but adopt "a juvenile" as 
the noun
for a bird in juvenal dress.  Others suggest that "juvenal-plumaged bird" 
be employed
to avoid ambiguity.  It seems to me shorter and simpler (and equally 
to say "a  juvenal" for an individual in juvenal plumage. The only objection
advanced is  that "juvenal" is adjeciival in form and origin; but this 
equally to  "juvenile." As a matter of English usage and grammar both words 
convertible into nouns. Such locutions as "an immature" or "a downy" are  
In the interest of precision and brevity, I recommend  that those who employ
"juvenal" to indicate the plumage should also use the  term "a juvenal" for 
a bird in
that plumage. Because of its ambiguity,  "juvenile" should be avoided in 
studies of plumage or where a  specific age stage is intended.*--E. EIS•N•
^NN, American
Museum of Natural  History, New York 24, New York.
* Without reference to the finer distinctions  relating to noun vs. 
adjectival use, the
editor is one who considers  "juvenal" a definite statement of stage (i.e., 
relating to a
bird in first  plumage) and "juvenile" a general indication of comparative 
youthfulness. These  are the meanings that these terms (hopefully) carry in 
"The Auk."." 
Anyone have a quibble or anything to add? 
Don Morgan
mntncougar at aol.com
_http://birdingnect.blogspot.com/_ (http://birdingnect.blogspot.com/) 

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