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RE: bcintbird-pics golden moment Rick Howie Sat Feb 04 09:08:12 2012

10-4 Barry. Now with this case firmly nailed shut, I think it is a good
thing us bino toters don't have to routinely separate too great a complex of
ages amongst passerines. Juvenile + adult can be enough. We can leave the
rest to you in the "skullers and ringers" group. Then of course  there are
the larophiles who get pretty caught up in feather trivia so perhaps the
skullers and gullers share kindred spirits. Hmmm, but we can't forget about
those who search for the elusive Hoary, so we have skullers, gullers and
pollers focussing on plumage minutiae for sure. Oh,  and the shorebird crowd
- we can't ignore  the mudders .

 

I've long had an interest in obtaining a full suite of Bald eagle plumage
photos along with the other raptors but have not pursued them recently. Lots
of challenges as we go lensing around.

 

Rick Howie  

 

 

From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of M Lancaster
Sent: February-04-12 7:56 AM
To: [EMAIL PROTECTED]
Subject: Re: bcintbird-pics golden moment

 

Rick et al,

 

>From Forsman:

Fourth plumage type (from fourth calendar year autumn)  - most birds have at
least one juvenile secondary feather (central) and one outer juvenile
feather. He also says that the tail is rather juvenile like, whitish with
dark terminal band.  In flight from below, the birds still show large white
wing patches, but the primary patch is now split from the secondary patch by
three or four largely adult type primaries - yes, which may still have
partly white bases. Tail is still rather juvenile like. Certainly the white
patches are separated but they are not large, indeed the primary 'patch' is
almost non-existent - 'spikes' on 'our bird'.

 

Fifth plumage type (from 5th calendar year autumn). The black and white
rectrices frequently show bold dark bars just inside the dark terminal band;
which I can see.  Underwings show less white than in previous plumages, now
mainly as white spikes confined to the base of some inner primaries but with
more white to the bases of the secondaries  - yes? It also seems to me that
the greater underwing coverts are moulting? If so, this would show more
white than otherwise.

 

Sixth plumage type (from 6th calendar year autumn) Underwing still shows
irregularly scattered white 'spikes' basally on some primaries and
secondaries -'our' bird has a distinct white patch on the secondaries.
However, he does state that the fifth and sixth plumage types are usually
not possible to separate in the field - unless you have in the field one
Alistair Fraser with camera??

 

It seems to me that apart from the adult like secondary patch, there are
also two ages of primaries with an inner patch being fresher. That indicates
that these and the secondaries have been moulted at least twice, that would
make it a minimum of three years old (i.e at least fourth plumage type). 

 

Adult plumage( thus 7th plumage type - my words) is attained from the 7th
calendar year autumn, therefore the bird will be 6 years old. 

 

He does state that it is possible, even likely, that southern and non
migratory populations may differ as regards moult sequences BUT, the birds
seen in Canada are of course from migrating populations.

 

Barry

 

M B Lancaster,
Currently - Tenerife, Islas Canarias

----- Original Message ----- 

From: Rick Howie <mailto:[EMAIL PROTECTED]>  

To: [EMAIL PROTECTED] 

Sent: Saturday, February 04, 2012 8:07 AM

Subject: RE: bcintbird-pics golden moment

 

So Barry: you are suggesting that this bird is at least 1 year older than my
first assumption of it being a sub-adult lll bird and possibly a lV.  I must
confess as to not knowing what to make of the white bases in the
secondaries. It may be that moulting coverts are exposing the bases more. I
agree that the remiges appear to have molted at least once and are adult
-like.. The wings are developing more of a two-toned look and the tail seems
close to adult type.  I don't see any retained juvenile secondaries which
project beyond the trailing edge of the wing which Liguori says is typical
of basic ll birds, so I am back to the older rather than younger category.
In Liguori's book "Hawks from Every Angle," he indicates that Basic lll
birds would have wide patches near the margins of the tail which this bird
clearly does not. I should have read that book earlier. Clark supports the
notion that the tail shows it to be at least a sub-adult or basic lV bird
with no white in the fanned tail. This is a very fortunate shot as I think
the rectrices are fanned enough that some white markings would show. These
lateral patches are generally gone by the time Basic lV is reached, but some
secondaries could retain some white at the base. So as a Basic lV it would
be in its 5th year of life and just into the 6th calendar year,  so I can
support your thoughts on hatch year.

 

Clark recognizes 6 plumages - juvenal, Basic 1-4 , adult. He suggests adult
plumage is reached as a 5 year old in 6th year of life. The BNA account
recognizes 5 plumages - juvenal, basic 1-3, adult -  with the adult plumage
being reached at age 4 in 5th year of life. So take your pick in terms of
how many plumage classes  - range 5-7. 

 

My conclusion is that Alistair's bird is 1 year older than it was this time
last year. And that conclusion is golden.

 

Rick Howie

 

From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of M Lancaster
Sent: February-03-12 10:48 PM
To: [EMAIL PROTECTED]
Subject: Re: bcintbird-pics golden moment

 

Hi Rick et al,

Forsman (1999) The Raptors of Europe and the Middle East, distinguishes 7
plumage types which includes adult. Juvenile (first CALENDAR year autumn/2cy
spring) to adult which is attained in the 7cy autumn and later.

 

This bird shows no signs of retained juvenile secondaries or primaries (to
my eyes) which would make it a 5cy/6cyspring and therefore hatched in 2007.
This assumes that Nearctic Golden Eagles follow the same timescale as
Western Palearctic and according to Liguori, (thanks Rick) this bird would
be classed as a sub-adult which he says is 4-5years old.

 

At least, that is how I assess the photo and the information.

 

Year of life is of course 1 yr less than calendar year AFTER first calendar
year. One cannot be one year of age until you achieve 12mths which of course
takes place in the second calendar year. 

 

 

Barry

M B Lancaster,
Currently - Tenerife, Islas Canarias

----- Original Message ----- 

From: Rick Howie <mailto:[EMAIL PROTECTED]>  

To: [EMAIL PROTECTED] 

Sent: Friday, February 03, 2012 5:19 PM

Subject: RE: bcintbird-pics golden moment

 

HI Alistair: it is always nice to see pictures of Golden Eagles and I note
your perception at separating it from the various plumages of Bald Eagles
which often confuse people. The additional pictures on your website were
very nice and present some additional insight into this bird and its age.
Which brings me to the subject of jargon.

 

I noted there that you referred to it as a juvenile. The normal use of the
term "juvenile" is for a raptor in its first year of life after being born.
Based on the lack of white in the primaries (your bird has white at the base
of the secondaries) and in the base of tail in your bird plus the mottled
body visible in one of your web pictures, I would suggest that it is well on
its way towards adult plumage.  Typically, the term used would be
"sub-adult" with a numeral assigned (where possible) to suggest an age.  In
this bird, I think it could be a sub-adult lll . This would be age 3  so the
bird would be in its 4th  year of life. I don't think it has reached class
lV.   Full adult plumage is normally attained at age 5 when the bird is in
its 6th year of life. 

 

I must confess that I don't have enough experience to sort out the
variations that can occur in the different age classes so I can't be totally
sure of placement in class lll or lV.   I think sub-adult l or ll birds
would have more white tail feathers retained after the partial molt out of
the juvenile plumage.

 

Categorization of Bald Eagles is done in the same way. Juvenile is used for
the bird in its first year of life and then the various sub-adult terms are
used to refer to the remaining plumages before the birds reach adult plumage
at age 5 or older.

 

If anyone has any further opinions on this bird, it would be great to hear
them. 

Cheers

 

Rick Howie  

Kamloops

 

From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Alistair B Fraser
Sent: February-03-12 8:01 AM
To: BCs Interesting Bird Pictures
Subject: bcintbird-pics golden moment

 

It is not that this is a superb picture, but as few shots of this locally
uncommon bird have been posted to the list, folks may allow it to sneak
through. 

 

Also discussed at,

 

http://blog.kootenay-lake.ca/?p=4089

 

Alistair

 

Alistair Fraser

Kootenay Lake

 



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