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 
  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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