[obol] Re: Juvenile bald eagle?
- From: Jeff Gilligan <jeffgilligan10@xxxxxxxxx>
- To: llsdirons@xxxxxxx
- Date: Tue, 8 Jul 2014 09:41:52 -0700
True - its an immature.
On Jul 8, 2014, at 1:50 AM, David Irons <llsdirons@xxxxxxx> wrote:
> David,
>
> While this Bald Eagle isn't an adult, it also isn't a juvenile. Generally
> speaking, birds are considered juveniles only so long as they display the
> first complete feather set that they grow after hatching. Once a bird starts
> the process of replacing that set of feathers, it is probably most accurate
> to no longer refer to it as a juvenile. This Bald Eagle is clearly a
> second-year bird–presumably hatched in 2013. Note the amount of white across
> the lower breast and belly and also the amount white on the underside of the
> wings. Hatch-year/juvenile/first-cycle Bald Eagles are mostly dark on the
> underparts with white mottling and lack broad areas of white on the
> underparts. They also show less white on the underwings than this bird. Also,
> note that the bird is molting flight feathers. The innermost primaries on
> both wings are just growing in. If this were a juvenile (hatched this year),
> it would not be replacing flight feathers in July. It also appears to be in
> the process of replacing the outermost tail feathers. Below I've cut and
> pasted the description of the first prebasic molt of Bald Eagles in their
> second calendar year of life. This account is in the Birds of North America
> Online species account for Bald Eagle. I think you'll find that it quite
> accurately describes your bird and where it is in its molt cycle.
>
> Basic I Plumage (from Birds of North America Online)
>
> Prebasic I molt incomplete, with some contour and flight-feathers (most
> notably some Juvenal secondaries) retained; initiated in spring of second
> calendar year with head and neck; body- and flight-feather molt later, and
> finally tail in late Jul–early Aug (Palmer et al. 1988).
> Basic I plumage similar to Juvenal plumage except crown noticeably paler,
> mantle usually with triangular whitish patch, upperwing-coverts with white
> mottling, rectrices paler, and trailing edge of wing uneven. Crown tan
> contrasting sharply with blackish-brown ear-coverts; breast 70–100% brownish
> olive with variable white mottling, but always darker than belly; belly and
> remaining underparts extremely variable, ranging from dark brown to nearly
> pure white; most individuals with inverted triangular patch of white mottling
> on the mantle; median and greater upperwing-coverts brownish olive and
> variably mottled white; and rectrices somewhat paler than in Juvenal plumage
> but still with dark terminal band. Primaries, secondaries, and rectrices
> decrease in length with age, thus retention of some longer, more pointed
> Juvenal secondaries produces an uneven trailing edge on the wing,
> particularly noticeable in flight. Outer Basic I rectrices also more rounded
> (less blunt-ended) than in Juvenal plumage.
>
>
> Bald Eagles in post-juvenile plumages might best be described as immatures or
> sub-adults depending on how closely their plumage resembles that of a
> definitive adult, but after they start molting the feather set they should
> not be called juveniles.
>
>
>
>
>
> Dave Irons
> Portland, OR
>
>
>
> Subject: [obol] Re: Juvenile bald eagle?
> From: jeffgilligan10@xxxxxxxxx
> Date: Mon, 7 Jul 2014 08:07:10 -0700
> CC: obol@xxxxxxxxxxxxx
> To: dkoskamp@xxxxxxxxx
>
>
> On Jul 7, 2014, at 8:02 AM, David Koskamp <dkoskamp@xxxxxxxxx> wrote:
>
> I saw this bird on July 5 flying over a ridge of Silver Star Mountain in SW
> Washington. Is it a juvenile bald eagle?
>
> http://fettster.smugmug.com/photos/i-v4kjhwx/0/O/i-v4kjhwx.jpg
> http://fettster.smugmug.com/photos/i-Xb6ggTX/0/O/i-Xb6ggTX.jpg
>
> Thanks!
>
> -David
>
>
>
> Yes.
>
>
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