[obol] Comments on the Newport Brown Booby
- From: Wayne Hoffman <whoffman@xxxxxxxx>
- To: obol <obol@xxxxxxxxxxxxx>
- Date: Fri, 31 Oct 2014 08:41:47 -0700
Hi -
I studied the booby at length yesterday afternoon, and took quite a few
photos. Based on my notes and photos, I have a few comments.
First, I compared its plumage to the criteria in Peter Pyle's
"Identification Guide to North American Birds Part II." Pyle has a drawing
of underparts pattern on Brown Boobies, and based on it, this bird would be
between 24 and 36 months old, or third cycle. Basically. the underparts,
below the dark chocolate upper breast are white with a light mottling of
brown. Behind the feet the lower belly is fully white. If the bird
survives, it would presumably achieve full adult plumage within the next
year.
Second, the bird has facial features indicating it is a female, although I
am not completely sure these are reliable on subadults. First is a dark
area extending a little out the bill from the eye. This is a female
character in adults. Secondly, the pale of the bill (more on color later)
extends way back onto the bare skin on the lower mandible. Again this is a
feature of adult females: this skin is dark on adult males.
My recollection of the accounts of Brown Boobies on the Pacific Coast north
of southern California is that most that have been sexed are females, so it
may be that females have a greater propensity to wander north. Females
average larger than males in these and other boobies.
Third: Soft Parts colors. This bird has yellow feet, but a duller yellow
than I have seen in adults in the tropics. The bill is pale, but in my
photos shows a distinctly pinkish tint. This is strongest in the middle.
The tip is fairly dark, and at the base the pink fades toward white.
Juvenile Brown Boobies have grayish bills and adults have yellow.
Lighting conditions yesterday afternoon were challenging, so I would really
like to see it again in better light. Hopefully it will stay with us a
while.
I will send photos to OBRC.
Wayne
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