[texbirds] Forster’s Tern with misleading impression of having a dark carpal bar

  • From: MBB22222@xxxxxxx
  • To: texbirds@xxxxxxxxxxxxx
  • Date: Fri, 25 Jan 2013 13:11:29 -0500 (EST)

After my last post I got some tern’s photos to check and all were Forster’
s  none were Commons. Several days ago I already posted photos of FOTEs 
molting  head feathers into alternate plumage (so black nape is not longer a 
field mark  separating those from COTEs). Here is an example of the 
‘illusion’ 
of a dark  carpal bar one might have when watching some FOTEs depending on 
light conditions  and view angle. Although COTE is possible to be found now 
it is an event rather  not likely to happen on Texas shore at this time of 
the year.  I can  understand people having trouble to separate these species 
as not too many  people spend a lot of time watching terns but I cannot 
understand why eBirds is  accepting winter (like from January) COTE records 
without verification. I have a  feeling that most winter COTE records from 
Texas 
are wrong.
 
Here is an example, a composite photo of one FOTE, an individual showing a  
dark carpal bar at one moment and does not just a moment later. Some tern  
feathers are build differently than non-tern feathers. When fresh those are  
covered by an ephemeral, powdery "bloom" of tiny white barbules on their 
upper  surface. This ‘bloom’ wears away and feathers became dark with age. 
Also,  dependent of lighting condition and view angle the same feather can 
look totally  different - like in two posted photos taken only less than second 
apart. But  during one second fast flying bird can move quite a lot and 
move from one  lighting condition to different one - even slight difference 
will show in photo;  see background difference. Hint: when I photograph birds I 
do that in manual  mode (almost exclusively and this works great for me) - 
this not only helps to  not ‘blow’ highlights but allows to compare photos 
later, specially when looking  for false contrast.  Many FOTEs completed 
their prebasic molt a couple of  months ago so some feathers are showing aging 
effect as well.
 
Here is an example of FOTE showing dark carpal bar (also remember that when 
 watching from the distance fast flying bird the hood can appear looking 
solid  black at some angles and photo might be needed to help confirm a true  
pattern):
 
_http://www.pbase.com/image/148470059_ 
(http://www.pbase.com/image/148470059) 
 
And here already posted photos that are showing FOTE head patterns in  
January:
 
_http://www.pbase.com/mbb/image/148393042_ 
(http://www.pbase.com/mbb/image/148393042) 
 
Mark B Bartosik
Houston, Texas
_http://www.pbase.com/mbb/from_the_field_ (h
ttp://www.pbase.com/mbb/from_the_field)
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