[EBB Sightings] Scaups: oiled or not oiled?

All;
 
I propose we open a discussion on identifying lightly oiled scaups during
oiled bird surveys. 
 
I suspect that many of use are using different criteria for identifying
them. 

My own criteria have changed over the last 3 weeks. This means the data I
have sent OWCN is not consistent. In fact, I revised and resent some of my
Alameda data to improve consistency.  
 
The eye-opener was going to Lake Merritt last week and spending an hour
studying a lot of male scaups from just a few feet away at the islands. I
saw a surprising amount of unexpected plumage variation in both greater and
lesser male scaups and was able to verify I was looking at feather color,
not oil.  
 
For example, I saw males with virtually all-brown flanks. Others had brown
flanks with unevenly spaced vertical gray lines.  Scaups with mostly brown
flanks, and especially those with vertical gray lines, are not very common.
I have been reporting birds with this plumage as lightly oiled, thinking the
brown is oil and the vertical lines are preening lines. That was probably a
mistake.
 
I saw other birds, usually male lesser scaups, with very dark irregular
patches on the flanks. This is also an uncommon plumage, and I have logged
birds with this type of plumage as oiled. Some were oiled. Some probably
weren't. 
 
I am now more conservative about identifying lightly-oiled scaups. Here are
the criteria I am using:
 
1. The bird is out of the water, regardless of plumage appearance. I do not
log scaups dabbling in a few inches of water near rocks or beaches. 
 
2. The bird is obviously waterlogged or ill, regardless of plumage
appearance. Frequently, the bird appears unkempt and has some feathers
askew. 
 
3. The bird has jet black irregular patches or streaks on the flanks, breast
or elsewhere. Since this is an uncommon plumage variation in males, I
believe we should log it because some of the time it will be oil. On
females, irregular black patches should be oil in all cases. 
 
4. A preening bird rolls on its side and the breast shows brown patches
(males), black patches, or black streaks. 
 
The last two criteria are much easier to see on males than females. If you
have any tricks for spotting oiled females, please forward. The only
female-specific criterion I can think of is if the white face patches are
blackened. 
 
Excessive preening is frequently cited as something to look for. I have no
experience observing how often healthy scaups preen, and so have no way to
objectively identify excessive preening. Hence, I have not included it as a
criterion.  
 
What are your thoughts on these criteria? What would you add or subtract?
Are the criteria too restrictive or not restrictive enough?  There are some
very experienced birders on this listserv. Let's hear your thoughts. I
volunteer to watch the thread and roll-up the responses. 
 
Making sure the data we are forwarding is accurate and consistent is crucial
to accurately assessing the wildlife impact of the spill. 

Steve Hampton: Since you're one of the key users of this data, please let us
know your thoughts. Your suggestions are particularly important. 
 
Harv Wilson