I'll put in my 2 cents, as I've been thinking about this a little.

To me, it did look like Kevin was responding to Darlene and offhandedly
contradicting her post. On the other hand, he could have just been reporting
what he saw and knew based on long experience to be true. Taking all the
personal stuff out of it, which I hope everyone will, a couple of points can
be made:

First, anywhere in the country, refuge volunteers often are not
knowledgeable sources of bird information, though our first instinct is to
think they would be. They're volunteers - they love the place and they
provide an incredibly valuable service to all of us who want to go and
visit, but they may or may not have any particular expertise. And if they
do, it may be in a field totally unrelated to birding - like geology,
wildflowers, mammals, butterflies, fish, etc. Sometimes you'll get lucky and
find one that really knows birds, but you're way more likely to find that by
walking around and looking for the people with binos and scopes, looking up
into the trees or out onto the flats :)

However, I have also found that if asked, refuge volunteers will give you an
answer, whether or not it's right. I don't blame them for that, they really
want to be helpful, and they may not realize just how important it may be to
one of us that it is really right. Often I find they're repeating
information they've heard from other visitors or experts, without really
being certain of the specific bird in question. Aside from that, even
knowledgeable experienced bird guides make mistakes, so of course they can
too. So my personal rule is that I either have to be able to identify it
myself, or stand around with a bunch of other birders until we reach a
consensus and I can see for myself what the field marks are that they're
using.

I also wanted to point out that another quick way to verify whether an
identification is reasonable for Nisqually (or Marymoor Park, Montlake Fill,
or other places that are censused frequently) is to check the current weekly
Tweeters reports for that location. If that group sees no terns (or
conversely, does see terns) during that time of year you can use that
information to verify or refute your tentative sighting.

Lastly, as just a middling birder myself, and struggling with gulls and
terns of all varieties, at least I've learned a bit of information I didn't
know before - lack of terns over winter months in places I inhabit. That
should narrow things down a bit! Assuming I venture out in the cold and rain
enough to spend hours puzzling over gulls ;) - Teresa