BIRD FEEDER VISITOR

We watch the birds and the birds watch us.  They watch to see when we refill the feeder, then they mob it.  We have our standard visitors, and occasionally we'll have some fly bys who grab a bite and run to better feeding grounds.  Today we have had a fly by one who was acting like they wanted to stay.  We have not been able to identify this new visitor.  Here are some pics.  I hope someone can tell us who our visitor is.

The pics were taken through a double pane glass.  He/she is about the size of a cardinal.  She is a very curious bird and doesn't seem to be afraid of us in the window.  She is not shy
The brownish gray top not she fluffs like the phoebes do. 

In 50 years of bird watching all over the country, my hunny and I have never seen this bird.  Can anyone tell us where we should look?  We've looked under fly catchers and orioles and have found none with the totally gray throat.

Possible Identification:

I went to look up several similar types of birds.  I think this is a Western Kingbird.  The following is a range map:

http://sdakotabirds.com/species/maps/western_kingbird_map.htm

You can go to this website to see pictures of them:

http://birdsbybaranoff.com/westernkingbird.htm

If this is my bird, he/she is a little off course.  Another article said that spring sitings where they shouldn't be are rare, but they can be sited in off areas in the fall.  Another internet article said they had been moving their territories eastward for the last 100 years.