I found a Yellow-green Vireo outside of Everglades National Park on June 12th.  June is a good month to look for them, so I looked for more.  I went to Upper Key Largo after my, where I have found them in the past; not only did I find one, but three!  Each bird was about 2 miles apart; that is a pretty insane find!  These are birds that are normally found south of the border.  South Texas will get a few each summer, and a few have wintered in California!  Each bird that I found was singing, making it easier to locate them.  They are not an easy bird to photograph, so it took some time to get record shots.  I went back to Key Largo two weeks after I sighted the three birds but didn’t hear or see any.  I went back three weeks later and found another singing bird.  This other bird was about three miles from the closest other birds that I had found.  These birds may have attempted to nest.  We did have a bird a few years ago that nested with a Black-whiskered Vireo; they had three babies.  Unfortunately, a Blue Jay seemed to dump them out of the nest.  The birds did not renest after that.  I still think that some of these Key Largo bird may have nested.  I will have to check each spring and summer to see if this could have happened.
I have included photos of all five birds that I have found.