I recently read an article about a group of Juncos, who, instead of migrating, stayed on a college campus. The Juncos that stayed behind became much more family oriented thatn the ones who migrated to the mountains. They took more care and stuck around while raising babies. They also canged in color a little bit to batter match their habitat. I would link the article, but I don't remember where it was.
I'm really not sure why I was suprised by it now that you explain it that waty with the dialects. I have noticed those in wild birds, some of the mockingbirds and Hawks sound slightly different in South Carolina as compared to here (any normal year I would got to my relatve's house in SOuth Carolina for at least a month). Something that I have found, is that Kiwi has his own "dialect" from living with me, because he had this special contact call that I taught him instead of a normal one. Now that Blizzard is here, he adopted her contact call and only uses our special one sometimes.
he's a riot!
His "blowing sound" reminds me of the angry cat noise my son makes when I wake him up in the morning!