That is a theory, the Blues are really Mountain Bluebirds. First of all, they don't have a ring of black around their eyes. they are also not very plump.
@The Boomerang
The Blues have a yellow beak and orange patches. So if they where a bluebird it would be the Eastern Bluebird. Also, I frankly think they look more like the Blue Finch than a Mountain Bluebird due to the yellow beak I mentioned earlier.Â
Most likely a mix of an Eastern Bluebird and a Blue Finch's traits. ((I go for Eastern Bluebirds because "yellow bills" are common in cartoon birds"))
Yeah, the Blues don't have orange chest, like the reference from bomb's mix from greater antillean bullfinch and crested myna traits.
I don't remember mentioning an orange crest, just orange 'patch', I think the movie showed that they're hybrids though.