What makes a bird “heritage”?

[RememberTheWay]

OH, now I mostly get it. I was wondering if these are all heritage breeds: https://www.rochesterhatchery.com/PoultryCategory/heritagebreeds
I was told that the Ameraucanas are EEs, so I'm not sure how that works.

The Ameraucana (spelled that way) are a heritage breed, breed true, and are recognized by APA. Easter Eggers also called Americana (spelled that way) are hybrids, do not breed true , and are not recognized. It's very confusing for people because they are both pronounced the same way. One is a purebred and the other is a mutt. Both lay colored eggs