I heard the same thing about Wyandottes as well as Marans or Rhode Islands, yet others report they had nice ones. I'm guessing it all depends on the breeds put together in a flock, depends on temperament of each individual bird, environment conditions can affect how birds get along in a flock, adding new birds can also change mood dynamics in a flock. & then some chicks can hatch out of an egg raring to run over other hatchmates on day one while other new chicks behave.
Although some breeds are reported to be more aggressive while some breeds are reported gentle, I personally believe alike breeds should be kept with their own kind. We have an all-Silkie flock now & they just seem to "understand" each other much better than mixing them w/ other breeds w/ aggressive reputations ~ although we have had Silkies mixed w/standard breeds before w/ peaceful results but we also had some bullying results too.
One just never knows how birds react, what set of circumstances shapes their temperaments. As owners we make the choices of breeds we think will work best for us.
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