Is that chaga?
I ask because I've occasionally seen that on birch trees and I thought that chaga was meant to be rare and limited to northern, colder, climes.
I can't say I've seen 'lots' of it, but more than I supposed I was expected to see. And I live in the south.
It could be, of course, but I'm thinking it is more likely to be a tree burl - a 'scab' (for want of a better term). Presumably it's some kind of growth or fungi, but I've seen too much of it for it to be the rare chaga.
Sorry, but I think they're just a couple of burls. Break a small bit off - if it comes off and is orangey inside then you've got chaga. But I'm pretty much convinced they're just burls.
I don't know, though, so more than happy to be proved wrong and find out precisely what it is.