I have to wonder... just how avian are the Hissho?

By in-game appearance, they are very... human looking. Now, don't get me wrong, I love their design, but I have to wonder... It's safe to say, at some point they lost their wings. They probably still have some kind of feathers (the old Endless Space art of them had feathers, not sure how canon it still is, design-wise). They have human looking hands which may or may not have talons. Body-wise, they have human-ish silhouettes, to the point where, looking at Tsuyu, I can clearly tell she's female, from a conventional human point of view. Now, looking at the female heroes, I can pretty confidently say... they have breasts. Here, as such, comes my question:

Are they more avian, or more like a mammalian with avian features? If they have breasts, do they have beaks? If yes, why have breasts, since it's pretty hard to breastfeed someone with a beak... Now don't get me wrong, an avian bipedal humanoid in fiction can range from the D&D Aarakockra, which are basically bipedal birds with arms, to Mass Effect's Turians, which are very birdy in physiology, though not immediately bird-shaped (crests and some kind of beaks, alien bird-looking chests, alien bird-looking feet), to DC Comics Hawkgirl, which is basically a winged human, and I really REALLY dig the Hissho design in ES2, being my second favourite race in the franchise, looks-wise (Vodyani come first, Cultists of the Eternal End come third), But I am just curious. A mammalian-avian-humanoid alien is very interesting as a concept to me and is the feel I get form them in their ES2 Incarnation.

Theorise or provide some lore to elucidate! I am really curious to see what you guys think:D

From what i've picked up in the game and stuff I remember it being said that while they are still somewhat avian, due to their genetic altering by the endless they've become alot more humanoid unlike the yuusho. Though I would say that they are still more or less avian since if i'm not mistaken their legs still show a more avian style of structure. That combined with the feather decorations they have which may be just put on the armor but sometimes do seem like they actually are part of the hissho themselves. Though most of their bodies is still hidden by their armor so we can only speculate

I may be very wrong here, but I think that in the story "The Flight of the Grey Owl," the two Hissho main characters glided using their wings. They didn't fly, mind you, but that alone should probably tell you that they still have at least somewhat hollow bones and light, agile bodies to allow for that

It's a bit hard to tell with the Hissho, but I think the most logical explanation is that for all intents and purposes they still retain most of their Avian characteristics: their hands may retain some wing features and I think it would make sense if their bones were lightweight, for example. Gliding instead of flying and general agility "in air" makes a lot of sense. In fact being lightweight and using lightweight weapons would just make them that much deadlier.

With that said, they could have some mammalian features like live birth, although I'm much more fond of the idea of actual.... well, eggs. I think it's just more interesting. The presence of beaks probably means that they don't suckle when young. Overall, I'd lean on the Avian side unless something explicitly mammalian (like live births and milk glands) is mentioned.