Birds molt. Keep them inside while they do it.

@Mary True but you may get more feathers from them by removing them manually.

Additionally, other birds may be domesticated for communication. That does assume that the herbivore humans are pre-industrial, and haven't developed other methods of long-range communication

@Mary and the best feathers are eider down, which you can get from the nests

Wild sheep, at the time they were domesticated, did not produce wool. It was a chance mutation that was then selectively bred as it was discovered to be useful. There were several thousand years between domestication and wool.

@Jack Aidley while i don't know much about ancient sheeps they probably still had fur that could regrow.

@Fallenspacerock shave your arm and tell us if it looks like modern sheep wool. shave a wild goat and tell us if you can make clothing out of it.....

@Xenophile i looked up what originally sheep looked like. Yes while they have way less wool but still more than a deer or something. And yes they were used to make clothing at least to my knowledge. So it may still be possible for the herbevoirs to domesticate them to the modern they Standard.

@Fallenspacerock: Sheep skins would probably have been used to make clothes, yes, but there's no evidence of producing cloth from their hair for thousands of years after domestication. I can't see skins alone being worth the effort of domestication and farming; when there are so many plant based options for making cloth and clothing.

@Jack Aidley yes maybe though still sheep have more hair than other animals and i don't think there is an animal that may serve as alternative.

@JackAidley, the wild precursor to the domesticated sheep may not produce wool, but a number of related species do -- and they shed it every spring to keep from overheating in the summer.

@Mark yeah there's probably a lot of potential species related to sheep that can do it too. But i still stand at my assessment that even ancient sheeps are a better source of textile than most other animals. I mean compare it to something like a deer.

well, just because those humans are herbivorous does not mean they wouldn't like to have tough clothing. Made of leather, maybe.

One example for beasts of burden/other would be plowing fields, turning mills or other things (there used to be a dog breed explicitly for turning food over the fire)

@Syndic but would they figure out leather if they weren't killing and harvesting animals for other purposes?

@coppereyecat even though they may be herbivores the still need to stay warm in winter. And i don't see any other material suitable for that.

@Fallenspacerock you're used to leather and other materials suitable to keep warm existing. But imagine you're an early human living in a climate where you don't need such things, and you don't already kill animals for food. Would you think, "I need to start killing animals to use their fur to keep warm so I can go further north"? Or would you think "I guess it just gets too cold up there, we'll keep living down here". MAYBE the first would happen, but it takes a long tradition of that to figure out the process of tanning leather. It isn't direct from animal, to clothing that doesn't rot.

@coppereyecat i don't think they would run around naked. Even in warm regions protection is key and yes animals are the most easy way to do it.

@Fallenspacerock, in warm regions, protection is mainly from the Sun, and a large straw hat works just fine for that.

@Mark yeah that is part of it but they would not walk around all they wearing nothing but a straw hat. It's extremely unlikely that they won't use any animal to get some kind of fabric or clothing. Because literally this is the easiest way to do it.

@coppereyecat indeed, it would be less obvious. But animals die without human intervention (sickness, predator animals, a bad fall...) so I think it would still be possible for a human to go "aww, poor animal. But I'm cold in the winter, and this animal does not seem to mind - since it does not need its hide anymore, maybe I can use it?" - and yes, tanning will take more steps to figure out, but "let's scrape off the stinking fat" at least should be obvious, so untanned hides would be used I think. And from there things can develop. From "found carcass" to "kill animal", from untanned to ...?