Answer by
SallyJ (1010)
Pigeon guano and other animal droppings were once used to soften or "tan" hides, but this is messy, stinky and hazardous to health. You can catch many diseases from animal droppings. You would be better off using vegetable tanning substances such as those derived from chestnut, oak, tanoak, hemlock, mangrove, and other sources.