home made gun powder out of pigeon poo?

[xpc]

If pigeon poop is the ingredient for gunpowder, wouldn't skyscrapers and mall awnings be a boon for reloaders?

Yes when mixed with the right ratios of brimstone and lamp black.

Don't quote me on this as it is from an old memory, as I remember the British and French (USA later) stopped the Germans from accessing the Canary Islands and other resources to get the raw ingredients for gunpowder (bird poop) and because of that during WW1 the Germans were the first to invent synthetic gunpowder.

Remember back then necessity was the mother of invention, though now I believe it to be laziness.