Ok, I don't speak Spanish. I admire anyone who can speak more than one language. So I have to rely on websites like google translate.
And they translate the verbage, 'Riqueza del guano' on this Peruvian stamp as 'guano wealth'

But I don't need to be able to speak Spanish to know what guano is!
Really? Are there so few things or events or people in Peru to honour that they dedicate a stamp to bird poop?
Am I missing something?