Guano, gwa'no, the excrement of birds. Commercial guano, used by gardeners for a fertilizer, is imported in sacks from rainless islands off the west coast of South America. On account of penguins, gannets, and other birds, immense amounts of guano have accumulated. Humboldt in his travels, 1804, was the first to call attention to the chance of making money by its sale, and its desirability as a fertilizer for land. One ton of guano is considered equal to thirty-four tons of barnyard manure. One small group of low rocks off the coast of Peru is reported to have yielded 14,000,000 tons of guano, valued at $840,000,000, before the supply was exhausted. Both Chile and Peru have derived large sums of money from these deposits, but they are now about at an end. To realize their magnitude, we have only to recall that these comparatively small tracts were used as breeding grounds for centuries by millions of birds larger than geese, and that no rain fell to carry the guano away. The Germans have found a supply on the coast of German Southwest Africa. See PERU; FERTILIZERS.