Why are peppers hot? A chemical called capsaicin makes your mouth burn, and it's the main ingredient in pepper spray. People and animals feel the burn, but surprisingly birds do not. Why? Biology. Animals and people chew up and destroy seeds, but a bird will swallow pepper seeds whole and when they defecate, the seed is intact and ready to grow.
So how can you make hot peppers less spicy? Remove the pith, the usually white or yellow internal part of the pepper with the seeds. A general rule of thumb is the yellower the pith, the spicier the pepper. But that's not true for a pepper like the ghost pepper, which doesn't have pith but is incredibly spicy; its heat is also in its skin. The Scoville Scale ranks peppers on their level of spiciness, with bell peppers at 0 Scoville heat units and the hottest, the Caroline Reaper, which clocks in up to 2,000,000 units.
Looking for something spicy? Make your own hot sauces with The Hot Sauce Cookbook or Hot Sauce!. Try Fiery Ferments to add some spice to condiments. Gone paleo? Check out The Spicy Paleo Cookbook. Vegetarians can crank it up with The Veggie-lover's Sriracha Cookbook. Browse The Sriracha Cookbook for all kinds of ideas.