Squirrels have the taste receptors that register capsaicin and birds don’t, so seed laced with chili pepper is a treat to a cardinal and a mouthful of fire to anything raiding the feeder. Sizzle N’ Heat is a no-filler blend (no millet, milo or corn) coated in pepper flavouring. Kevin Kelly’s trick: start with pure hot seed until the squirrels learn, then cut it with cheaper plain seed.