This is interesting, I was under the impression that chili peppers specifically evolved (spiciness) to be edible by birds but not mammals. Maybe that's an adaptation specific to tropical birds?
Perhaps the cinnamon or vinegar are the true repellents?
Evidence for this is that pepper varieties tend to be spicier in wetter environments, where the biological resources spent on producing capsaicin to fight fungus are more valuable than preserving them in case of drought.