there is a need to protect the health of hummingbirds by preventing the rapid microbial spoiling of sugar nectar used in hummingbird feeders , without using artificial preservatives . the invention is a method , composition and kit , for naturally preventing spoilage of sugar nectar liquid food by using a transition metal salt , an optional acidifying agent , and an optional functional additive . certain transition metal salts , such as copper sulfate are surprisingly effective in protecting sugar nectar even at micronutrient levels , below the level consumed by hummingbirds in their natural diet . the invention prevents the formation of unhealthy microbial growth , reduces the need for frequent changing , and keeps the sugar nectar fresh and healthy .