always wondered of the nutritional value of these, left out by people with good intentions, but probably doing more harm than good with those empty calories
You are correct. If you feed hummingbirds, dissolve a 1:4 ratio of sugar to water in summer (so 1 cup sugar to four cups water) or a 1:3 ratio in winter for extra calories/energy. Don't use the bottled red stuff, it's bad for them :)