|No dye, please!|
Photo by Mr. T in DC
The birdfeeders I most often see hanging outside homes here in the US are those for hummingbirds. And most often the feeders contain an unnecessary side order of red dye. The hummers who feed there end up processing a lot of red dye; whether this is directly harmful to the birds is under debate, but it's clear that this chemical is not needed in their diet. The feeders themselves are nearly always colored red, and this is enough of an attractant without the addition of a potentially harmful chemical. Likewise, there's no need to buy commercial products that contain preservatives as well as the dye--a homemade syrup of table sugar and water is better for the little beasties. (Recipe/instructions are easily found online.)
In addition to nectar, hummers feed on insects and spiders. They procure these on the wing, or pluck them out of webs or from inside plants.
But helping them out with sugar water is a lovely gift to the wild things--just hold the dye.