I have no explanation, but my local birds love this stuff. I have three kinds of woodpeckers, nuthatches, chickadees, blue jays, and never before seen at any suet feeder by me - juncos (they found a small cavity where they can land at the base of my Squirrel Buster suet feeder. My only theory is the strong smell attracts them (which I have to say is rather pleasant even to a human). Even after replacing it with another variety, the birds seemed to gravitate to where that used to be, and when I finally put another one there, they went crazy for it again.
As with all the Suet Plus products, the packaging is great, and a very welcome change from trying and failing to keep my hands clean with other packaging and being left with a pile of various plastic packaging.