We did not invent the concept of halos over bird feeders, and cannot guarantee that it is House Sparrow (HOSP)-proof given the myriad of designs and contexts that they are placed in. Though our survey data is largely favorable, it is also limited to just 12% of our customers who choose to participate, and assumes that they can correctly identify HOSP.
The original paper from the University of Nebraska published in 1994 did confirm that juvenile (first year) HOSP are halo-tolerant. If you feed all year long, the deterrence rate may decline in Summer, with juvenile-adult acclimation continuing indefinitely. Therefore, we recommend only feeding in the Fall-Winter-Early Spring.
New Magic Halo users should start out expecting a reduction in HOSP, and (possibly) better behavior for those that do adapt. If results are poor, you may need to "reset" you feeder system with a few months down time, switch seed type, or consider modifications. Please read our Users Guide for full details on how to optimize and get the most from your Magic Halo and feeding in general.
Before deciding on your purchase, we advise potential customers to read the following from FeederWatch and Sialis. In judging Halo efficacy, we ask that you examine your results with vs without, before vs after, and whether or not there's at least a net improvement in your bird feeding experience.
We appreciate your understanding.