|From page 9 of the U oof Neb Study (pdf)|
According to page 9 in the paper Monofilament Lines and a Hoop Device for Bird Management at Backyard Feeders (PDF) from the University of Nebraska, House Sparrows (HOSP) are unique in their aversion to hoops and lines (i.e. halo devices) given an unusual risk assessment.
2023 is our 5th year of hand-building and selling a custom 20" version of the Magic Halo, designed for hanging feeders and within the radius of the standard 1/2" shepherd hook. Though not HOSP-proof, it has proven very successful. In that time, our own study and survey data match that of the UNB paper, at about 85% effective overall.
The successful Halo user knows and understands the following:
- Halos and lines are HOSP-resistant, and as such, may not eliminate all HOSP from feeders.
- To achieve high efficacy, other HOSP deterrents may become necessary.
- Efficacy may vary throughout the year, lowest coming in Summer.
- Is prepared to remove and "reset" feeding & halo systems if necessary.