European starling feeding activity on repellent treated crops and pellets

• Anthraquinone did not effectively repel starlings from blueberries or sweet corn.
• Sucrose content of test matrix may have affected starling consumption.
• Starlings reached 80% repellency at 6275 ppm anthraquinone on CU Bird Carrier.
• Up to 35,000 ppm anthraquinone was not effective when repellent was not topically applied.
• SucraShield increased starling consumption of CU Bird Carrier as concentration increased.

The varied diet of European starlings (Sturnus vulgaris L.) can present challenges when working with starlings in experimental testing and holding situations and should be taken into account when testing repellents applied to food. Our purpose was to evaluate an anthraquinone-based repellent (Arkion Life Sciences, New Castle, DE, USA; active ingredient 50% 9,10-anthraquinone; hereafter anthraquinone) and SucraShield™ (Natural Forces, Davidson, NC, USA; active ingredient 40% sucrose octanoate esters) repellent for non-lethal protection of specialty crops (i.e., fruit, sweet corn) and grains. Our objectives were to evaluate (1) laboratory efficacy of anthraquinone applied topically to blueberries and sweet corn, (2) laboratory efficacy of anthraquinone applied to two pellet matrices, and (3) laboratory efficacy of SucraShield™ as a chemical repellent for European starlings. We found that anthraquinone was not an effective repellent for blueberries or sweet corn, although consumption of each matrix varied potentially due to sucrose content. Anthraquinone was an effective repellent on CU Bird Carrier pellets with 6275 ppm needed to achieve 80% repellency, whereas up to 35,000 ppm anthraquinone was not effective when the anthraquinone was not topically applied. SucraShield was not an effective repellent for starlings and in fact increased consumption of CU Bird Carrier as concentration increased.