We monitored provisioning behavior at 18 Bobolink (Dolichonyx oryzivorus) nests during 240.5 min of videotape data from June to July 2006, and observed 64 nest visits by adults while nestlings were fitted with neck ligatures. Adults pecked or pulled at the ligatures, often aggressively, at 72% of nests (n = 18) and 52% of visits (n = 64). These behavioral responses by adults indicate the neck ligature technique is more invasive than previously believed. We documented no mortality as a result of ligature placement, but researchers should minimize the time that ligatures are in place to reduce stress to both parents and nestlings.
Little, Lynn P.; Strong, Allan M.; and Perlut, Noah G., "Aggressive Response Of Adult Bobolinks To Neck Ligatures On Nestlings" (2009). Environmental Studies Faculty Publications. 20.