My neighbor in Akron claimed cardinals mate for life, so I watched a pair for 3 weeks to prove her wrong
Last month my neighbor Doris swore up and down that the cardinals at her feeder were the same pair for 6 years straight, so I started logging which birds showed up each morning with a cheap notebook and a pair of binoculars. About 9 days in, a second male started muscling in on the feeder and the "loyal" male chased him off, but then a female showed up that clearly wasn't his usual mate based on the duller crest. I brought my notes over to Doris and she just laughed and said "well, maybe I got a little carried away." Now I'm wondering if anyone else has actually tracked individual birds long enough to know for sure, because my 3 weeks of scribbles sure make it look messier than the bird books say.