The world's two oldest-known common loons once again returned to Michigan, United States. If they choose each other as mates, it will mark a record 26 consecutive summers together for the pair. The male, named ABJ, will turn 35 this year. The female, named Fe, is thought to be at least 36 years old. The pair's species record-setting 32 hatched offspring may explain their remarkable fidelity to each other: common loons do not mate for life, but researchers found that if two loons successfully hatch chicks together, they are more likely to pair up again the following year.