Arctic terns are small seabirds which have one of the longest migration patterns in the animal kingdom, covering 25,000 miles in a year. In Migrations, the terns are a near-constant presence, populating Franny’s dreams and driving the Saghani’s voyage to Antarctica. The long-flying birds symbolize the relationship between Franny and Niall.

Franny and Niall are different by nature, but their fascination with the natural world and the terns allows them to connect. Franny understands the terns’ need to migrate on a visceral level; her own life is a singular migration driven by instinct. Ornithologist Niall understands the terns’ behavior from a scientific viewpoint. Like the terns, Franny fascinates and awes him, but in order to sustain their relationship he would have to put her in a symbolic cage. He declines to. Their marriage ultimately can’t survive her flights.

Niall believes that human intervention in the natural world, even if well-intentioned, can only cause harm. At MER, he butts heads with other conservationists who are trying to retrain the terns’ behavior and breed out their migratory instinct. He feels it’s unfair to make the animals adapt to the devastation that humans have wrought on Earth. Niall’s refusal to interfere with the terns symbolizes the way he loves Franny.