The eggs of the wandering albatross take an eternity to hatch. During the incubation period of 78 days, one of the longest in the bird world, both parents take turns at the nest without food or water. Among some smaller species, fathers and mothers swap duties several times a day. But not the albatross. While one warms the egg, the other travels up to 3,500 km away, hunting mainly squid. Such far-ranging trips mean these seabirds exchange places an average of once in 12 days, but it can be as long as 30. Since they have a life span of about 50 years, the elderly ones struggle to cope with extended periods of starvation. Fionnuala McCully, a doctoral candidate at the University of Liverpool, U.K., was surprised to discover how they do it. When the COVID-19 pandemic grounded her from doing fieldwork, she worked on data that had been collected on the wandering albatross by her Ph.D. supervisor and collaborators. She didn’t have to sit in the biting cold on remote islands, being buffeted by strong winds, which help the birds glide over the Indian and Antarctic oceans.
Every two years, during the southern hemisphere’s summer, the seabirds return to land to reunite with mates, nest, and produce a single chick. They mate for life even though they don’t see each other between the breeding seasons. The age difference in most pairs is usually two or three years. But sometimes, it is much more. The most extreme case in McCully’s study was a widowed male in his late 20s who took up with an eight-year-old female. In another, a 30-year-old female paired with a 17-year-old male.
If the younger birds disappeared for a month, their elderly mates might become wasted. So they returned sooner than they normally would, within five or six days, to take their turns while their spouses left to refuel. “The birds were paying more attention to their partners’ condition and age than they were to their own,” says McCully.
This came as a surprise. Before the study, she expected the albatrosses to make decisions based on their own needs. When its partner arrives, the famished parent ought to be only too ready to leave. Sometimes, the incubating bird’s instinct to stay on the nest is so strong that its mate has to give it a push. “They have an overlap of an hour to three hours,” says the researcher. “They sit and have a cuddle.”
Based on research on other seabirds, there’s a theory the leaving bird appraises the arriving mate’s health and decides how long it can spend at sea. Their long-term relationships probably already inform the albatrosses of their mates’ limitations. “We think the birds have some ability to gauge how much pressure their partner can take,” says the researcher. Precisely how they do that is still unknown.
By returning sooner to relieve their fasting mates, the younger albatrosses sacrifice their own health. They might seem considerate, but McCully is quick to note that it’s in both birds’ interest to care for each other. If incubating birds reach a point when they cannot continue starving, they might abandon the nest. Raising young requires a partnership. “They can’t be single parents,” says McCully, “because you just cannot feed a chick in those conditions by yourself.”
This ought to make elderly spouses a liability. What makes them attractive as mates? “One of the big advantages of having older partners,” says the researcher, “is that they are experienced.”
Since wandering albatrosses reproduce under rigorous conditions and pairs rear only one chick every two years, they cannot afford to fail. The younger birds may be inexperienced at parenting. But they seem to be experts at performing visual health checks and estimating when to return. That’s a crucial relationship goal.
Since wandering albatrossesreproduce under rigorous conditions and pairs rear only one chick every two years, they cannot afford to fail