Wild Neighbors: Old as an Albatross

By Joe Eaton
Thursday February 04, 2010 - 08:59:00 AM
Courting Laysan albatrosses on Tern Island, Hawai'i.
Duncan Wright
Courting Laysan albatrosses on Tern Island, Hawai'i.

Last week I wrote about a recent study out of Cornell that attempted to find ecological and life-history factors correlated with longer life-spans in birds. The authors reported that larger birds lived longer than smaller species. Sociality, herbivory, and the tendency to nest on islands were also associated with long life, as measured by extreme records for banded birds.  

It’s interesting that even small birds tend to live longer than small mammals. Hummingbirds have to eat constantly to keep their metabolic fires stoked. You’d expect them to burn out in a couple of years. But according to records compiled by the U.S. Geological Survey’s Bird Banding Laboratory, North American hummingbirds can live as long as 12 years, the record held by a broad-tailed hummer. Compared that with the 2-year maximum for the short-tailed shrew, or the 3-year record for the Norway lemming. Bats tend to live longer than flightless mammals of comparable size, so you have to wonder just how the ability to fly contributes to longer lifespan. 

When you look at longevity records for some pairs of species or species groups—mainland North America finches versus the closely related Hawai’ian honeycreepers, for example—the island-nesting factor seems to wash out. The effect is strongest for large seabirds. The 10 longest-lived species in the BBL database are all seabirds: four albatrosses, three terns, a frigatebird, a tropicbird, and a puffin. Of the 10, eight nest only on islands, the exceptions being the arctic tern and Atlantic puffin. The Laysan albatross (50 years 8 months) ranked first, followed by the black-footed albatross (40 years 8 months.) 

Now, 50 years is impressive. Not many mammals live that long in the wild. There’s even a record of a 50-plus Laysan albatross that was part of a breeding pair. It does seem that these birds have somehow evolved a way to slow or postpone the aging process, as the Cornell team suggested. The authors related that to a lower risk of extrinsic mortality—death by predation, accident, or disease—that would have favored such traits. 

For the last 15 years, a Laysan albatross has been spending the winter at Arena Cove on the Sonoma County coast. Its age is unknown; it was in adult plumage when it first showed up, and apparently had not been banded. (I’m not sure of its current status. It was reported to have arrived for the season last October, but was not around when I visited Point Arena in November.) If the 50-year mark is at all typical of the species, it could still be a relatively young bird. 

Laysan albatrosses don’t attempt to breed until they’re 8 or 9 years old. Females lay a single egg; they’re capable of reproducing every year but sometimes skip a year if food is scarce. Laysan chicks are slow to mature, depending on their parents for up to six months after hatching. This doesn’t look like a species that’s just barely keeping ahead of its predators and other mortality factors. And in fact, the environment in which these birds evolved was just about predator-free. The remote Pacific islands on which they nested had no resident mammals. The tiger sharks that lay in wait for fledglings appear to have been the only significant threat. 

But things have changed. Polynesian voyagers inadvertently brought rats, which prey on both nestlings and adults, to the nesting islands. Mosquitoes, vectors of avian pox, arrived with later voyagers. Around the turn of the 20th century, commercial feather hunters took a major toll. At Midway Island, 54,000 Laysan albatrosses were killed between 1954 and 1964 to reduce the risk of collisions with aircraft. Driftnet and longline fisheries have taken thousands of these birds. 

The most insidious threat today, though, is the plastic we’ve dumped into the Pacific, floating in a petrochemical Sargasso the size of Texas. Adult albatrosses aren’t good at discriminating between edible floating objects like flying-fish eggs and inedible objects like Lego pieces. They bring it all home to their chicks, which starve to death with a gut full of toothpaste caps and little plastic dinosaurs. 

The Laysan albatross is a masterwork of evolution. But, like all too many species, it can’t evolve fast enough to keep pace with what humanity is throwing at it.