Birds of Midway Atoll
Black-footed Albatross / Phoebastria albatrus
Midway Atoll has the second largest Black-footed Albatross population in the world. In January 2008, the total number of breeding pairs on Sand, Eastern, and Spit Islands was 25,320.
Diurnal surface feeders. Unlike the Laysan Albatross, whose retinas possess a high level of rhodopsin enabling better night vision, the black-foots have limited nocturnal vision. Diet consists primarily of flying fish eggs. They also feed on squid and crustaceans. Squid, which float to the surface during darkness, are much more accessible to Laysans. Black-foots, on the other hand, rely on flying fish eggs, which are easier to locate during the day. The competition for food between Black-footed and Laysan Albatross is reduced due to this difference in prey items and feeding behavior.
Black-foots usually stay at least 20-30 kilometers offshore during the non-breeding months (July - November). During these months birds are distributed throughout the northwestern and northeastern Pacific.
Monogamous. If one of the mates should disappear or die, a new pair bond is created. Nests are made up of pieces of surrounding grasses, sand, or shrubbery. Black-foots like to nest in more open, less vegetated areas as compared to Laysans. The majority of their nests are located near beaches. Breeding begins in early November. One egg is laid and incubation lasts about 65 days. Both male and female incubate the egg. Incubation starts with the females who usually stay for a short two day span. The male then takes over, sometimes as long as three weeks. If the egg is infertile or breaks during incubation, relaying will not occur during that year.
Black-foot chicks begin to hatch in mid-January. Chicks live on a diet of flying fish eggs and squid oil. Both adults feed the chick by regurgitation. The chick will peck at the lower beak of the parent which stimulates the parent to regurgitate. The rich squid and stomach oil is filled with fatty acids and nutrients that can sustain a chick for a number of days while the parent goes out to sea in search of more food. Fledging occurs 4-5 months after hatching (June and July). Similar to the Laysans, the parents will often leave before the chicks have reached their full juvenile plumage. Relying on their fat reserves, the chicks survive on land, practicing take-offs until they master flight. Sub-adults return to their natal colony when three years of age but do not mate and nest until at least age five.