Feature

Albatross

The biggest sea birds are models of energy efficiency.

Veronika Meduna

Flying a few hundred nautical miles to gorge itself on seafood is all in a normal day's work for a hungry albatross on nest duty. The large sea birds spend more than 90% of their time at sea, cruising the world's oceans in search of food and taking the occasional rest on the water surface. However, albatrosses have to seek out land to breed, and often the breeding grounds will be far away from feeding areas.

During the breeding season, the nest partners alternate in guarding the brood and commuting up to 4,000km to foraging areas. Some travel for days. Often half-starved and exhausted by the demands of reproduction, the long-distance fliers conserve their already depleted energy resources by cruising with the prevailing winds, which makes longer trips more efficient than short journeys against the weather. Despite their airborne marathon, they return replenished and ready for another fast on the nest.

Paul Sagar, a marine biologist with NIWA (the National Institute of Water and Atmospheric Research) in Christchurch, says albatrosses and other closely related seabirds are models of energy efficiency, often commuting these long distances between feeding and breeding grounds on just a little more fuel than they consume during a nap.

The only time albatrosses are regularly seen beating against the wind to get to food sources nearby is during the chick-rearing period, when their brood has hatched and demands almost constant food supply.

Birds via Satellite

Sagar has been working with French colleague Dr Henri Weimerskirch, analysing data collected from birds equipped with satellite tracking gear to help scientists chart their journeys and energy metabolism. He says advances in satellite telemetry have allowed scientists to observe albatrosses and petrels during their time at sea. Most of the behavioural observations so far had been carried out during the short time sea birds spend on shore, but the largest part of their behaviour has previously eluded scientific scrutiny.

"Although albatrosses are among the largest flying birds, with a wing span of more than three metres, we knew nothing about their life at sea. We knew a lot about what happened on land but that was just about 10% of their whole life. For the rest of it, we knew how long they were away, but not where they went and what they were doing out there," he says.

While there had been a few observations from ships, biologists "knew nothing about the birds' ages, nor anything about their status in terms of whether they were breeding birds or not".

Satellite tracking has enabled scientists to follow the birds -- albeit only on a computer monitor -- when they take off on their ocean cruises.

Between them, Sagar and Weimerskirch studied various species of sea birds, some of them equipped with a range of high-tech gear: a transmitter for position tracking, a small probe for measuring the heart rate, and a mini thermometer for monitoring food intake by taking the temperature in the stomach.

The researchers found that albatrosses and petrels employ a foraging strategy which gives them the choice between energy-conserving casual feeding where ever they find prey during longer gliding trips and the calorie-burning short burst to the nearest source when the offspring squeaks for food.

Sagar says the bird's own physical condition will determine which option is taken. If the bird is approaching its threshold of energy depletion, it will opt for the energy-efficient version. Although a southern Buller's albatross may complete a return trip between the breeding colony on one of the subantarctic islands and the Tasman Sea, it will return renourished enough for the next shift on the nest.

Larger albatross species have a larger safety margin, because they have more reserves to get them through the incubation of eggs and chick rearing without getting too close to serious energy deficiency.

Longer Life

Albatrosses are among the longest-lived birds, often reaching about 60 years, and their energy-efficient lifestyle is one of the reasons for their longevity. Extended puberty is another. Some of the larger albatross species take up to six years to develop any interest in breeding; some are older than 10 when they establish their first nest.

Once they do, they bond for life. Sagar says the divorce rate of Buller's albatrosses is at 3.6%, and for partners to split up there needs to be rather serious case of incompatibility. Breeding pairs meet each year -- or every second year for larger albatrosses such as the northern royal albatross which breeds at Taiaroa Heads on Otago Peninsula -- to raise their single chick and then go their separate ways. Once the chick has fledged, it will spend several years cruising, until, one day, it turns up at its natal colony looking for a mate.

Male birds have a tendency to return exactly to their colony, while females will return to the island but drift to another colony nearby. Any risk of inbreeding is effectively eliminated.

While albatross chicks are an easy target for predators, the adult bird faces few natural threats. One of the potentially fatal threats comes in the form of commercial fishing boats. Hundreds of hooks are set by long-line fishing operations each night, and Sagar says up to 40,000 birds were killed in one year in the Indian Ocean alone.

Albe -- a royal wanderer

It wasn't the easiest of things to help a young New Zealander far from home....

Peter Moore

On 21 February 1998, after a big storm off the Patagonia coast of Argentina, a very weak southern royal albatross was found on a beach near San Antonio Oeste, unable to walk or stand up. A non-profit environmental organisation, Fundacion Inalafquen, took charge of the bird, and it was taken into backyard rehabilitation at Las Grutas to be restored to health by an enthusiastic couple, Bruce Johnson, an engineer from the US, and Maria Eugenia Picerno, a veterinarian.

As luck would have it, the bird was banded (R-54119) and the record quickly made its way to the Banding Office of the New Zealand National Banding Scheme here at the Science and Research Unit of the Department of Conservation. The bird had been banded as a fledgling on October 3rd, 1997, by Alan Wiltshire and team at Campbell Island, a nature reserve 600 kilometres south of New Zealand. This was part of a Science and Research Unit study of the population trends, dynamics and breeding success of southern royals.

Chick banding and eventual assessment of recruitment of the survivors to the island to breed as adults provides part of the picture of how the population is faring, and allows better interpretation of the trend in nesting numbers. Almost the entire population nests on Campbell Island -- about 8,000 nests each year -- and having apparently increased after the depredations of farming earlier this century, they have increased further in number, or at least fluctuated, since the 1970s.

A short time after it was banded, the albatross probably took its first flight and over the next four months made its way to Argentina, the normal pattern for nonbreeding birds. Royal albatrosses feed mainly on squid of the continental shelf and slope, rather than on more oceanic species, and they migrate from their breeding grounds in southern New Zealand waters to favoured feeding grounds near Chile and Argentina. Here they dine mainly on the squid Moroteuthopsis ingens, which dies and floats to the surface after spawning. Presumably the royal in question became exhausted during the storm when feeding in these waters.

Soon I was in regular email correspondence with Bruce Johnson about their charge which they had nick-named "Albe", as they needed reassurance as to feeding regimes, the health of the bird and how best to get it back into the wild. A few tips passed on from Taiaroa Head albatross colony helped also.

Curiously, Albe preferred fish to a squid diet -- possibly this is not very digestible in a captive situation, as chicks fed squid at Taiaroa Head are more prone to dehydration. Albe received 1-1.5 kg of fish per day and a vitamin/calcium supplement. In the heat of the summer in his dusty enclosure, he required hosing with water several times a day to keep him cool, an activity he enjoyed, biting at the water to drink the spray. There were other teething problems, such as vomiting caused by the bird eating ice plant in the enclosure.

I suggested that once healthy again, the best thing would be to take the bird to a high windy place, such as a cliff edge. An initial attempt at release in March from a sloping sand dune at the coast failed because of lack of wind. A couple of weeks later, and poor Albe needed rehabilitating from injuries sustained by crashing off a cliff. He had apparently failed to open his wings after walking off the edge, despite a stiff breeze. After a period of convalescence, Albe returned to good health, but showed no signs of leaving of his own accord.

After I returned to the office from a two-month winter holiday, Bruce sounded near his wit's end:

I am tied to the house and can't go anywhere because no one can seem to feed him...We are nearing the end of our rope.

Fish had become scarce, and for a month intake was reduced to 0.5 kg/day before returning to nearer 1 kg/day. Getting Albe out to sea to leave him to the vagaries of the wind was not an option because of the lack of access to a big enough boat or suitable retrieval gear if the release went wrong. Regular trips to the beach at least gave the bird exercise and the occasional short running flight in the shallows, but still provided unexpected mishaps.

The dog (Mini)...is a real character...She protects the Albatross at the beach from other dogs and sometimes people. Once a dog did charge the Albatross and knocked him flat...Now we take Mini every time for protection.

At this time in late August, Bruce mentioned that Albe was 10kg in weight. From an initial 6.7kg, he had stabilised at about 8kg in March-July but had increased again. Maybe he was getting a bit fat.

I suggested that fasting, rather than daily feeds, and increasing the gaps between meals might make him lean and hungry and more keen to leave. After all, breeding birds routinely fast up to three weeks when waiting for their partner to relieve them at the nest. Just a week later, on a stricter diet, he was much more lively, biting his patron and attempting half-hearted take-offs at the beach.

On September 16th, having lost a full kilogram of weight in three weeks, a 40-50 km/h wind allowed Albe to run across the sand and become airborne for 50 metres, then across the breakers for further bursts until he was out in the open ocean and "freedom". Eventually, Bruce lost sight of him and, after much patrolling of the coast for any sign, decided the release must have been a success.

A long 207 days of rehabilitation were finally over.

In that time Albe had been quite a media star, with several newspaper articles, radio and TV programmes about him. I'll miss Bruce's regular and entertaining updates on Albe's progress. Bruce and Maria were doing all the hard work, and learning from trial and error, but it was nice that my advice at least helped fine-tune the care of the bird, and kept their morale up.

In Bruce's words:

I want you to know how much we appreciated your help and encouragement in this effort. You were on target all the time and that should give you a good feeling.

Whether the albatross will be found again back on Campbell Island remains to be seen -- the first birds start breeding at six years of age, so some lucky albatross worker may find him there sometime after the year 2003. I'll be keeping Bruce posted.

Veronika Meduna is a freelance journalist with an interest in science stories.
Peter Moore is a scientist working in the Science and Research Department of the Department of Conservation in Wellington.