Light-mantled Sooty Albatrosses / by Jerry

This weekend we were out monitoring the Light-mantled Sooty Albatross chicks. These are the least common of Bird Island's four albatross species and the least rigorously studied. The main reason for this is the inaccessibility of their nesting sites – usually on narrow ledges half way down the cliffs, either alone or with a few others.



There is a section of the island though where the coast can fairly easily be walked, where long-term studies of nesting and fledging rates have been carried out. One calm day last October we split into two pairs and headed along this bit of coast, mapping any nest we could see. Finding them seven months later can be difficult so we'd planted numbered stakes, taken GPS waypoints, photos and written descriptions.
A happy bird, sitting on a nest that can't be reached.
Where nests are accessible we look for ring numbers, although the majority are unringed. Sooties are often more nervous than other species so approaching them can take a long time, with slow, calm movements. As with the other albatrosses (and pretty much all seabirds) earlier studies have shown them to be incredibly long lived, forming long-term pair bonds and returning to the same nest site year after year.

Slowly edging closer to a nesting bird. (Hannah's photo).
A middle-aged chick, still wearing it's downy collar.
They breed every other year, laying a single egg that they take turns incubating for over two months. Chicks then take roughly another five months to fledge, during which time the parents will travel up to 1000km on foraging trips, returning every few days with crops full of mainly crustaceans and krill (but also fish and carrion depending on availability).

Returning home through the snow.
Once fledged the chicks can spend between 8 and 15 years circling the oceans before settling down to raise young themselves. During winter the adults feed anywhere between the pack ice and up to about 40 degrees south.

One of the first LMSAs we saw from the ship.
One of the things the Light-mantled Sooty Albatrosses are known for are their aerial abilities. During courtship or while reaffirming pair bonds a couple will fly along the edge of the cliffs in an amazingly synchronised, close control display. Barely flapping their wings they glide, parallel to each other, around their nesting areas.




Territorial calls can be heard across the island; a high-pitched trumpet-like sound blasted out as they throw their heads back, defying anyone to challenge them to their nest.



The Sooties have had a tough few years in terms of breeding success, so we were pleased to see some healthy-looking chicks on our round this year. The species is classified as 'Near Threatened', with all the usual problems seabirds are facing – nest predation from terrestrial alien species is being addressed by projects like the South Georgia rat eradication, but by-catch from poor fishing practices, plastic ingestion and food availability in a changing ocean are still problems.

A young chick not far off fledging.

Jerry.