|
With a wingspan of 7-8 feet and a weight
of 7-11 pounds, the waved albatross (Diomedea irrorata)
is the largest Galapagos bird. On land they walk with
a waddle and appear to be very clumsy, but in the air,
they are among the most graceful of sea birds. They are
found on only one island, Espanola,
where they congregate in two major colonies, one at Pta.
Cevallos, and the other at Pta. Suarez, a visitor site.
Like other birds that primarily glide, waved albatrosses
rely on a strong headwind to take off. This, they find
at Pta. Cevallos. The Pta. Suarez colony is at the top
of a sea cliff, to which the birds can walk. They take
flight simply by jumping off. It is typical to find large
rafts of albatrosses sitting just off shore. Although
considered endemic not only to the Galapagos, but to Espanola,
where they exists in colonies of some 12,000 pairs, a
very small colony has recently established itself on Isla
de la Plata, off the coast of Ecuador.
Waved albatrosses, like other albatrosses,
spend part of their year at sea. The waved albatross,
does not travel very far, however, nor is it gone for
a very long time. From January through March, they are
found in the Pacific east of the Galapagos, and along
the coasts of Ecuador and northern Peru. Many often congregate
in the Gulf of Guayaquil. They begin to return in mid-late
March, the males arriving first.Waved albatrosses mate
for life, so the male returns to the previous year's breeding
territory and waits for his partner.
Waved albatrosses, like other albatrosses,
engage in a very lengthy, noisy, and complex courtship
ritual. Some of the basic steps are illustrated in the
strip to the right. The dance involves bill-fencing, in
which the partners bend, face each other, and rapidly
slap their bills back and forth. In another step each
faces the other in an upright posture, sometimes poising
with bill wide open. The bills are then shut with a loud
clap. Sometimes the birds will clatter their bills rapidly.
The dance also involves bowing, and parading around one
another with the head swaying side to side in an exagerated
sway, accompanied by a nasal "anh-a-annhh" sound.
These steps are interspersed frequently with bouts of
bill fencing. The dance is longer and more involved in
new pairs, or in pairs that failed to breed in the previous
season. For visitors lucky enough to see it,the courtship
dance of the waved albatross is a highlight of any Galapagos
trip.
|
 |
|
Between mid-April and July the pair produces
one egg, which is incubated by both parents for about
two months. Early in incubation, each parent takes long
stints, as much as three weeks, but as hatching nears,
the stints become shorter. The albatross does not build
a nest, but rather, lays the egg on the  ground. During incubation
the parents frequently roll the egg about, covering distances
as much as 40 m. The reason for this behavior is unclear,
but its value appears to be obvious since it seems to
be correlated with a higher success in hatching.
The chick is dark brown, and covered with
curly dark brown downy feathers. For the first few weeks
after hatching, one parent guards the chick while the
other forages for food, but after that, the chicks are
left in unguarded nursery groups while both parents spend
longer times at sea looking for food. Whatever food is
captured by the parents is held in the stomach, where
it is converted to an oily liquid. The parent can hold
this liquid in its stomach without digesting it for a
considerable amount of time, making its hunting expeditions
more efficient as it doesn't have to return frequently.
Upon returning to the colony, the parent finds its offspring
and then pumps the liquid into the chick's stomach. As
much as 2 kg of liquid can be forced into the stomach
at one feeding. This volume makes the chick swell and
look like an over-inflated brown bag. It can barely move
until the oil is digested.
By the end of December, the chicks have
fledged, and they leave their nurseries with their parents
and head for the western Pacific. Although their parents
return toEspanola the following
year, the fledglings remain away for five to six years,
at which time they also return to Espanola
to begin breeding for the first time.
|
