Tuesday morning was devoted to the seabirds
of the Galapagos Islands. Of the 140 bird
species found on the islands, 89 are seabirds. Two terns (the Sooty and Brown
noddy), two boobies (the Blue-footed and Red-footed), two frigate birds (Magnificent
and Great), Storm Petrels, Red Billed Tropic Birds and the Waved Albatross all
nest on the islands in significant numbers. The Galapagos has the world’s
largest colony of Red Footed Boobies and 30% of the world’s Blue Footed
Boobies. Other seabirds have settled permanently and are endemic to the
Galapagos, including the Nazca Booby, the Lava Gull, the Swallow-tail Gull, the
Galapagos Petrel and endemic subspecies of Audubon’s Shearwater and the Brown
Pelican. The most specialised endemic is the Flightless Cormorant, which is the
largest cormorant in the world at one metre tall and 4kg, and the only one
which cannot fly.
Its wings have become tiny (unlike the penguin it swims with
its feet and not with its wings) and the carina (keel) has become vestigial.
We had seen seabirds throughout the
Galapagos Islands, but we went to North Seymour
to visit their breeding site. The entire flat island was covered in nests,
mostly Blue Footed Boobies, Magnificent Frigate Birds and Great Frigate Birds,
but we also saw the Nazca Booby and Red Swallow-tail Gull nests. The Blue
Footed Boobies take their name from their clumsiness on land and their awkward
courtship dance - “bobo” means stupid in Spanish. The Blue Footed Booby males
offer sticks to females during courtship in a very similar behaviour to that of
mainland Boobies, even though Blue Footed Boobies on the Galapagos no longer
make nests with twigs (the Red Footed Boobies do).
We watched the juvenile
Boobies practise their stick behaviour, they were not very good at it and
looked puzzled as the sticks flew from their beaks. Other juveniles tried the
“sky pointing” and “foot waving” courtship behaviour, in a very amusing
Unlike Blue Footed Boobies with a single
egg, Nazca Boobies always lay two eggs. The one that hatches first pushes the
other egg out of the nest. It isn’t clear why this occurs, either an
evolutionary relic from times when Nazca Boobies had a rich enough habitat to
raise two chicks, or an insurance policy in case one egg fails to hatch.
We watched the magnificent acrobatics of
Frigate birds, able to swoop and harass other birds until they regurgitate on
wing, plunging down to catch the half-digested meal before it hits the water.
This aeronautic skill is essential for Frigate birds as they have a tiny
uropygial gland and can’t waterproof their feathers, so unlike other sea birds
entering the water would cause them to drown. The most prominent feature of the
Frigate Birds on North Seymour, however, was
not their flying but the bright red throat pouch on the males. To attract a
mate they inflate their scarlet pouch with air, making it nearly the size of
their entire body and forcing their necks to bend backwards.
Sadly North Seymour
was the end of our Galapagos voyage, so we had to make our way back to Baltra.
Our final vision of the Galapagos was of the ferry terminal, where all the
benches were occupied with sleeping sea lions.