Date: Sat, 4 Jan 1997 05:19:51 (GMT)
From: Deane Rink, Palmer Station
(Deane is Video Producer and leader of the LFA 2 field team.)
Humble Island
Humble Island... If ever a place were misnamed, Humble Island is it.
This small rocky outpost in Arthur Harbor houses six species of Antarctic
marine life, and they co-exist in nervous harmony, not always respecting
each other, but no one species such a threat that another has been forced
to leave.
The dominant species in number is the Adelie penguin. Over three thousand nesting pairs inhabit the island, almost all of which have built their nests from the tens of thousands of small rocks that pepper the land. They are a raucous bunch, squawking and braying all the time, as they constantly guard their nest from others, or from the predatory skuas that hover above. Adelie pairs take turns guarding their eggs, or chicks, depending on when in the austral summer it is. We visit the rookery in early January, and almost all the chicks have been born. They look like miniature bowling balls with fine gray fur, pot-bellied from the mass of seafood, predominantly krill, that have been regurgitated into their mouths by their foraging parents. Each pair seems to have two chicks, and the chicks nuzzle under one parent's wings while the other parent waddles down to the ocean's edge and launches itself in the water. The foraging parent will stay out the better part of the day, and return with enough gathered ocean goodies to gorge their youngsters. The Adelie nests are clustered together; this may seem odd on an island where there is plenty of room for spreading out, but the cluster effectively protects them from the predatory skuas, who can only make runs at eggs or chicks on the periphery. Indeed, we notice that, where nesting couples have only one chick, they are most often on the edge of the cluster, not in the center. There is survival value in the congregative behavior of these most social of birds. And for all their "cuteness," these Adelies are tough customers. Their black and white tuxedoed perfection may appear cute and cuddly, but try touching their wings sometime, or holding one in your arms, as the scientists who study them occasionally do, allowed by special permits under the Antarctic Conservation Act. The "soft" wings are actually hardened paddles that cut and slice through the water with amazing efficiency and dexterity, making these birds clumsiness on land an anomaly; underwater, they "fly" as gracefully as any seabird through the air. And their massive chest muscles make them almost impossible to restrain when picked up in a bear hug. Their wings strain to defeat the human's embrace.
But even the Adelies, secure in their group cohesion, wisely give way
to the group of elephant seals who have chosen to "invade" the
rookery. For some reason, the population of elephant seals on Humble has
increased over the last few years, and they represent a real threat to the
rookery, not because they might prey on the penguins, but because they might,
in their land lolligagging, accidentally roll over onto nesting areas and
crush birds or chicks. The elephant seals prefer to sun themselves and rest
from nights of foraging in the sea, in groups of ten or twelve. They lie
close to one another, sometimes too close, occasioning fights and unintentionally
comic threat displays. They will open their under-toothed mouths and bellow
at each other, rolling around for advantage like four young brothers forced
to share the same bed. The elephant seals seem not to notice the Adelies,
but when their frolicking threatens the birds, the birds cause a terrible
commotion, one that seems to cause the seals to grudgingly respect the space
of their neighbors. These elephant seals look like gigantic slugs, don't
move all that fast, and bear evidence of having been scarred by crawling
over sharp protruding rocks in their journey from beach to sunning spot.
They molt their fur every year, and therefore have a grungy look, like a
bum with his coat half off and half on. But their mere size ensures that
every other species on the island, including the humans that visit there
for scientific study, will give them a wide berth.
Wandering among the seals and the Adelies are a smattering of Chinstrap
penguins. No nests are found, but these birds walk through the colonies
of Adelies like visiting neighbors, which I suspect they are. The Chinstraps
are cleaner than the Adelies, another indication that they have just come
up form the beach on an inspection tour, and seem to wander around singly,
unpaired, unlike their Adelie cousins.
On the higher rocky crests of the island, scattered along a ridge line
that traces a crescent around the horseshoe shape of the island itself,
are approximately forty nesting sites of giant petrels. These are spread
twenty to thirty yards apart, and each nest is attended by a brooding pair.
These are big seabirds, weighing 10-15 pounds each and possessing a wingspan
of maybe four feet. The birds sit on their eggs with serene calm, and rarely
get disturbed when a researcher gently displaces them to inspect and weigh
their egg, or measure the dimensions of their chick. The giant petrels,
or "jeeps," will half-heartedly peck at the researcher, and she
has tiny cuts and scars to prove it, but refuses to wear gloves, because
the banding process she must do with each bird requires a certain degree
of manual dexterity. From this tagging, the researchers (Bill Fraser and
Donna Patterson) have been able to determine that these birds leave the
nest when fledged for four to six years, and make almost a complete world
circuit in that time, before they return to breed. These are among the most
well-travelled frequent flyers of the seabird community.
In much smaller numbers, hovering over it all, opportunistically looking
for a free lunch, be it a petrel egg or chick or an Adelie egg or chick,
are the last two species that inhabit Humble Island, the brown skua and
the south polar skua. Their incessant caw-caw-caw punctuates whatever silence
might prevail, and warns us humans, interlopers on this ancient island ecosystem,
that if we approach too closely, we might get dive-bombed. If we leave anything
on the ground, it might be swooped down upon and snatched. Do the skuas
see us humans as guardians of the penguins, interferers with their dinner?
Or are their nests somewhere on this island as well, and are their warnings
just the same as the penguin warnings, display gestures meant to protect
hearth and home? I know not, but as I hop in the zodiac and motor away from
Humble Island, I do know that I have spent a remarkable day walking closer
to a compelling aggregation of wildlife than I could ever experience in
the best zoo in civilization. The misnamed Humble Island has more wild animals
per square foot than the equally-misnamed Wild Animal Park ever dreamed
of.
Deane Rink
