birding-aus
TRAWLING ON AGULHAS BANK
As previously told, I came to S.Africa in order to take part in a benthic
fisheries survey with the RV "Africana", and I am most grateful to the
Fisheries Research Institute of S.Africa for this opportunity. My
particular quest, as always, were the amphipods, in this case new and
interesting species from inside hermit crabs--this turned out a bit of a
wild goose chase, and as a birder I should have known that there are no
wild geese in S.Africa. But the cruise as such concentrated on bottom fish
and squids, with trawling as the main collecting tool.
The Agulhas bank lies off the Cape peninsula, and has trawling grounds at
150-300m. These first days I needed to find my sea legs, learn to identify
the different fish species caught (All scientists take part in the sorting
and processing of the catch), and generally learn the routines of work on
this ship. But one could not help noticing all the many seabirds around,
such a different mix from what I am accustomed to from N.Norwegian waters.
We started from Cape Town in late afternoon, and soon began seeing Cape
Gannets, a few White-chinned Petrels, and a lone Subantarctic Skua. The
first true surprise for me was a flock of 100's of Sabine's Gulls resting
on the sea; these daintily elegant gulls are a real prize in our Barents
Sea area when we see one or two near the arctic breeding grounds, so
suddenly coming across hundreds of them was a bit of a shock!
The next morning we were on the banks, and the first thing I noted on
looking out in the morning were small groups of largish ashy-brown
shearwaters, black-framed whitish underneath. These were Cory's
Shearwaters. Later on , and especially after we had commenced trawling
("Over she goes!"), the attending "cloud" of seabirds could grow to a few
hundred birds. Dominant among these were three species of albatross, most
impressive in the air. On the sea this is tempered by their slighty
empty-headed expressions; they are dominant to all other seabirds, but
being so ponderously slow to get any message, they often barge in just too
late to get the choicest morsels. Their calls at those occasions show
clearly that they have had few music lessons as kids.
The three species are two smaller "mollymawks", the
Black-browed
Albatross and the beautiful Yellow-nosed Albatross, most of which have the
immaculate grey heads of the nominate subspecies (though we saw a few
white-headed ones of the Indian Ocean subspecies bassi). The third is the
larger Shy Albatross (not particularly shy!) with its pinkish bill.
In the air these albatrosses are most easily recognized by looking at the
underwings (surprisingly easy, as the birds wheel and bank all the time):
The Shy has a narrow black frame and "thumbprints" on the near wing, the
Yellow-nosed an intermediately thick frame, while the Black-browed has
almost more black than white. In all species young birds have more dark on
the underwing, but the differences remain fairly straightforward.
The most ubiquitous seabird around the ship, tirelessly following all day,
is the White-chinned Petrel, the Shoemaker of the sailors. This is a hefty,
dark, almost black petrel, with a strong conspicuous white bill and as the
name says, usually a white spot under the chin. They are quite bold and
make up in agility what they lack in weight. In squabbling their call is a
surprisingly "little-bird-like" high ti-ti-ti-ti-ti-ti. (Later, along the
west coast, we now and then saw "shoemakers" with much more white on the
face, almost like a painted clown face. They were Spectacled Petrels,
nesters from the Tristan area)
Great Shearwaters, quite colourful for a seabird with their dark caps and
warm brown backs, rather avoid the thickest throngs, but also compete for
the outthrow.
The Subantarctic Skuas, a slightly sinister dark presence usually hovering
over the melee, dive down and pick the choicest morsels apparently as they
please--these skuas are appreciably darker than the Bonxies of the north,
but otherwise seem to have mainly the same habits---they mercilessly harass
the Cape Gannets, who also are not averse to catch some fish behind the
ship. Among the skuas our Chief Scientist Rob Leslie, a noted seabird
specialist, drew my attention to a single very dark skua with much smaller
wing flashes, a very small bill and a clearly higher voice, and declared it
probably to be a South Polar Skua, a rarer guest in these waters.
Arctic, Long-tailed and Pomarine Skuas appeared now and then and stayed
with ship for a few hours, much as they do in northern waters. They mostly
were content to find their own fish behind the ship, and I saw only a few
chases.
Other visitors from the north were the Arctic Terns and the Sabine's Gulls,
vying for the crown of elegance among the ship followers. The terns were
not silent, as I had expected from the books, but uttered short
monosyllabic chips, quite different fron their calls in the breeding area.
Also the Sabine's gulls called now and then, their normal "ternal gull call".
Storm Petrels flitted irregularly through the wake of the ship, avoiding
the throngs as much as possible. Both European Storm Petrels and Wilson's
were present, and it took me some days to become proficient in recognizing
which is which at a glance. It is mostly a question of different flight
patterns, I believe, when the birds are too far away to see the wing
patterns and leg length.
On the Agulhas bank there are normally only a few Kelp Gulls present, but
later, on the western banks, the ship was "covered" with a hanging cloud of
gulls, up to hundreds being present. These Kelp Gulls remind one in many
respects of Lesser Black-backed Gulls, but they appear to be less
specialized: they have not so long wings and consequently lack the great
manoeuvrebility of the Lesser Black-backs, and at the other hand they are
not really very good at robbing the other seabirds either--many
half-hearted attempts resulted practically never in success. These gulls
are a very pretty picture against the ever blue skies; their wings are
lined in white both fore and back, and with their dark eyes they give a
rather benign impression, probably utterly misleading.
This is the picture as seen from the stern of the ship: a very diverse
seabird guild, almost completely dominated by "sail-planes" and with few of
the "submarines", the diving birds, that predominate in the north (The
Jackass penguins do not venture very far out to sea).
This picture is in many respects misleading, though. When one watches
forward from the ship, e.g. from the peculiarly named "monkey island", a
contraption on top of the bridge with a wide view to all sides (A somewhat
unsafe place to sit when the cloud of Kelp Gulls is in place, for obvious
reasons), the picture changes completely. Here, one sees the birds that do
not bother to hang around the ship for hours. And suddenly it appears that
the most common seabird of all is apparently the Cory's Shearwater ("A
Great Shearwater washed in too hot water"). These birds are everywhere,
sitting on the water till the ship is almost on top of them, and then
stretching their long necks and yellow bills and pattering out of harms's
way, often helped by their own jetstream. Small Sabine's Gulls fly
determinedly from nowhere to nowhere and do not bother about the ship, and
Gannets sit on the water, shine whitely in the distance, or even now and
then show off their fantastic fishing techniques, dive-bombing in a frenzy,
and looking for all the world like one of the better TV documentaries. A
few phalaropes skitter out of the way, looking as ever most incongruent
"little bird on a big sea"-like, even more almost than the storm petrels.
And always the White-chinned Petrels and albatrosses interminably circle
around the ship and cross before the bow.
With perpetually sunny days, mild temperatures, white-caps enough to make
the sea a wonderful study of white against all the myriad colours of the
water itself, but not too much to inconvenience the not too "sea-fast"
birder, trawling on the Agulhas bank can be a great experience, even apart
from the marine biology, which of course also was overwhelming. Tusen takk
therefore to the South African Fisheries Institute, to Chief Scientist Rob
Leslie and the other people on the Africana, and particularly to my host
Michelle van der Merwe of the South African Museum, for making this dream
come true.
List of species seen order follows SASOL-guide):
Jackass penguin Spheniscus demersus
Shy Albatross Diomedea cauta
Blackbrowed Albatross D. melanophrys
Yellownosed Albatross D. c.chlororhynchus
D. c. bassi
Southern Giant Petrel Macronectes giganteus
Northern Giant Petrel M. halli
Whitechinned Petrel Procellaria aequinoctialis
Spectacled Petrel P. conspicillata
Sooty Shearwater Puffinus griseus
Greatwinged Petrel Pterodroma macroptera
Cory's Shearwater Calonectris diomedea
Great Shearwater Puffinus gravis
Manx Shearwater P. puffinus
Wilson's Storm Petrel Oceanites oceanicus
Leach's Storm Petrel Oceanodroma leucorhoa (1 only)
European Storm Petrel Hydrobates pelagicus
Cape Gannet Morus capensis
(Whitebreasted Cormorant Phalacrocorax carbo) missed that one!
Bank Cormorant Ph. neglectus (mostly inshore)
Cape Cormorant Ph. capensis (mostly inshore
Crowned Cormorant Ph. coronatus (inshore)
Grey Phalarope Phalaropus fulicarius
Subantarctic Skua Cataracta antarctica
South Polar Skua C. maccormicki
Pomarine Skua Stercorarius pomarinus
Arctic Skua S. parasiticus
Longtailed Skua S. longicaudus
Kelp Gull Larus dominicanus
Sabine's Gull L. sabini
Hartlaub's Gull L. hartlaubii (harbours only)
Swift Tern Sterna bergii (inshore)
Sandwich Tern S. sandvicensis (inshore)
Common Tern S. hirundo (mostly inshore)
Arctic Tern S. paradisaea
Wim Vader, Tromsø Museum
9037 Tromsø, Norway
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