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This page describes highlights of some of the cetacean encounters
experienced during the 2009 field season |
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Please
also visit our field note archives from 2003 to 2008 by
clicking on the links below:
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3 May
2009: Chanonry Point, Moray Firth, Scotland
17:49 GMT
"Chanonry
Point is probably the best place in the UK for getting regular close views
of dolphins. The spit extends out into the narrow channel of the inner
Moray Firth, creating strong tidal rips where salmon congregate. Never
slow to take advantage of an easy meal, the local bottlenose dolphin
community is well aware of this excellent feeding potential and congregate
off the point an hour or two prior to high tide when the tidal rips are
strongest. Today, there are round six dolphins feeding off the point,
including a mother and calf pair and several other adults. The
mother-calf pair are tightly associated and surface repeatedly around 10 m
off the point where the adult is enjoying considerable success at catching
fish. Almost every time she surfaces, her mouth is open revealing the
flesh of some unlucky salmon caught between the rows of her conical teeth.
Further out, the adult dolphins are cooperating to herd fish in more open
water, diving repeatedly to reveal their tail stocks and then herding fish
in towards each other. Occasionally this technique results in frenzied
fish chases, the water being churned up into frothy white by the dolphins
manoeuvring just below the surface. The dolphins are not as aerially
active today as I have seen them on other occasions in the past, but we are still
treated to some of the characteristic high bottlenose leaps, with animals
powering themselves vertically from the water and re-entering head first in
a clean arc. The 15 or so people bravely standing at the point in the
chilly wind cheer in response to every leap".
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16 March
2009: Walvis Bay, Namibia
13:28 GMT
"We have
been told a group of around 20 dolphins has stranded alive in the
lagoon, and as we finally drive around a bend in the road and see them I
am shocked at the scene ahead. Out in the middle of the lagoon are
a scattered pod of large dolphins, some on their sides thrashing the
shallow water with their tails and others lying quietly on their
bellies. People have already arrived and most of the animals are
accompanied by at least one human carer.
As we park the
car and move out over the sand towards the dolphins, it becomes clear that
this will be no easy mission. The sand quickly changes into a thick
slimy mud more than knee-deep in places - not the sort of habitat you want
to carry cameras and other equipment! Furthermore, the dolphins are
quickly identifiable as bottlenose dolphins - one of the largest dolphin
species and with adults measuring around 3.5 m and potentially weighing up
to 500 kg! As we near the animals I can hear a multitude of
high-pitched whistles - the piercing tonal cries of distressed dolphins
which are highly audible in the air all around. The regular sharp
exhalations of the dolphins also breaks the silence. It looks like we
will be here for some time, since the high tide is not due for another 6 hr
and even at its highest the water depth here is only a metre or so. I
concentrate firstly on collecting some data - dolphins off Namibia are
rather poorly studied but the
Namibian Dolphin Project established a
photo-identification catalogue of identifiable bottlenose dolphins last year
and they are keen to know which individuals are present here. I wade
carefully through the mud around the stranded animals and try to obtain a
clear photograph of the left and right sides of the dorsal fins. The
nicks, notches and scars on the fins will allow us to match the dolphins to
the animals in the existing catalogue. It's no easy task...time and
time again the camera gets misted by the exhalations of the dolphins blown
towards me on the wind, and several times I have to move quickly out of the
way of thrashing tails. The mud itself makes manoeuvring around the
animals very difficult, and its a slow and tedious process to document all
19 individuals.
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Moving around
the dolphins I notice that most of the whistling is actually coming from one
group of animals - a pair of large adults and three small calves including
one very young animal. The calves whistle loudly and continuously,
slapping their tailstocks vigorously and clearly in distress. No-one
knows which adults the calves belong with, since they were stranded
separately and moved to the nearest adults. Quite possibly one of the
adults further up the lagoon which never stops thrashing throughout the
stranding was the mother of one of them. Unfortunately, the youngest
calf suddenly stopped breathing after an hour or two, and could not be
saved.
Once I finish
collecting the photo-identification data, I go and sit with a dolphin and do
my best to keep it's skin moist and stop it from burning in the wind and
sun. We also dig out the mud from under their bellies and flippers to make
them more comfortable. Otherwise, it is a waiting game for the tide.
The initial enthusiasm of the human volunteers begins to wane after a few
hours, as people begin to get cold and the water shows no signs of rising.
Some of the dolphins are suspiciously quiet, and its hard to imagine what
kind of strain they must be under in this unfamiliar predicament. Some
thoughtful people wade through the mud to distribute flasks of coffee and
baskets of sandwiches which is a definite moment of relief for everyone
sitting in the water!"
Several hours
later the tide finally rose sufficiently for the dolphins to be manoeuvred
into slightly deeper water. Once their bellies were clear of the mud
the dolphins moved themselves, propelling themselves through the shallow
water with powerful thrusts of their tails and re-grouping into their
preferred social units. Most of the animals found their way out of the
lagoon and were not seen again during the subsequent days. One adult
re-stranded overnight and had to be taken by vehicle to a suitable release
beach in Walvis Bay the next day where it swam away strongly.
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5 March
2009: Walvis Bay, Namibia, research boat
11:33 GMT
"There
are dolphins galore here today...almost everywhere we look small pods of
Heaviside's dolphins are leaping and splashing as they feed amongst
flocks of terns. We have already spent over an hour approaching
small groups to photograph their dorsal fins, and still there are many
more dolphins spread out ahead of us. Most of the animals are busy
foraging and don't pay much attention to our boat, but the occasional
small group break away from their feeding and swim rapidly towards us to
bow-ride at the front of the boat. At the moment we have a group
of around 10 dolphins playing around the boat - this is the most
interactive group we have encountered today and they seem content to
surf the swell waves alongside the boat for a prolonged duration,
sometimes rushing ahead to ride the bow-wave.
The sharp exhalations of surfacing dolphins are all
around us.
One or two
dolphins swim immediately next to the engine propellers, appearing almost
stationary in the water as they keep level with the boat's slow speed.
Others get bored with the sedate pace and swim rapidly away in a wide loop
to race back to the bow again with seemingly endless energy".
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4 March
2009: Walvis Bay, Namibia, research boat
11:09 GMT
"The
boat operators here have been reporting leatherback turtle sightings in
the centre of the bay, with several sightings per day during the calm
weather in the morning before the afternoon wind picks up. We are
out in the centre of the bay where most of the sightings have occurred,
and it is not long before the large head and distinctive dorsal ridges
of a leatherback roll at the surface. This is a big animal, and
with the engine off we can clearly hear the sharp exhalation of its
breath as it breathes at the surface between dives. Not much
further on, and two more leatherbacks appear at the surface ahead of our
boat. Unlike the previous turtle, these ones seem to be resting at
the surface and we edge the boat forwards to try and get a closer look.
One of the leatherbacks allows us to
approach to within a couple of metres before taking a final breath,
raising its flippers and diving down into the murky water and out of
sight".
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3 March
2009: Walvis Bay, Namibia, research boat
09:10 GMT
"This
morning we have been tracking the same group of bottlenose dolphins that
we were watching yesterday in the lagoon, and they are once again
showing how adept they are at hunting in the shallows. This time
they are close in off a sandy beach, feeding close to a group of
fishermen who are beach seining. The dolphins seem to take
advantage of the human fishing operation, giving the fishermen a lesson
in catching fish as they chase fish into the shallows and trap them
against the beach.
Today the
dolphins are feeding individually rather than herding the fish
cooperatively, but the scene is still impressive as some individuals almost
strand on the beach in pursuit of their prey".
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2 March
2009: Walvis Bay, Namibia, research boat
11:17 GMT
"A group
of five bottlenose dolphins are patrolling the lagoon, entering water
shallower than 1 m depth in their efforts to locate and herd fish.
As we watch, the dolphins circle a shoal of fish and then drive it
rapidly in towards the narrow beach, almost stranding themselves as they
manoeuvre in the shallows. The fish erupt into the air in an
attempt to escape both the dolphins and the beach, and the dorsal fins
of the dolphins turn in rapid circles at the surface as the animals
chase the fish and then move back out into slightly deeper water.
We watch the
group for several hours, and they repeatedly perform this same coordinated
hunting behaviour, rushing in towards the shore with fish flying out of the
water ahead of them. Bottlenose dolphins never fail to produce
something fascinating for us to look at!".
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2 March
2009: Walvis Bay, Namibia, research boat
08:33 GMT
"The
dolphins are in a playful mood this morning - a small group of
Heaviside's dolphins charge through the grey swell to greet our boat,
and spend several minutes bursting out of the water in fast surges on
either side of us. It's practically impossible to photograph them
when they are behaving so unpredictably, and the overcast sky doesn't
help since we can't track the animals as they move along underwater due
to the dark sea.
Despite the
overcast conditions the beautiful markings on
the dolphins show up clearly - the pale grey forward portion of the dolphins
stands out against the sharply-demarcated darker grey-black cape that
extends over the rear part of their bodies. The dolphins also raise
their heads out of the waves during some surfacings to reveal their small,
indistinct beaks and conical heads. Although the encounter is brief it
is memorable for the energy these small dolphins have".
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1 March
2009: Walvis Bay, Namibia, research
boat
09:02 GMT
"A
group of feeding terns catches my eye off our port bow, and as I scan
the area with binoculars a long back and small stubby dorsal fin roll
slowly at the surface underneath them. A humpback whale is
travelling beneath the birds, although we can't determine whether the
whale is actually feeding or not. It is an unusual time of year
for a humpback to be present in this region, as most should be further
south on the feeding grounds at present. The whale itself also
looks unusual - it is rather small and its back and sides are covered in
small white scars.
We take the opportunity to approach the animal to photograph it's dorsal fin
and strange flank markings. The whale isn't fluking so we aren't able
to get images of the tail flukes which might help to match the whale to
existing catalogues for West Africa to determine where it originates from.
But the animal is certainly distinctive enough to be recognised again
without too much trouble".
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1 March
2009: Walvis Bay, Namibia, research
boat
07:09 GMT
"If
I didn't know better I would think I was in the North Sea on a summers
day watching harbour porpoises. But although they look slightly
similar, the small cetaceans I am watching are not porpoises - they are
Heaviside's dolphins, with their distinctive tall triangular fins and
marked colouration pattern. The two dolphins are apparently
foraging in the glassy seas, with dives of several minutes interspersed
with several quick rolls at the surface.
They are mostly indifferent towards our research boat today, obviously too
busy searching for food to come and bow-ride. So we concentrate on
getting usable photo-identification images of their dorsal fins for adding
to the
Namibian Dolphin project catalogue".
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Ketos
Ecology ©
2009
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