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The island of Mull is unique with its vast diversity
and spectacular splendour of its landscape and wild life. The beautiful
rugged Hebridean terrain and maritime influences give rise to micro
climates on either side of the mountainous centre of the Isle of Mull.
On the mountains and to the east of Mull, we have one of the wettest
places in Scotland. On the west coast and particularly on the Ross of
Mull (south west peninsula of Mull) and Iona in the spring and summer
there are long, sunny, breezy days to allow you to walk the white powder
beaches and explore the wonderful natural history on the many coastal
walks in the area. See walks and
beaches.
The Ross of Mull where Seaview
is situated has a similar climate to the island of Tiree (20miles west
of Mull) , which is one of the sunniest places in the UK.
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Below are photographs
taken of our resident wild life on Mull accompanied by narrative of some of the animals and birds you are likely
to encounter on your travels around the Ross of Mull, as well as on the
isles of Iona, Staffa and Lunga.
EAGLES ON 'EAGLE ISLAND'
The Isle of Mull is one of the best locations in the UK to see
eagles - golden eagles (Aquila Chrysaetos) and the largest
eagle, the white tailed sea eagle (Haliaeetus albicilla).
The Golden Eagle
is a large, supremely elegant raptor
favouring Mull's remote mountains and crags and is often seen as a dot
in the distance soaring over a high ridge. Despite this, its wide slow
circling flight is often sufficient to recognise it. A good telescope
helps too! In the May to June breeding season the eagles are territorial
and are often chased by ravens and crows.
The Golden Eagle soars with wings raised in a shallow 'V' shape. The
adult eagle has a dark brown body, tawny to golden crown, heavy
feathered legs and a long tail. Juvenile birds have extensive white
areas on the wings. Hunting on remote peaks and uplands of Mull,
occasionally visiting coastal cliffs,
(photo
courtesy of VisitScotland) the eagles prey includes crows,
mountain hares and rabbits, in winter carcasses of sheep or deer. There
are a number of pairs on the Ross of Mull and John & Jane can give you
an indication of where you are likely to view them.
Sea Eagle - Gaelic: Iolaire-suile-na-grein - 'Eagle with the
sunlit eye'
The
Sea Eagle is enormous and is the largest bird in the UK, up to
35% larger than its cousin the Golden Eagle with a wing span of over 2.5
metres.
The foremost and easiest place to see Sea Eagles in the UK is on
Mull; there are a number of sea eagles on the south of Mull just a few
miles from Seaview. John & Jane can advise you on the likeliest place to
see them. On Mull, the sea Eagle usually nests on a the flat crown of a
tree, building the nest with a huge pile of sticks. Sea Eagle chicks
usually hatch from late April onwards and fly the nest in July or early
August. In south Mull there are a number of pairs who hunt for dead or sick
fish from the sea lochs picking them out of the water with their feet.
They also eat hares and rabbits. When mating you often see dynamic
aerobatics including mid air tumbles.
(Photograph courtesy of Bryan Rains @
WildaboutMull)
Adult Sea Eagles have heavy striking yellow bills and a
large whitish head with a white, short but distinctive fan shaped tail.
Its wings are wider and longer than the juvenile. Young Sea Eagles are
dark with the white tail and head developing towards maturity at five
years of age. Sea Eagles are rarely far from water, perching on dead trees, rocks
by the shore or soaring over a sea loch. They are less wary of humans
than golden eagles and can often be seen at fairly close quarters.
RSPB White Tailed
Sea Eagle Viewing Centre
at Loch Frisa, Isle of Mull.
Open from April to mid July.
Meeting Place: North end of the Forestry Commission Loch Frisa track
between Tobermory and Dervaig on the B8073.
Early booking advisable on Tel: (01688) 302038 from mid March
onwards or pick up a leaflet at Seaview for details on how to get there.
Cost: £4 for adults £2 for children. For further information about
the sea eagles and the tracking project the RSPB is doing please click
here |
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THE OTTER
ON MULL
The Isle of Mull and the Ross of
Mull in particular is one of the best places to see the otter - Lutra
Lutra or Eurasian Otter. The Gaelic name is Biast Dubh
meaning 'black skin or fur'. Unusually the Mull Otter is a day or
night hunter and the main influence on it's decision to hunt is the
tide. (Photograph
© Bryan Rains)
The otter has a long slim body, a flat skull with powerful jaws, webbed
toes, and a rudder like tail used for under water propulsion. Otters can
close their ears and nostrils when under the water. There are two layers
of fur; stout waterproof hairs and a tick under layer of fur providing
insulation. The fur is a chestnut brown in colour with a lighter colour
on the belly. The otter needs access to fresh water burns to clean their
insulating fur. An otter's diet comprises of a mixture of fish, crabs,
lobster, birds & frogs; the Ross of Mull has many features which are
ideal for otter habitat especially the many bays with seaweed and rocks
along with the freshwater burns running into the lochs. Over the years
John has seen evidence of otters in most areas of the Ross of Mull
coastline. The best time to see the Mull otter is usually on an
incoming tide from low water towards high water, just offshore where you
can watch them swimming in the seaweed or running on the rocks &
seaweed. Towards high tide the otters retreat to their holt.There is no guarantee that you will see an otter on
any particular day or place - however with patience, perseverance and
cunning you just might! |
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THE ILLUSIVE CORNCRAKE
Crex Crex
The
corncrake Garra-gart in Gaelic is from the same family as the
moorhen or coot but differs in that it prefers dry land. Although
scarce, the corncrake is making a comeback on the Scottish Islands,
especially on Iona and here on the Ross of Mull (Fidden), due to the
farmers cutting the hayfields later in the season. This allows the
corncrake to breed without being disturbed.
The Isle of Iona in particular has seen an increase in the numbers of
corncrake and they are now spreading outwards to Fidden and Creich on
the Ross of Mull. All these locations are easily accessible from
Seaview. There are also corncrakes on the Treshnish Isles (see
Treshnish Trips).
The corncrake arrives from mid April onwards from as far away as Africa
crossing the Sahara desert enroute to the western isles of Scotland and
then leaves again in August. In flight the corncrakes bright chestnut
coloured wings and trailing legs are unmistakeable. They nest in hollows
at ground level in the reeds, iris beds and meadows.
Generally a solitary bird except when nesting it is reclusive and
secretive hiding in tall reeds, grass and yellow iris in damp areas in
fields around Iona village and Abbey. The corncrake's presence is
betrayed by a rasping 'crek crek' call (which sounds like a very loud
grasshopper!) and by May and June they are heard in the very early
morning and evening throughout Iona. You are more likely to hear them
than see them, but if you are patient enough and are prepared to sit and
wait you will be rewarded with a sighting.
Don't take the car - you can't on Iona anyway, but
listen! listen! listen! Once you have identified the area the call is
coming from, then watch! watch! watch!. Silence and patience is the key
to success.
The photograph of the corncrake was taken by Jane
in the summer of 2005 when she was on Lunga. At the time Jane was
returning to the boat and whilst coming down the path towards the beach
she could hear this very loud rasping grasshopper sound coming from the
tall grass and undergrowth nearby..............and then as bold as you
like a corncrake appeared and continued to make this awful racket. Not
quite believing her luck, Jane captured the bird on camera by simply
pointing the camera and clicking away whilst gently walking towards it,
hoping that at least one of the photographs would come out clear enough
to prove she had seen and not just heard this rather elusive bird! Talk
about beginner's luck! |
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SEALS
AROUND OUR COAST
The
Common Seal Phocca Vitulina and the Grey or
Atlantic Seal Halichoerus grypus are found around the
coastline of Mull and the surrounding remote islands.
The Common Seal has a blunt or flattish head, while the Grey Seal has a
more pronounced nose or snout. The Common Seal have their young in the
summer, and the Grey Seals have their white furry pups in the autumn.
The seals you usually see basking on the rocks around the Ross of Mull
at Fidden, Erraid and Red Bay are Common Seals. John is able to help you
in locating and viewing the seals.
Common Seals are well camouflaged for their environment living ashore in
sheltered waters around the Ross of Mull. The young seal pups are born
in July/July and have sleek coats and flippers; within a coupe of hours
they are able to swim and for a couple of months swim close to their
mother.
Sammy the seal, an old fat seal with a scar across its back is
resident at Fionnphort pier and is fed by local fishermen. He waits
until he hears the fishing boats coming in, either to moor up for the
day or to land their catch and then Sammy makes his appearance.
He has become a great summer attraction for visitors old and young
alike. This photograph shows John feeding Sammy some 'Fingal's
Breakfast' many summers ago. When we last saw Sammy he was accompanied
by a 'friend' but we don't know if it was male or female. Either way
Sammy is obviously passing on his knowledge of 'fishing'
Grey
Seals, during birth and breeding times generally come together in the
offshore islands around the Ross of Mull and Treshnish isles in
September through to November. Three weeks after giving birth the
females conceive again. The mothers come ashore during this time to feed
the beached white furry pups. In this time the pup puts on an enormous
amount of weight due to the rich milk. The pup then quickly fends for
itself, learns to swim, and loses it white fur quickly developing its
adult sea going coat.
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EVERYONES
FAVOURITE - PUFFINS
Puffins are members of the Auk family or Alcidae. In Britain
there are three other members of this family who nest around our shores
- the Guillemot, Razorbill and Black Guillemot. The puffin that visits
us here on Staffa and the other Treshnish Isles is the Atlantic
Puffin.
This wee fella, is about 30 cm tall and has a wing span of about 45
cm; it is black above and white below with a white face; the plumage is
similar for both male and female. The bill is spectacular - brightly
coloured and ridged in summer, orange, red, yellow and blue. The eye is
brown and surrounded by a bright red ring; above and below the eye are
hard pieces of grey skin and behind the eye is a distinct crease in the
feathers. The legs and feet are red with black toenails.
The Puffin walks in an upright position which gives it
a Penguin like stance and it is adept at swimming under water, using its
wings half folded. The wings are small for the size and weight of the
bird and this means that Puffins have to flap very fast, between 300-400
beats a minute, to keep themselves airborne.
Puffins are expert at gliding into high winds on the
cliffs and manoeuvre using their feet as rudders - they are not
particularly graceful at landing, very often crash landing into the
scrub on the cliffs.
In the winter, the plumage is quite different - much less colourful,
but as they are far out to sea in the winter months they are rarely
observed. The Puffins return to land in late March or early April.
Puffin colonies can be on flat grassy topped islands
or cliff tops, grassy slopes, vegetated cliffs and even in crannies and
among boulders. The islands around Mull are in fact ideal nesting sites.
Puffins nest underground, unlike their cousins the Razorbills and
Guillemots. They excavate a burrow, approximately 2 metres long, a bit
like a rabbit burrow and at the end is the nesting chamber where they
lay a single white egg.
Many of the burrows are used year after year and as long as they return
early and have survived the winter, the same pair of Puffins tend to
come back to the same burrow. At other times, a new pair must excavate a
fresh burrow in the cliff, usually at the edge of a large colony.
Puffins are skilled miners: they have sharp powerful bills which pull at
the soil and turf and the claws on their bright red feet are extremely
strong and sharp. It takes many days to dig a new burrow so new pairs
are keen where possible to use unoccupied burrows.
Puffins often nest near rabbits - sometimes they take
over rabbit burrows. As burrows are being refurbished or new burrows
excavated, display among the Puffins increases daily. The pair is
together nearly all of the time; the male is slightly bigger and his
bill is larger, brighter and ore distinctly ridged. The main display
between the pair is billing and cooing with the birds touching bills
and gently nibbling each other's head and neck feathers.
Mating takes place on the sea after the male has goner through a
ritual of head flicking and wing fluttering. A single egg is laid in
the nest chamber and is incubated by both parents which lasts
between 38-43 days. Puffins coming ashore with fish in their bills
are the first signs that the eggs have begun to hatch.
The chick is very small on hatching and is covered with fluffy black
down. In the early days the chick is brooded by one of the parents
to keep it warm and dry but is soon left unattended as both parents
go out to sea fishing. The chick is fed in the nest to start with
but at a couple of weeks old it starts to meet its parents at the
mouth of the burrow. Chicks grow rapidly and at six weeks old it is
fully feathered; at this time the chick starts to come out of the
burrow at night and then finally one night at about 7 weeks it
leaves the burrow altogether and flies out to sea.
Information courtesy of Roy Dennis's book 'Puffins'; photographs
taken by John & Jane Noddings, Bob Winnings & Roger Morgan
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DEER
There are three species of deer on Mull - red,
roe deer and fallow deer. The most common of the three species you are
likely to see is the red deer - these are quite active at dusk and dawn
as they come down from the hills to graze in more open land; during the
winter months the deer come down from the mountains to forage on the
lower ground and you are very likely to see them whilst driving through
Glen More. Species information supplied courtesy of
The British
Deer Society
RED DEER (Cervus
elaphus)
The
Red Deer is the largest land-mammal in the UK. Summer coat is reddish
brown to brown, winter coat is brown to grey. No spots present in adult
coat. Large, highly branched antlers in the stag (male).
Adult size: Stags 90-190kg, 107-137cm at shoulder. Females
(hinds) 63-120kg, up to 107-122cm at shoulder.
Antlers: Highly branched. The number of branches increases with
age. Up to 16 points in native animals. The angle between the brow tine
and the main beam is always more than 90 degrees.
Life span: Exceptionally up to 18 years. Heavy infant mortality
at and shortly after birth and during first winter in some Scottish hill
populations.
Habitat: Within its range in England and southern Scotland occurs
in woodlands and forests but can adapt to open moor and hill on Scottish
hills and south-west England.
Food & feeding: Grazers of grasses, and dwarf shrubs e.g. heather
and bilberry. Woody browse, e.g. tree shoots, is taken when other food
is limiting e.g. during winter
Origins
& history: Red deer migrated into Britain from Europe 11000 years
ago. They were used extensively by Mesolithic man as a source of food,
skins and tools (bones and antlers). Neolithic man developed agriculture
and cleared swathes of forest to make way for fields. This loss of
forest encouraged the decline of red deer populations, which became
confined to the Scottish Highlands, south-west England and a few other
small, scattered populations. The Normans protected red deer in parks
and "forests" (often devoid of trees!) for royal hunting, but this
protection was lost during the Mediaeval period causing another decline
in numbers in England. Victorian re-introductions of "improved" stock
(often inter-bred with larger related species such as Wapiti), escapes
from deer parks, natural spread and increase in the Highlands and an
increase in forest and woodland cover since the early 20th century mean
that red deer are now widely distributed in Britain and are expanding in
range and number.
Social
organisation: In woodlands red deer are largely solitary or occur as
mother and calf groups. On open ground, larger, single sex groups
assemble, only mixing during the rut and in the Highlands of Scotland
large groups may persist for most of the year.
Vocalisation: Stags roar and grunt during the rut. Hinds bark when
alarmed and moo when searching for their young. Calves emit a
high-pitched squeal when alarmed and may bleat to their mother.
The rut: The breeding season, or rut, occurs from the end of
September to November. Stags return to hind's home ranges and compete
for access to hinds by engaging in elaborate displays of dominance
including roaring, parallel walks and fighting. Serious injury and death
can result but fighting only occurs between stags of similar size that
can not assess dominance by any of the other means. The dominant stag
then ensures exclusive mating with the hinds.
Breeding:
Only stags over 5 years old tend to achieve matings despite being
sexually mature much earlier (before their 2nd birthday in productive
woodland populations). In woodland populations hinds over a year old
give birth to a single calf after an 8 month gestation, between mid-May
to mid-July each year. Puberty may be delayed until 3 years old in hill
hinds, which may give birth only once every 2 or 3 years.
Activity: Red deer are active throughout the 24-hour period but
make more use of open spaces during the hours of darkness in populations
experiencing frequent disturbance. Peak times of activity are at dawn
and dusk. In the Highlands of Scotland red deer use the open hill during
the day and descend to lower ground during the night.
Economic factors: Grazing of tree shoots and agricultural crops
puts red deer in conflict with farmers and foresters due to economic
damage. Conversely, many country and forest estates can gain substantial
revenue from recreational stalking and/or venison production. Red deer
are also farmed for their venison and are kept as ornamental park
species in the UK. Whether in conflict or used as a resource, red deer
populations require careful management to maintain health and quality
and ensure a sustainable balance with their environment.
ROE DEER (Capreolus capreolus) Image supplied courtesy of
The British Deer Society
Adult
Size: 10 to 25kg, 60 to 75cm at shoulder (bucks - males slightly
larger than does - females).
Colouration: Summer: reddish brown. Winter: grey, pale brown or
(occasionally) black.
Antlers: Rugose, short (<30cm), 3 tines (points) on each.
Lifespan: Max: 16 years. Bucks rarely exceed 5 years, does 6 to 7
years. Heavy mortality at and shortly after birth and during first
winter.
Social groups: Solitary, forming small groups in winter.
Time of birth: May to June.
Number of offspring: Up to 3, usually 1 or 2 kids.
Gestation period: 9 months (4 months of no embryonic growth
followed by 5 months of foetal growth).
Food & feeding: Browsers that actively select different food
types including herbs, brambles, ivy, heather, bilberry & coniferous
tree shoots.
Habitat: Woodland and forest, but may occupy fields when at high
densities.
Status: Common & widespread. UK Distribution. Throughout Scotland
and England except parts of Kent and the Midlands.
Recognition: Small & elegant. White rump patch with short tush in
females. Black nose, white chin.
Origins & history: Roe deer are native to Britain, having been
present since before the Mesolithic period (6000 to 10000 years b.p.).
Forest clearance and over-hunting led to roe deer becoming extinct in
England by 1800 but remained in wooded patches in Scotland. Several
reintroductions during Victorian times and their subsequent, natural
spread aided by an increase in woodland and forest planting in the 20th
century has meant that roe deer have become widespread and abundant
today.
The rut: The rut, or breeding season, occurs between mid-July to
mid-August. Bucks become aggressive and maintain exclusive territories
around one or more does prior to this period. Fights between bucks can
result in serious injury or death, the winner taking over the losers
territory or attendant doe. Does do not maintain exclusive territories
but live within overlapping home ranges. Males usually mate with several
females and females mating with several males has also been observed.
Courtship involves chasing between the buck and doe for some time until
the doe is ready to mate.
Activity: Roe deer are active throughout the 24-hour period but
make more use of open spaces during the hours of darkness in populations
experiencing frequent disturbance. Peak times of activity are at dawn
and dusk. Long periods are spent "lying up", which is where the deer
lies down to ruminate between feeding bouts.
Economic factors: Browsing of tree shoots and agricultural crops
puts roe deer in conflict with farmers and foresters due to economic
damage. Conversely, many country and forest estates can gain substantial
revenue from recreational stalking and/or venison production. Whether in
conflict or used as a resource, roe deer populations require careful
management to maintain health and quality and to ensure a sustainable
balance with their environment.
Vocalisation: When alarmed bucks and does (males and females)
give a short bark, which is often repeated. During the rut does make a
high-pitched piping call to attract a buck who makes a rasping noise as
he courts the doe.
Delayed implantation: Although mating occurs in August the
fertilised egg does not implant and grow until January. This is thought
to be an adaptation to avoid giving birth during harsh northern winters.
FALLOW DEER (Dama dama)
Recognition:
Intermediate in size between roe and red deer. There are four main
variations in coat but many minor variations also exist including a
long-haired version found in Mortimer forest, Shropshire. The common
variety is the familiar tan/fawn colour with white spotting (becoming
long and grey with indistinct spots in winter) on the flanks and white
rump patch outlined with characteristic black horse-shoe. The Menil
variety is paler, lacks the black bordered rump and keeps its white
spots all year. The black variety is almost entirely black with no white
coloration anywhere. Finally, the white variety can be white to sandy
coloured and becomes more white at adulthood. This is a true colour
variety and not albinism, which is rare. The fallow is the only British
deer with palmate antlers.
Adult size: Bucks (males): 84 to 94cm at shoulder, 46 to 94kg.
Does (females): 73 to 91cm at shoulder, 35 to 56kg.
Antlers: Palmate in adult (>3 years), increase in size with age,
up to 70cm long.
Life span: Exceptionally, 16 years, bucks (males) rarely exceed 8
to 10 years.
Status: Non-native but considered naturalised. Locally abundant
and increasing.
UK distribution: Widespread in England and Wales, patchy in
Scotland.
Habitat: Mature broadleaf woodland with under-storey, open
coniferous woodland, open agricultural land.
Food & feeding: Preferential grazers of grasses although trees
and dwarf shrub shoots will be taken during autumn and winter.
Origins & history: The extant species of fallow deer found in
Britain was introduced by the Normans in the 10th century although some
would suggest that the Romans attempted to introduce it here much
earlier. Fallow deer were prized as ornamental species and were
protected in Royal Hunting "Forests" for royal sport. During Mediaeval
times many deer parks that held fallow deer were established and these
and more recent park escapees have given rise to the free-living
populations in Britain today.
Social Organisation: Group sizes as well as the degree of sexual
segregation varies according to population density and habitat. Groups
of adult males and females, usually with young, remain apart for most of
the year in large woodlands, only coming together to breed. Sexes freely
mix in large herds throughout the year in open, agricultural
environments.
Vocalisation: During the rut bucks groan tremendously and does
with fawns give a short bark when alarmed.
The rut: Behaviour is dependent upon the environment and
population density. In most populations bucks maintain a traditional,
defended rutting stand. In others a temporary rutting stand is
maintained to attract sufficient does to herd them into a harem. In
areas with very high buck densities a lek may be formed. In lower
density areas bucks may simply seek out receptive females. During
conflict, the escalation of display behaviour in bucks, from groaning
and parallel walks to fighting, is in common with other larger species
of deer.
Breeding: Adult does give birth to a single fawn in June after a
gestation of 229 days.
Activity: Fallow deer are active throughout the 24-hour period
but make more use of open spaces during the hours of darkness in
populations experiencing frequent disturbance. Peak times of activity
are at dawn and dusk. Most hours of the day time are spent "lying up",
which is where the deer lies down to ruminate between feeding bouts.
Economic factors: Browsing of tree shoots and agricultural crops
puts fallow deer in conflict with farmers and foresters due to the
potential economic damage. Their propensity for reaching very high local
densities can result in high local levels of damage. Conversely, many
country and forest estates can gain substantial revenue from
recreational stalking and/or venison production. Fallow deer are also
farmed for their venison and are one of the most important ornamental
park species in the UK. Whether in conflict or used as a resource,
fallow deer populations require careful management to maintain health
and quality and ensure a sustainable balance with their environment. |
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WHALES, DOLPHINS & PORPOISES AROUND OUR SHORES
This
information has been provided directly
from the website of the
Hebridean Whale & Dolphin Trust
which is a small charity based in
Tobermory. The Trust employ several
members of staff and volunteers who
conduct research, provide education and
carry out important conservation work of
several of our cetaceans found around
the shores of the west coast of
Scotland.
WHAT IS A CETACEAN?
Whales, dolphins and porpoises belong to
a single group of marine mammals called
the cetaceans (order Cetacea). The word
cetacean comes from the Latin ‘cetus’
meaning large sea creature, and the
ancient Greek ‘ketos’ meaning
sea monster. Cetaceans are marine
mammals that evolved from their land
mammal ancestors around 55 - 60 million
years ago and have adapted perfectly to
an aquatic life during this time. There
are currently about 83 species of whale,
dolphin and porpoise in the world, but
new species are still being discovered;
24 of these have been recorded in the
waters off western Scotland.
Cetaceans are mammals that are insulated
by a thick layer of blubber (fat) in
order to maintain a body temperature of
about 37°C. They surface to breathe air
through their blowholes, which close
automatically below water. Most species
have a dorsal (back) fin, ranging from a
small bump on a sperm whale to a tall
killer whale fin; all species have two
pectoral (side) fins and a fluke (tail).
Cetaceans are divided into two
groups:
Odontocetes – the toothed
cetaceans, containing about 70 species
of whale, dolphin and porpoise. As well
as teeth, all species have a single
blowhole. Odontocetes use echolocation
to find food and to navigate. The most
numerous family is the Delphinidae,
which includes all of the oceanic
dolphins.
Mysticetes – the baleen
cetaceans, containing about 13 species.
Instead of teeth, all species have
baleen plates growing from their upper
jaw which sieve prey such as small
schooling fish and plankton from the
water. Baleen is made from keratin, the
same substance as human hair and
fingernails. Mysticetes have two
blowholes and are not known to
echolocate.
Cetaceans and Sound
Sound is very
important to all cetaceans: they have
sensitive hearing and use a range of
sounds to communicate, to locate food,
to avoid predators and to navigate.
Vocalisations can be divided into two
types:
1. Tonal calls, such as
whistles, ‘whale song’ and groans are
used chiefly for communication,
2. Clicks, either
singular or in bursts, are mainly used
to explore the environment and find
food.
Many cetaceans are highly vocal and
produce sound to communicate with one
another. These sounds range from simple
calls to keep a group together or to
display aggression, to more complex
repertoires displayed during breeding
seasons, such as the humpback whale
‘song’. Odontocetes have developed
sophisticated echolocation systems,
where sound emitted in a directional
beam hits an object and the ‘echo’ that
returns allows the cetacean to locate,
identify and range the object.
Researchers onboard Silurian
can listen to and record the sounds made
by cetaceans; this means that animals
can be detected which are not visible,
either because they are underwater, or
because the environmental conditions,
such as a rough sea, make it hard to see
them.
Migration
All cetaceans
make daily movements in order to find
food. Some of the species seen in the
Hebrides, including the bottlenose
dolphin and the harbour porpoise, are
believed to be resident all year round
and occupy a range along the west coast
of Scotland. Others make seasonal
migrations between warm water breeding
grounds and cold water feeding grounds.
Minke whales and common dolphins,
amongst other species, are frequently
seen off western Scotland between May
and September taking advantage of the
abundant fish. Occasionally humpback
whales are seen in Hebridean waters;
these whales are known to make one of
the longest seasonal migrations between
breeding grounds off Africa to feeding
grounds around Iceland and Norway.
Reproduction
As mammals,
cetaceans give birth to live young
following a gestation period of between
8 and 16 months. A single calf is born
tail first and must be lifted to the
surface by its mother to breathe.
Cetaceans are social animals and other
females may offer assistance in lifting,
protecting and even feeding newborn
calves. Feeding on a fat-rich,
nutritious milk, growth is very fast.
For example, a newborn blue whale
consumes more than 100 litres of milk
per day and grows from roughly seven
metres at birth to 15 metres at seven
months of age. Calves stay close to
their mothers, and will suckle for
anywhere between several months to
several years, depending on the species
and the environmental circumstances. For
cetaceans in general, low reproductive
rates are offset by relatively long life
spans and high survivorship of calves
due to intensive parental care.
Life in the
Ocean
Cetaceans are
well-adapted to a life beneath the waves
having evolved for millions of years
from land mammal ancestors. The body is
streamlined to reduce drag and energy
usage; external features including the
ears and reproductive organs are tucked
inside the body behind slits; cetaceans
have no hind limbs although some
vestigial bone fragments of the pelvis
and legs can remain. Unlike land
mammals, cetaceans have do not have hair
(although some species may have a couple
of facial whiskers) or fur coats because
this would further increase drag. They
are instead covered in a thick layer of
blubber to keep them warm in the cold
sea. Their fore-flippers have a bone
structure similar to a human hand,
but bones are elongated and webbed with
skin to help with swimming. The dorsal
fin aids stability in the water and the
tail provides powerful propulsion by
beating up and down. The nasal openings
have migrated to the top of the head to
form one or two blowholes to make it
easier to breathe at the surface.
Cetaceans are able to dive to great
depths for extended periods to hunt for
food. Sperm whales can dive to depths of
2500 metres for up to two hours. They
are able to store huge amounts of oxygen
in their blood and muscles, and divert
oxygen to the brain and heart. The lungs
actually collapse under great pressure
during a deep dive; some whales are
thought to suffer from ‘the bends’
(decompression illness) if they surface
too rapidly.
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Last amended
08/01/2012
© 2000 - 2012 |
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