- Shortage of food for seabirds has led to a catastrophic
breeding season with some of the most important colonies containing thousands
of birds failing to fledge a single chick.
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- Scientists are alarmed that internationally important
colonies of seabirds are facing population crashes after years of poor
breeding success that seems to be rapidly worsening.
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- While overfishing may be a factor, the scientists believe
climate change may be the principal reason. Warming waters in the North
Sea mean that plankton, on which the food chain depends, are suffering
their own crisis. Warmer winter temperatures of as much a 3C mean that
normally abundant plankton species have virtually disappeared.
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- Three seabird species which together number half those
breeding in the UK - the northern fulmar, black-legged kittiwake and common
guillemot - have all declined as a result.
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- The Joint Nature Conservation Committee, official adviser
to the government, said that the fact that normally resilient guillemots
suffered such a dramatic food shortage in 2004 raised serious concern among
biologists that widespread changes in the marine ecosystem may be having
an impact on seabirds, the top predators.
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- The findings come on the eve of a controversial meeting
of the EU fisheries ministers whose job this week is to fix the annual
quotas for fish catches in European waters, particularly cod quotas in
the North Sea. They are set to reject European commission demands to close
large areas of the North Sea to fishing in a bid to protect fish stocks
- coincidentally the largest no-go area would be off Shetland where these
sea birds have suffered the worst declines.
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- The scientists say that the key prey species for all
these birds is the lesser sand eel. Its abundance is directly linked to
the quantity of plankton available in spring and summer.
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- Martin Heubeck, who carries out the Shetland Survey,
said: "These sea birds are very long-lived, maybe 20 to 30 years,
so a decline takes some time to show. If conditions are not right in any
year because there are not enough sand eels then many decide not to breed
at all but conserve their strength for another season. More and more have
been doing that but those that do decide to breed have been having little
success.
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- "Still worse the huge effort they put into trying
to successfully fledge chicks exhausts their own reserves, and many of
the adults die too."
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- This year thousands of dead adult guillemots have been
found on the coast of Scotland. Most normally moult immediately after breeding
in order to build themselves up for the winter but many of these had insufficient
reserves to complete the moult and died.
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- Mr Heubeck, of Aberdeen University, said some sea birds
like Arctic terns which bred in the Shetlands, sometimes producing thousands
of chicks, have turned up this year and then dispersed again without bothering
to start to breed.
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- All the sea birds that are in trouble have sand eels
as a primary source of food, especially for their young. First year sand
eels appear off the breeding colonies in the spring when the sea birds
decide whether to build their nests, and in June the juveniles appear,
in time to feed the chicks.
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- It is not just abundance of sand eels that matters, it
is also their calorific value. If the sand eels have a bad season with
too few plankton to eat, then the seabirds that eat them do too.
-
- The only seabirds that are increasing in numbers at the
moment are gannets and cormorants, both of which are big and powerful enough
to feed of other fish species - notably herring and mackerel - which are
currently abundant.
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- Mr Heubeck said the future was uncertain because trends
in plankton and sand eel populations were hard to forecast. It was also
difficult because of the age of seabirds.
-
- Some northern fulmars first ringed in the 1950s were
still alive and well. What was most concerning was that some of these adult
birds were exhausting themselves and dying in the effort of trying to breed.
-
- The decline in the sea bird population has only been
so fully documented because of the oil industry in Shetland. The survey
was set up to make sure that the oil industry was not causing pollution
that would upset the famous sea bird populations.
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- The survey has shown that the oil terminal at Sullom
Voe has had no effect on bird numbers but enabled the documentation of
declines for other reasons.
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- Species in peril
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- Common guillemot (Uria aalge)
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- An auk that lives at sea except when breeding from May
to August. Sometimes thousands of guillemots will share the same cliffs
nesting on tiny ledges, each female laying a single egg. They do not breed
until five or six years old and live 30 years or longer. Black with white
chests and black dagger-like bill. Length 42 cm
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- Dropped 50% in numbers in Shetland since 2000
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- Breeding success Fair Isle, Shetland 2004 - nil
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- Black-legged kittiwake (Rissa tridactyla)
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- The loud call kittee-wake ringing out along the cliffs
as the bird flies to and from its nest gives this seagull its name. It
spends its winters out to sea but breeds along the high cliffs on all northern
coasts, particularly in the northern isles, often in colonies of many thousands.
Blue-grey back with black wingtips, yellow bill and black feet and legs.
Length 41 cm.
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- Breeding numbers nationally dropped 25% in 10 years,
in Shetland 69%.
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- Breeding success Orkney 2004 - nil
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- Northern fulmar (Fulmarus glacialis)
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- Gliding flight with wing span of more than a metre. Back
and upper wings blue-grey but appears white in flight. Can live more than
50 years.
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- Breeding population nationally dropped 35% in eight years.
Fledged chicks per nest site dropped from four to one in south-east Scotland
over same period.
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- Guardian Unlimited © Guardian Newspapers Limited
2004
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- http://www.guardian.co.uk/conservation/story/0,13369,1377794,00.html
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