Completely
exhausted and emaciated,
this tiny little bird, a meadow pipit, Anthus pratensis,
arrived at Surtsey after a 20-24 hours flight from Scotland.
On arrival the weight was only 12.0 grammes!
great black-backed gull
Larus marinus
Summer 1986, 23 years after the eruption, a few pairs of Larus
fuscus were breeding
on a lava terrain on the southern part of Surtsey. In he following
years they increased largely
in numbers, and a colony was slowly formed also including Larus
fuscus, Larus marinus
and Larus argentatus.
The formation of the gull colony marked a new era in plant colonization
and succession on Surtsey, as these gulls had considerably stronger
impact than other breeding birds earlier established on the island.
In the first weeks of the Surtsey eruption gulls were seen roosting
on the shores of the
new-born island. Ever since, birds have been important in the development
of the
exosystem on Surtsey through enrichment of the soil with their excrements
and sispersal
of plant seeds to the island.
Fulmar (Fulmarus glacialis)
and black guillemot (Cepphus
grylle) were the first species
of birds to nest on Surtsey in 1970, when one nest of each species
was found in the cliffs
on the southern part of the island. In 1974 great
black-backed gull (Larus marinus)
started breeding on Surtsey,
kittiwake (Rissa
tridactyla) in 1975, herring
gull (Larus argentatus) in 1981,
lesser
black-backed gull (Larus fuscus)
in 1986 and finally glaucous
gull (Larus hyperboreus) in
1993.
Gulls
outside one of the plots inside the gull-colony.
© c/o www.vulkaner.no
The gull species build nests of vegetation, sea-weed, feathers
and other available meterial,
while the fulmar (Fulmarus
glacialis) and black guillemot
(Cepphus grylle) do not use
nest building materials or only slightly arrange pebbles under their
eggs.
The nests of the black guillemot (Cepphus
grylle) and kittiwake
(Rissa tridactyla) are confined to sea-cliffs of the
island, which are very unstable and change considerably between
years due to wave erosion. Vegetation has not become established
at their nest sites.
The kittiwake (Rissa
tridactyla), however, roosts in great numbers on the northern
ness
of Surtsey and enriches the soil with excrements.
In the early years the nests of the fulmar (Fulmarus
glacialis) were mostly confined to
the sea cliffs but in the last 15 years it has also established
nes sites inland, mainly in
the cliffs of the old craters where small concentrations of about
5 - 15 pairs are now
found in five different locations on the island.
Gull
watching the area around the gull-colony.
© c/o www.vulkaner.no
In 1986 the first nests of the lesser black-backed
gull (Larus fuscus) were
found on
a lava flat on the southern part of Surtsey. This marked the initiation
of the dense gull colony
on the island that now consists of the lesser
black-backed (Larus fuscus), herring,
(Larus marinus) and glaucous
gull (Larus hyperboreus). These species,
with the exception
of the great
black-backed gull
(Larus marinus), usually nest in colonies
and the nests
can be within a short distance (<10 m) of each other. They build
nests that are mostly
made of plant material.
This clearly shows the connection between the increasing numbers
of birds - and the
vegetation.The more vegetation - then more nest-building material,
and the more birds -
the better the soil and so more plants will grow up.
A
nest of great
black-backed gull (Larus marinus)
in a patch of Honkenya peploides
plant 1977
In 1990 more than 150 pairs were in the colony, but it is estimated
that the number had risen
to at least 300 pairs in 1999. When the first plots were established
in the gull colony in 1990
the effects of the gulls on the vegetation were noticable. At that
time only two species were
found in each plot and vegetation cover was around 30% (all
Honkenya). In 1998 the
number of species in the plots had risen to between eight and ten
and several species in
addition to honkenya etc had attained a high cover in the plots.
Total vegetation cover
in the plots at that time had reached 100%. Outside the gull-colony
there has not been
an increase in species number.
The gulls were spspected to have negative influence on the development
of plant succession
by tearing up plants for use as nest material. It has now become
obvious, that the gulls have proved to be very important components
in the simple life community now established on
Surtsey (1981).
Obviously the importance of the gulls was not just confined to the
nest. The gulls or their
young seek shelter in the Elymus tufts leaving droppings and food
remains behind, enriching
the soil. A selfsufficient ecosystem has been established on Surtsey,
composed of vascular
plants, fungi, various invertebrates with different demands, birds
and no douby different microorganisms. The ecosystem is of course
simple and probably unstable, but it is
obviously the beginning of a more complicated ecosystem to be developed
in the future.
That was in 1981, and since then there is no doubt that it has developed,
and so it has
to a much larger extent than many thought when Surtsey came up from
the bottom of
the ocean back there in 1963.
Text mainly extracted from reports made by
Borgthór Magnússon and Sigurdur H. Magnússon,
Icelandic Institute of Natual History, Reykjavik, Iceland.
Surtsey Research Report No. XI
Birds found in the text above:
Gull: Sea-bird of Charadriiformes order, sub-order
Lari, whcih includes:
black-headed gull Larus ridibundus
herring gull Larus argentatus
great black-backed gull Larus marinus
(1,75 m vingespenn)
lesser black-backed gull Larus fuscus
glaucous gull Larus hyperboreus
Krykkje kittiwake rissa
tridactyla
Other birds:
Havhest, northern fulmar
fulmarus glacialis
Teist black guillemot
cepphus grylle
|
Here you can find more about:
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Bird migration
|
|
Plants |
|
Insects |
|
Sealife |
|
Fossils on Surtsey |
|
How life developed |
|
The eruption |
|
Picture-review |
See the
last report from Surtsey Research - 2009. Click here
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