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The
summer 1997/1998 (October 1997- April 1998) is the second season that Jeroen
Creuwels is spending on a rocky island just in front of the Antarctic
continent. Instead of making pictures of sunsets and establishing new
swimming records Jeroen is supposed to be dedicated to his main job at
Ardery Island, which is studying birds.
A description of the research activities is described in Research activities on Ardery Island summer
1997/1998.
Fulmarine petrels on Ardery Island
Fulmarine petrels are a group of
fulmar-like birds which all breed in the Southern hemisphere, except one:
the Northern fulmar (Fulmarus glacialis, in Dutch: Noordse
stormvogel) which breeds in the Atlantic Ocean and the Northern Pacific. The
other species of the fulmarine petrel-group are: Southern giant petrel
(Macronectus giganteus), Northern giant petrel (Macronectus
halli), Antarctic petrel (Thalassoica antarctica) and the
Southern fulmar (Fulmarus glacialoides), Snow petrel (Pagodroma
nivea) and the Cape petrel (Daption capense). All these
species breed in Antarctic and sub-Antarctic regions.
The word Fulmar is a compound of the two Nordic words "ful" and "mar",
which means "foul gull". It is probably brought to the Hebrides by the
Vikings, where the word had commonly been used in the Gaelic language since
the eleventh century.
The meaning of "foul gull" refers to its spitting ability (and sometimes
amazingly well-aimed) of the birds to eject a sticky and smelly stomach oil.
It is used to keep other birds or possible predators on a distance. All
fulmarine petrels have spitting qualities, on Ardery Island especially the
capes and the snowies are the notorious spitters.
Ardery Island is declared a Specially Protected Area (SPA) under the
Antarctic Treaty as it hosts 4 species of breeding fulmarine petrels (i.e.
Southern fulmars, Antarctic petrels, Cape petrels, Snow petrels).
Jeroen's study focuses mainly on the two biggest species of the fulmarine
petrels breeding on Ardery Island: the Antarctic petrel and the Southern
fulmar. But also additional data on the breeding ecology of the Snow petrel,
the Cape petrel and the South polar skua (Catharacti maccormicki)
will be collected.
History of the
Ardery Island Project
The petrels on Ardery Island
have been studied by Jan van Franeker since he spent the summer of 1984/85
on the island. This was the start of a long-term project on fulmarine
petrels on Ardery Island by the Institute of Forestry and Nature Research
(in Dutch: Instituut voor Bos- en Natuuronderzoek, abbreviated to: IBN-DLO)
on the Island of Texel, The Netherlands. The Dutch seabird-biologist Jan van
Franeker works at IBN-DLO and is very experienced working on seabirds in
Antarctica. He has spent four summers on Ardery: 1984/85, 1987/88, 1991/92
and 1996/97.
In 1996 he started a series of Ph.D projects with Jeroen's being the first
one. During this season he had a big task to teach Jeroen what petrels look
like, what they do, and how to study them, as Jeroen was new in the field of
seabird-ecology. Jeroen will continue the field work for his Ph.D thesis
until summer 1998/99 when a new Ph.D student will take over the research on
Ardery Island.
Individual quality in fulmarine
petrels
Jeroen's Ph.D project is called "Individual quality in fulmarine petrels", a
title which might not be very clear and an explanation could help to
understand what he actually wants to study.
Every single bird has its own character and its own habits, and not every
bird is equally as good at searching for food or raising offspring. In
particular, Jeroen is looking at how successful individual petrels are in
rearing chicks.
Bringing up children is just as costly for birds, as it is for humans.
Petrel parents have to spend time and energy on their offspring, but also
take risks by protecting their vulnerable egg or chick. All these efforts
could be seen as "investments" in their young, as often these activities
affect their own survival. It takes more energy to collect food for two than
only for yourself, and they will sit longer on their nests when they have an
egg or a chick even in a dangerous situation when predators as Skuas or
Giant petrels are in colony.
Therefore every bird has to judge how much it will "invest" in its young in
terms of time, energy and risks. Sometimes it would be wiser not to have
kids, for example when food is scarce.
Biologists try to measure how much the parents invest in their offspring.
A way to do this is to look at the weight changes of the parents in the
breeding season. For example, how much weight does a parent loose while
incubating an egg or searching for food? Does a bird with good body
condition loose as much weight as a bird in poor condition?
Body
condition is assumed to be an important factor for the breeding success of a
particular bird. Heavier birds will normally be in a better condition as
they will have more fat reserves. So, the body condition of a bird is
influenced by its weight.
An artificial nest-system has been developed at the Institute of Forestry
and Nature Research (IBN-DLO) to monitor the weight changes in the petrels.
Petrels are sitting on these artificial nests, which record the weight of a
bird almost continuously. The weights can be monitored throughout the
season, without the disturbance of manual weighing (further description of
the artificial nest system is given in Research activities on Ardery Island summer
1997/1998).
Body condition could be influenced by food availability at sea, but also
by the ability of a particular bird to find food, or to make the right
"decisions" during the breeding season. Examples of important questions are:
when do I lay an egg?, how much effort should I put in sitting on an egg
when my nest is icy and my egg is cold?, how long should I wait for my
partner to take over the incubation shift?, etc.
Such qualities are not always easy to measure, but from age estimations,
nestsite locations within the colony, behaviour, weight changes, timing of
events in the breeding season, etc. Jeroen hopes to determine which parent
is good or poor in rearing offspring.
During his Ph.D study Jeroen will try to understand not only the qualities that influences the body condition but also the qualities that influence the breeding success in another way. He will investigate the variation in individual qualities and body condition existing in the Antarctic petrel and the Southern fulmar, and how it related to their breeding success.
During the 1998/1999 summer a new Ph.D student will study the differences
in foraging strategies among the four fulmarine petrel species breeding on
the island. This study will try to determine how these species can live
together and how they minimise their competition for food. Where each
species collect their food, how much time they spend looking for food at
sea, what they eat, and how much energy it costs to bring the food to the
growing chicks, etc. will be studied.
CCAMLAR
The principle reason for long-term research on Ardery Island is attributed
to nature management and interactions between seabirds and fisheries in the
Southern Ocean in particular. Such studies are coordinated by CCAMLAR, the
Convention on the Conservation of Antarctic Marine Living Antarctic
Resources, which is a fishery agreement for the exploitation of fish and
krill south of the Antarctic Convergence zone. It came into force in 1982 to
protect the marine Antarctic ecosystem in a more ecological way. Instead of
protecting species seperately the CCAMLAR tries to protect the Antarctic
marine ecosystem as a whole. To achieve this it is not only setting catch
limits for ecologically responsible harvesting of fish and krill, but also
promoting the study of the harvested species in relationship to other
organisms in the Antarctic waters. This involves interactions between the
harvested species (e.g. krill and krill-eating fish), as well the
interaction with species that depend on these resources like penguins,
seals, whales, etc.
For this purpose a monitoring program (CEMP = CCAMLAR Environmental
Monitoring Program) was established to follow the population trends of
several species. Among the selected species for the CEMP are Crabeater seals
and Adelie penguins, but also two fulmarine petrels: Antarctic petrel and
Cape petrel.
Although the millions of petrels are important consumers in the Antarctic
ecosystem, they have had minimal study. Unlike crabeaters and adelies, who
collect their food in the Antarctic pack-ice region, petrels fly further
distances to open waters far away from the Antarctic sea-ice. They also have
a much larger component of fish in their diet. These are the reasons why a
long-term program on fulmarine petrels was started on Ardery Island by the
Dutch Institute for Forestry and Nature Research (IBN-DLO) in close
cooperation with the Australian Antarctic Division (AAD).
The long-term results on breeding success, and annual differences in body
condition might shed some light on the interactions between the petrels and
the fish and krill they consume, or even on a broader scale on possible
conflicts between seabirds and fisheries in the Southern ocean.
Breeding cycle of fulmarine petrels
All the fulmarine petrel species breeding on Ardery Island (i.e. Antarctic
petrel, Southern fulmar, Cape petrel and Snow petrel) have a similar
breeding cycle. This cycle is the same for all the fulmarine petrels,
although the time schedule is slightly different between the species.
The
pair-bond is quite strong and relatively stable among fulmarine petrels.
Pairs normally remain together from year to year and they meet each other in
the spring. This is the period of their courtship, when they also
make their preparations to the nests for a new season and copulate (up to a
couple of times per day).
After this period they have their "honeymoon" or "pre-egg laying
exodus" as it is called in the biological literature. They go to the
sea to get reserves for the new season. After a certain time both partners
come back for the egg laying.
The female will lay her only egg, and soon after that she will leave to
search for food at sea and to recuperate. Her partner will then take the
first incubation shift. When she returns she will take over for her
shift and he will go out fishing. This continues for the whole
incubation-period. The incubation period finishes when the chick
hatches. In the beginning the chick will be guarded by one of the
parents while the other is out at sea collecting food for itself and for its
young. Both partners change shifts in the guarding period, until
the chick is big enough to be left alone. South polar skuas are cruising
along for food for their demanding chicks and they are trying to catch a
small unattended chick whenever possible. After this period, both parents go
out foraging and the chick will be left alone in between the food
deliveries.
At the end of the breeding season the chick starts flapping its wings, and
wanders off the nest more and more often and finally the chick
fledges in a few days.
What they do at sea, or in wintertime is still largely unknown, but will be studied in more detail in future projects of the Dutch Institute of Forestry and Nature Research (IBN-DLO).
What 97/98 |