Fróðskaparrit - 01.01.2009, Side 102

100
YEAR-ROUND VIDEO SURVEILLANCE OF INDIVIDUAL NEST-SITE
ATTENDANCE OF NORTHERN FULMARS IN THE FAROE ISLANDS
breeding colony suggests that suitable nest-
ing sites constitute a precious resource to ful-
mars; along with several additional key fac-
tors that are important to seabirds and other
long-lived bird species (e.g. Forbes and
Kaiser, 1994; Naves etal., 2006). By usingsur-
veillance cameras we were able to collect ex-
tensive data on the timing and duration of
events going on at a number of selected
nest-sites, thus enabling us to address issues
and aspects of the annual cycle of the
species raised by other studies. Since we did
not succeed in individually marking but a
few nesting fulmars, or otherwise identify in-
dividual birds, we presume that the high
nest-site fidelity (even following the loss of
partner; Hatch, 1987b) and mate fidelity
demonstrated in previous studies (see Intro-
duction), based on individually recognizable
birds, also apply to the Faroese colonies.
Hence, we initially assumed that fulmars
recorded at a giwen nest-site were the same in-
diwiduals from time to time, although this
prowed not always to hawe been the case as
shown by obseruations based on thefew indi-
uidually identifiable birds in the study colony.
Post-breeding period
The parents stop feeding the young before it
is fledged, though usually they remain in the
colony or neighbourhood of it for still some
time and in the Faroes the adult fulmars
desert the breeding colonies from mid-Au-
gust (the young from mid-September),
though some may still be around at the end
of September (Fisher, 1952; Salomonsen,
1955). According to our observations the
timing of post-breeding departure varied
considerably, presumably depending (at
least partly) on breeding success; successful
pairs abandoned the breeding colony in late
August or in the beginning of September,
whereas those that failed left much earlier
(Table 5). In three cases in June 2006 nests
were abandoned during egg stage (nos 1, 2,
and 6), presumably due to disturbances
when the birds were caught in order to be
fitted with GPS-data loggers. Other studies
have shown that capturing and handling in-
cubating fulmars may cause desertion, or
make the birds stay away from the nests long
enough for predators to take their tolls (e.g.
Furness and Bryant, 1996) and that distur-
bance may cause breeding failure not only in
the year of capture but also reduce breeding
success in the following year (Ollason and
Dunnet, 1978). Hence, it is reasonable to as-
sume that the disturbances may have af-
fected breeding success and therefore also
timing of departure and length of the au-
tumn absence from the study colony.
Moulting is an energy-demanding pro-
cess in birds (e.g. King and Murphy, 1985)
and for most Procellariiformes it is more or
less well separated in time from reproduc-
tion (del Hoyo et ai, 1992). This is presum-
ably also generally true for the Northern Ful-
mar that undergoes a single, complete
moult, the timing of which apparently varies
according to breeding status; the moult
starting later among breeders than non-
breeders and failed breeders (Hatch and
Nettleship, 1998; Allard et ai, 2008). At the
Eynhallow colony in Orkney, Carrrick and
Dunnet (1954) noted the occurrence of
moulting fulmars (including primary moult)
among supposedly failed-breeders, already
in July, whereas in a Canadian study in High
Arctic no signs of primary moult were de-
tected (Allard et ai, 2008). With reference to