Fróðskaparrit - 01.01.2009, Blaðsíða 94

92
YEAR-ROUND VIDEO SURVEILLANCE OF INDIVIDUAL NEST-SITE
ATTENDANCE OF NORTHERN FULMARS IN THE FAROE ISLANDS
Number of potential nest-sites (+/- SD) Number of countingdays Number of nests with chicks or eggs Percentage of potential nest-sites occupied by breeding birds
June 2004 34 (+/- 4,0) 3 13 (eggs orchicks) 38
June 2005 31 (+/-4,8) 9 9 (chicks) 29
April 2006 32 (+/-7,1) 2 8 (eggs in June) 25
June 2007 27 (+/- 3,5) 8 10 (eggs) 37
Table 2. Number of pocencial nesc-sices (escimaces from 2-9 monchly councs) and percenCage nescs which sub-
sequendy concained eggs or chicks.
cember 6, 18, and 28 (for more details see
Fisher, 1952:348ff). Salomonsen (1955)
stated that the breeding Faroese fulmars ar-
rive irregularly through November-Decem-
ber (rarely earlier) and that the breeding sites
are fully occupied about New Year; though
the non-breeders do not arrive until at the
end of March. As egg-laying does not com-
mence until late May and early June the pre-
breeding period in the Faroes (and in other
regions) extends over 5-6 months which, as
suggested by Salomonsen (1955), may be a
result of competion for nest-sites and lack of
interspecific competitors in winter. In British
colonies arrival dates seem to be associated
with breeding-colony size with occupation
of nest-sites taking place earlier in larger
colonies than in smaller ones (Fisher, 1952),
whereas in the Canadian high Arctic arrival
occurs later, presumably in response to pre-
vailing ice and climate conditions (Mallory
and Forbes, 2007).
Although fulmars are present at the
colonies during a prolonged pre-breeding
period, the numbers vary and mostly there
is a peak in nest-site attendance in April, fol-
lowed by a distinct drop in May and a sub-
sequent peak in June. The exit in May, for
about three weeks prior to egg-laying, was
noted by Venables (1952) at a colony in
Shetland, and this so-called pre-laying exo-
dus (or „honeymoon") is a trait that the
Northern Fulmar apparently has in common
with all, or at least most, species of Procel-
lariiformes (Fisher, 1952; MacDonald, 1977b;
Warham, 1990; Mallory and Forbes, 2007).
As to the Faroes, Salomonsen (1955) did not
mention any pre-laying exodus but stated
that the greatest number of fulmars being
present was from April to June. Both sexes
participate in the exodus, though some
males do not take part or visit the nest-site
intermittently (MacDonald, 1977b). Copula-
tions occur through an extended period of
time though just before the exodus the fre-
quency peaks (Hatch, 1987a; Hunter, 1998).
It is generally assumed that the exodus is as-
sociated with the females' need to accumu-
late energy required for egg-formation and
for both partners to prepare for strenuous
bouts ofincubation (Warham, 1990;Mallory
and Forbes, 2007, 2008).
In this study we examine the annual
cycle of nest-site attendance at a small
colony of Northern Fulmar in the Faroes,
where the species is an abundant breeder
(Jensen et a\„ 2005), focusing on the non-
breeding season (i.e. September to June)