Fróðskaparrit - 01.01.1983, Síða 82

THE AUTUMN MIGRATION AT AKRABERG,...
85
NUMBER OF
SPECIES
Fig. 8. The diversity of species through the observation
period.
Thus, in accordance with the prevailing
wind conditions, it turned out that »irregular«
migration from Scandinavia exceeded »nor-
mal« migration of both Wheatear and Red-
wing.
Migrants from the NE to the S.
Almost half of the recorded species can only
be considered as migrants from Scandinavia,
Great Britain, or the Continent (appendix 2).
The diversity of species (fig. 8) and the
figures of the single species (fig. 9) show a
large occurrence, previously unknown, of
these Continental migrants. Several waves
of arrival occurred, such as Sep. 20th to
22nd (Tree Pipit, Robin Erithacus rubecula,
Whinchat Saxicola rubetra, Willow Warbler),
25th to 28th (Willow Warbler, Goldcrest
Regulus regulus, Blackcap Sylvia atricapilla),
and Oct. 9th to 11 th (Goldcrest, Chiffchaff
Phylloscoyus collybita). The smaller birds,
migrating by night, showed a tendency of
arriving at Akraberg, itself (fig. 3, A—D)
and after that they scattered to the best
habitats, most species to Sumba (fig. 3, F).
Arrival of birds, normally migrating by
night, took place in full daylight (Sep. 20 th,
for instance) and continued during the follow-
ing night.
Whinchat, Robin, and Willow Warbler
showed the same pattern of occurrence (fig.
9) with a wave of arrival from Sep. 20th.
During the following weeks the number of
birds was gradually decreasing, either be-
cause of migration or because of exhaustion.
Fig. 9. Occurrence of Robin, Whinchat and Willow
Warbler in the observation period.