Náttúrufræðingurinn - 1968, Blaðsíða 125

NÁTTÚRUFRÆIÐINGURINN
233
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SUMMARY
(íoosc llarnacles (Lepas spp.) on Surtscy Pumice
by Finnur Gudrnundsson and Agnar Ingolfsson
During the years 1964—1966 one of us (A. I.) was engaged in a comparative
study of the l'ood and feeding habits of Icelandic gulls. In the course of this
study it was found quite unexpectedly that goose barnacles (Lepas spp.) were
an important food item in gulls collected in October/Novembcr 1965, at Sancl-
vik on tlie Rcykjancs Penisula in S. W. Iceland. This was unexpected because
at high latitudes goose barnacles rarely occur in sufficient abundance to become
a likely food source for sea-birds. Table 1 gives a detailed picture of the
incidence of goose barnacles in various gulls collected in the Sandvik area
during the last three montlis of 1965. The table sliows tliat the percentage
of gulls (all species lumped together) wliich had fed on goose barnacles
increased until October 18, when it reached the maximum of 70%, but
after that the percentage quickly decreased. Although goose barnacles were
among the chief foods taken by the gulls in the Sandvik area during the above
period, they by no means confined themsclves to this food item as they some-
times do when some foods (e. g. capelin (Mallotus villosus) or sandeel (Ammo-
dytes lancea)) are present on a very large scale. In only 40% of the gulls that