Náttúrufræðingurinn - 1997, Side 13

were recovered dead and 77% of those within
the fírst year (Table 1). Mean age of these birds
was 285 days (1 July was taken as day of hatch).
The oldest bird, a hen, was five years and two
months old when controlled.
There was no sex difference in site fidelity of
ptarmigan banded as adults, and cocks and
hens were recovered or controlled at a later
year in similar portions; cocks 23% (n=64) and
hens 19% (n=91) (chi-square=0.339, p=0.560).
The sex composition of the breeding popula-
tion was equal, but it was easier to trap hens
than cocks and the sex ratio of 155 unbanded
adults caught was 41% cocks;59% hens. This
is significantly different from an equal ratio
(G=4.712, p=0.030). This ratio was used to
calculate expected sex composition of ptarmi-
gan banded as juveniles at Kvísker and control-
led there at a later year. The observed figures
were 20 cocks and 14 hens and this is signifí-
cantly different from the expected distribution
(G=4.305, p=0.038). These results imply that
cocks show a higher fidelity to the natal areas
than hens.
Only seven birds (0.8%) of 916 banded were
recovered outside the Kvísker area proper, all
shot, including one 227 km from Kvísker (Fig.
6). All shot birds had been banded as juveniles
and non of them was sexed. There is no hunting
at Kvísker or on neighboring properties. So
only the small fraction of the population
traveling long distances (>20 km) is exposed to
hunting. This implies that hunting is an insig-
nifícant factor in the total annual mortality of
the Kvísker ptarmigan population. This makes
the comparison of population trends at
Kvísker, Hrísey and NE-lceland all the more
interesting as the two latter populations are
heavily hunted.
PÓSTFANG HÖFUNDA/
AUTHORS ADDRESSES
Ólafur K. Nielsen
Náttúrufræðistofnun Islands/
Icelandic Institute of Natural History
Pósthólf/Box 5320
IS-125 Reykjavík
Hálfdán Bjömsson
Kvískerjum
IS-785 Fagurhólsmýri
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