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■ SUMMARY
Rock Ptarmigan Density
AND HEATHLAND VEGETATION
in Suður-Þingeyjarsýsla,
NE-Iceland
The purpose of this paper is to analyse the re-
lationship between breeding density of Rock
Ptarmigan (Lagopus mutus) and different
types of heathland vegetation. The study area
was in NE-lceland (Fig. 1). This is an area of
extensive rolling heathlands. The Icelandic
ptarmigan population has a 10-year cycle
(Finnur Guðmundsson 1960) and 1993, the
study year, was a low year. Differences in
spring density between high and low years on
study plots in NE-Iceland have been c. 6-fold.
Differences in spring density between differ-
ent census plots within the same year have
been c. 8-fold (Ólafur K. Nielsen 1995).
The count point sites were placed in 7 main
heathland areas so as to cover a gradient from
the coast and 50 km inland. Within these areas
a total of 42 count sites were chosen using a
map (1:50.000) and a grid with points placed
by using a random function. The only prereq-
uisites were that the count sites should be
100