Náttúrufræðingurinn - 2005, Page 45

Tímarit Hins íslenska náttúrufræðifélags
4. mynd. Varpstaðir hettumáfa í Eyjafirði árin 1995 og 2000. - The breeding distribution of Black-headed Gulls in the Eyjafjörður
region in the ycars 1995 and 2000.
máfar verpa og vita hvort sama
stofnþróun á sér stað þar.
Hettumáfar eru ekki vaktaðir
annars staðar hér á landi á jafnstóru
svæði og í Eyjafirði og því er ekki
vitað hvort fækkunar hafi gætt víðar.
Upplýsingar eru til um að ýmis
hettumáfsvörp hafi horfið, en einstök
slík dæmi segja lítið til um framvind-
una í heild. Það er jafnvel hæpið að
álykta af niðurstöðunum í Eyjafirði
að hettumáfum hafi fækkað á íslandi.
Æskilegt væri að bæta við fleiri vökt-
unarsvæðum í mismunandi lands-
hlutum. Fróðlegt er að hafa í huga að
verpandi hettumáfum fækkaði
stórum (um tugi prósenta) í norðan-
verðri Evrópu á tíunda áratug 20.
aldar.18 Vera kann að sömu breyting-
ar hafi átt sér stað hér á landi. Á
vetuma heldur meginþorri íslenskra
hettumáfa sig við Bretlandseyjar,
Noreg eða suður með vesturstíönd
meginlands Evrópu.13 Stofnbreyting-
ar á vetíarstöðvunum gætu gefið vís-
bendingu um hvort íslenski hettu-
máfsstofninn sé að dragast saman.
SUMMARY
Monitoring of Black-headed Gulls
Lartis ridibundus in Eyjafjörður
(N-Iceland) 1995 and 2000
The largest continuous region in Iceland
where Black-headed Gulls Larus
ridibundus (Fig. 1) are monitored is the
Eyjafjörður district, N-Iceland. Their
total breeding distribution in Iceland is
shown in Fig. 2, and the Icelandic breed-
ing population is now estimated at
25,000-30,000 pairs,11,5 distributed at per-
haps 600 sites (Icelandic Seabird Colony
Registry). Monitoring in Eyjafjörður is
conducted every fifth year, but the first
complete census was carried out in
1990.3 The present paper contains the
results for 1995 and 2000. The monitor-
ing area (556 km2, or 0.5% of the country)
is shown in Fig. 3.
In 1995 Black-headed Gulls were
found nesting at 32 sites in Eyjafjörður,
altogether 1547 breeding pairs, and 1325
pairs at 48 sites in the year 2000 (Fig. 4).
Site details and numbers of breeding
pairs in 1990,1995 and 2000 are given in
the appendix. Thirteen of the 1995 sites
were deserted in 2000, so 29 new sites
had become occupied by 2000.
A continuous decline has taken place
since 1990, when there were 1709 pairs
breeding in the monitoring area3 (sever-
al figures re-analyzed, see Appendix). A
9% decline occurred between 1990 and
1995 but 14% between 1995 and 2000,
which indicates an increased rate of
decline. Over the ten-year period of
1990-2000 the overall decline was 22%,
or on average 2.5% a year. Unpublished
information for the same eight sites
between 1980 (450 pairs in total) and
1990 (362 pairs) gave an average decline
of 2.0% per annum. This is much the
same as the decline between 1990 and
1995 (2.2%), while the rate picked up
during 1995-2000 (3.1%).
Breeding Black-headed Gulls were
distributed very unevenly in the moni-
toring area, the largest concentration
being in the vicinity of the town of
Akureyri (of around 16,000 people). In
1990 there were 727 pairs at the outskirts
43