Sterna, bind 14 nr 3 (PDF-fil) - Museum Stavanger

Litteratur
Bergman, G. 1963: Ficglenes liv. Oslo. 192 pp.
Creutz, G. 1966: Die IVasseramsel. Wittenberg Lutherstadt. 140 pp.
Haftorn, S. 1971: Norges ficgler. Oslo. 862 pp.
Moody. C. 1955: Display-flight of Dipper. Brit. Birds 48: 184.
Kobson, R. W. 1956: The brecding of the Dipper in North Westmorland.
Bird Stirrly 3: 170-180.
Witherby, H. F., F. C. R. Jourdain, N. F. Ticehurst, B. W. Tucker 1948: The
Handbook of British Birds, vol. 11. London. 352 pp.
Summary: Bigamp and two broods among Dipper.
Bigamy has been proved for the first time among the Dipper, Cinclus cinclus,
in two instances:
0rsta. blore & Romsdal, 1972: A male fed the nestlings in two different
nests, which were ahout 800 metres from one another. In each nest there were
6 ncstlings. 'The age differcnce betwecn thc nestlings in the two nests was
about 11 days. The bigamy was not discovered before the nestlings in both
broods had hatched; and the reason for bigamy is therefore uncertain.
Lyngdal, Vest-Agder, 1974: A malc was discovered feeding the nestlings
in two different nests which were about 700 metres from each other. In
each nest there were 4 nestlings, and the age difference was about 3 weeks.
The bigamy was not discovered before the nestlings in the first brood had
left the nest. It is uncertain why bigamy arose. The male probably fed both
the "flown" birds in the first nest and the small nestlings in the other.
Clearly one of the reasons why bigamy very seldom occurs among the
Dippcr, is the fact that there is a surplus of males.
It is moreover the first time that it has been recorded in Norway that the
Dipper can sometimes have two broods per season (all 7 cases in Co. MØre
& Romsdal):
In 1973 the second brood was found in 2 of 38 nests (about 5.3 Yo)
and in 1974 in 4 of 62 nests (ahout 6,s %). Tliis seems to hc very few
compared with wliat is usual in Central Europe.
Author's address: N-6060 Hareid.