Staphylinidae from Lütje Hörn Island (German Bight)
(sampled with pitfall traps 1989 and 1990)
Summary and downloadable pdf-file of Rose (1998) - Abh. Naturw.
Verein Bremen 44 (1): 135-145.
Die Besiedlung von Düneninseln früher Sukzessionsstadien im
Nationalpark Niedersächsisches Wattenmeer durch Kurzflügler (Coleoptera:
Staphylinidae) am Beispiel von Lütje Hörn
[Colonization by rove beetles (Coleoptera: Staphylinidae)
on Lütje Hörn Island as example of a dune island in early stage
of succession in Lower Saxony Waddensea National Park]
Abstract: In 1989 and 1990, 1285 rove beetles out
of 70 species were caught in pitfall traps on Lütje Hörn island, one of
which (Stenus bohemicus Mach.) had never been recorded on the old East-Frisian
Islands before. 24 species (34%) were considered to be indigenous even though
the rescue effect may lead to misinterpretation. Compared to Northwestern
Germany, the proportion of coastal species, and those at least halotolerant
as well as inhabitants of sandy shores is quite high on Lütje Hörn. Also,
the proportion of older dune and shore deposit inhabitants is high compared
to Northwestern Germany. Finally, Lütje Hörn is rich in saprophilous species.
Flight activity, often coming along with saprophily of several
rove beetles, seems to have a considerable part in early colonization of
dune islands by those species. Strong evidence for this is a significant
correlation (r=0,873; a=0,01) between flight activity in the coastal area
(measured by occurence in colour traps on other islands) and the occurence
of species rich subfamilies (20 and more species) of rove beetles on the
young dune island Lütje Hörn.
Another good indication for a connection between flight activity
and early island colonization is shown by a comparison of the results of
the two years of investigation. As a lucky coincidence (for science), in
winter 1989/90 (before the second investigation took place) several strong
stormtides inundated the island totally. So there had to be nearly a complete
recolonization by beetles in spring 1990. As a most probable consequence
of this, on Lütje Hörn a greater proportion of flight active species
(especially among the more abundant species) had been recorded in 1990 compared
to 1989. Other possible ways of colonization are on the water surface (hydrochorous)
and by phoresy, but surely flight is involved in the colonization process.