Oystercatcher is a common migrant in both spring and autumn at
Skogsøy and is the most numerous of the wader species. The
species migrates early in the season with the first birds being noted
passing north towards the end of February. Numbers build up rapidly and
by mid-March it is possible to see over 1-2000 birds in the course of a
few hours seawatching. After the end of March numbers drop rapidly,
although passage continues well into May.
Oystercatcher numbers seem to be fairly well monitored on their
wintering grounds further south in Europe. However, these winter counts
do not give much information regarding the various populations
in the Norwegian population are little known;
counts from Skogsøy should help to address this.
interesting phenomenon I have noticed is that there are indications
of a shift in migration tactics as the season progresses; this may
indicate that differing populations are invloved in the spring
migration. Early in the season (before the end of March) the majority
of birds pass immediately after dawn with numbers dropping rapidly
throughout the day. As the season progresses passage is spread out
throughout the day without any peak around dawn. It is a well known
fact that this species also migrates at night.
Migrating Oystercatcher, March 2012
The species is also common in the autumn migration with peak numbers in
July to mid-August. The vast majority of birds have headed south by
mid-September, although occasional birds are seen into early November.
The following diagram shows the maximum recorded in a given three day
period (green line, scale on right hand axis). In order to give an idea
of the frequency of observation observer effort is presented as the
blue line (number of visits) and the orange lines (number of days the
species was recorded). More comprehensive data is available on the
Skogsøy downloads page.
nominate rate, ostralegus
of the continental population that breeds in
Norway. Recoveries of
birds ringed in the breeding season in Norway show that the U.K. is an
important area, especially for birds of the year in September. From
October onwards more recoveries have come from between Denmark and
France, although France is likely to be over represented due to
ring I found in an Eagle Owls
nest was from a bird over 30 years old and ringed on the south coast of
Above and below:
Migrating Oystercatchers, Skogsøy, March
The record count is 2850 heading north 28 March 1982.
All of the big (>1000) counts I have had in spring have been
during light tailwinds (S or SW), usually with light haze. References Bakken,
Runde, O. & Tjørve, E. 2003 Norsk
Ringmerkingsatlas Vol 1, Stavanger Museum, Stavanger Wernham,
Toms, M.P., Marchant, J.H., Clark, J.A., Siriwardena,
G.M. & Baillie, S.R. (eds) 2002. The Migration Atlas: Movements
the Birds of Britain and Ireland. T & AD Poyser, London.