Strandskata - Strandskade - Meriharakka - Huîtrier régulier
| Pictures in Gallery | Numbers at Stag Rocks, Northumberland |
The 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 involved. Trends in the Norwegian population are little known; counts from Skogsøy should help to address this.
Tjeldstø, June
2006
One
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.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.
It is the 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 shooting.
Record:
The record count is something over 3000 individuals.
Weather:
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, V., Runde, O. & Tjørve, E. 2003 Norsk Ringmerkingsatlas Vol 1, Stavanger Museum, Stavanger
Wernham, C.V., Toms, M.P., Marchant, J.H., Clark, J.A., Siriwardena, G.M. & Baillie, S.R. (eds) 2002. The Migration Atlas: Movements of the Birds of Britain and Ireland. T & AD Poyser, London.
I
