The migration of Red Knots through Porsangerfjord in spring 2010: a progress report on the Norwegian Knot Project

We report results of the Norwegian Knot Project for 2010. The stopover population in Porsanger, N Norway, was estimated at 36,000. The first Red Knots Calidris canutus (12,250) had already arrived by the time of the first count on 13 May. Counts suggested large arrivals around 15/16 May (population then 25,000) and 19/20 May (population then 36,000). The main departures were from 25 to 28 May. The distribution continued to shift to the east with almost all birds up to 25 May being in Lille Porsangerfjord and Veidnes. There were frequent attacks by Peregrine Falcons Falco peregrinus on the big flocks at Lille Porsangerfjord, but it is suggested that this site is the safest place in the Porsanger area because the wide mudflats enable birds to gather in larger flocks, which have good visibility of approaching Peregrines. On 25 May numbers on the east side of Porsangerfjord built up to about 5,000, possibly due to birds leaving Lille Porsangerfjord because of strong easterly winds. Six birds from catches of 499 Knots on 26 and 27 May 2009 were sighted away from the breeding grounds in June 2009 (in Norway, England and the Netherlands). These birds were all in the lower half of the mass distribution. Subsequently, in addition to two seen on the breeding grounds in 2009, 117 were sighted on the breeding wintering and staging areas in summer and autumn 2009, winter 2009/2010 and  spring 2010. The mean wing and bill length and mass at the time of capture of these birds was no different to that of the total catch, showing that there had been no differential mortality in sexes (size) or mass in the 2009 migration. In May 2010 321 individuals were re-sighted at Porsangerfjord that had been marked there in May 2006–2009. This is 17.8% of all birds that had been colour-flagged and which were expected to still be alive. Up to 31 October 2010, 207 Porsanger-flagged knots had been re-sighted abroad; eight Porsanger-ringed knots had been controlled abroad and 31 knots ringed abroad had been caught at Porsanger. All the records from abroad are within the breeding, migration and winter range of the islandica subspecies of the Red Knot. There were 12 re-sightings in Iceland of birds on spring migration proving that some birds switch migration route between years. There were also 58 sightings of Porsanger-flagged birds in spring away from Porsanger, all in N Norway, and three sightings in SW Norway in autumn.