Timing, staging, speed and destination of migrant Wood Sandpipers Tringa glareola breeding in Scotland

Apart from ringing recoveries and data on changes in mass at staging sites, little is known in detail about the migrations of the Wood Sandpiper Tringa glareola, an Afro-Palearctic migrant whose numbers are declining. To obtain data on the timing and speed of migration, staging periods and locations, and their wintering grounds, we fitted geolocators to breeding Wood Sandpipers in Highland Scotland. The median last date on the breeding grounds was 25 June (range 18 Jun–2 Jul) for three birds over five southward migrations. Tracked birds staged for a median total of 15 days (range 11–17 days) at one or more sites in Scotland, Wales, England, France, Spain, Portugal and Mauritania before continuing south to Senegambia (i.e., Senegal and The Gambia), where the median first date was 14 July (range 3–23 Jul). The southward migration of ca. 5,000 km from Scotland took a median of 18 days (range 14–20.5 days), plus an estimated 1–3 days for the initial accumulation of fuel on the breeding grounds, thereby giving an average speed of migration of ca. 250 km per day. The wind direction and speed appeared to have no adverse effect on the southward migration. Tracked individuals spent the non-breeding season in Senegambia or Senegambia and southern Mauritania. The median last date in West Africa was 8 April (range 29 Mar–15 Apr). The birds staged for a median total of 18.5 days on the northward migration at one or more sites in Algeria, Morocco, Spain, France and England. Strong westerly winds are believed to have caused eastward drift over the Sahara during two northward migrations. The median first date back on the breeding grounds was 4 May (range 1–4 May). The northward migration took a median of 23.5 days (range 18.5–36 days) plus an estimated 8-day period for the initial fuelling in West Africa in order to cross the Sahara, so the average speed of migration (ca. 160 km per day) was slower than the southward migration.