I have been out at night at the Swakopmund Salt Works together with Mark Boorman on almost twenty occasions to ring terns between February 2006 and January 2014. During this period, I ringed 326 Common Terns and fitted one of them, an immature bird, with ring 4H39662 on 23 March 2007. This individual was then sighted in the Netherlands at Vooroever 1, 1671 SG Medemblik (N 52° 46´ 15” E 05° 07´00”) on 12 and 18 August 2023 – 16 years, 5 months and 2 days later and 8,429 kilometres (straight-line distance) from Swakopmund Salt Works! The sighting was reported to the Arnhem Scheme in the Netherlands, which reported it to SAFRING in Cape Town, South Africa, which in turn informed me.

There have been other notable records involving ringed Common Terns. On 26 November 2001, I found a dead ringed Common Tern on the beach opposite the saltworks. The bird had been ringed nine days before by Mark Boorman, a Swakopmund resident. On another occasion, a Common Tern I had ringed on 1 January 2011 was found dead in Norway on 15 April 2017. The birds depart from Namibia in April every year and fly up the African coastline to Europe and Scandinavia where they breed. On their way north, two Common Terns ringed by me, one on 24 March 2007 and another on 28 December 2011, were recaptured and released by a French bird ringer on 3 and 7 April 2013 respectively at Lagune de la Somone, 47 km southeast of Dakar in Senegal. The birds were on their way to their breeding grounds in Europe and Scandinavia.

In September every year, these terns travel from the Northern Hemisphere down south to spend the summer in southern Africa. They travel far more than the 8,500 km straight line between the points of capture and recapture because they follow the coastline and search for food along the way. This means that they travel around 20,000 km each year between the Southern and Northern Hemisphere.