The secret life of a dead sandwich tern

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A dead bird on a beach is hardly anything to get excited about. However, a dead bird with a ring around its leg spotted in December 2018 in the Garden Route was reason for excitement. The unusual ring around the bird’s leg, inscribed with the words ‘British Museum London’, revealed interesting information about this migratory bird.   

The Nature’s Valley Trust (NVT) program director Dr Mark Brown’s eight year-old daughter found the dead sandwich tern (Thalasseus sandvicensis) while the research team was ringing kelp gull chicks on Lookout Beach in Plettenberg Bay. Having been carefully trained by her dad to check every dead bird on the beach for rings, Kate came back with the surprise.

dead sandwich tern

Photo: Mark Brown

Long distance migration of sandwich terns

dead sandwich tern

Mark Brown

The team finally received feedback and shared the news on 11 May 2019. The bird was ringed as a chick on Lady’s Island Lake in Wexford, Ireland on 22 June 2001. This particular bird was therefore 17.5 years old. “The direct line (between Wexford and Plettenberg Bay) equates to about 10 000km, so imagine the mileage racked up for the last 17 years,” says Brown.  “This shows the value of our local long-term bird ringing work, and the value of checking birds on beaches for rings,” explains Brown.

Sandwich terns breed in North America, the United Kingdom, Europe and the Middle East – and migrate down to South America, Asia and Africa annually.

Why ring birds?

sandwich tern migration

The NVT started ringing gulls and oystercatchers in December 2012, but Brown, an ornithologist, has been ringing birds for 19 years. Ringing birds can provide a lot of data on wild birds. “Monitoring ringed birds gives us great data on dispersal movements, especially young birds that travel quite far, and info on site fidelity (birds that stick around as adults) and longevity,” says Brown. He says they regularly see or find birds 15 years and older. CapeNature ringed birds in the area before the NVT inherited the program seven years ago.

The NVT have ringed around 1 500 kelp gulls to date, re-sighted or re-trapped 61 of those and recovered 53 dead individuals, with many more reported by other people too. Kelp gulls do move around, but not nearly as much, explains Brown. His team recovered birds from as far as Umhlanga, Port Elizabeth, Mossel Bay and Still Bay.

bird ring from dead sandwich tern

Photo: Craig Nattrass

Report ringed birds

Always look to see if birds have rings around their legs. SAFRING, based at the University of Cape Town, coordinates all ringing in southern Africa. Ringed birds can be reported this website. 

The NVT is also involved in white-fronted plover monitoring in Plettenberg Bay.

Written by: René de Klerk

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