'YourTern' project: Damara tern also breeds in winter

The Damara tern (Sternula balaenarum) is mainly found on the Namibian coast and is considered endangered. For the past three years, the 'YourTern' project has been supporting further research into the seabird and its protection with funding from Holland.

The Damara tern not only breeds in summer, but also in winter. This is one of the many new insights gained by the project. They came across breeding birds and recently fledged juveniles in July, explained Ruben Fijn from the consultancy 'Waardenburg Ecology'.

At a presentation for the Namibia Bird Club in Windhoek he added, that the chicks of the breeding birds are likely to fledge end of July and in August. However, it is not possible to say whether the same individual can breed twice a year or either in winter or summer.

Together with the Namibian experts Jean-Paul Roux, Mark Boorman, Holger Kolberg and Hartmut Kolb, Fijn is investigating many unanswered questions as part of the 'YourTern' project. Is the Damara tern a migratory bird? A substantial part of their population is probably not, said Fijn.

The answer to this question is important for the protection of the seabird. It breeds almost exclusively on the coast of Namibia, from Lüderitz via Walvis Bay and Swakopmund to the mouth of the Kunene River. Experts estimate the population at around 8,000 birds.

The Atlantic offers ideal conditions for the Damara tern, emphasised Ruben Fijn. The constant strong wind ensures constant upwelling of nutrient-rich water from deeper layers. It offers plenty of food for plankton and thus small fish, which the bird feeds on.

'YourTern' also protects the Damara tern

For centuries, the inhospitable coastline offered the Damara Tern natural protection from humans. However, this has changed drastically in recent decades. One settlement after another is being built on the coastal strip. Four-wheel-drive vehicles and quad bikes are also threatening the breeding grounds.

The 'YourTern' project therefore also aims to draw attention to the threat and promote the protection of the seabird. To this end, they are working together with the Namib Desert Environmental Education Trust (NaDEET), said social marketing expert Jolanda Veldhuis, of the Vrije Universiteit Amsterdam. She is the driving force behind the educational part of the ‘YourTern’ Project together with her compatriot Bas Engels and Master of Science students.

In a small eco-education centre in Swakopmund and on excursions, pupils learn about the bird and its sensitive habitat. The 'YourTern' team has also developed a board game that sensitises the children in a playful way.

Mini tracking devices for research

Back to the question of whether it is a migratory bird or not. According to the article on Wikipedia, the Damara Tern migrates towards the equator during the Namibian winter. However, Ruben Fijn and the Namibian experts doubt that this is true for the entire Namibian population (see also the detailed article on the Damara Tern on Namibian.org).

To collect evidence, it would be necessary to ring birds on a large scale. But catching them is not that easy, as Fijn explained in his presentation. The experts have constructed a large frame that lies flat in the sand. By means of a hinge and springs, it springs up on one side and falls to the other side together with the net. The mechanism is triggered by remote control.

Bird dummies and typical calls emitted by loudspeakers attract the terns. Unfortunately, only a few birds settled in the area of the trap. And the calls also attracted unwanted visitors like a jackal. 

Compared to the effort involved, a ring provides little information - and only when it is sighted. According to Ruben Fijn, there are therefore plans to equip some birds with mini transmitters. In this case, however, ‘mini’ means light as a feather.

Because the rule of thumb for transmitters is: no more than 3 % of body weight. For the Damara tern, which weighs a maximum of 55 grams, 1.5 g is therefore the upper limit. And unfortunately these mini transmitters are expensive.

Donations are therefore welcome. Find out more on the website of the 'YourTern' project. On the Facebook page you will find regular updates and many photos.

Sven-Eric Stender