Breeding eagle rays

The birth of two white-spotted eagle rays makes Burgers' Zoo (Netherlands) the biggest breeder of this species of ray. Biologists and animal keepers were able to celebrate births of this animal for the twentieth and twenty-first time.
The young eagle rays (twins weighing 2.5 kilo each) seem healthy and are being well cared-for behind the scenes. Burgers’ Zoo is the only zoo in Europe, and one of only six other aquariums worldwide, known to breed these rays successfully.

Eagle rays require a very specific environment, water current and water quality, and are sensitive to disease. The rays at Burgers’ Zoo Ocean live in the next-to-largest basin; adult rays have a wingspan of 1.7 metres and a thin tail more than 3 metres long. This zoo’s rays are fed individually every day in order to control what, and how much, each animal eats. The breeding success shows that the conditions are favourable.

The zoos and aquariums that keep eagle rays stay in close contact with one another. Some of the young rays born in at Burgers’ in Arnhem have already been moved to other aquariums. Before they are moved the animals undergo DNA testing, on samples taken from a part of the stinger, to determine who the father is – the mother is already known, as the pregnancy is quite visible. In moving the animals to other aquariums, the DNA results are taken into consideration. By avoiding the pairing of related individuals, inbreeding is prevented and the genetic variation in zoo populations is secured as much as possible. The European breeding programme for the eagle ray is coordinated by Burgers’ Zoo.