WARSAW, Poland (AP) — A bison reserve in eastern Poland says seven young female animals are traveling to Spain to help boost a bison herd there.

Michal Krzysiak, head of the Bialowieza National Park, says Monday that the bison — aged between 1 and 4 years old — have been put on trucks and were on their way to two breeding farms north of Madrid. He expected them to arrive there mid-week.

Krzysiak said one of the Polish reserve's goals is to help develop new herds and increase bison as a way of preserving the species.

Wild bison were extinct in Europe before World War I. The new bison are the offspring of 12 selected captive animals.

There are some 1,900 bison in Poland now, including 690 in the Bialowieza reserve.