JOHANNESBURG - Scientists were excited to discover a journey made by 2,000 zebras. They believe it is the longest trip made by any animal in Africa.

The zebras travel between two countries in a part of southern Africa. Wildlife experts discovered the journey after attaching tracking devices to some of the zebras.

The finding is a rare bright spot. Nowadays, large groups of wildlife traveling together are hard to find. Human land use has limited animal migrations. One study on the subject found sad news. Plants and animals disappear much faster now than before humans arrived on the scene.

The zebra trip occurs in a huge area of southern Africa. The area includes national parks at a spot where five African countries meet.

"It goes to show us that nature still has some surprises," said Robin Naidoo. Naidoo is a nature scientist at the World Wildlife Fund. The WWF led the two-year study on the migration.

He said the migration was not detected until scientists could use GPS tracking technology. The technology is easier to get now than it was 20 years ago.

A Long Way From Home

The zebras travel a 300-mile round-trip in search of fresh grass and water. They start in floodplains at the beginning of the African wet season. The zebras follow a route across a wide river and end at full waterholes and fresh grass. They spend about 10 weeks there before heading back.

People already knew the zebras left their home at the floodplains and returned months later in the dry season. Until recently, they didn't know where the animals went.

Scientists put tracking collars on eight zebras. They monitored the zebras' travels by satellite in 2012 and 2013. The findings were published recently in the nature magazine Oryx.

Scientists had to put the zebras to sleep to track them. They fired tranquilizer darts from a helicopter. Then they landed and attached special GPS collars, Naidoo said.

David Wilcove is a nature expert at Princeton University. He thought the finding was remarkable. Large animal migrations are rare and people are just beginning to understand them, Wilcove said.

Wildebeest also migrate, but in the Serengeti in East Africa. It's possible that they cover more ground than these zebras, but they wander around more. And more wildebeest migrate at a time.

Migration Routes Must Be Protected

The southern African zebras move largely in a straight line. They travel 6 to 12 miles farther from start to finish than the wildebeest travel, according to a study described by Naidoo.

Tony Sinclair is an expert on African animal migration. He said the zebras have to move through "human-dominated lands." The migration could be lost if more protective measures are not put in place.

Sinclair said that there are ways to protect the long migration route. People whose land is crossed by the migration may benefit from protecting it. Linking it to tourism could save the migration and bring in money.

In 2004, a fence blocking a zebra migration route was removed. About 15,000 zebras traveled the re-opened route in 2008-2009, according to a study.

Much remains to be learned about the Namibia-Botswana migration. The World Wildlife Fund said a longer study is needed to know if the migration is the same every year. They also want to know how the zebras know to migrate.

The zebras pass similar areas with fresh grass and water areas closer to their starting point during their migration. However, instead of stopping there they make a longer trip. The zebras could be following a pattern so ancient it has become an instinct, says the Oryx article. It could be in their genes.

Mike Chase, who helped in the zebra study, said the migration stirs the heart.

"We all yearn for that, the romance of wild, open spaces," Chase said. "There are very few places left on our planet where animals and wildlife have the natural ability to roam."