Six mated pairs of whooping cranes—one of the most endangered species of crane in the world—will make a new home at the Smithsonian Conservation Biology Institute in Front Royal, Virginia.

The institute hopes to successfully breed the pairs (which is notoriously difficult in captivity), adding a few more to the approximately 900 whooping cranes alive on the planet, the National Zoo announced in a press release.

The cranes were all transported to SCBI on Sunday from their respective homes. Five pairs came from the Patuxent Wildlife Research Center in Laurel, Maryland, and one pair came from the National Zoo in D.C. They were transported in individual crates, according to the SCBI, but each crane was placed right next to its mate on the two-hour ride to their new home.

Whooping cranes mate for life, but it’s almost always necessary to assist them in reproducing in captivity, according to the National Zoo. Scientists are still investigating why exactly this is the case, and SCBI plans to use its six new mated pairs to study whooping cranes’ hormones in captivity. This is the first time SCBI will be home to whooping cranes, but the institute has plenty of practice rearing other species of crane, some even more endangered: white-naped cranes, red-crowned cranes, and hooded cranes. (Chris Crowe, the lead crane keeper at SCBI, even has experience making cranes fall in love with him).

Any new chicks will be candidates for reintroduction into the wild. The institute says the chicks will be raised by their parents or they will be fostered by a more-experienced pair.

Right now, only 52 of the 163 mated pairs of whooping cranes in captivity regularly produce eggs, the zoo says. That makes it even more important to breed new pairs and introduce some genetic diversity into the captive flock. Also to that end, scientists at SCBI are hoping to find better ways to freeze whooping crane semen, so they can put it to use in the future.

Each pair of cranes will have its own outdoor enclosure that’s 50 yards long and 16.5 yards wide. They’ll all be equipped with the accoutrements necessary for crane mating and chick-raising: two ponds, three water troughs, and a little shelter for the cranes.