As far as arks go, the shipping container housed at Sedgwick County Zoo in Wichita, Kansas, appears to be an unusual vehicle for protecting species.

Nonetheless, the work there is likely to play a critical part in reversing one of the world's worst conservation disasters: the unintentional introduction of brown tree snakes to the Pacific island of Guam. The advent of the snakes at the conclusion of WWII wiped out a large number of local birds, animals, and lizards, including the Guam kingfisher, Guam rail, and Guam flycatcher.

The kingfisher, also known as the Sihek, is one of these near-extinct species, and British conservationists are working with Guam and US colleagues to prepare to reintroduce it to the wild. They are using the container at the zoo as a quarantine facility for rearing fledglings.

Claire McSweeney, a Whipsnade Zoo conservationist, who is assisting the staff from Sedgwick County Zoo and the Smithsonian Conservation Biology Institute on the project, said they currently "have four birds that have been hatched from eggs collected from other zoos in the US and we expect to have a total of nine by next summer," adding that they will then "return them to the wild, and hope to follow up with a similar annual number for the next few years, and so establish a self-sustaining wild population."

Read: 49% of birds are already extinct around the world

The brown tree snake's introduction to Guam's biodiversity first had a sluggish effect, and it wasn't until the 1970s and 1980s that conservationists, who were by this point growing increasingly disturbed, realized that the snake was now widely responsible for the extinction of local species. The snakes, who are skilled climbers, spend the majority of the day on high branches where they consume tiny mammals, eggs, and birds, with disastrous results.

The remaining 29 kingfishers were seized and sent to US collections; they were bred, bringing the total number of kingfishers kept in captivity in US zoos and Guam to about 140. At that point, the kingfisher population on the island was nearly wiped out. In order to hatch and raise young birds that will be released back into the wild the following year, eggs from these collections are currently being sent to Sedgwick.

McSweeney and her team are in charge of caring for the eggs and making sure they successfully hatch. 

Even though the kingfisher egg is not much bigger than a marble "that can be a tricky business," McSweeney added that they are "succeeding and should have nine or so hatchlings ready to go back to the wild by next year."

"We will be monitoring them round the clock to make sure they are healthy, disease-free and are ready to be returned to the wild," she said.

Read: UK: Former quarry a new safe haven for endangered birds

However, the birds won't return to Guam. More than two million brown tree snakes still live on the island. Instead, environmentalists want to relocate the birds to Palmyra Atoll, which is over 6,000 kilometers away from Guam.

John Ewen, a conservation biologist at the Zoological Society of London and a member of the birds’ recovery team, said that "Palmyra is predator-free and its rainforest can provide nesting materials and food for the birds."

In contrast to its British equivalent, the Guam kingfisher will consume insects and lizards as part of its diet instead of fish.

"The hope is that the birds will thrive in Palmyra and establish a breeding population there," Ewen added. "After that, we will have wild population to send birds back to Guam – once its snake problem has been resolved."