Officials from the Department of Land and Natural Resources in Hawaii found three critically endangered Hawaiian crows dead at the Pu'u Maka'ala Natural Area Reserve less than two weeks after they are reintroduced into the wild.

According to the report from Hawaii News Now, the three dead birds found in the natural area reserve were part of the five young alala birds released in hopes to reintroduce the native bird species back into the wild. The two remaining alala were recaptured and returned to a Big Island aviary.

"The loss of these three birds is difficult for the entire community, including the many people who have cared for these birds since their hatch and have worked steadfastly to prepare for their release," said Bryce Masuda, project manager at San Diego Zoo Global's Hawaii Endangered Bird Conservation Program, in a report from Hawaii Tribune-Herald.

The five native Hawaiian birds were released on December 14, 2016. DLNR officials observed the birds to be doing well at first, eating from feeders placed in the area. However, three of the birds suddenly died weeks later. The cause of death of the three birds is still not determined. Official necropsy reports could take several weeks to complete. Experts noted that some level of mortality is to be expected when trying to reintroduce bird species back in the wild.

This is not the first time that reintroduction efforts of the alala birds ended badly. In 1990s, conservationists, with state officials, released 27 alala in South Kona. However, 21 of the native birds succumbed to diseases and predation. The remaining six birds were then returned to captivity.

Alala is a native Hawaiian bird species that were listed as critically endangered. These birds were considered to be extinct in the wild since 2002, with captured population at the Keauhou and Maui Bird Conservation Centers managed by San Diego Zoo Global's Hawaii Endangered Bird Conservation Program.