THE SOURCE: “Do No Harm” by Mark Jerome Walters, in Conservation in Practice, Oct.–Dec. ­2006.

The ‘alala had declined to only a few dozen birds by the early 1970s, when biologists warned that “midnight” for the traditionally sacred creatures was near. Once common in the cloud forests of Mauna Loa, the Hawaiian ­raven—­believed to guide the dead to the ­afterlife—­was near ­extinction.

Fearing the loss of the last remaining ‘alala, biologists captured a half-dozen to breed in captivity. Housed in understaffed and underfunded state facilities, the birds failed to reproduce. More were captured. Most grew old without leaving behind a single ­offspring.

Why didn’t they repro­duce? Were they disappearing because of loss of nesting habitat or as a result of attacks by alien predators? Were they weakened by exotic diseases? The rare birds were an increasingly alluring topic of research, writes Mark Jerome Walters, a University of South Florida journalism professor. Al­though some biologists warned that close observation of breeding pairs seemed to drive the birds from their nests, scientists believed that time was running out. Time-lapse movie cameras were installed near several remaining wild nests. But the cameras clicked loudly when they powered up. About 3,800 hours of nesting activity were filmed, but many of the pairs abandoned their nests during the study. By 1980, when the project ended, fewer than three dozen ravens were left, two dozen in the wild and nine in captivity without ­offspring.

By 1992 the wild ‘alala population had shrunk to 11, nine of which lived on Cynthia Salley’s ranch. She refused to let the biologists in to study them. “There are only a few ‘alala left in the world,” she recalled telling them. “You’ve got one experiment trying to raise them in captivity. And you’ve got other experiments to study them in the wild. Well, I’ve got my own experiment going on here. It’s called the ‘Leave Them Alone Project.’” Environmental groups sued for ­access.

Meanwhile, the National Re­search Council, an independent scientific group in Wash­ington, weighed in. Leave the ‘alala in the wild, their report said. Allow qualified biologists to pluck eggs from the nests of the ravens to be hatched in new, professionally staffed, and better-funded facilities. Within months, so many ravens had hatched that they could be returned to Mauna Loa. Initially they thrived, but soon began to succumb to disease and hawks. Twenty-one of the 27 released ‘alala were gone by 1999. Three years later, none remained alive in the wild. The questions about their demise have never been fully answered. Today, 52 remain in captivity.

The tragedy of the ‘alala is an ­all-­but-­universal parable about endangered species, writes Walters. The “lure of technology” tips the balance toward action instead of minimizing the risk of making matters worse. Saving the ravens became a consuming mission for many biologists at the end of the last century, but harm was done by going to great lengths to do good. Some­times, Walters says, the best policy with endangered species is one laid out by Hip­pocrates 2,400 years ago: First, do no ­harm.