A pair of lifelong mates were shot in Kentucky during November.
One of the birds survived but was later euthanized after rehabilitation efforts failed.
Whooping cranes are America’s tallest birds and were once a common sight across parts of the country.
But by the 1940s, the use of the pesticide DDT, hunting and habitat loss wiped out all but 14 of the birds.
Careful breeding has restored some the population, but numbers are still sufficiently low that shootings, drought and other factors can pose a dire threat to the species' survival.
Only 13 are released into the wild each year by the conservationists who supervise their captive breeding.
The birds don't reach sexual maturity until they are about 5 years old and usually have only one chick at a time. Only one in four of the hatchlings survive the first year.
The current population of the 5-foot-tall birds is distributed among three main flocks in North America.
Wildlife officials in Kentucky recently announced a $15,520 reward for information about the November 2013 crane shootings.
Photo: Louisiana Dept. of Wildlife and Fisheries