By Laura Smith-Spark, CNN
January 16, 2014 -- Updated 1919 GMT (0319 HKT)
Wildlife officials seek the killers of two rare whooping cranes in Kentucky
The birds are thought to have been shot in the same incident in November
A reward is offered for information leading to those responsible for the crime
Whooping cranes are the most endangered of all of the world's crane species
(CNN) -- The hunt is on for the killers of two extremely rare whooping cranes, shot as they spent the winter in Kentucky.
The birds are thought to have been illegally shot in a single incident in November, the U.S. Fish and Wildlife Service and the Kentucky Department of Fish & Wildlife Resources said Thursday.
Now a reward is being offered to help track down the killers.
Whooping cranes are the most endangered of all of the world's crane species, according to the release, and are protected under two federal laws.
Fewer than 500 of the long-legged birds live in the wild in the United States. Seven of them were in Kentucky this winter.
The first bird was reported injured on November 25 in Hopkins County, the news release said. Two days later it was rescued because it had become very weak, but its upper leg was shattered and it had to be euthanized.