The reward for information leading to the person or persons who illegally killed a federally protected grizzly bear in eastern Idaho is up to $15,600.
The Center for Biological Diversity on Thursday announced it's contributing $5,000.
The Humane Society of the United States and Humane Society Wildlife Land Trust also on Thursday announced they're offering $5,000.
The U.S. Fish and Wildlife Service has already offered $5,000 to the reward that includes $600 from the Citizens Against Poaching.
Official say the Citizens Against Poaching hotline received a tip on Saturday and investigators located the decomposing carcass of a young grizzly bear in the Caribou-Targhee National Forest near Island Park.
The Idaho Department of Fish and Game says it's working with the Fish and Wildlife to learn more about what happened.