More advocacy groups have filed lawsuits seeking injunctions to stop researchers from surgically sterilizing more than 200 wild mares in Central Oregon. The Bulletin reports the American Wild Horse Preservation Campaign and The Cloud Foundation jointly filed a lawsuit on Monday against the Bureau of Land Management arguing that the agency had violated the groups’ First Amendment rights by rejecting their request to record the procedures. Bureau officials say they are still reviewing the latest lawsuits. The U.S. Bureau of Land Management has said the research in Hines, Oregon, would help determine whether the three methods to be studied could be safely used to control the wild horse population. Front Range Equine Rescue and Friends of Animals have also sued the agency over the proposed sterilization.