A lot of people seem to use "killing" and "murder" interchangably, though they are different in more than legal ways. A building collapsing can kill a person, as can a landslide, and an uncontrollably skidding car. A lion attacking a human and eating his organs is no murderer, and neither is that human for defending themselves by killing that lion before he can finish his attack. One human killing another does not necessarily have to be murdering them. Initiation of violence, and intent, determine the difference between killing and murder. Even self-killing and self-murder have their own words (suicide is one). Also crows; They gather in murders all the time. Please consider applying the correct word to the context you wish to discuss.