Wildlife population management requires knowledge of factors that affect population sustainability. Mortality is one of the most important of those factors. Without a clear understanding of the causes of mortality, decisions by managers of whether or how to intercede may be inappropriate. Wildlife biologists are usually the first to discover, assess, and respond to wildlife mortality. Biologists who make accurate, complete and timely field investigations, and proper collection and shipment of samples to a diagnostic facility are essential for an accurate diagnosis. In combination with wildlife disease specialists, biologists can identify causes of wildlife mortality, detect long-term patterns in factors that affect the survival of populations, and take appropriate corrective action to minimize the impact of some mortality factors on wildlife populations.