Biologists and other research scientists constantly monitor the welfare, living conditions, and health of reindeer, as well as the ecological health of their habitat, and they make recommendations and set quotas designed to ensure that game resources and natural biodiversity are protected, managed, and maintained. Many factors, some of them difficult to measure or predict, are analyzed including natural cycles, parasites, disease, short-term weather conditions (relative harshness of winter or summer), long-term climate changes, and condition of food sources. Hunting is not the only factor affecting reindeer welfare, but it is one area that can be managed to some degree.