Final answer:
The change in moose population between 1996 and 1997 could be best explained by severe winter conditions, a rise in tick populations, a doubling of the wolf population, or the immigration of a new wolf parvovirus, all of which can affect mortality and health.
Step-by-step explanation:
To best explain the change in moose population between 1996 and 1997, we must consider several factors that affect wildlife populations. These can include severe weather conditions, the presence of parasites such as ticks, changes in the numbers of predators, and the introduction of diseases. For instance, a severe winter could lead to increased mortality due to exposure and scarcity of food. Simultaneously, a rise in tick populations could lead to increased disease and weakened health among the moose, making them more vulnerable to environmental stresses and predation. The doubling of a predator population, such as wolves, could lead to an increase in predation on moose. Lastly, the introduction of a novel disease like the wolf parvovirus could significantly affect moose if the virus is transmissible to them, directly through contact or indirectly by affecting the health of their predators, which can lead to behavioral changes that impact moose.