Final answer:
Infection by a deadly disease and competition for shelter are factors that could cause a decrease in bat populations, while an increase in food and decrease in predators typically aid in population growth.
Step-by-step explanation:
The factors that could cause a decrease in the bat population in a cave are infection by a deadly disease and competition for shelter. An increase in the food supply and a decrease in predators would generally be beneficial to the bat population, so these are not likely causes for a population decline. In contrast, a deadly disease like the white-nose syndrome, which is known to affect bat populations, could significantly reduce their numbers. Similarly, competition for shelter could lead to some bats being unable to find suitable living conditions, which could also decrease the population.
Examples of factors causing bat population decline include scenarios where pesticides reduce the insect population that bats feed on, leading to starvation, or environmental changes that favor certain predators or diseases. These factors demonstrate density-dependent influences on bat populations where the impact varies with population size and density.