If want a direct answer it would be the decrease in mice, but if you want to get technical the decrease in grain spills caused mice to leave so that would be the indirect cause
The population changed the way it did because the mutation allowed the mutated animals to better survive in their environment compared to the normal species. Their size made them capable of getting food from higher branches that the normal species couldn't reach. THE ANSWER WAS ON GOOGLE
Axis, earth, new, moon, half, moon, full, eclipse, lunar. Your welcome
