A temperature of 25°C can be considered as a room temperature. It is an optimal temperature for the most living beings which cell potential is considered as standard. It is known that at 100°C water boils, so this temperature cannot be standard, cells will degrade at this temperature. Similarly 0°C and –273°C are too cold, water of the cells will freeze, cells will freeze, and cell potential will not be optimal.
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