Endotherms are animals whose body
temperature is regulated mainly by internal bodily processes. Endotherms are
warm blooded animals such as birds and mammals that maintain a constant body
temperature independent of the environment. Endotherms require high quantities
of fuel to produce heat for their survival under low external temperatures.
Limiting factors are resources or other factors in the environment that can lower the population growth rate. Limiting factors include a low food supply and lack of space. Limiting factors can lower birth rates, increase death rates, or lead to emigration.
This could be the different times you did the experiment