Please help me? I do not understand this biology question?

The classic way to test if two geographically isolated groups of animals are different species is to see if they will interbreed, and if so, will their offspring be fertile. Doing this test in the wild without disturbing the animals is difficult, if not impossible, because the only way to do the experiment is to artificially "force" pairings between males and females of the different groups. It is not reasonable to just sit there and watch, "hoping" to see a random opportunity for two individuals of the different groups to get together--you might end up waiting your whole life for something like that to happen. Just observing their behavior really isn't going to help, since the accepted biological definition of a species is not a group that eats or behaves differently, but rather, a group that is strictly reproductively isolated. Even if you already knew some species-specific DNA markers to examine, you'd still have to go in there and collect sample to isolate DNA--even if all you did was get the samples from animals that just happened to have died, you still have to go in and get it--how you would do that without creating a disturbance is beyond me. Doing it all in the lab is way easier--just collect males and females of each of the two groups, and play cupid under controlled conditions. But you're still not finished--you also need to test whether any offspring from those matings will in turn, also breed. Doing it in the lab is easier because you can control the conditions of the experiment, and you can easily follow the results.

1) FIrst observe the color, size, number, eating habits,(during day and night times) of the mice on both sides without disturbing them. Most of the chances to identify that the mice belong to same species or not can be doing this.

2) Collect young male and female mice, as well as mature/older male/female mice for your experiment. Store them in a cage provided with food/water and medicines if required, collect samples (hair, blood, excreta etc) from those experimental mice from time to time as per your experimental requirements.