Re: How should the territoriality of mice best be tested?

Hi Steph,

Your experiment sounds both interesting and promising. I think you are on the right track, but I do have a few suggestions that might help you.

First of all, you need to pay attention to the sex of your experimental mice. From the background reading I did, female mice are social creatures and males tend to be aggressive towards each other. This fundamental difference in behavior could definitely affect your results. To simplify the interpretation of your data, you should use mice that are all the same sex. You might want to consider choosing male mice, as they would be more likely to demonstrate territoriality in the first place. As one of my former advisors used to say, "If you're going to study a phenomenon, it has to happen!" However, using male mice for the experiment means that you'll probably have to keep them in separate cages after you finish the experiment; this might be a problem if you don't want to keep cleaning multiple mouse cages indefinitely.

You should also consider the social history of the mice before you start the experiment. This means that the condition (alone or with others) in which they were living both in the pet store and after you bring them home might affect their behavior in the experiment. In other words, mice of either sex that were raised alone might be expected to show more territorial behavior than mice that were raised in the company of others.

The final suggestion that I have, and probably the least feasible, is to replicate your experiment. Whenever you do an experiment like this, you need to have multiple replicates (experimental mice, in your case) so you don't base your conclusions on the behavior of only one individual. You want to be able to draw, from your observations, a conclusion that can be applied to mice in general. If, for example, the mouse you observe happens to be socially dysfunctional for some reason and eats his cagemate, you might erroneously conclude that mice are cannibalistic. The idea behind experimental replication is that by observing many mice, you will be able to document OVERALL territorial behavior in mice, rather than the INDIVIDUAL behavior of a single mouse. I realize that it may be difficult dealing with the number of mice that you would need for adequate replication in your experiment. However, I strongly suggest that you use at least two different mice as your experimental subjects. If I am interpreting correctly the description of your experiment, you may already have this covered.

The general set up of your experiment sounds pretty good, given the above caveat regarding replication. I applaud you for recognizing the need for an experimental control!! To test for a territorial response in the separated mice, you might want to keep them in separate rooms so they can't see or smell each other until you put them together. And think about the following questions: How do you plan to introduce the previously separated mice to each other? If you introduce one into the cage of the other, what behaviors would you expect to see from each of the mice? Do you think the "guest" would act the same way as the "host"? Which mouse, guest or host, do you think would demonstrate territoriality? How would these responses be different if you put both of the separated mice into a neutral empty cage that had not held mice?

I hope this long answer helps you design and perform your experiment. It's a lot of information, but these are the kinds of things you need to consider when doing experiments in biology. Good luck with your project!

Allison J. Gong
Mad Scientist