2. Animals can distinguish different odors
3. Imprinting
2. Olfactory imprinting and learning
3. Very percise
4. Long distance homing cue
A couple of years back I put together a couple of web pages of information on Research Methods for a course I was TAing. The links are below. We went over material from the second link (Research Methods 2) in class. Actually, in retrospect I think it may have been more productive for us to have discussed some of the topics included in the first link (Research Methods 1). I encourage you to take a look at both these links in some detail. If you have questions by all means bring them up in class.
I think the primary feature of any researcher is their drive to ask questions. Of course, in different fields the way that these questions are approached takes on a variety of forms. However, in science the principle way that questions are answered (or at least investigated) is through some form of experiment. The notion that an experiment must be filled with controls, hypothesis tests, and large pieces of flashing equipment is a rather narrow view of how science is conducted. Unfortunately, it is a view that has been fostered by a variety of sources in our society (not the least of which is television and the popular media). Regardless, good science, that is, science that aims to answer a question, may involve nothing more than taking your lunch and a pair of binoculars out into a field on a sunny day and watching a pair of ducks forage for food. The point is that there are lots of different ways that science can be carried out. The important aspect is the nature of the questions that are being asked and the way that the questions are being investigated.
With respect to reading (or listening) to material critically, this largely involves asking questions. Whether the material you are critically reviewing has been well done or not, you should still be able to ask yourself (and others) a wide variety of questions. In many cases these questions can lead to the creation and development of new experiments designed to provide the answers. This is how Science (with a big "S") works, and it is one of the primary reasons why people who work in science spend so much of their time publishing papers in journals or going to conferences to give talks. By getting the research out into the public domain other researchers can pose questions and seek the answers.
You will notice that even in the very short time that we spent suggesting possibly ways that one might go about testing if Porto Rican tree frogs use olfactory cues to navigate you will remember that a couple dozen questions/suggestions were raised. Any one of the points raised could have become the central feature of a research study. All of the issues raised were also, in some form or another, examples of critical commentary. Admittedly, some were more critically structured than others, but they all had at least a grain of critical thought in them that could be developed and expanded upon.