Week 7 Overheads


Olfactory Homing

1. Different chemicals, different regions...different odors

2. Animals can distinguish different odors

3. Imprinting

4. Learning

Salmonid Fishes

1. Return to birthplace to spawn

2. Olfactory imprinting and learning

3. Very percise

4. Long distance homing cue


Other Animals that use Olfactory Cues in Navigation

Turtles, Canids, Muskidae, etc.

Pigeons

Wallraff proposes:
  1. Olfactory gradient map
    • Wind directions
  2. Olfactory map has low signal to noise
    • Initial vanishing bearings not reflective of homing
    • Air sampling required
      • More sampling, better vanishing bearings
    • Can be used to home from areas never visited before
    • Not an exclusive navigation system
Wiltschko proposes
  1. Olfactory homing overstated (non-existent?)
  2. Meteorological arguement
  3. Prevent pigeons sense of smell by:
    • Olfactory nerve section
    • Zinc sulphate
    • Blocking nostrils
    • Transport in air controlled containers
    • Local anaesthetics
  4. Effects of trauma?
    • Local anaesthetics can cause disorientation
    • Interaction with sun compass?
  5. Environmental angle?
    • Presence/absence of winds?


Approaches to Research and Critical Thinking

There were some difficulties with the Critical Review Papers. I suspect these problems stem from a general lack of exposure to how to conduct research experiments. If you do not know how to design and develop an experiment then I can see how it would be difficult to critically review and interpret an experiment described in a journal article.

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.

Research Methods 1

Research Methods 2

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.


Return to 403 course page.