What is your argument?
Your topic is a straight expository or explanatory topic. It doesn't seem to be an argumentative topic in which you persuade your readers of a particular point of view.
Check these sites for information about argumentative essays.
I have to make a persuasive speech out of this question modifying it if necessary. Do you have any suggestions on how I can modify it and make it persuasive?
You need to research this question. What are the different theories about the navigation of migratory birds?