The Irony of Ignorance
The birds claim that they are incapable of accepting the quest because they are ignorant. They do not see, in their ignorance, that all that stand between them and enlightenment is experience. By taking action they can learn the necessary skills to accomplish the quest.
The Irony of the Mirrored Pool
All the time that the birds are traveling through the valleys, they are seeking the Simorgh. When they finally arrive at his home, they look into the pool only to see their own reflections. The Simorgh is not tied to a location as a physical being but is actually manifested in all living beings. He was within each of the birds the entire time, but they were unable to see him until they successfully overcame each of the trials.
The Irony of Desire
In the Valley of Love, the birds learn that love is eternally linked to suffering. What they desire will always cause them pain, yet still they desire it. The object of their esteem is the only reason they suffer, because they desire.
The Irony of the Hoopoe's Advice
The hoopoe has already achieved enlightenment, so he needs nothing from these birds. When they ask him to elect a king for them, he tells them to find the Simorgh. He knows who the Simorgh actually is, however, and understands that he dwells within all of the birds. By telling them to seek him, the hoopoe is telling the other birds to turn their attention inwards and examine their hearts. They don't need a king if they learn to govern themselves well.
The Irony of Death
As the hoopoe explains, everyone dies. What one does in life doesn't really matter because in the end one dies just the same as everyone else. This is why he encourages the birds to take responsibility for their lives, since they really have nothing to lose.