2 Species gorger in play...

[Paraluke]

Suppose I have only 2  {Species Gorger} in play. By my upkeep, do I have to bounce both or can I just choose to bounce one?

[Wally]

I believe its both.

If both the triggers will go on the stack together, then they will resolve individually and both will require targets.

[Pleeb]

Don't you chose targets when they go on the stack?  Just have each ability target the same creature. The first one resolves moving your creature to owner's hand, then the second trigger fizzles because its target is no longer in play.

[MementoMori]

Species Gorger doesn't target.

[Paraluke]

Yea if it says target, I might think I can pass off targeting the same creature, but its not so I'm just wondering.

[Giggle the Draco Genius]

Yes you would have to do both. Since you pick what creature to return during resolution not when it is put on the stack.  First would resolve you bounce one then the other would resolve and you now only have one choice.  This is assuming that these are the only creatures you control

RESOLVED