Triggered abilities *always* go on the stack. It has nothing to do with what the ability is, whether it deals damage or targets things or [makes Squirrel tokens][1]. If you see the magic words "when", "whenever", or "at", you've got a triggered ability and it goes on the stack when it's triggered.

Obligatory comp rules:

> 112.1b An ability can be an activated or triggered ability on the stack.
>
> 112.3c Triggered abilities have a trigger condition and an effect. They are written as "[Trigger condition], [effect]," and include (and usually begin with) the word "when," "whenever," or "at." Whenever the trigger event occurs, the ability is put on the stack the next time a player would receive priority and stays there until it's countered, it resolves, or it otherwise leaves the stack.


  [1]: http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=12458