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. 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.

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. 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.