Where are all of the command line tools installed?
The whereis command only looks in the standard executable paths. Try which bower instead. Here's an example from my machine. I used "git" because I don't have "bower" installed.

~ 506 whereis git
/usr/bin/git
~ 507 which git
/opt/local/bin/git


whereis returned the path of the system-installed version of "git". which returned the path of the version that actually runs when I type "git" at the command line.