If you use both bower and grunt in your node.js project and you don't like to perform bower install manually every time while you already have a grunt default, here's a simple task you can add to your Gruntfile.js using bower's programmatic api:

grunt.registerTask('bower', 'Install bower dependencies', function() {
    var bower = require('bower'),
        done = this.async();
    bower.commands.install().on('log', function(result) {
        grunt.log.writeln('bower ' + result.id + ' ' + result.message);
    }).on('error', function() {
        done(false);
    }).on('end', function(results) {
        done();
    });
});

Note that it has to be asynchronous. Now you can add it into your default task:

grunt.registerTask('default', ['bower', 'concat', 'uglify']);

And make sure you have bower in your npm dependencies:

npm install bower --save

Now you don't even need to install bower globally and you can run everything you need with one grunt command.