"He watches the birds."
Translation:Él mira los pájaros.
To second Luis and expand on his advice, you would use the "personal a" only if the birds were his pets or he otherwise held real affection for them.
I think of mirar more often as "to look at" (or watch, or stare at) while ver is "to see." I also appreciate the nuance in usage communicated here -- http://spanish.about.com/od/usingparticularverbs/qt/ver_mirar.htm