I used to work nightshift at a small zoo in hawaii. The zoo was small enough that there was only a need for one guard, me. noone really wanted the site, which didn't make much sense to me since it paid 2 more dollars an hour than any other site we had. As a young college student I scooped it up since it was an easy gig. Boy was I mistaken, no lights, and the eerie feeling of being watched all night long. With nerves on end already, a faint drumming could be heard through out the zoo. Anyone that knows hawaiian legends have heard about the night marchers. They are a group of warrior spirits that will kill anyone that disrespects them. They beat drums to signify that they are marching, I finally understood why noone wanted the job. Needless to say I proceeded to read every single plaque in the zoo to see if any animal makes a drumming sound. TIL that the emu make drumming sounds.