Could it be bones? As in the wooden sticks that are made to be shaped like short ribs because originally, people used the ribs to make those sounds? You hear it in Cajun music. Or it could just be something simulated. It's hard to tell. When I looked the band up, the only mentioned was "percussion" without disclosing what it was. Sometimes in Arcadian, Cajun, and Canadian music one person will do "feet" which sounds a little like wood on wood. They put down a little wooden plank and then tap on it with their feet while playing another instrument.
I wonder if it just the percussionist tapping their two drum sticks together?
*Edit - Never mind, not bones. Johnny is probably right.
Addicted to The Sims since 2000.