It does have a transponder, just not the more modern ADS-B (or mode-S) type you are used to thinking about.
This helicopter has the older original mode-3A type transponder with a 4-digit squawk. You are probably familiar with things like squawk “1200” for VFR. The squawk is assigned by ATC before takeoff and sometimes changed inflight.
Because they are operating in the Las Vegas area they also have the required mode-3C (or just “C”) which includes an altitude encoder. Mode-C is required in the Vegas area and depicted as required on the Vegas sectional chart.
If you were using software such as PlanePlotter you would actually be able to see both the 3A squawk codes and C altitudes. PlanePlotter can even perform MLAT with 3A squawk codes and provide position much like FlightAware does with mode-S.
As we get closer to the January 2020 deadline you will see more of these aircraft using the “older” style transponders upgrading to ADS-B.
Hope this helps. The military uses the 3-A/C and mode-s / ADS-B like civilian traffic, and also has modes 1, 2, 4, and now 5.
Edit: Yes, I realize that the PlanePlotter feature used to determine position using Mode-A radar pulses is actually called “Beamfinder Plus” and it is not an MLAT procedure that requires multiple receivers. I initially used MLAT above because I thought FA users here would be more familiar with the term.
For those interested, PlanePlotter has three different Beamfinder modes, one of which (Mode-A) only requires a single receiver and one ATC radar head interrogating the aircraft.