Yes, but only if they've filed a flight plan. Same is true for fixed wing a/c.
Here is one of the University of Michigan's Survival Flight helicopters and one of Grand Rapids Spectrum Health Aero Med helicopters for example: N155UM N176BA
webtrak.bksv.com for my area (Sacramento, CA) tracks in my opinion a whole lot more than any of the other flight radars online. It's intended use is for noise complaints.
I use virtual radar and most helicopters do not transmit location data via ADS-B. I've often wondered why it is not required for aeromedical flights to do so at least.