Finding and eliminating the nearby food source is the most effective way to persuade vultures to roost somewhere else. Large roosts which pop up out of nowhere are usually due to a reliable, nearby food source. It can be as simple as a shopping mall with wide open dumpsters outside of every restaurant or grocery store, or a dairy farmer who isn't burying dead cows in a timely manner.
Shooting several of them while they are on the roost is also very effective. You will need a USFWS migratory bird permit to do that. Contact your closest USDA Wildlife Services office. They will provide you with the permit form, and do a site visit to confirm that you have done adequate nonlethal methods as required for the USFWS to authorize your permit.
You can expect a lengthy wait for the USFWS to issue the permit. Wildlife Services are pretty quick to respond to setting you up with the permitting process.
Already on it. Got the form 37 and permit application submitted.
Landfill so no doing away with the foodsource.
I'm looking for something longer lasting once the shooting and effigies are done that doesn't involve them paying me until eternity to move effigies and pop shellcrackers.