One thing to always keep in mind with military aircraft is that they don't have the same transponder requirements as civilian/commercial. They have the option to fly without squawking or squawk as a totally different aircraft. What you are seeing as a tanker could very well be a fighter jet. At any given time, you can bet there are at least twice the number of birds up than shown on the ADS-B maps.
One thing to always keep in mind with military aircraft is that they don't have the same transponder requirements as civilian/commercial. They have the option to fly without squawking or squawk as a totally different aircraft. What you are seeing as a tanker could very well be a fighter jet. At any given time, you can bet there are at least twice the number of birds up than shown on the ADS-B maps.