What does it mean when you hear one toilet gurgle when another toilet in the house is flushed?

I believe you have a venting problem -- most of the time the stack vents pressure

To outside -- when water goes down one toilet it forces air out of the line and in your

Case it takes the path of lease resistance -- bubbling out in other toilet because of

A plugged vent... Birds build nests in vents and gutter downspouts -- need a

Properly cover... Best way is to snake drain is down the vent pipe to clear it

Please rate my answer

Biggsie is correct about snaking the vent. Do it from the roof if its safe up there. Run enough snake to reach roof top to basement floor plus 10-15 ft more. The gurgle is the air venting itself out your other toilet because it can vent up the blocked stack. Once you have rodded the vent install a Provent or roof vent cap to cut down on future blockages.