There is a blockage in your main sewerline.
Your toilet will gurgle and bubble when flushed due the flapper valve on your toilet, or small vent pipe and even because of a crack in the toilet. To overcome this plumbing issue try changing the toilet flapper, which does not cost much, and if the issue is a major one contact a professional plumber near at once.
Your drain line is plugged somewhere after your shower and toilet line are connected. The reason for the gurgle in your toilet is because air is trapped in the drain and your toilet is the closest place for air to flow to. If you had a vent on your toilet trap arm then it would gurgle in the vent rather in your toilet but your drain is still plugged and needs to be snaked out and maybe your drain line needs to be examined for right grade or broken.
Of course it will gurgle if there is a partial blockage or poor venting .The waste and soil lines do connect and if there is an object causing a restriction then gurgling is quite common.
Clear the stoppage in the line that is causing things to gurgle.
check the vent pipe probably blocked
Probably because all the water gets moved around when you flush it. xD
Snake out the main lines and check the vents
Sounds like they share a common pipe to drain.
The lower toilet is acting as a vent. Check the vent stack for debris, bird nest, critters, etc.
A mainline stoppage.
Gurgle is a noun (a gurgle) and a verb (to gurgle).
Drain is partially clogged or the vent pipe is stopped up. Also check the vent holes underneath the rim of the toilet and clean them out.
There is a slight blockage in your sewer line which is creating air pockets, which eventually finds its way and escapes through the toilet and the sink.
The drain is plugged somewhat between the upstairs and downstairs. Need to snake the drains.
The toilet will gurgle as it sucks air through out the toilet trap. You may even hear it suck air through a nearby sink or the tub. Sometimes it may just drain slow or weak.
Often a toilet will gurgle after flushing for one or more of the following.1-the drain line has a partial blockage2-the vent line has a partial blockage.3-the toilet itself has a partial blockage.4-Incorrect installation of sewer/vent toilet lines.There are a couple of other rare circumstances that may cause this, but the majority is related to the above. If the toilet is able to flush and no signs of slow draining or back up, then it is most likely the vent line that is obstructed.Sounds like verbatim what I had posted over a year ago
As the sink emptied it made a sound like a gurgle.The baby began to gurgle as mum tickled his tum.
Probably because the line is still at least partially clogged.
I enjoyed listening to the waterfall's gurgle.
to get gurgle you plant seeds until you get him. it's how I did it
Many people have Gurgle.
Gurgle was a Royal Gramma Fish
The drain may gurgle as the water goes down it.