Plate surfing should be an Olympic sport.
In a cockatiel’s world it probably is.
The way it works is like this. You set a plate down on the table in front of someone.
Someone with feathers spies it. Something on it looks tasty.
So of course that means it is time for a closer investigation….and a taste test.
If the dish pashes muster, it is officially yours under the “What’s Yours is Mine” law. So then you have to climb on to stake your claim. Or pull the desired item off the plate to indicate ownership.
At this point, the plate’s (former) owner must make whatever adjustments are necessary in order to accommodate the natural pecking order. If they are gracious they may offer to share.
You may also wish to reserve some of the contents of the plate for later. In this case, if you are still working on one item, then simply placing one foot on the item in reserve is a good way to indicate it is up not up for grabs.