How do tree platforms work in Snakebird?

I am trying to understand when a tree platform will support a snakebird and when it will not. It does not seem to be consistent to me at this time.

For example, in level 3, the snakebird begins resting on a tree platform. After moving right twice, the snakebird is horizontal and supported by the platform, as shown below. But moving in any direction (down, right, or up) will result in the snakebird falling down off of the platform.

Here's the position after pressing down:

Why does the snakebird fall from the platform when its tail is still on top of it?

Here's another conundrum: After grabbing the cherry to the right of the spikes, the player must traverse back to the left side to grab the strawberry. The player does this by getting in an L shape, shown here:

After moving to the left twice, the snakebird will be fully supported by the tree platform:

Likewise, I expect the player should be able to put the snakebird in a backwards L position next to the right-side tree platform, move right twice, and be fully supported. This is not the case. Here is the backwards L:

Here is the position after moving right twice:

Why does the tree platform on the right not support the snakebird when it was approached in an identical way as the one on the left?

This is causing me great confusion. Is this intended behavior or a bug?

I'm new to this game, but if anyone has some examples of tree platforms from later levels, especially ones that elucidate how they work, please share them.

There are no "tree platforms" in Snakebird. That stuff is just scenery.

You're being held up by either the fruit and the dirt in those pictures.

Everything you can rest on in Snakebird is in the foreground, I think a comprehensive list would be:

• The floor

• Fruit

• Other Snakebirds

• Movable blocks/shapes

Gotta say though, possibly one of the best asked questions I've seen on StackOverflow.