Frog movement is biased towards the southeast

Frogs slowly move South East instead of moving around uniformly.

In any given enclosure, after a small amount of time, frogs will start clumping at the South East corner, with very few frogs moving around in other areas, and absolutely no frogs near the North West corner of the area.

Here I spawned a bunch of frogs in the middle of a closed square.

 

The frogs then, as expected, started to spread out as they moved.

 

But as time went on, the frogs started to slowly move towards the South East corner of the enclosure and ended up all clumped next to the corner.