[Fixed - persists in 3.63] Grouses will not land

[Buoidda]

The other day I saw a black grouse land on the ground I realized they almost never do that.

I started bird watching and on one occasion a grouse "flying high" did so for more than an hour on a single tile.

I'm sure this "staying in flight" time should be checked at least for grouse family birds. They are heavy birds and don't want to stay in flight for very long as in once they take off they are already looking for a spot to land.

[Sami]

Still flying is very old glitch which has troubled all the birds in the game occasionally. It's a result of new bird's life task (eg. "stay alert and observe the surroundings") being assessed for the creature without checking the flying condition. The contradictory tasks then caused the birds freezing in their flight.
Some tweaks have been now made to hopefully prevent the issue in the future.

Fixed - persists in 3.63.