I was always taught, basically no. They are day VFR only.
Tim
Birds most certainly do fly at night one of my heaviest bird strikes was in the pitch black. A heavy bang on the screen which after landing was covered in blood and mess.
I have also had an Eagle fill the screen over the Alps at 14000 feet. It was a fantastic sight to see that bird of prey drop a wing and avoid my aircraft at such close proximity.
Also had another large bird miss the prop and hit the tail on my second solo many moons ago in a C152 the sound was horrendous and scared the Sh~t out of me
In cloud ? Not yet
Pace