That all depends on when your clock is set. Your clock should determine whether it's Nightime or daytime.
Murkrow is found in the Lost Tower, at night, and only in Pokemon Diamond.
noctowl and hoothoot
In Pokemon Diamond, I would say it is easy to find a Noctowl or Hoothoot after it becomes dark.
it's night on diamond when it's 8pm-4am on your DS clock
Mukrow can be found at Eterna forest at night.
eterna forest at night in Pokemon diamond
in the tower at night
i have a pokemon book that tells me where every pokemon is. and you cant find it in diamond or platinum only in pearl (at the eterna forest night only)
Eterna forest at night, but in Pokemon pearl, not diamond.
You can get Duskull by using the Pokeradar on Route 224 in Pokemon Diamond. You must use the Pokeradar at night in order to find and catch Duskull.
you get hoot hoot at night in the marsh game
in the shaymin area you can mostly catch him at night..