Sculk Shriekers placed by the player does not summon the Warden or give the darkness effect.

I tested this over and over again and could not get the Warden to spawn after I place a Shrieker down. When I find a Shrieker that is naturally generated it summons the Warden and gives the darkness effect. If I pick up that Shrieker with silk touch and place it down again the Warden will no longer spawn.