I picked up my rare Crow as a secondary to a rare Glowfly! So I picked to Crow to capture... it took me much longer to then find a rare Darkmoon Glowfly again, but eventually found a rare secondary to a green one.
To all the people not removing the spawns of the level 1-4 Darkmoon Glowflies looking for a rare Crow, while profiting from my diligence in doing just that:
I'm on to you and now I am purposely leaving all the single spawn Glowflies up while camping the other spawns to make sure they respawn as level 4 or below.
There's another way to look at this. They could well be leaving them there because they know there's still a lot of other people wanting to capture the glowfly. It's not all about people who want Crows.