I would say a mature buck, the nocturnal thing plays a huge factor where I hunt. I can glass the big boys right up until bow season then poof, gone. I get pics of mature (3.5+ year old) bucks on my trail cams right up until they shed their velvet, then they seem to dissapear until the rut, IF I even ever see them again. With old mature Toms, I still see them often during turkey season if there are old Toms on the property, locating them is relatively easy if they are in a vocal mood which is more often than not, coaxing them in can be hit or miss though. Imagine using a crow call to locate mature bucks on your property, heh.