I don't know for sure, it might be due to the biblical reasons mentioned, but for some reason I always thought it was because it was "public" property, and they felt the need to give the hikers, bikers, bird watchers, etc., their time also. Most of that refuge is flat with good "walking roads" which are great for family hikes and such... so the hunters get it on Mon thru Sat, and the non-hunters get it on Sunday.