Dear Solomon:
Please let me clarify. Usually there are obvious guards at the entries. I have blocked no entries, as you said earlier to err on the side of too much ventilation. Good advice, because the weather is moving into the 80s here again.
What I meant about the observation window is that the bees were flying in so quickly from the entrance side that they were slamming into the BACK side. (This is a top-bar hive.) No guards, or at least not a strong enough force to monitor the entrances. I have never seen this hive without guards.
I do think they recently swarmed. It used to be a spooky-strong hive only a few weeks ago. I saw two empty queen cups, and my hive recently went from having bees crawling all over the inside of the hive, to being down in numbers, lethargic and unmotivated-looking.
I will take your advice and stop the feeding. They do have capped stores. I'm thinking I need to make sure this hive is queen-right. I see no eggs, and just a marginal amount of capped brood.
(P.S.: The only reason I use a Boardman is because I can actually place it INSIDE the top bar hive, not out in the open like it's designed to do for a Lang.)
I think the hive may be weakened due to a swarm, and I set them up the other day for serious robbing, even though the feeder was hidden inside the TBH.
What do you think???

Sondra