The evening sun dips below the reeds at Fort McHenry’s mitigated wetlands. Volunteer naturalists lead bird walks here during migration. I usually try to attend a few each year, especially since the wetlands are normally closed to the public. It’s such a unique ecosystem in this otherwise paved-over urban landscape. The osprey nesting platform was not in use; the ospreys seem to prefer the tops of light poles, power line towers, and ship cranes. There were plenty of tree swallows nesting in the swallow boxes, though. A few of their heads were poking out of the holes. We didn’t see anything unusual on our walk, but it was still a nice way to end the day.