Sorry, no pictures but I'm pretty confident it was an Anna's. A Google search shows that one of their recent annual reports listed Anna's hummingbird as a new acquisition as well. I was there in June and the terraria were present and occupied. They would have been easy to miss. Checking on Youtube, a few of them can be seen in the following video: At 3:04, the stump in the bottom middle part of the image is a terrarium. The little hole in the top of the stump is the viewing window. There is another terrarium under the stick next to that stump, and the stick has to be moved to see it. At 3:38, the log that you can see in between the two people is another terrarium. The cracks in the log are the viewing windows. There are several others on the opposite side of the pathway that can't be seen in the video but are similarly tiny and hidden.
Amur Tiger "Titan", a 3.5 year old male from John Ball, is on display. They hope to breed him with Talya.
Interesting snippet: 600 sturgeon released locally with a touch tank for the 3-6 year old sturgeon on display at th NHM and bigger ones at the Aquarium! I assume the releases locally in Ohio will become a regular feature in future!
