Time has passed and 5 of the 6 turtles have survived it. Regrettably, one died in May 2015. The Feisty Five seem to be survivors.
I now know why I have not been able to count more than 5 turtles. I found the carcass of one of the turtles today. It is much smaller than the turtles are now. My last 6-count was on/or about 05/03. [See featured image above.] I took a “Bale of Six” photos on that day. Subsequent pictures never showed more than 5. Based on size, I think the death occurred just after that date. I do not know why it died. I suspect I had a sick turtle.
Today, I hope to give them the chance to adapt to a different word–that of an Outdoor Aquatic Habitat
Once it is a bit warmer, and I have built covers for protection, I plan to let them live outdoors until about October.