BRUNSWICK, Maine (NEWS CENTER) -- Every spring, thousands of wood frogs make their way to Nat Wheelwright's half-acre pond to reproduce.
"These frogs are amazing," stated Wheelwright, a biology professor at Bowdoin College. "Most people don't even know that they are mating right in their backyards in early April if you live in a rural area."
The frogs leave behind hundreds of thousands of eggs which hatch into tadpoles, and over the course of the summer, those tadpoles mature into wood frogs.
"Life is hard for a tadpole," he explained. "Probably only one in a hundred makes it out of the pond."
Last year, he estimates there were hundreds of thousands of wood frog tadpoles in his small pond - which is unique because it has no fish in it.
Then, one day in mid-June, things changed.