- [David] Whether you arrive in Windham, Connecticut from the north, south, east, or west, the first thing to greet you is a large green face.

- They've got a lot of character too, don't you think?

- They do.

Four big bullfrogs as solid as anvils planted there on the Willimantic Bridge like a concrete lily pad right in the middle of town.

So I'm sure I'm not the first person to ask this, but what's with all the frogs?

- So welcome to Windham.

That is a very popular question.

A lot of people who arrive here say "What's the deal with the frogs?"

- [David] At the pharmacy and the library on Main Street, the hospital and the local radio station, Windham honors amphibians.

The town's only real rival in frogmania may be Calaveras County, California, home of the Jumping Frog Jubilee celebrating Mark Twain's famous 1865 short story.

But Windham's association with amphibians predates that by more than a century, an obscure bit of colonial history.

- 1754, summertime is right in the middle of the French and Indian War.

So people were a bit on edge.

I think I saw some numbers that there were approximately 100 people living within the general area of this green right here.

- So they heard a noise?

- They heard a noise, and it was about 100 yards into the woods off the road.

- [David] Susan Herrick is a herpetologist aka a frog biologist who was born and raised here.

- Men are getting up out of their houses and arming themselves against what they thought was an invasion of either natives or somebody else during this rough period of time.

And everybody was apparently "afeared for their lives" is what some of the writing is.

- Because of the noise.

- Because of the noise.

- [David] Local historian Bev York picks up the tail.

- They got their muskets and their pitchforks and some of the militia started to go up the hill toward the sound.

- What did they think it was?

- Well, they thought it might have been natives.

- They thought they were under attack.

- They thought they were under attack by natives.

- [David] Don't let the piece of the lily pond fool you.

Mating season for bullfrogs happening just this time of year can get pretty fierce.

Just ask the BBC's David Attenborough - [David] The males occupy the center of the pond and fight to hold a place there.

(dramatic music) Their calls will attract females, but they will have to get to the center if they're to meet the strongest males.

- The way that bullfrogs breed is the males who are the biggest and the baddest of the pond set up a territory on the pond edge.

So like if this table were a pond, right, they'd be set up five, six feet away from each other and they would sit there all summer, this is my spot.

And they croak with that jug-a-rum call that everybody is so familiar with to tell other frogs that are in the pond "I'm here and this is my spot--" - Don't even think about it.

- "All you other males buzz off because I'm holding the spot for the ladies."

- [David] Herrick believes the terrible sound that so spooked the locals in 1754 was the result of a colonial climate disaster.

- It's purported that there was a drought here at that time in 1754 between late June and early July.

Apparently it was pretty dry and I think the pond edge shrunk a little too much.

And they gave up trying to hold territories and did what we call an acquisition strategy, switching.

So instead of defending territories, they did what's called a leck, which is where all the males just sort of gathered together and display themselves, sort of like a singles bar, if you will.

- So instead of singing a froggy love song, they were kind of having a communal, primal scream.

- Having a mosh pit, exactly.

- In her research at the University of Connecticut, she spent more than 3000 hours recording bullfrogs in the wild.

- This is what a frog pond would normally sound like.

(frogs croaking) So that's whole songs.

Now here they start switching notes.

So they're listening to each other.

- [David] She's built a recreation of what the 1754 frog pond might have sounded like with all of the bullfrogs bleating at once.

- So this is what I think it could potentially have sounded like on the battlefield, so to speak.

(frogs croaking) - Sounds like a big swarm of angry bees.

Nevertheless, when word got around that this little town had panicked taking up arms against a bunch of bullfrogs, the story had legs.

- The story had legs, the story had legs.

And from all over people started talking about the people, those Windhamites who couldn't tell the difference between a bullfrog and an Indian.

- The great Windham frog fight became an American tracheomalacia, the stuff of epic comic poems, at least three of them.

Before the US had a national currency, bank notes issued by the Windham Bank featured a frog standing on top of another frog.

In 1905, the local opera house even mounted an operetta, a musical, "The Frogs of Windham" which has enjoyed several local revivals.

And to this day, the local brewery has an annual Hop Fest.

So you've embraced the frog, which was originally sort of a joke at Windham's expense.

- A joke at Windham's expense, but we're pretty good at laughing at ourselves, yep.

- The bridge itself is an example of that good humor, built 20 years ago by the state of Connecticut, the locals insisted it paid tribute to their heritage.

- Apparently it was pretty embarrassing for the colonists back then.

But nowadays we look back and we laugh and we think, oh, that that must have been the equivalent of nowadays online ribbing.

- So forever these frogs will troll the town of Windham.

- Troll the town of Windham forever.

- [David] Willie, Manny, Windy, and Swifty may not sing and dance like Michigan J Frog of "Looney Tunes" fame.

♪ Hello my baby, hello my honey ♪ ♪ Hello my ragtime gal ♪ But Connecticut's famous frogs are hard not to love.

Like The Frog Prince in the 1971 "Tales From Muppet Land".

- He turned into a prince.

- How about that?

He really did.

- Mother of amazement.

- [David] A happy ending in this case for small town New England.

- It brings tourists to town to see the bridge.

That's why you're here.

You came to see the bridge.

- Absolutely.

(gentle music)