Right off the hop, Wascana Centre naturalist Matt Tokaruk knew he was hearing something different.
It was, he suspected, the trilling of a gray tree frog, a species never seen before in the sprawling Regina park.
In fact, it still hasn't been seen, but Tokaruk recorded the sound and sent it to two biologists, who concurred with him that it was indeed the elusive gray tree frog.
"I was pretty pumped to hear it," Tokaruk said. "It's exciting — it's quite a bit outside its normal range."
Listen — Matt Tokaruk's recording of a gray tree frog in Wascana Centre:
Some gray tree frogs have turned up on the east edge of the province, but this would be new for Regina, Tokaruk said.
The nocturnal amphibians are easy to overlook. They're small (about five centimetres long), grey and live in the trees.
They also have some chameleon-like abilities — shifting from grey to green to match the background.
They haven't yet been photographed in Wascana Centre, but that may be just a matter of time.
Meanwhile, it's not the only surprise naturalists have had in the park. Not long ago, a rare American water shrew was spotted, Tokaruk said.
Birders have also been talking about seeing rare orchard orioles, a rust-coloured variant of the more common Baltimore oriole.
The park that sometimes seems overrun with Canada geese is in fact home to or visited by some 70 species of birds and 20 to 30 species of mammal, according to Tokaruk.