Researchers at the Calgary Zoo are worried about the number of northern leopard frogs they are seeing in the wild.

Ecologist Lea Randall counts frogs in slough, rivers and creeks across Southern Alberta.

In a small pond ringed by cattails north of Brooks, Randall recently waded through the water. It’s one of 68 water bodies Calgary Zoo researchers have been monitoring across southern Alberta for six years.

They're counting the northern leopard frog and studying its habitat to see if the population has rebounded after a big decline in the late 1970s.

"We don't have a firm grasp as to why the decline occurred, but there is definitely some good hypotheses," she said.

Those include drought, changing land-use patterns and fungal infection.

"I think a lot of the reasons why we lost them don't necessarily relate to things like poor water quality. I think it was the reasons like drought and disease. So they're not exactly a good indicator species necessarily, but in the same sense, if you have a wetland that has leopard frogs you know you have a healthy wetland."

Numbers not promising

Randall says many die in winter and the numbers – so far – don't look promising.

"It seems that we're not getting the recovery we hoped for. They're not in decline like they were back in the 1970s, so that's the good news,” she said.

Currently, the northern leopard frog is listed as threatened in Alberta. Zoo researchers will keep tracking them and hope the numbers will tell a better story soon. The team will publish some of its results later this fall.

Frogs Lea Randall

Ecologist Lea Randall wades through a small pond ringed by cattails north of Brooks looking for northern leopard frogs. (CBC)