This nearly patternless mutation was once known as Rana pipiens burnsi, the plain leopard frog.
I stood ankle deep in waters still chilled by the Minnesota winter, listening to the yodels of distant loons, and hoping that in at least one of the flooded swales along this roadway I would finally find at least one of the 2 frogs—1 light colored, the other dark-- for which I was then searching. Both now simply mutant phases of the northern leopard frog, Rana pipiens, were once considered subspecies. The light one had been referred to as the plain leopard frog, R. p. burnsi, and the dark one as the Kandiyohi leopard frog, R. p. kandiyohi. I had first seen both when I was a kid as preserved specimens at a New England biological supply house. Now, a half century later, I hoped to find and photograph them.

On that first trip, made in May, the water was still chilly but air temperatures were in the high 70s to low 80s. Cattails and other emergents were flourishing, mosquitos were rampant and bloodthirsty, and leopard frogs, normal colors and patterns predominating, were abundant.

But I did succeed in finding and photographing a few of each of the hoped for mutants. Both were just as attractive as I remembered them being.

Now, a decade later (I don’t rush into anything!), I was back in Minnesota but a bit further north than my previous trip. It was mid-January, and temps were unseasonably warm, hovering at or just above freezing. The week before the temperature varied from zero to minus 30! In recognition of the season, we were birding, with great gray owls, not leopard frogs, being the target taxon.

This was a good thing, for except an open canal on Lake Superior and plowed roads the whole region was icy and snow covered. The mosquitos of summer were not missed; the leopard frogs were.

But having experienced both seasons, a temperature variance of more than 100 degrees Fahrenheit brought the hardiness of those leopard frogs into sharp focus. The adaptations of poikilotherms in boreal regions is remarkable indeed!