Frog population explosion part of normal cycle

There’s a quiet invasion going on in the Rainy River District and it could be coming right to your back yard.
At least that’s what Bob and Lori Green of Fort Frances discovered.
The Greens have a two-acre lot in the west end on Colonization Road and last week, their small, man-made backyard pond took on the appearance of a Biblical plague or a scene from an Alfred Hitchcock thriller.
“I came out here and saw dozens of them in clumps, some on top of each other, by the pound,” said Lori. “It was really weird.”
Not exactly.
According to Ministry of Natural Resources biologist John Van den Broeck, this is not the first report of such a phenomenon in the district.
“There appears to have been an eruption of northern leopard frogs in the district over the last two years—particularly in the west end around Lake of the Woods,” said Van den Broeck.
Van den Broeck noted adult leopard frogs normally inhabit open fields and forests, but return to ponds and rivers to hibernate in the mud during the winter. To find them congregated in such numbers around a small artificial pond is somewhat unusual, but not inexplicable.
“It would appear the adult frogs are attracted to the pond to feed,” he explained. “Their home range is small (500m sq.), so it is likely they will return to the river to over-winter. They will not over-winter in the pond, although it would be suitable for reproduction.”
That’s not likely since Lori says they usually keep exotic fish in the pond, which would devour any tadpoles in short order. However, since the Greens did some extensive renovation of the pond, there were no fish in it this year, so some frogs may have laid eggs there in the spring that survived.
Field naturalist Henry Miller said he too has noticed an increase in the number of leopard frogs in the district this summer, although he offers no explanation for it, except to point out these kinds of “boom and bust” cycles are not unusual in many species.
“These things seem to run in cycles,” Miller explained. “Over the last few years, we’ve seen a reduction in numbers of lynx because the hare (its principle prey) are also down.
“When the hare come back, so will the lynx,” he predicted.
“There are quite a number (of frogs) this year, but they had almost disappeared for a while,” he continued. “I have noticed the garter snake population is down, but I don’t know if that has anything to do with it or not,” he added.
The garter snake is one of the chief predators of the leopard frog—as are raccoons, kestrels, crows, ravens and coyotes. And now that the frogs are back, will there be more garter snakes next year?
“Perhaps, said Miller.