A case for frogs

FORT FRANCES—When I was a kid, frogs leapt aplenty in the backyard. Living along a water source may have had something to do with that, as might have the name—Frog Creek.
But the ecosystem along that winding body of water isn’t home to near the numbers of little leapers that it one was. Research suggests frogs are highly-sensitive to changes in the environment—a “canary in the coal mine” of sorts.
Frog experts are few and far between in Rainy River District, but even the ones who are far away are familiar enough with the ecosystems here to shed some light on whether or not our green-back friends are on their way out or just rolling with the tides of environmental change.
If you type Michael Oldham’s name into an Internet search engine, it doesn’t take a rocket scientist to figure out he’s in the know about nature.
As a botanist and herpetologist, Oldham works for the Ministry of Natural Resources’ Natural Heritage Information Centre in Peterborough, where experts maintain and compile information on rare, threatened, and endangered species in Ontario.
“One of the reasons [frogs] are said to be good indicators is because they are both terrestrial and aquatic,” Oldham said by phone from his office in mid-June.
“Most species are dependent on one or the other [land or water], so you kind of have to have a good terrestrial habitat, as well as a good aquatic habitat, [for frogs to flourish],” he noted.
“Frogs also are generally pretty common and widespread, and that makes it easier to monitor and detect if there are changes [in the environment],” he added.
It’s not in their nature to move far if conditions around them change. In fact, they only may go a kilometre or two if there is another colony of frogs living nearby.
Generally though, if conditions become poor, frogs probably would just die out from that local area.
But counting on frogs as an absolute indicator of environmental change has its downside, Oldham warned, because they also are relatively short-lived and prolific when conditions are right.
As such, populations can quite naturally go up and down to a fair degree.
For example, if it is a very dry year and ponds dry up before the young have had time to transform to full-blown frogs, then all of a sudden numbers can seem a lot lower.
“It may be nothing to do with human change, it may be natural, so that’s maybe one reason why frogs are not that good of an indicator, because it is very hard to know for sure if the change you are observing is a natural one or a non-natural one,” Oldham noted.
Northwestern Ontario, including Rainy River District, has about seven species of frogs and one toad. And according to the NHIC, it is a fairly diverse area in the province for the species.
Among the variations here are the Spring Peeper, Boreal Chorus Frog, Wood Frog, American Toad, and one species that needs no introduction—the Leopard Frog.
Its numbers, in particular, have been reported as declining in other parts of Ontario and west into the Prairies, said Oldham, although he only could speculate on the reasons for the apparent fall-off of one of the most common frogs seen hopping around ponds and marshes.
“In parts of Canada, leopard frogs have apparently declined quite a bit,” noted Oldham. “There was some suggestion that those declines were mainly out from Ontario westward. Especially into the Prairies and in British Columbia, leopard frogs have just plummeted in numbers.
“[But] apparently there is some recovery going on and they are rebuilding [in numbers],” he added.
“A number of the pesticides and various agricultural chemicals have been implicated in amphibian declines and as you may have heard, deformities [in frogs] have been linked to pesticides fairly heavily,” continued Oldham.
“Even things like lawn chemicals can certainly affect frogs. It can get washed into ponds and affect the larvae, which are often more sensitive than the adults.”
The best place and time to do a frog count usually is during the breeding season and the hatching season. In between, frogs make themselves scarce.
“All species of frogs are easiest to find in the spring when they are breeding because they come together at a breeding site in a pond or a marsh,” Oldham explained.
“Males go to the ponds first, call, and attract the females, they mate and lay their eggs, and then disperse back into the marshes and woods,” he said.
“Then they aren’t in such large numbers until later in the summer when you get the young ones that emerge—then there can be frogs all over the place.
“But like lots of species, many of the young don’t survive. Frogs produce hundreds of young, but only a few make it to adulthood,” Oldham said.
Frogs also do quite well in multi-species populations, but not when a variety of amphibian is introduced that is not natural to their habitat, such as the bull frog.
Bull frogs are highly predacious and they’ve been introduced in British Columbia where they are not native and are becoming a major predator on native frogs, who aren’t in the know about the enemy that looks friendly enough sitting over there.
“Even though bull frogs are native in southern Ontario and they do co-exist with other frogs species, they also do prey on frogs,” noted Oldham. “But in areas like B.C., where the native frogs aren’t used to dealing with a large frog predator—all of a sudden they are in trouble.”
Meanwhile, at the NHIC, data collected throughout the province on rare plants, animals, and vegetation communities (including butterflies, moths, and dragonflies) is used by MNR planners, park managers, municipal planners, and other bodies involved in development of anything that might alter the landscape.
“We maintain a province-wide ranking system to say how rare things are and the ones we consider to be rare enough, we gather location information on,” Oldham said.
“And a relatively small subset of those are the ones who get on the list either nationally or provincially, and have some sort of a legal protection [as endangered],” he explained.
“Certainly one animal [surveyed] from your area is the bald eagle,” added Oldham. “It is more common in your area than anywhere else and yet it’s still listed on the endangered species list.
“There are hundreds of breeding pairs in Northwestern Ontario, but they’re much more in trouble in southern Ontario and they’ve been on the [endangered] list for quite a while, mainly due to the post-DDT era where a number of birds like the peregrine falcon and the bald eagle declined.
“Now we have got rid of that [pesticide] and those birds are slowly but surely increasing.
“There is probably a species that will come off the endangered list at some point in the future—and it’s great when something comes off the list because generally more go on than come off,” Oldham conceded.
For more information on frogs and endangered species in Canada and North America, visit nhic.mnr.gov.on.ca/nhic_.cfm
(Fort Frances Times)

Facebooktwitterredditpinterestlinkedinmail