Skip to content
Join our Newsletter
Join our Newsletter

Croaking

The heat rushed at us as we stepped off the trail on the outskirts of Oliver, British Columbia. Grasses brushed our legs, thistles tore at our ankles, and Red-wing Blackbirds kamikazeed on the hot wind. A few dozen steps and we were at the pond.
67550_l

The heat rushed at us as we stepped off the trail on the outskirts of Oliver, British Columbia. Grasses brushed our legs, thistles tore at our ankles, and Red-wing Blackbirds kamikazeed on the hot wind. A few dozen steps and we were at the pond. Horsetails feathered the edges and reeds struggled up from a surface constellated by water striders and boatmen. Above the water, Green Darners enforced a no-fly zone for other unlucky insects.

Despite this bucolic industry, the shallow pool - small enough to spit across  - seemed completely out of place in the middle of a flat, dry field. And it was: Sara Ashpole put it there.

"This is the floodplain of the Okanagan River," she said, gesturing broadly. "At one time it was dotted with ponds and marshes and other wetlands. All gone now."

When I began investigating threats to British Columbia's amphibians, Ashpole was one of a handful of dedicated scientists labouring to save the province's disappearing frogs and salamanders - a race against time set with more hurdles than a steeplechase.

Backed by the World Wildlife Fund, Habitat Stewardship Program of Environment Canada, and Ducks Unlimited, Ashpole and crew had engineered 13 ponds as part of a program to restore habitat for the south Okanagan's beleaguered amphibians. Here, in Canada's only Bunchgrass Bioclimatic Zone (a fancy term for desert), some 85 per cent of natural wetlands had been lost to burgeoning urban and agricultural development. Of the remainder, many were already compromised by invasive species and chemicals - a disastrous situation for amphibians reliant on wetlands for breeding. The Northern Leopard Frog ( Rana pipiens ), denizen of the once-widespread marshes ringing the lakes, was long gone. The Columbia Spotted Frog ( Rana luteiventris ) - always uncommon in dry environments because of its need for permanent water - was a scattered phantom. And the rare Tiger Salamander ( Ambystoma tigrinum ) was down to but a single known breeding site.

Loss of wetlands was only one problem facing B.C.'s frogs. And the south Okanagan was a microcosm of all the top conservation threats contributing to a dramatic, worldwide decline in amphibians in recent decades: rampant habitat loss, pollution, invasive species, and emerging pathogens such as the deadly chytrid fungus (see sidebar: A Global Perspective). Not surprisingly, climate change was exacerbating the effects of all.

Just how serious was the situation?

"It's really bad news - so global," Darrel Frost, a pre-eminent herpetologist who manages the global Amphibian Species Database out of New York's American Museum of Natural History told me that summer. "Entire families disappearing. The first tropical frog I collected was a [member of genus] Craugaster . The entire genus - 30 species - is almost gone now."

Three years later, the only change is that things are worse. Having so many of the world's amphibians under threat is a sign of widespread environmental degradation that's likely to affect humans sooner than later. And removing an entire insect-eating trophic level from global ecosystems could have a range of disastrous consequences.

"It's clear," Frost said, "that the public simply isn't aware of the severity of the situation. Because if they were, they would be very, very afraid."

 

HABITAT LOSS

Most of Ashpole's efforts were aimed at helping a true dry-climate species, the Great Basin Spadefoot ( Spea intermontanus ). Spadefoots prefer ephemeral ponds that form with spring rains, so their breeding is explosive and development unusually rapid. Eggs hatch in as little as two days and the tadpoles feed voraciously. Because ephemeral ponds are short-lived and often oxygen-poor, the tadpoles are also adept air-gulpers.

When Ashpole began her project in 2006, known spadefoot breeding sites in the south Okanagan had been reduced from hundreds to a dozen. Rather than dig ponds in entirely new areas, Ashpole constructed pools within 500-metres of known breeding sites. Her hope was that spadefoots passing through would colonize the new ponds, and use them in years when rainfall wasn't sufficient to fill ephemeral wetlands. It seems to have worked: spadefoots quickly adopted nine of Ashpole's original ponds and, as of spring 2011, the same percentage was using16 constructed or "dramatically enhanced" wetlands.

"The ponds are doing great," she recently said from the University of Waterloo where she lectures as an assistant professor. "We haven't missed a year of monitoring. Either myself or one of my students has checked. We have breeding and metamorphic success in about 70 per cent of ponds annually  - though not always the same ones."

Given this breeding rotation and the unpredictable nature of desert weather, it's important to keep both wetlands and upland foraging habitat intact as a buffer against population fluctuations. The latter may prove more of a challenge with spadefoots, which require loose soil in which to burrow for camouflage and to avoid heat and drought.

A French study suggests that some burrowing frogs might last up to 10 years buried in a semi-dormant state until favourable conditions tease them back to the surface. In the Okanagan, a decade languishing underground could put spadefoots beneath a parking lot, subdivision, or new vineyard. As opposed to the somewhat livable orchards of yore, the pounded-down soils of vineyards and other development are highly detrimental to burrowers like spadefoots  - and Tiger Salamanders, another of the Okanagan's growing list of threatened amphibians, reptiles, fish, birds, and mammals.

When Ashpole arrived in the Okanagan, there were four known breeding sites for Tiger Salamanders. One suffered a chemical spill that killed everything; another filled with goldfish that consumed all other organisms; and a third, on private land, treated with Copper Sulfate to kill algae, killed the salamanders as well (she currently has a paper in press about this). And then there was one. Without serious intervention, the Tiger Salamander is as good as gone  - unlike the spadefoot, it hasn't yet shown up in any of Ashpole's ponds.

"The fines for contravening wetland regulations are pocket change," Ashpole noted at the time.

Ashpole also recounted a meeting over preservation of Tiger Salamander habitat. The response of officials wasn't How much can we save ? but rather How much can we afford to lose ? When a campground in the floodplain sold for $25 million to support  the development of 1,500 houses, Ashpole and others found it difficult to fathom the government's lack of concern over such impact in an area already so badly in need of rehabilitation. They aren't alone. In July 2011 the B.C. Auditor General commented in a report about the government's shameful track record with respect to environmental compliance and enforcement, particularly in the Okanagan.

 

POLLUTION

Loss of habitat is most evident to the public, but another of development's side-effects  - pollution -  is more insidious. The otherwise inviting sparkle of Osoyoos Lake, for instance, masks the lowest water quality of any large lake in Canada: shoreline development has destroyed fish and amphibian habitat; wetlands  - nature's chemical filter and answer to flood control  - have disappeared; boat traffic has caused erosion and pollution. Ditto for decades of unmonitored agricultural practices and increasing street runoff via storm drains; the Okanagan River carries pollution south from communities to the north; and increasing use of fertilizers has created ideal conditions for milfoil and other aquatic weeds which, in turn, bring snails, parasites and disease.

Chemical exposure is unavoidable where big-money cultivars require high crop yields. Unfortunately, many common fertilizers, fungicides and pesticides are highly toxic to other animal life. Organophosphates  - a common class of agri-chemical  - are potent neurotoxins with various rates of breakdown in the environment. Research has demonstrated their acute effects on amphibian eggs and hatchlings, and chronic illness and DNA damage in adults.

Christine Bishop, a Research Scientist with Environment Canada and adjunct professor at University of British Columbia, studied egg-hatching success in the Okanagan, correlating these with pesticide presence and water chemistry. Her findings were bleak: compared to ponds in organic orchards and other reference sites, ponds in conventional orchards consistently showed almost 100 per cent egg mortality. More worrying, those eggs were laid in springtime before orchards had even been sprayed, indicating the presence of residual chemicals.

Bishop found that ponds located 0.5 to 1.0 kilometres from sprayed orchards were also accumulating pesticides. If you're wondering about the persistence of invisible chemicals in the environment and threats to human health, you're echoing a growing fraternity of scientists wondering the same thing.

Given that little overall effort is being aimed at reducing pollution per se, increasing public education and awareness of the effects of various chemicals is the current approach.

 

INVASIVE SPECIES

The issue of invasive species would seem easier to tackle - except that chemicals are also often used to wipe out these organisms. Invasive fish like carp, goldfish, and bass occur in 80 per cent of Okanagan ponds, scarfing eggs and larvae, destroying habitat, and deoxygenating the water. It's hard to convince people that tossing alien fish into a pond for recreational or ornamental value can lead to catastrophic environmental problems while government agencies still list the anachronistic practice as a viable way of controlling mosquito larvae; with annual West Nile Virus scares, it seems, people are willing to follow any recommendations. Fish, however, are a minor nuisance compared to the most problematic invader: the American Bullfrog ( Rana catesbeiana ).

"Bullfrogs are a huge threat," said Bishop, who began monitoring the species' spread in the Okanagan with Ashpole back in 2006, and continues to do so. "If they move from the few ponds they currently occupy into Osoyoos Lake, then travelled upriver, it will have a massive impact on the valley's already threatened amphibians."

Native to eastern North America and recognized as one of the world's 100 most invasive species, the American Bullfrog is a massive conservation issue in B.C. - literally and figuratively. From a few individuals released decades ago, populations have grown to wreak havoc on Vancouver Island and the Fraser Valley. The trouble is their preferred food - other frogs, particularly young ones - and that they'll also eat anything else they can get their mouths around: crayfish, salamanders, snails, snakes, baby turtles, even small mammals and birds. They're also prolific: a single female lays tens-of-thousands of eggs, a high proportion of which survive - in part because most animals find bullfrog tadpoles distasteful.

A Victoria-area bullfrog eradication program removed well over 10,000 animals from two-dozen water bodies between 2005 and 2010. The biggest challenge is that after establishing themselves in a pond, bullfrogs eliminate native species through predation and competition; by the time they gleefully begin feeding on each other, it's too late for species they've displaced to recover, and the ever-opportunistic bullfrog has already spread to nearby ponds and lakes.

Despite these efforts, Ministry of Environment biologist Purnima Govindarajulu has maintained for years that the Vancouver Island problem is too far gone to spend limited funds on attempted eradication.

"In areas where there's no hope of eradication - because it's too costly or would require control forever - it's better to put money and effort into habitat restoration for native species and hope for some balance of co-existence," she said.

For instance, threatened Red-legged Frogs ( Rana aurora ) living with bullfrogs recognize them as potential predators and display anti-predator behaviours, but red-leggeds naïve to bullfrogs display no anti-predator behaviour in the latter's presence - it has to be learned. There's also the issue of co-existence through ecological separation.

"Once [Red-legged Frogs] are done breeding in late winter, they move from wetlands into upland habitat - far away from bullfrogs that have yet to emerge," noted Govindarajulu. "But if you destroy upland habitat and force red-leggeds to hang out in wetlands, they will eventually be eaten by bullfrogs."

Yet Govindarajulu has some hope.

"Eradication may be unrealistic in some places, but in others you can stop bullfrogs from spreading by increasing public education," she said. "In places where bullfrog populations are so far contained - like the Okanagan - you do have a good chance of eradication."

 

GLOBAL PATHOGENS

The bullfrog's proclivity for mass consumption of fellow amphibians is bad enough, but a related issue could prove even more deadly: the bullfrog may be a natural vector of the highly contagious, pathogenic chytrid fungus (or Bd).

In a Vancouver Island project, Govindarajulu found that in ponds supporting bullfrogs, Bd was detected in about 50 per cent of individuals. That is, Bd was always present in bullfrog ponds, whereas in ponds without bullfrogs the fungus may or may not have been detected. The hypothesis of invasives like bullfrogs moving Bd around hasn't been studied well-enough to pronounce on yet, however, Bd in the Americas has been strongly linked to the importation of the African Clawed Frog, Xenopus laevis . Imported from Africa in the thousands, it was used in human pregnancy tests in the 1930s and '40s. It's a known carrier of Bd that appears resistant to its ravages.

Likewise, speculation that the decline of Northern Leopard Frogs around Creston (their only stronghold in B.C., where a recovery program is underway) may be due to Bd is possibly premature: there simply aren't enough data.

"We're still figuring out where Bd is in the province," cautioned Govindarajulu about leaping to conclusions, "but we're definitely telling people 'if you see lots of dead frogs somewhere let us know.'"

In 2008 the Ministry of Environment began a survey to assess the prevalence of Bd in B.C. amphibians, aiming to provide baseline information for management plans, part of collaborative academic research on ecological factors that influence Bd prevalence and emergence. Data was collected using swabs from juveniles and adults, with emphasis on species of conservation concern. The study also made regional comparisons of Bd prevalence in widely distributed species like Western Toad, Columbia Spotted Frog, and Wood Frog. Over 1,000 samples were tested and the results - which Govindarajulu will soon publish in an academic journal - show Bd present almost everywhere in the province, at percentages between 0, in the case of Coastal and Rocky Mountain Tailed Frog, to 71 with the more terrestrial Wood Frog. (One of the places Bd has not yet been detected is the Sea-to-Sky corridor.)

Whether a Bd-bullfrog connection materializes or not, the latter has already made it difficult for the B.C. species on which the most effort has been expended: Oregon Spotted Frog.

 

SPECIES DESTRUCTION

One rainy fall morning I headed north from Langley in the Fraser Valley on a road that bent around farmland and isolated chunks of forest. Entering a non-descript driveway, a thick roadside clot of creeping, tangled vegetation had opened onto Mountain View Conservation and Breeding Centre, a wildlife refuge for species-at-risk like Northern Spotted Owl, Vancouver Island Marmot, and, as a row of corrugated metal cattle tanks would reveal, Oregon Spotted Frog ( Rana pretiosa ; OSF).

By the time the OSF was separated by name from the Columbia Spotted Frog in 1997, it was already on the edge. As of 2011 it has disappeared from 95 per cent of its former range: rooted out and destroyed in California, there remain 20ish populations in Oregon, four in Washington, and three in B.C. - many far-separated. Unsurprisingly, in 1999 OSF was the first species to be emergency red-listed by the Committee on the Status of Endangered Wildlife in Canada. A recovery team pulled tadpoles from the wild to raise for enhancement purposes; Vancouver Aquarium, Greater Vancouver Zoo and Mountain View were all brought on board to help.

Counting OSF adults is only feasible during breeding season, when you least want to disturb them, so populations are monitored by egg-mass counts. Fortuitously, each female lays but a single egg mass in a communal floating mat.

B.C.'s population of breeding adults - estimated at 400, is a tiny number spread over three sites. They aren't gene pools, but gene thimbles , risking the inevitable problems of low genetic variability.

At Mountain View eggs laid that March, and tadpoles, were first kept in shallow trays with warm water and then moved to outdoor tanks where they could develop resistance to natural pathogens and learn anti-predator behaviour (the screened-in tanks were constantly over-flown by birds). Where survivorship to metamorphosis is generally less than five per cent in the wild, a good year at Mountain View saw upward of 75 per cent survivorship in the tanks. But raising frogs proved labour intensive and costly ($10/frog plus months of work) and though up to 2,200 froglets were marked and released each September to feed and become wild-adjusted before winter, there were very few recaptures. Where did they go? Is this particular recovery model worth it?

Govindarajulu, who coordinates the program, and others weren't sure, and subsequently decided a variety of methods should be investigated. The project now also includes successful captive breeding - captive adults overwintered in cold chambers are induced to breed in spring - in which egg masses are raised to hatching and then returned to the wild, removing the cost of raising the tadpoles/frogs. Elsewhere efforts are underway to see if froglets raised faster and released earlier in summer have a greater chance when released than others kept to a larger size and cut loose the following spring. Govindarajulu is now much more optimistic on the program.

"I feel good because it's more research-based now," she said recently. "Instead of just doing things because we think it helps, we're saying 'this is working, this is not.' We're not yet at a point where we can actually help the species based on what we know, but we're on our way to systematically addressing the knowledge gaps that will help to do so."

In any case, the bigger problem may be what OSFs are reintroduced to .

Like the Okanagan, the Lower Fraser is one of Canada's most heavily modified landscapes. Wetlands have been filled, drained, and watercourses channelled. Flooding is rampant, fertilizer and pesticides in heavy use, the invasive bullfrog and Green Frog (another eastern transplant) legion and happy to eat small OSFs. Not exactly the kind of wild needed to recover a species.

Habitat degradation will always be a problem because, as Govindarajulu pointed out "humans like to live where amphibians already live."

"Psychologically, we'd like it if the main problem were bullfrogs and Bd and not habitat degradation, but clearly that's not the case."

Or, as Darrel Frost squarely put it:

"The planet is over capacity and we're stressing it out.

"I don't think there's one causative factor. Air and water quality is a worldwide problem and I have an awful feeling that the canary in the coalmine is real."

Is there any hope for B.C.'s pressured amphibians? Govindarajulu believes that B.C. isn't as bad as other parts of Canada where there's been larger-scale removal of wetlands.

"No amphibian species has been completely extirpated (destroyed) here," she said wistfully.

"However, B.C. is definitely verging on disaster: wetland removal is continuing and, in some cases, accelerating. Remaining wetlands are under chemical and biological threat, and several species are on the very brink - so it's good there are so many projects underway and that the public is, in some sense, responding."

 

Sidebar

 

A Global Perspective

Although amphibian declines are tied to several worldwide meta-problems, most are related to the global spread of the deadly fungus, Batrachochytrium dendrobatidis (chytrid or Bd) and how vulnerability to this organism has been accelerated both by anthropogenic factors and climate change. Bd is essentially a meteorite plowing through the world's frogs.

Statistics are staggering. As of 2011, up to 200 of the earth's 6,500ish amphibian species have fully disappeared since 1979, and some 32 per cent of the remainder are on the brink of extinction. In Central America extinctions form a wave of disaster moving south around 28 km/year, beginning with the disappearance of the Golden Toad from Costa Rica's Monteverde Cloud Forest in the mid-'80s.

Dozens of tropical American frog species have also disappeared or been displaced from high elevation. A multi-country conservation initiative with the genus Atelopus found that of 110 species, a third have disappeared, and the rest are at risk. Other frog populations have seen a 95 per cent drop in as little as six months.

To date, Bd has been found all over Europe, Japan, Africa, North America, Mesoamerica, and South America. In Canada, Bd is mostly known from live animals and museum collections in Ontario, Quebec, and British Columbia.

Few are more closely apprised of the rapidity with which species are disappearing than American Museum of Natural History herpetologist Darrel Frost.

"In the late '80s I ran into a WWF guy at a conservation meeting who was concerned about frogs. I remember thinking 'Frogs are going to go extinct ? Ha!' So I asked a herpetologist working in the tropics. 'We're worried about rhinos and elephants now,' he'd said, 'but in 10 years it's going to be the frogs.' Unfortunately he was right."

 

A Local Perspective

Compared to ravages elsewhere, the biggest worry for Whistler's amphibians is being pushed from one pond to another. Still, if you're a provincially declining species with limited breeding sites like the Western Toad, this could spell local doom. The Western Toad was long thought to breed only in Lost Lake. The tadpoles school in shallow habitat adjacent to a busy beach where they - and tiny, post-metamorphic toadlets - were threatened by people, pets and relentless trail traffic. Following a municipally commissioned study, protective fencing and signage were erected and, three years on, they're finally having an effect.

"Lost Lake's fencing is really working now," said Whistler naturalist Bob Brett, who works locally with amphibian experts on contract and at Whistler's annual Bioblitz. "It's part of the muni's yearly work to put it up and [tadpoles] are protected from humans and dogs. But not necessarily toadlets - their exit point from the lake varies and we don't know where they go - so for now it's easier to just protect the breeding area."

Brett spearheaded the Whistler Biodiversity Survey proceeding the 2010 Olympics, and extensive sampling in the Resort Municipality of Whistler (RMOW) turned up the usual suspects - Pacific Chorus Frog, Rough-skinned Newt, Northwestern and Long-toed Salamander - but also healthier-than-thought populations of threatened Coastal Tailed Frog and new records for highly endangered Red-legged Frogs.

Whistler amphibians were also "salvaged" (moved temporarily or permanently) on various environmental-impact contracts during construction for the 2010 Olympics. One happy result was the discovery of new Western Toad breeding sites in Cheakamus Crossing and the parking lots below the waste transfer station. Maintaining breeding habitat for these resident populations is now a priority of post-Olympic mitigation. An unhappy result, however, is that some salvage and mitigation didn't work very well.

The multi-million-dollar Sea-to-Sky Highway project rerouted a 2 km section through previously undisturbed forest and wetlands near Pinecrest, 14 km south of Whistler, interrupting the migration routes of Red-legged Frogs. Despite the transportation ministry's $1.5-million efforts to build passages under the highway and fencing to direct amphibians through these, hundreds are still being killed on the road.

"They should never have put that highway in there," said Squamish conservationist John Buchanan of the scattershot of ponds separated by lava rubble and forest, noting how frogs move from one pond to another during migration. "They built it, but, of course, frogs are still trying to get from one pond to another."

The transportation ministry continues working on the issue but it may never be resolved, permanently impacting an already endangered species.

Since Brett started finding Red-legged Frogs in the south end of the RMOW, the basalt area north of Brandywine has been protected, but the Olympic parking lots still represent fragmentation and permanent loss of foraging and breeding habitat. Not to mention ephemeral ponds used by other amphibians.

"It still comes down to habitat and we don't have any protection for ephemeral ponds," said Brett. "Whistler has lost at least 72 per cent of its natural wetlands."

Despite Whistler's wilderness "feel," this figure echoes highly impacted areas like the Fraser Valley and Victoria where the average loss of wetlands is around 75 per cent.

"The big culprits are the two valley-bottom golf courses," noted Brett, "but over the past five years all three Whistler courses have become more interested in providing natural habitat for amphibians; they're accommodating because they see so much wildlife on the courses."

Remediation, however, is not the take home message. "We still have to protect what natural wetlands we have versus 'restoring,' which is totally hit-and-miss in terms of what gets done and what might use it."

 

Find Out More

Okanagan Lake Water Quality Society

olwqs.org

 

Amphibian decline information and programs

amphibianark.org

amphibians.org

amphibianweb.org

globalamphibians.org

helpafrog.com

savethefrogs.com

vanaqua.org/frogs

yearofthefrog.org

Bullfrogs in B.C.

Victoria 24-hour hotline (250-858-FROG).

For information and to report sightings: bullfrogcontrol.com

To see the swabbing procedure for detecting chytrid fungus check out the video tab at http://www.amphibianark.org/frog_gallery.html "Field sampling techniques for living amphibians" and "How to swab a frog for chytrid."

 

To learn more about swabbing or report frog die-offs observed in the field email: Purnima.Govindarajulu@gov.bc.ca

 

 




Comments