Award-winning feature (2011 IRMA award of merit) in British Columbia magazine on how biologists everywhere are mobilizing to try to understand what’s behind a worldwide decline of frogs and other amphibians, and what's being done to help the frogs' plight in that province.
44 BRITISH COLUMBIA MAGAZINE: SPRING 2010 WILDLIFE T he heat rushes at us as we step off the trail on the outskirts of Oliver. Rustling grasses brush our legs and thistles tear at our ankles. Yellow warblers and red-wing blackbirds rise and fall on the hot wind. A few dozen steps and we’re at the pond. Horsetails feather the edges and a few reeds struggle up from the soupy water. Water- striders constellate the surface while dragon- flies and damselflies patrol the air above. Despite the buzz of life around it, this shallow, south Okanagan pool—so small you could spit across it—seems completely out of place in the middle of this flat, dry field. And it is: biologist Sara Ashpole put it here. “This is the floodplain of the Okanagan River,” she says, gesturing broadly. “At one time it was dotted with ponds and marshes and other wetlands. All gone now.” Ashpole is one of the dedicated British Columbia scientists working to keep frogs and other amphibian species from disappearing from the province. Backed by Environment Canada and the World Wildlife Fund, Ashpole and her crew have engineered 14 ponds in the past few years as part of the South Okanagan Puddle Project, a program to restore habitat for the area’s beleaguered amphibians. Here in the bunchgrass bioclimatic zone—a fancy term for desert—nearly 85 percent of lowland wetlands and 40 percent of cattail marshes have been lost to burgeoning urban and agricultural development. Of the remaining areas, many have been compromised by invasive species and chemicals. It’s a dire situation for amphibians of the Okanagan Valley that rely on wetlands for breeding. The northern leopard frog (Rana pipiens), denizen of the once-widespread marshes ringing the Okanagan’s lakes, now is found only in the Creston Valley. The Columbia spotted frog (Rana luteiventris)—always uncommon in dry environments because of its need for permanent water—is but a scattered phantom in the Okanagan. Loss of wetlands, however, is only one of the problems facing B.C. frogs. The south Okanagan is a microcosm of the issues that have caused a dramatic worldwide decline in amphibians in recent years. All of the top global conservation threats are present here: by LESLIE ANTHONY photography: STEVE OGLE Biologists everywhere are mobilizing to try to understand what’s behind a worldwide decline of frogs and other amphibians. Here’s what’s being done to help Kermit and friends at home in British Columbia. IT’S NOT EASY
Transcript
44 British ColumBia magazine: spring 2010
wilDlifE
the heat rushes at us as we step off the trail on the outskirts of oliver. rustling grasses brush our legs and thistles tear at our ankles. yellow
warblers and red-wing blackbirds rise and fall on the hot wind.
a few dozen steps and we’re at the pond. horsetails feather the edges and a few reeds struggle up from the soupy water. Water-striders constellate the surface while dragon-flies and damselflies patrol the air above.
despite the buzz of life around it, this shallow, south okanagan pool—so small you could spit across it—seems completely out of place in the middle of this flat, dry field. and it is: biologist sara ashpole put it here.
“this is the floodplain of the okanagan river,” she says, gesturing broadly. “at one time it was dotted with ponds and marshes and other wetlands. all gone now.”
ashpole is one of the dedicated British Columbia scientists working to keep frogs and other amphibian species from disappearing from the province. Backed by environment Canada and the World Wildlife Fund, ashpole and her crew have engineered 14 ponds in the past few years as part of the south okanagan puddle project, a program to restore habitat for the area’s beleaguered amphibians. here in the bunchgrass bioclimatic zone—a fancy term for desert—nearly 85 percent of lowland wetlands and 40 percent of cattail marshes have been lost to burgeoning urban and agricultural development. of the remaining areas, many have been compromised by invasive species and chemicals.
it’s a dire situation for amphibians of the okanagan valley that rely on wetlands for breeding. the northern leopard frog (Rana pipiens), denizen of the once-widespread marshes ringing the
okanagan’s lakes, now is found only in the Creston valley. the Columbia spotted frog (Rana luteiventris)—always uncommon in dry environments because of its need for permanent water—is but a scattered phantom in the okanagan.
loss of wetlands, however, is only one of the problems facing B.C. frogs. the south okanagan is a microcosm of the issues that have caused a dramatic worldwide decline in amphibians in recent years. all of the top global conservation threats are present here:
by lEsliE anthonY photography: stEVE oglE
Biologists everywhere are mobilizing to try to understand what’s behind a worldwide decline of frogs and other amphibians. here’s what’s being done to help Kermit and friends at home in British columbia.
it’s not easy Being green
Sp10 p72.indd 44 2/16/10 5:04 PM
45British ColumBia magazine: spring 2010
habitat loss, pollution, invasive species, and the deadly Bd fungus (Batrachochytrium dendrobatidis)—which has spread through europe, japan, africa, north america, Central and south america. Finally, exacerbating all the other problems, there are
the effects of climate change—less snow in the mountains, spring droughts, ephemeral ponds evaporating before amphibians can reproduce, increased uvB radiation on eggs causing higher rates of deformity and mortality.
just how serious is the situation? darrel Frost, one of the world’s pre-eminent herpetologists, manages the global amphibian species of the World online database out of new york’s american museum of natural history.
“it’s really bad news—so global,” says Frost. “Whole groups and maybe even entire families are disappearing.”
the statistics are staggering. save the Frogs, an international non-profit group dedicated to amphibian conservation, warns that as many as 200 of the world’s more than 6,400 amphibian species have disappeared since 1980. and nearly one-third of those remaining are threatened with extinction.
“the very first tropical frog i collected was Craugaster,” says Frost. “the whole genus is at risk and whole fleets of species are already extinct or well on their way.”
Frost recalls a conservation meeting he attended in the late 1980s where a representative from the World Wildlife Fund first raised his concern about frogs.
“i remember thinking, ‘ha! Frogs are going to go extinct?’ so i asked a herpetologist working in Central america, and he agreed. ‘We’re worried about rhinos and elephants now,’ he said, ‘but in 10 years, it’s going to be the frogs.’
“i really think 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 coal mine is real.”
it’s not easy Being green• like these pacific tree frogs, populations of most frog and amphibian species in British columbia are but a shadow of what they were two decades ago.
th
om
as
Kit
Ch
in &
viC
to
ria
hu
rst
Sp10 p72.indd 45 2/16/10 5:04 PM
46 British ColumBia magazine: spring 2010
Most of biologist sara ashpole’s efforts have been aimed at helping a true
dry-climate species, the desert-dwelling great basin spadefoot (Spea intermontana). spadefoots prefer temporary ponds that form with spring rains and then dry up, so their breeding and development are unusually rapid. eggs hatch in as little as two days and the tadpoles feed voraciously.
When ashpole started her pond project in 2006, there were 12 known spadefoot breeding sites in her lower south
okanagan study area. rather than dig ponds in entirely new sites, ashpole constructed new pools within 500 metres of known breeding sites. her hope was that spadefoots passing through the area would colonize the new ponds, and use them in years when rainfall wasn’t sufficient to fill the natural ephemeral wetlands. and it’s worked: so far, spadefoots have adopted 11 of ashpole’s 14 artificial ponds.
in addition to wetlands for breeding, many amphibians also require upland foraging habitat. spadefoots specifically need loose soil in which to burrow for camouflage and to avoid heat and drought.
some studies suggest these creatures may be able to remain buried for up to 10 years, surviving in a semi-dormant state until favourable environmental conditions tease them back to the surface. that’s the
good news. however, in the quickly developing okanagan region, spadefoots languishing underground for a decade may become buried beneath a new subdivision or vineyard. as opposed to the somewhat liveable orchards of yore, the pounded-down soil of vineyards and other developments are highly detrimental to burrowers like toads and tiger salamanders (Ambystoma tigrinum)—another of the okanagan’s growing list of threatened amphibians.
a second consequence of development, rising pollution, can be as detrimental
to frog populations as habitat loss. shoreline development around scenic osoyoos lake, for instance, has consumed former fish and amphibian habitat. Wetlands, which naturally filter water and control flooding, have disappeared, while water pollution continues to rise from increased boat traffic and runoff from streets via storm drains.
agricultural fertilizers, fungicides, and pesticides used to produce higher crop yields also can be toxic to animal life. Christine Bishop, an environment Canada
scientist based in delta, studied ponds in the south okanagan’s agricultural habitats to see how water chemistry and the presence of pesticides might correlate to the hatching of amphibians’ eggs in those ponds. her findings were dramatic. on non-agricultural conservation areas used as control sites, the hatch rates averaged 80 percent or better; on conventional orchards, nearly all amphibian eggs failed to hatch.
“and remember,” Bishop stressed, “eggs are in the water in april and may, generally when orchards are in the early stages of spraying.”
wilDlifE
what’s BEing DonE: habitat re-creation
thE proBlEM: habitat loss
what’s BEing DonE: assessment studies
thE proBlEM: pollution
• below left: a columbia spotted frog hides among fallen maple leaves in the fraser Valley.
below centre: a red-listed species in British columbia, the northern leopard frog is down to its last breeding population in the creston Valley.
below right: the great basin spadefoot, a desert-dwelling species in the south okanagan Valley, is increasingly threatened by agriculture and development.
th
om
as
Kit
Ch
in &
viC
to
ria
hu
rst
th
om
as
Kit
Ch
i n &
viC
to
ria
hu
rst
ste
ve
og
le
Sp10 p72.indd 46 2/16/10 5:04 PM
47British ColumBia magazine: spring 2010
• Biologist sara ashpole and writer leslie anthony visit one of several temporary spadefoot breeding ponds ashpole has created near osoyoos as part of the south okanagan puddle project.
Sp10 p72.indd 47 2/16/10 5:04 PM
48 British ColumBia magazine: spring 2010
the researcher also found that ponds as far as one kilometre from conventional orchards were accumulating pesticides. that finding is a warning for human residents of the region as well as amphibians.
as in the okanagan, development has modified the lower Fraser valley landscape dramatically. Wetlands have been drained and filled, and watercourses channelled. agricultural fertilizers and pesticides are widely used.
habitat degradation will always be a problem, says ministry of environment provincial herpetologist purnima govindarajulu, because “humans like to live where amphibians already live.”
it’s difficult to convince people that tossing a few fish into a pond for
ornamental or recreational value is a problem. some believe it’s a practical way to control mosquito larvae and thereby minimize the threat of West nile virus. as a result, invasive fish such as carp, goldfish, and bass now occur in 80 percent of okanagan ponds, devouring amphibian eggs and deoxygenating the water.
even more problematic than these introduced fish species, though, is the bullfrog. native to eastern north america, Rana catesbeiana is recognized as one of the world’s 100 most invasive species.
“Bullfrogs present a huge potential threat to the okanagan,” says Christine Bishop of environment Canada. “if they were to move from the three or four ponds they currently occupy into osoyoos lake,
then travel upriver, it would have a massive impact on the valley’s already threatened amphibians.”
From a few bullfrogs released decades ago on southern vancouver island and the lower mainland, populations have grown to wreak havoc. Bullfrogs’ preferred food is other frog species, particularly young ones, though they will eat almost anything they can fit into their mouths: crayfish, salamanders, newts, snails, snakes, baby turtles, even small mammals and birds. they can reach up to 20 centimetres in length (not including legs), compared to just five centimetres for a pacific tree frog.
Bullfrogs are also prolific breeders: a single female can lay tens of thousands of eggs, and a high proportion of offspring will survive—in part because most animals find bullfrog tadpoles distasteful.
wilDlifE
what’s BEing DonE: eradication and education
thE proBlEM: invasive species
• below: purnima govindarajulu takes a swab sample from a green frog near agassiz to test for the presence of the contagious fungus Batrachochytrium dendrobatidis, known as chytrid or Bd.
Sp10 p72.indd 48 2/16/10 5:04 PM
49British ColumBia magazine: spring 2010
as the provincial ministry of environment’s Frogwatch website explains: “most of B.C.’s native frogs are little more than a bite-sized snack for bullfrogs, and there is evidence that bullfrog colonizations of lakes are followed by declines in the native red-legged frog and pacific chorus frog populations.”
Biologist stan orchard runs a victoria-area bullfrog eradication program. in the past three years, his teams have removed some 13,000 bullfrogs from more than 50 lakes and ponds. he resists what he calls “baseless assertions” that the vancouver island bullfrog problem may be too far gone for eradication to succeed.
“With the right tools and some ingenuity, bullfrog eradication is feasible and practical,” he wrote in a letter published in victoria’s Times Colonist newspaper last november.
in areas that have become overrun and “would require control forever,” provincial herpetologist purnima govindarajulu suggests that “it’s better to put money and effort into habitat restoration for native species and hope for some balance of co-existence.”
For some species, that co-existence may be achieved through habitat management. red-legged frogs (Rana aurora) for one, appear able to avoid bullfrogs if given the opportunity.
“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,” says govindarajulu. “But if you remove upland habitat and force red-legged frogs to hang out in wetlands, they will likely eventually be eaten by bullfrogs.”
there is still hope, govindarajulu says, for areas not yet infested with bullfrogs.
“eradication may be unrealistic in some places, but in others you can stop bullfrogs from spreading by increasing public education,” she says. “in places where bullfrog populations are so far contained—like the okanagan—you do have a good chance of eradication.”
• above: an adult pacific tree frog clinging to the outside of a Mason jar seems tiny compared to the bullfrog tadpole inside. in adulthood, the invasive bullfrog readily devours the province’s smaller native frog species.
left: workers restore a wetland near chilliwack that had been drained for farmland. they will remove the invasive bullfrog tadpoles they have collected to encourage native frogs to re-colonize the area.
Sp10 p72.indd 49 2/16/10 5:04 PM
50 British ColumBia magazine: spring 2010
another potential major contributor to the decline of native B.C. frogs is the
unchecked spread of the highly contagious fungus Batrachochytrium dendrobatidis, known as chytrid or Bd. one hypothesis scientists are exploring is that invasive, Bd-resistant species like bullfrogs may be communicating the disease.
the province’s ministry of environment initiated a survey in 2008 to assess the prevalence of Bd in B.C. amphibians. the objective is to assemble baseline information that can be used to better understand the ecological factors that influence the emergence and spread of Bd.
“We’re still basically figuring out where Bd is in the province,” says herpetologist purnima govindarajulu, “but we’re definitely telling people ‘if you see lots of dead frogs somewhere, let us know.’”
researchers took swab samples from all frog and toad species in B.C., as well as some salamanders. they put emphasis on species
most at risk, such as the endangered oregon spotted frog (Rana pretiosa), which is down to perhaps 300 breeding adults in just three known breeding sites in the province. and they also focused on widely distributed species, such as the western toad (Bufo boreas), Columbia spotted frog (Rana luteiventris), and the wood frog (Rana sylvatica), for regional comparisons of the prevalence of Bd.
as of december 2008, more than 1,000 samples had been submitted to the provincial lab. the results and ongoing analysis will help biologists develop management plans for the future.
“several species are clearly declining,” says govindarajulu, “so it’s good that there are so many projects underway in the province and that the public is, in some sense, responding.”
When it comes to disappearing frogs, British Columbia, like many jurisdictions around the world, is doing what it can . . . but watching closely.
wilDlifE
• alert BC Frogwatch (e-mail: [email protected]; www.env.gov.bc.ca/wld/frogwatch) if you see new colonies of bullfrogs or have them on your property. On the website, click Report a Frog Sighting for an online form.• attract native frogs to your backyard pond by creating ideal habitat. (Do not attempt to relocate frogs or tadpoles,
which can kill eggs, spread disease, or introduce invasive species.) Preserve or plant native shrubs along your pond’s shoreline. Where possible, create corridors to nearby forest. Temporary ponds are especially valuable; do not convert these to permanent ponds with fish. Finally, forgo chemicals that kill insects, which frogs need for food.
• invite speakers from the Bullfrog Project ([email protected]) to talk to your Vancouver Island group of nature lovers. May to August, coordinators travel the Island giving presentations and offering workshops to train new wetland stewards.• learn to identify B.C. frogs and their distinctive calls so you can report sightings to BC Frogwatch (www.naturewatch.ca/english/frogwatch/bc/field_training.html).• teach children to leave all frogs where they find them. “Adoption” of bullfrogs as pets appears to be a primary cause of their spread from pond to pond. Under B.C.’s Wildlife Act, it is, in fact, illegal to capture, transport, keep, or sell bullfrogs.• tell your friends and family members about the bullfrog problem. Public awareness is key to preventing further spread.• Volunteer to help with ongoing BC Frogwatch programs throughout the province. Find projects in your
area on the Who’s Who in B.C. page of the BC Frogwatch website (www.env.gov.bc.ca/wld/frogwatch/whoswho/whoswho.htm).
• Bc frogwatch program (www.env.gov.bc.ca/wld/frogwatch). Click on Lots of Links for dozens of sites relating to frogs and their habitat, locally and globally. • the Bullfrog project (http://web.uvic.ca/bullfrogs/index.htm). • south okanagan puddle project (www.env.gov.bc.ca/wld/frogwatch/whoswho/puddle.htm). • save the frogs (www.savethefrogs.com).• amphibiaweb (http://amphibiaweb.org).• Amphibians and Reptiles of British Columbia: Royal BC Museum Handbook by Brent Matsuda, David Green, and Patrick Gregory (Royal BC Museum, 2006).
t
info
how You can hElp B.c. frogs
what’s BEing DonE: surveys and analysis
thE proBlEM: deadly fungus
• above: the critically endangered oregon spotted frog has disappeared from 90 percent of its native habitat in the pacific northwest.
below: considered one of the world’s 100 most invasive species, the bullfrog soon eliminates native frogs from any pond it colonizes.
th
om
as
Kit
Ch
in &
viC
to
ria
hu
rst
Sp10 p72.indd 50 2/16/10 5:04 PM
51British ColumBia magazine: spring 2010
• Biologist purnima govindarajulu searches a site near agassiz for evidence that the endangered oregon spotted frog may be breeding here.
