Canadian Wildlife/Frozen for Life

for

life

By Leslie Anthony Illustration by Jacqui Oakley

As a group, they’ve outlived the dinosaurs. As individuals, they may outlive you. But turtles are far from safe in this country — and winter habitat protection may be the key to their survival

One very cold Boxing Day, James Baxter-Gilbert and Julia Riley left the comforts of holiday time with family and friends, hopped in their car and drove to the remote east side of Ontario’s Algonquin Provincial Park.

Baxter-Gilbert donned an orange emergency flotation suit — the kind carried on fishing boats and oil rigs. He attached a rope to himself, tied it off on a tree and walked out on the frozen bay of a small lake.

Playing rope out from the shore, Riley watched calmly as he promptly fell through up to his waist. “You OK?” she called. “Yeah,” he replied, clawing his way out of the water back onto solid ice, only to walk 10 steps and fall through again. The vignette repeated itself as Baxter-Gilbert alternately cut holes in the ice with an auger and his own weight.

Were they scouting ice-fishing hotspots? Training for winter search and rescue? Not quite. This is the face of turtle conservation in the Great White North, and the pair

20 CANADIAN WILDLIFE

likely weren’t the only herpetologists (those who study reptiles and amphibians) so engaged that day. Most scientists who research these animals — more typically considered log-lounging icons of summer — eventually end up scouting their subjects through blankets of snow or sheets of ice. “You really can’t say you’re a Canadian herpetologist until you’ve done winter work,” says Riley, who relishes the paradox of searching out cold-blooded animals in a frozen landscape.

Indeed, Riley and Baxter-Gilbert’s outing — to measure dissolved oxygen (DO) at suspected turtle hibernation sites — was no anomaly. Between them, Baxter-Gilbert, a master of science student, and Riley, a reptile-species-at-risk researcher, have logged a diversity of projects with seven of Canada’s eight native freshwater turtles: Blanding’s, map, musk, painted, snapping, spotted and wood. Only the eastern spiny softshell is absent from their list. Most were

jan + feb 2013

jan + feb 2013

CANADIAN WILDLIFE 21

conservation efforts that involved tracking the movements of turtles via radio telemetry, and a large share included winter work. But why the seasonal preoccupation?

The University of Sudbury’s Jacqueline Litzgus — Canada’s top turtle researcher and supervisor to both Riley and Baxter-Gilbert — explains: “We’re at the northern limits for most of these species, so time spent overwintering at this latitude represents at least half their lives…. What happens in summer with respect to food and growth is important to fitness and breeding, of course. But if you can’t survive winter, your fitness is zero.”

Thus, the questions why and where turtles choose to take their annual naps have become a focus of conservation efforts in this country. And because turtles are very particular about site choice — and highly vulnerable during hibernation — threats to overwintering habitat can quickly override other conservation considerations, such as pollution, food sources, and availability of basking or nesting areas.

Knowledge of turtle overwintering habitat needs is growing, but it provides only cold comfort if it can’t be applied to conservation. Unfortunately, for animals that first appear in the fossil record 220 million years ago and have changed little since, it’s a race against time.

Canada’s Native Freshwater Turtles

Turtles likely arrived in Canada from the southeastern U.S. after the ice ages. Today, the country is home to eight freshwater species, which live at the northern most edge of their ranges.

Turtles are in troubled waters worldwide, but very much so in Canada. Most species here eke out only a marginal existence, as habitat has been degraded and fragmented by roads, agriculture and urban development.

Essentially, our turtles are stuck where they are, many in isolated pockets. They’re not going anywhere fast, and they’re not doing well.

Nearly all Canadian turtle species show significant declines in both absolute numbers and viable populations.

Efforts to protect them, however, are lagging. At the national level, the Species at Risk Act protects threatened, endangered and extirpated species on federal lands. Yet critical habitat, a key component in recovery planning, has so far been identified only for the Nova Scotia population of Blanding’s turtle. In Ontario, the only jurisdiction in which all eight of Canada’s species can be found, seven are considered at risk (provincially and/or federally threatened, endangered or of special concern). Of this group, only the wood turtle benefits from provincial regulations to protect its habitat. In Quebec, meanwhile, five of seven species are considered threatened or endangered (a potential eighth, the spotted turtle, hasn’t been seen since 1950). So while declines continue in hare-like leaps and bounds, protection moves at the speed of, well, a tortoise.

The problems start with basic biology: all turtles are long-lived and slow growing, with late sexual maturity (at 10 to 30 years) and long reproductive lives (up to 50 years).

Ecologically, these characteristics offset the typically high numbers of eggs and hatchlings lost to predation and subsequent low recruitment rates. This balance evolved in concert with a low rate of adult mortality — not entirely unconnected to their protective shells — and it has allowed turtles to survive cataclysmic events in the Earth’s past and to diversify on every continent and in every ocean.

Species exhibiting such life-history traits, however, cannot quickly or easily replace adults, leaving populations susceptible to extirpation after sudden episodes of high adult removals. Risks are ever-present. Despite their demonstrated resilience, turtles simply aren’t equipped to deal with the man-made threats of their active season — high road mortality while moving to and from nesting or overwintering sites, as well as over-harvesting for food or the pet trade. The hibernation season offers no respite.

Turtles face three major challenges in overwintering survival: freezing, predation and “acidosis,” the toxic accumulation of metabolic and respiratory lactic acid in tissues. Study after study has demonstrated that turtles select hibernation sites to minimize these threats. Within broader aquatic or wetland habitats with continuous ice cover, for instance, turtles tend to select sites where water temperatures stay close to 0 C for the duration — keeping their metabolisms as low as possible. But how they make

jan + feb 2013

their choices varies greatly. Species more tolerant of acidosis may choose anoxic — oxygen-poor — mud. Others will arm-wrestle over sphagnum hummocks or rock caverns in the same wetland. In regions where the ice cover is rare or inconsistent, turtles may hedge against acidosis and hibernate in areas with periodic access to air, even though this raises the risk of predation. Hatchlings, meanwhile, may overwinter in various aquatic situations or hollow roots, or may even remain in the nest.

Not knowing where the preferred sites are for a species or population at risk presents a significant conservation problem in terms of mitigating damage or destruction to such areas. Construction companies, for example, often use winter for certain types of work because it’s easier to drive heavy equipment across frozen soil and wetlands. This presents more of a hazard than just accidentally crushing snoozing turtles. “Blanding’s, spotted and snapping turtles choose the coldest areas of stratified water, so the biggest threat during hibernation is changes in hydrology,” Litzgus says. “Any alterations to water flow, inputs or outputs will change the thermal profile available to turtles — which in turn can increase the risk of acidosis or predation.”

Christina Davy, a doctoral candidate working on population genetics of several Ontario turtles in the Laboratory of Molecular Studies at the Royal Ontario Museum, witnessed such a catastrophe first-hand in Pinery Provincial Park, northeast of Sarnia, Ont. She was monitoring painted, snapping and musk turtles in an isolated, groundwater-fed oxbow of the Ausable River. At one end was a culvert with a beaver dam that maintained water levels. In November 2010, fearing rising waters, the park superintendent decided

jan + feb 2013

to trim the top of the beaver dam with explosives, despite being warned that the whole thing would probably blow.

“The explosion obliterated the beaver dam,” Davy says.

“The water immediately drew down two metres, leaving only a few puddles where there were riverbed depressions….

Later in the winter, an ice jam in the culvert backed up more water but then broke and drained again. The net effect was total destruction of overwintering habitat and a lot of dead turtles. What really annoyed me was that this was a protected area, yet no mitigation was taken to deal with the impact.”

Conservation efforts get even muddier when a population is spread between jurisdictions, as with the spiny softshell turtle in Lake Champlain. “The overwintering site is in the United States,” explains Yohann Dubois, a biologist with Quebec’s Ministère des Ressources naturelles et de la Faune who oversees several turtle recovery efforts in that province. “It’s the ‘jet-setter’ of our turtles — summer on the Quebec side and winter in the U.S.” Not that the 20-kilometre journey is much of a vacation. This isolated, already endangered population was further threatened when the Vermont Agency of Transportation replaced an old causeway a decade ago, part of which spanned an overwintering site used annually by an estimated 124 female turtles. It was “quite a project to protect this site,” Dubois says of working with his conservation counterparts in Vermont.

In addition to the challenges of promoting conservation across jurisdictions, the Lake Champlain aggregation points to further complexities in the turtles’ hibernation equation.

The high fidelity of these softshells to their site speaks to its important structural and chemical characteristics, as the CANADIAN WILDLIFE 23

unique Genetics mean each species may need its own conservation plan species requires highly oxygenated water and the right substrate. Biologists radio-tracking turtles through the ice, however, suspect that the area also provides important social interactions, notable as a place where roaming males are guaranteed to find females. Dubois points to similar communal overwintering sites for map turtles recently discovered on Lac des Deux-Montagnes near Montreal.

The importance of communal hibernacula to springtime mating — well understood in wide-ranging animals like snakes — is now apparent for turtles. But it isn’t always uniform, even within species. Just ask Erica Newton, who studied the overwintering ecology of endangered Blanding’s turtles in and around Kejimkujik National Park in southwest Nova Scotia. “We found that turtles overwintered in extremely diverse habitats, with low to high DO, and variable temperature regimes. Hot springs even kept some sites at 8˚C all winter. In the dead of winter they moved very little, but if it warmed up they’d move around,” says Newton.

“We even documented an act of copulation in January.”

In fact, unlike other Blanding’s populations, in which turtles mate in spring, Nova Scotia’s mated in October and November. Some males visited several overwintering sites to mate with as many females as possible before settling in to hibernate. While some turtles overwintered alone, most overwintered in groups of up to 13 individuals. “Winter is the most communal time of year for this species, so conserving these spots is important [because] they represent the majority of mating opportunities,” Newton says.

In other words, with such a large percentage of the breeding population present, if only one area or its occupants is destroyed, the effects can be disastrous. In a now-infamous paper, Dr. Ron Brooks, doyen of Canadian turtle-ology, described the calamity that befell a snapping turtle population on Lake Sasajewun in Algonquin Park that had been monitored since 1972. Over three winters in the late 1980s, otters killed more than half the adult turtles hibernating under the ice.

The circumstances leading to these events are unknown; they had never been observed before, and haven’t been seen since, but the deaths provided an unwelcome opportunity to observe the effects. Recent models by Litzgus’s doctoral candidate Matt Keevil show that the number of adult females in the population, which was constant up until that time, dropped suddenly by 60 per cent. It has remained relatively stable at this new, smaller population size to this day — some 25 years later — with zero sign of recovery.

24 CANADIAN WILDLIFE

Such dynamics are even more worrying at the genetic level. “We don’t know what we think we know about these species,” laments Davy. “We have what we consider good spatial ecology and habitat information, but population genetics are telling us something completely different.”

Her findings show genetic connectivity within Blanding’s, snapping and spotted turtles to be so different that each likely requires its own conservation strategy — even in the same geographic area.

One reason appears to be “effective population size,” or EPS. A census of adult turtles in a population might count 10 males and 10 females; but if genetic analysis reveals that only one male is mating with all 10 females (as can be the case — turtles are notoriously fickle), then EPS is not 20, but 11. Snapping turtles, it turns out, have a much lower EPS than spotted turtles, which seem better able to sustain smaller, more inbred populations without collapsing. The effect of removing individuals from snapping turtle population is thus much worse than for spotted turtles.

Losing even a handful of breeding females to a winter disaster could spell doom.

Because it is so imminently possible to mess up the critical overwintering habitat of a species, the only thing standing between extirpation and conservation may be the people who are willing to brave the cold on their behalf. But it isn’t always as easy as tying yourself to a tree.

“Wood turtles need wiggly, un-silted, fast-flowing rivers with cobble or sand bottoms and sandbanks at the bends,” says Litzgus. “But since logging is a threat that changes hydrology and siltation, overwintering sites are often in remote areas that are physically challenging to get to.”

Studying such creatures can also be sketchy. Litzgus admits that sometimes data collection becomes too unsafe. “We’re really careful. Students are required to do winter safety and ice training. They wear floater suits and carry ice picks to pull themselves out of a hole if need be.

No one has ever had a serious accident — at least not that they’ve told me about.”

Whatever the risks, they don’t faze Riley. “Tracking wood turtles in winter is neat because you get to go out on fast-moving but ice-covered rivers,” she enthuses. “Sometimes you can even see the turtles through the ice.”

Baxter-Gilbert also has no qualms sharing stories of his own dedication. “We were snowshoeing out to a site and I was breaking trail through really deep snow with all our water-quality equipment. I was sweating and got completely winded. Suddenly, I just leaned over and vomited!” he recalls, with considerable more enthusiasm than you’d expect. “Of course, I kept going” he finishes. “That’s how much I love turtles.”

Fortunately, he’s not alone in his fondness, as Canada now boasts more turtle researchers and conservation initiatives than ever. Given the range of threats and meteoric decline of these slow-moving creatures, it may indeed be such fondness that saves them. a

jan + feb 2013