Blanding’s Turtles vs Leatherback Turtles: A Tale of Two Canadian At-Risk Species

By: Katie Zajac, Canadian Species Initiative Research Assistant

The world of turtles is incredibly diverse, with more than 350 species worldwide, from giant tortoises on isolated islands, to ocean dwelling giants, to common backyard pond species. Two highly captivating members of this group are found in Canada: the Blanding’s turtle and the Leatherback turtle.

Blanding’s Turtle: medium-sized freshwater turtle with yellow colouring on throat, chin and plastron and yellow spots on domed shell.

Leatherback Turtle: largest of all sea turtles with a ridged leather-like shell and powerful flippers.

While both turtles, these two species are about as different as turtles can be:

Blanding’s turtles
(Emydoidea blandingii)

Habitat: Freshwater wetlands such as shallow ponds and swamps, with dense vegetation

Nesting habitat: Sand or gravel near wetland habitat

Location: Great Lakes-St Lawrence area and Nova Scotia

Diet: Omnivore – insects, fish, amphibians, and aquatic vegetation

Ecological role: Maintain the balance of their wetland ecosystem by controlling small prey species

Life history: Hibernate in mud from October to April before emerging to forage, breed, and nest during the summer

Leatherback turtles
(Dermochelys coriacea)

Habitat: Open ocean

Nesting habitat: Tropical beaches

Location: Pacific and Atlantic Oceans

Diet: Primarily jellyfish

Ecological role: Support marine ecosystem health by controlling jellyfish populations

Life history: Forage in open waters and migrate annually from northern waters to tropical nesting locations

Despite these differences, both species are listed as at-risk in Canada (Blanding’s: Threatened; Leatherback: Endangered) and face similar threats in their respective environments such as habitat loss and fragmentation, collisions with cars or boats, egg predation, illegal pet trade and hunting, and climate change. Slow life-history traits in both species (long-lived, late maturing, low reproduction rates) make population recovery difficult. Fortunately, we can help through conservation strategies that offset the impacts of threats such as population reinforcement through methods like head-starting or wild-to-wild translocations.

A Blanding’s turtle basking on a log. This is the most common place that turtles are spotted.

A Leatherback turtle swimming. A bit harder to find.

Head-starting is an ex situ (in human care) conservation technique where eggs or young turtles are raised in captivity until they reach a large enough size to be released back into the wild, giving individuals a “head start” in life. The goal of this strategy is to either increase population size (demographic augmentation) or to improve the rate of survival or an imbalance in age, sex, or life stages (demographic manipulation).

This is a recommended strategy to improve recruitment and reverse the decline of Blanding’s turtle populations, in conjunction with threat mitigation measures and habitat restoration. There are at least four headstarting programs for Blanding’s turtles in Ontario alone, including one in Rouge National Urban Park where 603 two-year old hatchlings have been released since 2014! Monitoring has shown that head-started hatchlings have greater probability of surviving to adulthood than wild-born turtles thereby boosting populations.

A young Blanding’s in the headstarting program. Photo: Hannah McCurdy-Adams.

For Leatherback turtles, however, a head-starting program is not recommended at this time. In a recent assessment of the management needs for the Eastern Pacific subpopulation facilitated by the Conservation Planning Specialist Group it was determined that due to knowledge gaps in relation to Leatherback biology and ecology, as well as appropriate husbandry techniques, further research needs to be conducted and in situ threat reduction strategies should be priority, including mitigation of fisheries bycatch. These steps will better prepare conservation practitioners to implement ex situ conservation measures in the event that urgent action is needed, or population decline is not prevented through interventions in the wild alone.

To see another example of how population reinforcement through headstarting can support declining turtle populations in the wild check out Wildlife Preservation Canada’s Western Painted Turtle headstarting program in BC’s Fraser Valley.

To learn more about how ex situ conservation roles can help prevent extinction of species in the wild check out the Canadian Species Initiative, a partnership founded by WPC and African Lion Safari and host of the Conservation Planning Specialist Group regional resource centre in Canada.

Coming face-to-face with a Blanding’s turtle in a dried up swamp land; the result of climate change and the threats that this population faces.

Processing three Blanding’s turtles as part of a mark-recapture program (all turtles handled with permits).

Stephanie Winton, the Canadian Species Initiative Coordinator gives a travelogue presentation on her experience working on reptile conservation projects in Mauritius as the 31st Canada’s New Noah.

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