Getting a Head Start
Protecting turtle eggs from predators to increase the number of successful offspring plays a key role in turtle conservation. Yet even then, the probability of tiny hatchlings surviving to adulthood is incredibly low. To boost those odds—especially for species and local populations in extreme peril—some programs use a practice called “headstarting.” It involves rearing hatchlings in captivity for anywhere from a few months to almost two years before release.
“We’re just trying to get them up to a size where they can more easily avoid predation,” says Andrew Lentini, curator of amphibians and reptiles at the Toronto Zoo, which has been running a Blanding’s turtle headstarting program in the recently created Rouge National Urban Park since 2012.
The native adult Blanding’s population in the Rouge River watershed is so depleted due to roadkill, nest predation and a lack of habitat connectivity, that the zoo sources the eggs used in its program from the Ontario Ministry of Natural Resources and Forestry. The MNRF gets them from “non-viable” nests elsewhere in the province, usually uncovered during highway construction. The zoo hatches and raises the young for about two years and then, each year in June, releases 50 Blanding’s turtles into the park. All of them are marked, tagged and some are equipped with radio transmitters for subsequent monitoring and tracking.
One benefit of the indoor rearing: these turtles are already as big as a typical six- or seven-year-old naturally reared Blanding’s. Even so, not all will reach adulthood. However, Lentini says population models indicate that releasing 50 turtles a year for 17 to 20 years will create a stable, self-sustaining adult population of 150 Blanding’s in the area. “We’re into our fourth year of releases, so we’ve got about another 15 years to go.”
Across the country, in B.C.’S lower Fraser Valley, Andrea Gielens, project lead for B.C. wetlands wildlife at Wildlife Preservation Canada, runs a similar program in tandem with the Greater Vancouver Zoo for the endangered coastal population of the western painted turtle.
“Our goal for release is a minimum size of 30 grams,” says Gielens. “We want to make sure that we’re not just throwing a bunch of tiny turtles out there that are going to get predated right away. We want to make sure that they are going to survive to breed.”
Under the program, which began in 2013, they rear 175 to 200 turtles a year. The eggs are collected from at-risk nests in late May to early July by Gielens and others on the project, and typically released in August or September the next year. Since male western painted turtles reach maturity around seven or eight, and females a little later, the current milestones are limited to tracking the turtles’ survival and growth. But soon they’ll begin looking for signs of breeding and then successful nesting, says Gielens.
“Then we’re going to start looking at the survival of those offspring and their growth over time. Eventually we’ll have our first breeding of babies born from our augmented program. But that’s quite a few years off.”