Do turtles really breathe through their butts?
Courtney Leermakers, Wetland Conservation Technician
Megan Young, Adopt-A-Pond Conservation Steward
Donnell Gasbarrini, Adopt-A-Pond Coordinator
As autumn brings bright colours of orange, red, and yellow to the trees, we also know to expect more rain, cooler temperatures, and shorter days. With these environmental cues, the reptiles and amphibians of Rouge National Urban Park begin traveling and settling into their overwintering sites. All reptiles and amphibians are ectothermic, or cold-blooded. This means they rely on their environment to control their body temperature. For example, they lack responses like shivering to heat up, or sweating to cool down. As such, as it gets colder, their body temperature decreases, causing all of their inner systems to slow down significantly – their heart rate drops dramatically, their metabolism slows to a near-halt, and they take fewer breaths per hour– and they brumate through the winter months. Brumation is a state of inactivity caused by extended periods of decreased temperatures. So, it is a condition similar to hibernation, but it is a term used specifically for reptiles and amphibians. Unlike hibernation, where warm-blooded animals are in a deep sleep and do not move, cold-blooded animals in brumation are still awake and will move on warmer days. Did you know that unlike bears that need to eat a lot of food before hibernation, reptiles and amphibians stop eating before they begin brumating? Their metabolism (or digestion of food into energy) is so slow in cold temperatures that if they kept eating, they wouldn’t be able to digest their food and it would rot in their stomachs over the winter!
All 8 of Ontario’s turtle species brumate under water or deep in the mud – they must find a spot that remains liquid all winter long. Since all of their inner systems significantly slow down, they are expending so little energy that they no longer need to breathe atmospheric air (air from above the water’s surface). This means that they can brumate below the ice surface, as long as the spot they’ve found does not freeze solid. When they are in this state, their main source of oxygen is from the water that surrounds them! They DO breathe through their butts during the winter, whereby the thin tissue in their cloaca (the area that turtles use to pee, poo, and mate) acts like the lining of their lungs: absorbing oxygen and releasing carbon dioxide. This is enough to get them through the winter when their reduced activity leads to very low oxygen demands.
The turtles here in Ontario face longer winters than those of the same species found further south (e.g. in the mid to southern USA). Since turtles do not grow during brumation, this means that turtles in Ontario grow at a slower annual rate. The shorter “active season” (spring – fall) also means that turtles in Ontario generally only have time to lay one clutch (or group) of eggs per year, whereas it is more common for many species further south in their range to lay two clutches per year. These constraints make turtle populations of Ontario more susceptible to threats, as their ability to recover from these threats is much slower at the population level.
Every year, Adopt-A-Pond releases 60 juvenile Blanding’s turtles into Rouge National Urban Park, which are tracked twice per week from spring to fall to monitor movement. You can read more about this project on our website: Toronto Zoo | Adopt A Pond – Urban Turtle Initiative. Since turtles are moving less in colder months, we’re able to decrease the tracking frequency to a few times per month in the winter. We have also attached temperature data loggers on the turtles that constantly record water temperature from fall to spring. We also collect water chemistry data, for example the amount of oxygen in the water, over the winter. When we combine this information, it helps us better understand the turtles’ habitat preferences for overwintering sites, which is especially important in these restored habitats. If you are interested about the research being collected during the winter months check out our blog: Winter wetland adventures – how do researchers study reptiles in the winter? | Adopt-A-Pond News (wordpress.com). All of this work would not be possible without our partners, including Parks Canada and the Toronto and Region Conservation Authority.