Trent University PhD candidate Josh Feltham studies Ontario’s only lizard

Did you know that reptiles and amphibians are proportionately the most engendered vertebrates in Canada?

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Photo by Kevin Chan

That’s why Trent University PhD candidate, Josh Feltham, conducted his research to discover the best ways to protect them.

His research at Trent University in the Environmental and Life Sciences program with a focus on Conservation Biology explored three topics:

  1. Body size;
  2. Mating strategy; and
  3. Habitat selection.

His goal was to establish the key landscape features that limit the high latitude range limits of reptiles, and more specifically, the five-lined skink: Ontario’s ONLY lizard! In central Ontario, the high latitude range limit for skinks is only about 100 km north of Peterborough along the southern edge of the Canadian Shield.

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Photo: Josh Feltham

Josh and his supervisor, Dr. Joseph Nocera, wanted to gain a better understanding of skink habitat at northern range limits to help inform Ontario & Canada’s habitat protection policies for endangered reptile and amphibian species. 

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Photo by Kevin Chan

To conduct his research, Josh:

  1. Used surveys to provided details about the environment where the lizards lived
  2. Took measurements to provide information about latitudinal variation in body size
  3. Tagged the lizards to estimate population size and track the movement of individuals within the population.

First, Josh wanted to discover if high latitude skink populations are generally larger than low latitude populations and the difference between female & male body size. He found that males are larger than females with a particularly noticeable difference in head length and width.

The difference in body size is most pronounced in female body length, which may relate to how a female looks after her young offspring, or her “brooding behaviour“. Larger bodied females may be more successful when brooding their eggs in comparison to smaller bodied females.

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Photo by Kevin Chan

Second, Josh was interested in skink mating behaviour. Skinks are polygamous, which means they mate with multiple partners during the same season! Research supports the theory that polygamy evolves in circumstances where the breeding population is clustered together because of a limited resource.

Josh learned that skinks are clustered together during the early spring breeding season. This facilitates access to multiple partners without the need to expend too much energy.

Third, Josh collected data about the habitat that skinks were selecting. He found that skinks require open habitats, with rocks to hide under and bask on. In the early spring, they select specific rocks that slope toward the southeast. Under these conditions, skinks can reach their optimal body temperature of 20 to 25 Celsius two to three hours before the ambient air temperature.

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Photo by Kevin Chan

Temperature is the thread that connects all elements of Josh’s research. Skinks, like all reptiles, are ectothermic. Ectotherms are species that rely on external sources of heat to maintain their bodily functions.

Skinks require access to warm sites early in the spring. The warm sites are not evenly distributed on the landscape; therefore, the skinks are clustered in their distribution during the mating season which facilitates a polygamous mating system. Body size is also connected to temperature because large individuals can maintain a stable body temperature more easily than small individuals.

The limited availability of sites with suitable temperature conditions forces skinks to be clustered together. This shapes almost every aspect of their ecology and it makes them vulnerable to population decline and extinction.

Even small changes to the landscape may result in a serious decline of skinks  – which is happening to almost all reptiles and amphibians in Canada.

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Photo: Josh Feltham

The most practical application of Josh’s research is in species conservation. The data from Josh’s research has already been used to restore skink habitat in Thousand Islands National Park and to develop hiking trails in Kawartha Highlands Provincial Park.

Josh says,

“Working full-time as a Professor at Fleming College’s School of Environmental and Natural Resource Sciences while completing a PhD has been challenging; however, none of the challenges have been associated with Trent University as the close proximity of the university made it easy for me to go to class, attend meetings, and participate in events on campus. The association between Trent University and the Ministry of Natural Resources and Forestry (MNRF) was also critical in my case as my supervisor, Dr. Joseph Nocera was a biologist for the MNRF. Finally, the small, community atmosphere made getting administrative tasks and resolution of challenges much easier than it would be at a large institution with a more corporate approach.”

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