Ask any seven year old to find you a skink, they’d probably start turning over rocks. Quiz any landholder about where to find a snake, and they’d likely point at their woodpile. While it seems to be common knowledge about where to find certain reptiles, ecological research is just catching up in defining the habitat requirements for many species.
Recently, our team classified the niche requirements for nearly forty species of reptiles in the temperate Box Gum Grassy Woodlands of south eastern Australia. It’s estimated that less than 4% of these critically endangered woodlands remain. The majority are found as fragments on private property undertaking primary production (ie. farms). These woodlands provide habitat for over fifty reptile species. Reptiles make up a vital component on the farm, providing both predator and prey roles. It’s important to understand specific habitat requirements for reptile species in order to determine if they could be affected by traditional farm practices in these areas.
Over ten years the team made 4,287 observations of 52 species in the woodlands, which ranged from Brown Snakes to Rainbow Skinks, Legless Lizards to Geckos. Of these species, 39 could be broken into six distinct guilds based on the similarity of habitats they used. Broadly, these guilds were; log-dwelling, surface rock-dwelling, bark dwelling, tree/log dwelling, outcrop dwelling and terrestrial (i.e. leaf litter and open ground).
As may have been predicted, Blue-tongue Skink was found to be log-dwelling, Iridescent Litter-skink was found to be litter-dwelling, and three species of snake were deemed to be associated with surface rock. Many of us would not be surprised too that the majority of gecko species were found under bark. Determining the niche requirements for individual species gives insight into their ecology, whether they are specialist in their needs for habitat, or more general, and so help determine what farm activities might impact these species.
Furthermore, exploring the specialized needs of groups of reptiles can help us pinpoint which are most affected by human induced practices. A closer look revealed that 80% of all species belonged to guilds associated with old growth aspects of woodlands on farms. Old growth characteristics include fallen timber and large old trees as well as non-renewable habitats such as bush rock and rocky outcrops.
While ‘bush rock’ sounds like something that typically belts out of regional pubs on a Friday night, in this case it refers to lightly embedded surface rock. Under traditional farm practices bush rock is often collected up on a property, or displaced by cattle. Bush rock is non-renewable, meaning once it’s gone, it may never be replaced. We found that seven specialist species of reptile were associated with bush rock or rocky outcrop habitats and so the loss of these areas from a farm would impact these species in particular.
Similar to bush rock, fallen timber is often tidied up on a property – it may be piled up and burnt, or taken for firewood. Once removed, large fallen logs can take decades to build up again at levels that can support reptiles. Our study found that five specialist species were linked to large mature tree and fallen timber habitats. Removing timber (standing or fallen) for firewood would impact these species negatively – meaning local populations of these timber utilizing species could disappear and, due to woodland patch isolation, not repopulate years later once timber levels build up again.
A large number of landholders are improving the condition and extent of Box Gum Grassy Woodland on their properties through a variety of measures, such as reducing grazing intensity and replanting native species. Many are able to do this with the assistance of state and federal agri-environment incentive schemes such as the Environmental Stewardship Program.
The reduction in grazing, and increase of vegetation cover through planting can assist some tree or semi-tree dwelling reptiles. However, grazing management alone is not enough. This is because programs rarely fund farmers to retain both old growth and non-renewable resources. Without incentives and policies, few landholders have the ability (or requirement) to protect these critical habitat areas. Future programs and policy are needed that preserve bush rock, rocky outcrops, fallen timber and large trees in order to improve reptile biodiversity on our farms.
Based on article:
Michael, D. R., Kay, G.M., Crane, M., Florance, D., MacGregor, C., Okada, S., McBurney, L., Blair, D., and Lindenmayer, D. B. (2015). "Ecological niche breadth and microhabitat guild structure in temperate Australian reptiles: Implications for natural resource management in endangered grassy woodland ecosystems." Austral Ecology