Defence Establishment Orchard Hills baseline reptile surveys

The Greater Sydney Local Land Services (GSLLS) engaged the Gulbali Institute for Agriculture, Water and Environment, Charles Sturt University to undertake baseline reptile surveys on Defence Establishment Orchard Hills (DEOH) in western Sydney during November 2023. Twenty-four sites within Cumberland Plains Woodland were established across twelve zones representing two treatment types: 1) areas designated for thinning trees and shrubs, and 2) areas designated for revegetation of trees and shrubs. These zones were matched with two control types: 1) retained trees and shrubs, and 2) retained mixed grassland, where no management interventions are planned to occur. Reptiles were surveyed using pitfall and funnel traps, time (1 hr) and area-constrained (2 ha) active searches of natural habitat, visual encounter surveys and inspections of artificial refuges (corrugated galvanised steel and roofing tiles). A total of 24 species, comprising of 15 reptile species and nine frog species from nine families were recorded during the survey period. The grass skink Lampropholis guichenoti accounted for 87% of all individual reptiles recorded across the core survey sites. Most frog species were recorded incidentally along Blaxland Creek and on two large dams during an opportunistic audio call survey. Generalised linear models were used to explore treatment and survey method effects. Mean reptile abundance ranged from 3.8 to 6.1 individuals per site, and ‘reveg trees and shrubs’ supported significantly more individuals than other site types. Pitfall traps and roofing tiles were the least effective survey method for detecting reptile numbers during the survey period compared to active searches, visual encounters, funnel traps and sheets of galvanised steel, which were the most effective survey methods. No differences in mean reptile species richness were evident among treatment or control sites.
Key management recommendations include:
• Conduct a follow up survey after the thinning trials and revegetation to explore the short-term response of reptiles to management interventions.
• Maintain leaf litter and debris piles in the mixed open grassland areas as this microhabitat provides important shelter sites for less abundant species such as the garden skink Lampropholis delicata and weasel skink Saproscincus mustelinus.
• Consider introducing small rock piles or rock meadows in the mixed open grassland areas as this will provide important habitat for grassland species, including the locally rare eastern striped skink Ctenotus robustus as well as provide terrestrial vertebrates with protection from fire, climate extremes and predators.