Joining forces for the Collared Delma

Pullen Pullen Catchments Group (PPCG) and Kholo Creek Catchment Group (KCCG) have joined forces in a project designed to enhance habitat for the vulnerable legless lizard, the Collared Delma (Delma torquata), in our catchment areas. The western suburbs of Brisbane are considered a stronghold for this species, however its habitat (typically eucalypt forest with grassy understory and rocks) is threatened by factors such as changing land use and the encroachment of invasive weeds.

The project, Improving Collared Delma trajectories in Brisbane’s western suburbs, involves the assessment of local properties for suitable Collared Delma habitat, surveys to record populations and habitat enhancement measures. The latter include weed management and, in selected areas, the extension of habitat with imported rocks and native tussock grasses.

Area ranked highly for Collared Delma habitat,
project property assessment, June 2022

Thus far 22 properties in the catchment areas have been assessed, using a habitat assessment tool devised by project team members Paul Grimshaw and Jim Williams, with advice from local Collared Delma expert, Stephen Peck.

The assessment process included observations of the topography, soil, rock types and vegetation (including weed coverage). Those with features consistent with known Collared Delma habitat, such as north or west facing rocky slopes, open eucalypt forest and limited weed encroachment, were ranked most highly.

Collared Delma on a project property, October 2022

Surveys for Collared Delma have now been conducted on 11 of the 22 properties, with sightings recorded at two of the most highly ranked properties. These findings underline the utility of the assessment tool developed for the project; it will be an important outcome from the project that can be applied in future research.

Another crucial component of the project is weed management in areas with potential Collared Delma habitat. This work has commenced on several of the assessed properties, focusing on selected areas where invasive weeds such as Creeping Lantana (Lantana montevidensis) are affecting the capacity of otherwise suitable areas to support Collared Delma populations.

Before and after weed management on a project property, showing removal of invasive species from rocks, October 2022

In the final stages of the project, weed management will be supplemented in selected areas with the planting of tussock grasses and placement of rocks. This will further enhance habitat for Collared Delma by providing protected areas for the lizards, and simultaneously assist in retarding the re-encroachment of invasive weeds.

The project will continue until 31 March 2023. It is supported through funding from the Australian Government.

Article ompiled by the Collared Delma Project team (Paul Grimshaw, Liz Gould, Mervyn Mason, Justin Miller, John Ness, Stephen Peck, Gillian Whitehouse, Jim Williams), November 2022.

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