Find the ant, then the butterfly.
The Arid Bronze Azure Butterfly (Ogyris subterrestris petrina) is listed as critically endangered under the EPBC Act and the WA Biodiversity Conservation Act 2016, with only two known subpopulations in Western Australia. Its larvae live inside the nests of a single sugar ant, Camponotus sp. nr. terebrans, at the base of mature eucalypts in semi-arid woodland. Without large colonies of that ant the butterfly cannot persist, so surveys start with the ant.
Trace Ecology runs both stages of ABAB surveys for projects in the Goldfields, Wheatbelt and semi-arid woodlands of WA. We also survey habitat for the Inland Hairstreak (Jalmenus aridus), a priority-listed WA butterfly that also depends on ants. See also Targeted Threatened Fauna Surveys.
How we survey
Surveys follow DBCA's survey guideline for the Arid Bronze Azure Butterfly (2020).
- Host ant survey first. Mature trees are sampled at random across the site, at night after sunset or by day at the tree base, with the number of trees set by the site area. Trees beside roads and tracks are included, where the ant and the butterfly are found more often.
- Butterfly survey where large ant colonies are found. Standard transects around the colonies, walked in fine weather with a forecast maximum of at least 23°C. Butterflies are photographed to confirm identity, then released.
- Timing. To show the butterfly is absent, the guideline asks for three repeat surveys at least two weeks apart in the main flight period, mid-September to late October, or five outside it.
What you receive
Mapped host ant colonies and habitat, butterfly survey results, an assessment of likely impacts, and recommendations for avoidance, further survey or management, written for EPBC referrals, EPA assessment and clearing permits. Taking or disturbing a threatened species in WA needs a threatened fauna authorisation, so early survey leaves the most room to design around the species.
Related project: ABAB and Inland Hairstreak surveys, Goldfields.
Frequently asked questions
Can an ABAB survey be done at any time of year?
The host ant survey can be done in most months. Butterfly surveys need warm, fine weather, and absence is most efficiently shown in the main flight period from mid-September to late October.
What if the host ant isn't found?
If no large host ant colonies are present, the guideline does not require a butterfly survey. The report records the ant survey effort so that conclusion can be checked.
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