Development assessment: How hard do we need to look to find a threatened species?

In any ecological survey, there is a chance that a species occupying a site will not be detected during a survey of that site. Georgia Garrard’s research has investigated detectability issues in the Western (Basalt) Plains grassland community on the northern and western fringes of Melbourne in close proximity to Melbourne’s urban growth boundary, where there is continual pressure for development.

While many ecologists are aware of issues of imperfect detection during biological surveys, policy has yet to catch up with this issue. It’s still the default assumption of most environmental impact assessments that a species that is present at a site will be detected during a survey of that site. A number of modelling methods now exist for characterising species’ detectability, some of which enable us to determine how many repeat surveys are required to be confdent of detecting a species if it is present. Georgia Garrard’s interest is a variation on this: How long do we need to spend surveying in a single visit to a site to achieve a reasonable chance that we will detect a threatened plant species if it’s present?

To find out more read ‘Detectability, search effort, needles & haystacks – How hard do we need to look to find a threatened species?’ on pages 3-5 of AEDA Decision Point Issue 34.