Can the Judas technique be applied to pest birds?

The Judas technique was evaluated for its use as a technique to assist with the control of the common starling (Sturnus vulgaris). This technique uses the natural behaviour of a gregarious animal to betray the location of itself and its companions through radio-telemetry. Two trials were conducted to assess and develop the technique for starlings. The first trial was conducted near the western edge of the starling's current established range in Australia, at Penong in South Australia. Nine out of ten radio-tagged birds were successfully tracked from the ground and air. Estimates of the areas utilised varied from 1.1 km(2) to 96.5 km(2) (100% convex polygons). Night-time roosts were found for three of the nine radio-tagged birds and control (shooting) recovered just one bird directly associated with a Judas starling, as well as the radio-tagged bird. The second trial was conducted at Munglinup near Esperance in Western Australia. Munglinup is the site of a recent infestation of starlings and is the most western-known outlier of this pest in Australia. At this site, five radio-tagged starlings tracked from the ground and air, utilised areas ranging from 0.7 km(2) to 51.6 km(2). Reduced fidelity to roosting trees impaired our ability to destroy starlings here. However, the real value of the Munglinup trial was to expand the geographical area known to be occupied by this population from 103 km(2) to more than 225 km(2) and to identify habitats and roost sites used by the starlings. We conclude that the Judas technique could be applied to starlings and other pest birds with similar social structures as a means of strategic surveillance rather than as an adjunct to control per se.