To test the effectiveness of patagial marking with cattle ear-tags for Australian White Ibis (Threskiornis molucca), 105 adults and 58 nestlings were fitted with tags on each wing. Resighting frequency of adults, survival of nestlings, breeding behavior and foraging movements were monitored. The resighting frequency of wing-tagged adults was compared with resightings of 160 adults marked with colored leg-bands. Survival rates of wing-tagged nestlings were compared with an equal sample of 58 nestlings fitted with colored leg-bands. Over six months, 96% of tagged adults were resighted and there was no indication of impaired flight, with foraging movements ranging up to 30 km. Wing-tagged adults were more likely (40%) than color-banded adults (28%) to be detected in a one-off survey three months after marking and 65% of tagged birds were observed nesting. Higher mortality was observed among smaller nestlings (<1100 g) compared with larger nestlings marked with wing tags, but not among those marked with leg bands. Inspection of the wings of two adult and two juvenile birds recaptured 6–8 months after marking indicated only minor feather abrasion, although further study is needed to assess long-term impacts. Because patagially-fitted cattle ear-tags are more visible than colored leg bands, can be fitted quickly with minimal trauma, and seem to have few adverse effects, they appear to be an effective technique for individually marking large adult birds.