Figure 3. Colony size estimates made by experienced ground counters using a traditional technique (green; n = 2–4) and those made by counting digital imagery captured by a small UAV (blue; n = 7–9) which was flown concurrent to ground surveys.

Colonies of varying size were sampled on Australian islands: breeding Lesser Frigatebirds Fregata ariel (a) and Crested Terns Thalasseus bergii (b) at the tropical Ashmore Reef Commonwealth Marine Reserve as well as on the nearby Adele Island in April 2014 and moulting Royal Penguins Eudyptes schlegeli (c) on the subantarctic Macquarie Island in April 2015.