Many Pterodroma species are threatened, and translocations to predator-free islands are desirable for several species. As these birds are highly philopatric, only chicks that have not yet imprinted on their natal colony should be transferred but techniques to identify suitably aged Pterodroma nestlings are needed. We investigated feeding frequency, meal size and chick growth in Pycroft's petrel (P. pycrofti) on Red Mercury Island, New Zealand to provide this information. Mean daily probability of being fed decreased from 0.47 60-23 days before fledging to 0.004 in the last seven days before fledging. Mean meal size was 34 g and morphometric measurements at fledging were similar to mean adult measurements. The best indicator of chick age was wing length. Transferable Pycroft's petrel chicks should have wings measuring 149 - 184 mm and weigh 218 - 250 g.