All detailed information are from Jahncke's (1994) discovery of nesting colonies on the Paracas Peninsula, Peru, in 1992 and 1993. These colonies do not represent the entire population of the species, so information may be different in other locations. Summary below based on Brooke (2004).
Mean colony size low, with about 15 pairs, with densities ca 3 nests/100 m². Colonies built into crevices and holes in saltpeter deposits, on sloping ground within 5 km from ocean. Nocturnal on breeding grounds.
Single white egg (ca 32.2 x 24.2 mm, n = 155) laid between June and early August. Incubation averages 47 days (range 37-70 days, n = 28), with parents' shifts lasting three days or less. Most chicks fledge in November, the mean nestling period being 75 (n = 17) and 80 (n = 29) days in 1992 and 1993 respectively. In 1993, mean fledging weight was 70.5 g, hatching success 55%, fledging success 63%, and overall breeding success 36%. Nests in deeper cavities and smaller entrances were more likely to be successful.
Data from roadkill near Iquique, Chile, suggests that breeding happens later in the year further south, with most fledging in late March to April.