The breeding biology of Australian Pelicans (Pelecanus conspicillatus) was studied on the coast of South Australia between 2002 and 2004. This study aimed to compare breeding on the coast with previous studies of inland breeding Australian Pelicans and to test whether this species exhibits siblicidal brood reduction. Nests were generally constructed on the ground in spatially and temporally discrete colonies. Nests within colonies were 1.3 ± 0.5 m apart (Range = 0.6–4.5; n = 327), whereas colonies were 329 m apart (Range = 21–1,136; n = 63). Within colonies, 80% of nests were initiated within 10 days of each other. Colonies contained 41.0 ± 37.6 nests (Range = 1–148; n = 63). Most colonies were initiated during the austral winter and spring (June–September) in contrast to opportunistic breeding in inland areas. Clutch size averaged 1.92 ± 0.36 eggs (Range = 1–4; n = 2,297), and incubation lasted 32 days (Range = 28–38; n = 57). Hatching success averaged 41.5 ± 38.6% (Range = 0–99; n = 24 colonies), the number of nestlings that survived to join a crèche was 20.3 ± 22.4% (Range = 0–66; n = 24 colonies), and fledging success averaged 15.3 ± 18.3% (Range = 0–61; n = 24 colonies). Aggression among nestlings and resulting wounds were observed in 48% of broods (n = 64). Mortality during the 10-day nestling period was high (5.5 ± 2.2%/day; Range = 2.5–10.0; n = 45) and was the major determinant of overall breeding success. These findings suggest that Australian Pelicans exhibit siblicidal brood reduction.