BreedingBreeding

Breeding

In Australia, the subspecies breeds between June and March in colonies of various sizes (generally between 2–400 pairs but up to 700 pairs in Western Australia (Dunlop et

al. 2015; Dunlop 2018). Colonies can be located on coral shingle on coastal islands, or coral cays, on sandy islands and beaches inside estuaries, and open sandy beaches, laying 1–2 eggs (rarely 3) in a nest scrape (Higgins and Davies 1996). They nest in clear view of the water and on sites where the substrate is either sandy or on shell-grit and the vegetation sparse. In Western Port Ramsar site, Victoria, birds use seagrass covered beaches to nest on Rams Island.

Incubation duties are shared but females probably spend more time at the nest whilst males actively provision females before and after laying, as is the case with Little Terns (Cramp 1985; Cabot and Nisbet 2013). Incubation lasts for approximately 18–22 days (Lindsey 1986; Higgins and Davies 1996). Chicks may be guarded by one parent for the first day or two. However, it is not unusual for chicks to be left alone whilst the adults undertake foraging bouts (C. N. Greenwell. pers. comm. 2020). Chicks fledge at about 20 days. Nesting birds are sensitive to disturbance and can become extremely agitated when disturbed by humans or other animals. Females often crouch on the ground; however both sexes have been known to attack intruders (Higgins and Davies 1996; Lindsey 1986).

There is a high natural rate of breeding failure as breeding sites can become inundated during extreme weather events, such as high tides and storm surges or be smothered by wind-blown sand. Colonies tend to occupy areas rather than fixed sites, and nest sites can be abandoned after one or more years, even if they have been successful (Saunders and de Rebeira 1985).

Interbreeding has been recorded between Fairy Terns and the Little Tern in South Australia (Cox and Close 1977), Victoria (Norman et al. 1996), NSW (Ross et al. 1999) and Tasmania (E.J. Woehler pers. obs).