142Wildlife Conservation Plan for Seabirds

142 Wildlife Conservation Plan for Seabirds

Roseate Tern (Sterna dougallii)

TABLE Species information for the Roseate Tern (Sterna dougallii)

The Roseate Tern (Sterna dougallii) is a slender medium-sized tern with a very long, slender drooping bill. The species is slightly bigger than Black-naped Tern (S. sumatrana) and smaller, slimmer than Common Tern (S. hirundo) and White-fronted Tern (S. striata). The species has an almost cosmopolitan distribution. In Australia the species can be found in subtropical and tropical waters from south-west WA to south-east Qld. The species nests on sand-dunes, sand-spits, shingle beaches, reefs (Snow and Perrins 1998), saltmarshes and rocky, sandy or coral islands and cays (del Hoyo et al. 1996), showing a preference for densely vegetated sites in temperate regions but sparsely vegetated sites in the tropics (del Hoyo et al. 1996). It also shows a preference for nest sites close to clear, shallow, sandy fishing grounds (Snow and Perrins 1998) in tidal bays and sheltered inshore waters (Snow and Perrins 1998). Throughout the year the species often rests and forages in sheltered estuaries, creeks (Urban et al. 1986), inshore waters and up to several kilometres offshore (del Hoyo et al. 1996), moving to warm tropical coasts after breeding (Snow and Perrins 1998). The species breeds in large, dense single- or mixed-species colonies that may contain several thousands of pairs (del Hoyo et al. 1996). It remains gregarious throughout the year, roosting in large groups (Urban et al. 1986, Snow and Perrins 1998) and feeding singly, in small loose groups (Snow and Perrins 1998) or in flocks of many hundreds of individuals (Urban et al. 1986, Snow and Perrins 1998). It is regularly found in mixed species flocks with Lesser Noddy (Anous tenuirostris) and White Tern (Gygis alba) (Ramos 2000). Its diet consists predominantly of small pelagic fish (Urban et al. 1986, del Hoyo et al. 1996; Surman and Wooller 2003).

The global population is estimated to number 200,000–220,000 individuals (Delany and Scott 2006). The overall population trend is uncertain, as some populations are decreasing, while others are increasing or stable (Delany and Scott

2006). The Australian population has been estimated to be at least 15,000 pairs (Milton et al. 1996). Recent Australian population estimates and trends are unknown.

Predators of eggs and chicks include the White-bellied Sea-Eagle (Haliaeetus leucogaster), Silver Gulls (Chroicocephalus novaehollandiae) and lizards (Higgins & Davies 1996; Hulsman et al. 1999). Ruddy Turnstones (Arenaria interpres) and large skinks (Egernis kingii) are also suspected predators in some locations (Hatch & Szczys 2000). The Black Rat (Rattus rattus) is a suspected introduced predator; after a rat baiting program on Wreck Island (Great Barrier Reef) the production of young increased (Burbidge & Fuller 1998; Hulsman et al. 1999).