Friday, January 7, 2011

The Entrance, NSW





The Little Tern (Sterna albifrons) is Australia’s smallest tern. It is listed as an endangered species in New South Wales. The species is an ecological specialist, needing specific conditions for feeding and breeding and it currently has a population and distribution reduced to a critical level, with poor recovery potential in the face of severe threats. There is a breeding colony on the Central Coast, and though the main nest sites are fenced, it is in a very busy area and most people seemed to treat it as just another seagull.

The Little Tern in NSW is strictly a coastal species, nesting in estuaries or on coastal beaches, and feeding in nearby waters. Most of the nesting sites in NSW are sand-spits, sand islands or beaches within or adjacent to the estuaries of rivers, creeks and coastal lakes. Nesting usually occurs at or near the mouth of the estuary.

Little Terns nest on the ground in the open. The nest is a simple scrape, usually unadorned, although sometimes lined by the birds with shell fragments, tiny pebbles or other material. Nests are typically located on flat or gently sloping ground, on a loose, sandy substrate with abundant surface shell-grit or pebbles, and bare or almost bare of vegetation. The birds appear to select sites with good visibility all around for the sitting bird, and with good camouflage for the mottled eggs and chicks. Nests are usually located close to the water, mostly within 150 m of, and less than 1.5 m above the high water mark. Little Terns tend to avoid vegetated areas and will abandon a traditional nesting site if it becomes too overgrown. However, clumps of vegetation, driftwood and other beach debris are important for
providing shelter and shade for the chicks once they leave the nest.

While currently Little Terns breeding in Australia are classified with those breeding in eastern Asia as subspecies sinensis, it is thought that not only might the Australian birds eventually be recognised as a separate subspecies, but that the genetic differences between Little Terns breeding in south-eastern Australia and those breeding in the Gulf of Carpentaria might see the Australian Little Terns classified as two distinct subspecies.

Little Terns return to NSW during September to November. Nesting begins in October or November and continues through into January or February. Numbers then decline as the birds leave on migration from March to May. The group at The Entrance included both breeding (with yellow bill) and non-breeding birds, and a number of juveniles with buff-brown plumage. I didn’t go near the nesting site, but have heard reports from site monitors that there are babies there.