Little Tern chicks less than 24 hours after hatching.
Like all ground-nesting birds, Little Terns are susceptible to a high level of predation by foxes, cats and dogs. Little Terns choose to breed on beaches, which of course are also very popular with humans particularly in summer, so the birds also have to contend with people stepping on their eggs and vehicles running them or the chicks over.
There are a handful of Little Tern breeding sites in NSW such as at Botany Bay in Sydney and Culburra near Nowra. Cumberland Bird Observers' Club members assist each year at these sites by educating the general public, keeping dogs away from the birds and studying the birds.
Each November, at the Culburra site the National Parks and Wildlife Service (NPWS) places two fences around the breeding birds. The first fence carries notices warning the public about the possibilities of treading on eggs. The second inner fence is electrified to keep out foxes which have in the past destroyed every single nest.
A volunteer's typical day at Culburra is as follows:
- 8am: Enter the electrified area (where most of the nests are located) and inspect all known nests. The adult birds will all take flight and call loudly at this disturbance but don't be distracted by this and accidentally tread on a nest. Note how many eggs or chicks are in each nest. If you find a new nest, mark it with a new numbered tag and add it to the location map. Don't confuse a Little Tern nest with a Red-capped Plover nest - a plovers eggs have a slight green tinge to them. If new unbanded chicks are present and you are a bander, place a unique band on the chick's leg.
- 8.30am: Having left the electrified area, take up a position amongst the small sandhills with your telescope. Remain still. The adults will fly near you calling loudly but after a few minutes they'll ignore you and go back to their parental duties.
- 10am: For more than an hour you have tried unsuccessfully to see the coloured leg flags on the birds sitting on some of the nearby nests. The birds move quickly and won't always allow you to get a goo view. Many birds have four rings or flags on their legs: a permanent numbered metal ring on one leg with a coloured flag above it plus two coloured flags on the other leg. The flags a like plastic rings but they stick out a bit making it slightly easier to see the colour. When a bird lands on a nest your job is to record these rings in the correct order (red over blue, black over metal for example). In this way individual birds can be identified and we can learn how often the birds breed and with whom.
- 10.12am: Success! One of the birds sitting on nest 42 lands next to the nest (just a scrape in the sand) and stands there long enough for you to focus the telescope and read its flags. It moves over to the nest and the sitting bird takes off. Your bird moves onto the nest and settles down onto the eggs. You record the colours on your worksheet.
- 11.30am: A dog appears inside the outer 'fence' (which is a loose structure). You quickly shoo the dog out again and speak firmly but politely with the owner who is strolling along the beach. You ask them to put the dog on a lead and point out that the area has been laced with 1080 poison to kill foxes but that it also would kill a dog. You are met with indifference.
- 1pm: Nest 38 on your left has one chick being brooded by one parent. The other parent flies in with a tiny fish in its bill. The day-old chick's head appears from under the sitting bird and grabs at the fish. Although small, the fish appears to be a monster meal for the chick but it swallows it.
- 2pm: Other chicks are located just outside the electric fence in the low vegetation. They only stayed in the nest for a day and then started walking to find protection in the plants. The parents follow a regular feeding pattern. They fly in and, facing into the wind, almost hover over the same patch of vegetation calling to their chicks. Once spotted, the parent lands, feeds the chick and then takes off all in a matter of seconds. The chicks remain hidden until the next parent arrives.
- 3pm: A few people turn up at the outer fence. You go over and have a good old yarn to them about the birds. They are genuinely interested in the birds and are appreciative of your efforts and the work of the NPWS.
- 5pm: You've ascertained the leg colours of 5 more breeding birds meaning that now, combined with the efforts of other volunteers, more than 90% of the breeding birds have been identified.
- 6pm: You assist a bander set up a trap on nest 57 because both adult birds are unbanded. Inside the electrified area you lie motionless on the sand and wait for the birds to return to their eggs. With the bird captured you record the bird's number and leg flag pattern.