A 10 day private trip to Ashmore Reef in January, 10 days of pure birdwatching. The journey from Darwin to Ashmore turned out to be a bit slow on the bird front. A few Crested Terns were seen loafing on floating bits of timber and several Brown Boobies were perched on navigator markers in Darwin harbour, then to my great excitement four Irrawaddi Dolphins (Orcaella brevirostris) bobbed past the bow – unexpected to say the least.
A few Lesser Frigatebirds and mixed flocks of Common and White-winged Black Terns were concentrating on baitfish, several Streaked Shearwaters seen later that afternoon. More cetacean excitement with a pod of 6 False Killer Whales followed shortly afterwards by several large pods of Tropical Spinner Dolphins (Stenella longirostris). At first light the following day I saw the first Sooty Terns of the trip quickly followed by 4 Pantropical Spotted Dolphins (Stenella attenuate). After a rushed breakfast – I didn’t want to miss any action – more Sooty Terns were seen and a Green Sea Turtle (Chilonias midas). By mid morning Common Noddies were mixed with Sooty Terns and excitement reached new levels with a superb view of one Tahiti Petrel. The extraordinary sight of two lemon migrant butterflies Catopsilia pomona pomona, which were living up to their name, this species was also recorded on Ashmore later on the trip. On the approach to Ashmore large numbers of birds were seen at sea, Lesser Frigatebirds, Sooty Terns, Common Noddies, Black Noddies and Great Frigatebird.
After our arrival I investigated West Island, hot conditions seemed to slow the bird activity down. However a nice selection of species were found but unfortunately no vagrants. Birds recorded on West Island included Eastern Reef Egrets, with white morphs easily outnumbering grey birds. Other birds of the same genus included Little Egrets and 1 Great Egret. Red-tailed and White-tailed Tropicbirds were both breeding. Nine Oriental Cuckoos, a Sacred Kingfisher, a pair of Magpie Larks and several Buff Banded Rails were the only land birds seen. The Rails were splashing in saltwater pools on the foreshore. A Crested Tern was observed picking up a Green Sea Turtle hatchling from the surface of the ocean, the Tern dropped the poor helpless hatchling twice back into the water before finally flying off with it calling madly as it was joined by another Crested Tern. West Island usually has a good selection of waders, a large herb field in the island’s centre often attracts loafing waders. They feed on insects found amongst the low mat of grasses and prostrate weeds. Whimbrels are common on the island and often use the shade of Octopus bushes that form the shrubby fringe around the island. Wader species found as single birds on West Island included Lesser Sandplover, Eastern Curlew, Sharptailed Sandpiper and Oriental Pratincole. Ruddy Turnstones, Greater Sandplover, Pacific Golden Plover, Grey-tailed Tattlers, Common Sandpiper, Sanderling, Greenshank and Red-necked Stints were all common.
Middle Island was heaving with birdlife with an estimated 7,500 pairs of breeding Sooty Terns protecting what appeared to be newly laid eggs. Large loafing flocks of Sooty Terns and Common Noddies camped on wet sand calling continuously, the cacophony was almost deafening. A constant stream of terns flying to and from the island, these incubating birds soaking their belly & breast feathers with seawater, by flying low, skimming the surface of the water, almost stalling before flying off again. These birds then returned to their eggs to moisten and cool them down.
Both Red-footed Boobies and Great Frigatebirds were breeding and sitting on eggs. Hundreds of Lesser Frigatebirds were also present on the island some of which were sitting on newly completed nests but none were seen with eggs. Several hundred Brown Boobies were also preparing to breed, their nests placed on the ground, unlike the Red-footed Boobies preference for bushes or shrubs. Common Noddies and Black Noddies were loafing on the sandy beaches as the tide crept up with numbers getting up into the high hundreds – what an impressive sight. Black Noddies are always less numerous but easier to pick out by their smaller size, long thin bill and their darker plumage. Several Masked Boobies were hanging about to complete the trifecta, their behaviour indicating a readiness to breed.
Migratory waders congregated around East Island in large numbers when compared with West or Middle Island. The muddy sand flats here must be rich in food. It was interesting to note the mix of species with Sanderling, Great Knot and Curlew Sandpiper feeding together in substantial numbers, in my experience this is an odd combination.
East Island also has an impressive number of seabirds, for starters, an estimated 10,000 pairs of breeding Sooty Terns, a smaller colony of Crested Terns and a pair of courting Masked Boobies. Evidence of a previous breeding cycle of Common Noddies was apparent by numerous desiccated fully fledged juveniles. What caused this partial failure in their breeding is unknown. Several thousand Common Noddies and well over 100 Black Noddies were present loafing on the shoreline and sand flats with huge numbers of Sooty Terns.
Two sandbars were investigated during the high tide, one situated several kilometres south of East Island the other positioned mid way between Middle and East Island. Over 10,000 migratory waders were counted including significant numbers of Grey Plover (600), Pacific Golden Plover (300), Greater Sandplover (1,200), Sanderling (320), Great Knots (1,600), Bar-tailed Godwit (2,500), Grey-tailed Tattler (1,300), Whimbrel (350) and Ruddy Turnstone (800). Half a dozen Asiatic Dowitchers and Black-tailed Godwits were also seen. Several of these species were seen in Internationally significant numbers. Ashmore Reef really is a fascinating birding location.