The NSS Bird Group went on another pelagic survey in the early morning of 26 April 2015. Our route was almost the same as in previous survey, along the Singapore Strait.
Quite a number of birds and bird species showed up compared to the previous trip.
The first significant sighting was a lone Swinhoe’s Storm Petrel which showed up early crossing the strait from west to east, just after 7am.
Next we reached the familiar yellow buoy. This time around we saw around 30 resting Lesser Crested Terns, some in breeding plumage.
We saw our first Aleutian Tern around 8:30am flying from west to east, not far after the yellow buoy. This was the first of three Aleutian Terns seen in this trip.
Things quietened down substantially and it was not until 9:50am that we saw another bird, this time a Greater Crested Tern (Swift Tern)
It took another hour before the next highlight of the trip. A flock of 36 White-winged Terns were feeding next to anchored ships, among them a few breeding plumaged birds with black heads and underparts were seen. There was a flurry of activity and we managed to see them picking up jellyfish on more than one occasion (see Gallery at the end of the article). We also noticed another Aleutian Tern flying by around the same area.
Our most exciting moment however happened when a tiny speck of a far away bird was spotted by Colin Poole. Even from a great distance, it appeared big. So the boat gave chase and as it drew closer we recognised it as a frigatebird. It turns out to be a juvenile frigatebird that is either a Christmas Island Frigatebbird or a Lesser Frigatebird. As the juvenile plumage is hard to identify conclusively, we will hand over the finding to the Records Committee to deliberate. (See Update at the bottom of the article)
After the excitement, the return journey was relatively quiet. Activity picked up after we saw another Aleutian Tern at around 1:40pm followed quickly by a Bridled Tern and another rarity, an adult Parasitic Jaeger (Arctic Skua) trailed by a Swinhoe’s Storm Petrel and lastly, another Bridled Tern. They were all travelling from west to east.
All in all it was a fruitful trip. Our final count include:
White-winged Tern (36)
Lesser Crested Tern (35)
Greater Crested Tern (1)
Aleutian Tern (3)
Bridled Tern (2)
Little Tern (2)
Swinhoe’s Storm Petrel (2)
Frigatebird spp (1)
Parasitic Jaeger (1)
Grey Heron (3)
Swiftlets spp (10)
Update from David James, an expert on frigatebirds (1 May 2015)
Your initial diagnosis is correct, Lesser Frigatebird.
Firstly, the proportions are wrong for CI Frigatebird, the bill, neck and tail are not long enough and the base of the wing is does not broaden obviously close to the body.
The belly patch is too small, with black already reaching the base of the legs. It shows what I described in my 2014 article as a triangular belly patch with the the front corners stretched out as axillary spurs. That description can be problematic as the ‘triangle’ shape appears to vary depending on the viewing angle. In Francis’s FY7D382 it looks nothing like a triangle, but in Con’s shot with the bird preening ‘triangle’ is a good description. The belly of frigatebirds is a complex 3 dimensional surface, not usually noticed in other birds. The spurs are also a bit too short and narrow for a juvenile CIF.