Some birds cannot be identified?

Some birds in Singapore are difficult to identify. Some other birds might actually be impossible to identify in the field here??

By Sin Yong Chee Keita Groups of birds like sparrowhawks and flycatchers are known to be notoriously difficult to identify. These birds, however, can usually be distinguished in the field by referring to the multitude of identification features. Our team has previously prepared various references for raptors, flycatchers, pipits, and more flycatchers. There are other species pairs that are even tougher, and these include the Common vs Pacific Swift, Northern vs Brown Boobook, Blyth’s vs Amur Paradise Flycatcher, Red-necked vs Little Stint, and Javan vs Kentish Plover among others. The two Swifts often fly very high up in the sky, making it difficult to see their diagnostic features. The Common Swift additionally is extremely rare in Singapore (with only three records), so most birds are generally assumed to be Pacific Swifts unless proven otherwise. The two Boobooks can be told apart via their underparts, or more reliably by their call. The Northern Boobook, though, is rarely heard in Singapore and there is only one known recording of them calling here. The two Paradise Flycatchers are actually not too difficult to identify with decent looks in the field, but identifying them from photographs is a much tougher task as lighting and angles can heavily affect their colours and contrasts. The two stints and plovers present a slightly different problem, in that the Stints are generally too far away in Singapore that their key identification features cannot be seen. Most birds are assumed to be Red-necked based on their abundance and the Little Stint only has two confirmed records. The Javan Plover, with only one accepted record, is best identified in their breeding plumage, unless multiple excellent photographs with different angles and comparisons are available. Yet having said that, these groups of birds can still mostly be identified. There is an even more exciting group of birds that, at least based on current knowledge, simply cannot be conclusively identified in the field in Singapore. Edible-nest Swiftlet and Black-nest Swiftlet Two species of Aerodramus swiftlets are on the Singapore checklist right now, the Edible-nest Swiftlet and Black-nest Swiftlet. These two birds differ in measurements, with the former being smaller than the latter, and those with experience handling the birds can make educated guesses of the birds flying around in the field. The main problem is that these identifications can never be confirmed unless either the birds are caught or are seen flying on their nests – the Edible-nest Swiftlet has a bare, white nest made from saliva, while the Black-nest Swiftlet has their nests black due to the feathers they add. Additionally, the Himalayan Swiftlet is suspected to be in Singapore by some (with some controversy), but as of now there are no confirmed records. We have indeed seen birds that seem to be different from the residents we are familiar with, but until a properly validated record is available, likely through an unfortunate crash victim if anything, this species will not be added to the Singapore checklist. Unidentifiable Aerodramus Swiftlet Edible-nest Swiftlet and a Black-nest Swiftlet colony in Singapore. Photo credits: Keita Sin Himalayan Cuckoo vs Oriental Cuckoo These cuckoos were treated as the same species until they were split based on their songs. They cannot be distinguished in the field purely by sight. Their measurements differ enough that they can be identified when caught, however, such size differences cannot be accurately discerned in the field, and other field marks are also extremely similar. Of this species pair, the Himalayan Cuckoo is the only one included in the Singapore Bird Checklist, but the reality is a little more complicated than that. The admission of the Himalayan Cuckoo in Singapore is only based on two confirmed records of this species that were mist-netted back in 1995. However, based on numerous records of birds that were historically collected in the region, we know that the Oriental Cuckoo is a species that can well occur in Singapore based on their distribution range. The songs of this rare species pair (that actually seem to exhibit some clinality…), is unlikely to be heard in Singapore since they are winter visitors. A Himalayan/Oriental Cuckoo in Singapore Pin-tailed Snipe and Swinhoe’s Snipe This species pair can only be conclusively identified in the field by their outer tail feathers. The Pin-tailed Snipe has thin, pin-like tail feathers, while the Swinhoe’s Snipe has thicker ones (in-hand photos here). These outer tail feathers are usually only seen when the birds are preening or when landing from a flight. Several morphological features have been discussed by our friends Ayuwat and Dave from Thailand and Malaysia respectively, where these snipes are typically easier to observe than in Singapore. Separately, call behaviour has been suspected to be useful, but again seems not to be diagnostic. The two species have distinctly different...