ML143326511

Age

Not specified

Sex

Not specified

Observation details

I photographed an adult at Tobishima on Oct 2 that we later identified as this species. Identifying silent cuckoos, even adults such as this bird, can be difficult if not impossible. Field marks consist of average differences that are slight with much overlap – there seems to be no clincher besides vocalizations. In Europe where the Oriental Cuckoo (C. optatus) is a vagrant, except for far eastern Europe, the key marks separating it from Common Cuckoo are 1) its smaller overall size, 2) slightly heavier bill, and 3) usually rusty-buff vent that is almost unmarked (Mullarney et al. 2009). Other marks include the “shade” darker gray upperparts of Oriental Cuckoo, but the dark barring on belly is basically the same as shown by Common Cuckoo (Mullarney et al. 2009). Another European guide, however, states that the barring is always quite wide on Oriental Cuckoos and, as a result, is more conspicuous than on many Common Cuckoos, though there is some overlap between the two species (Beaman and Madge 1998). This guide also describes the Oriental Cuckoo as darker gray without the contrast between rump and black tail that is typically shown by the Common Cuckoo. Of interest, since the photo above shows this, is the tendency of Common Cuckoo to hold the wings and tail “limply” unlike Oriental Cuckoo (Beaman and Madge 1998). Brazil (2009) states that many Oriental Cuckoos have yellowish-buff undertail coverts, but stresses the differences in underwing pattern: Oriental Cuckoo shows bold white barring on inner primaries and outer secondaries with barred underwing coverts vs. Common Cuckoo that shows a rather uniform underwing panel that appears much whiter than the Oriental Cuckoo; Common Cuckoo has a less contrasting and shorter central wingstripe that only reaches to primaries 5 or 6. Shimba (2007) says that the Oriental Cuckoo is darker and has wider barring on belly. The new “Cuckoos of the World” (ErritzØe et al. 2012) states that these two species are easily confused, but that the Oriental Cuckoo has a 1) wider tail (up to 1/3 wider) with fewer black bars, 2) lack of barring on white leading edge of wings, 3) much darker underwings with fewer white bars and spots, 4) bill stouter, deeper and tip sharply curved on adult males, and 5) wider barring on underparts, including the undertail-coverts (little or no barring in Common Cuckoo). Under the “similar species” section of the Common Cuckoo account, it simply states that the Oriental Cuckoo always has buffish undertail coverts barred dark brown (rare in Common Cuckoo, and with little or no barring) and the underwing stripe is wide and conspicuous across underside of dark and nearly unspotted secondaries (ErritzØe et al. 2012).

Technical information

Model

Canon PowerShot ELPH 500 HS

ISO

1600

Focal length

18.8 mm

Flash

Flash did not fire, auto

f-stop

f/5.8

Shutter speed

1/320 sec

Dimensions

1654 pixels x 1241 pixels

Original file size

581.23 KB