A strange cuckoo has troubled our minds the last days on Helgoland. Could it be an Oriental Cuckoo, a species not yet recorded safely in Europe outside its Russian breeding grounds?
The Cuckoo in question (picture by Thorsten Stegmann). Note the dark upperparts, the tiny appearance and the barring on the underparts.
On May 25th, local warden Felix Timmermann checked in early morning ID features of birds for his forthcoming trip to the Ural mountains, including the voice of Oriental Cuckoo. Only an hour later, he heard a Hoopoe-like call. The call sounded like the introduction part of Oriental Cuckoo song, but the bird remained unseen. Felix informed me, but I had no time to check due to a breeding bird survey on the neighbouring dune island. The next morning, only a few hundred meters away, another Hoopoe-like call (three syllables) was heard, but again no sighting of the bird.
In the morning of May 27th, a “strange Cuckoo” was seen by several birders at the 2nd site. I became a bit excited and went to see the bird. When I saw it, I realized several features consistent with what I knew about the ID of Oriental Cuckoos, so I tried to take pictures, especially in flight. The bird then flew to the other side of the island and was relocated there and gave excellent views. A check of the literature suggested that we needed to trap the bird. In the evening we erected mistnets close to his favoured site, but although we played the female call, which is supposed to be good for trapping cuckoos, the bird was not seen again. Also next morning we tried to trap, but it seemed that the bird had finally taken of, with a lot of caterpillars in his belly.
Looking in the literature, it became evident that not a single feature is unique to Oriental Cuckoo (except the song), but a combination of the features pointed towards Oriental:
Size: The bird looked tiny and short-billed in the field
Upperparts: Rather dark for a Common Cuckoo; some retained tertials and secondaries indicate a 2nd-year bird.
Underparts: The belly-streaking was not as dense in Common Cuckoo. On the pictures we counted 7-8 complete black bars from belly to breast. The width of the black bars varied between postures, but certainly they can be more obvious in Oriental. The vent and undertail coverts produced a large, unbarred peachy-buffish patch. Only the longest undertail-coverts were more whitish with black bars.
Underwing: The bird showed a White’s Thrush like underwing pattern with a broad white stripe. The lesser underwing-coverts were unmarked and buffish. The primary barring was rather bold, but the exact number of white bars could not be counted, as the bases of the primaries are partially covered by the greater coverts.
As Common Cuckoo is quite rare on the island in spring, it seems unlikely that several birds were involved in the sightings. So, we face a Cuckoo which calls like an Oriental, looks at least to me like an Oriental – but is this enough for a 1st record for Europe outside the Russian breeding areas? The Finnish birds have not been accepted, as there were some features odd for Oriental, like a call of three syllables, wing length (see Lindholm & Linden 2003, Alula 4: 122-133). Also the Helgoland cuckoo uttered a call with three syllables. However, this might be just a disturbed introduction of the song.
Oriental Cuckoo has not been safely recorded in Europe outside the Russian breeding grounds. However, it certainly should be on the radar of European birders!
Any comments on the ID of the bird – good or bad news – are very welcome!
The Helgoland Cuckoo in flight from below. Note the obvious underwing panel, especially the unmarked lesser underwing-coverts. Note also the barring and the pattern of the undertail coverts.
Note the retained juvenile tertials and the pattern of the undertail coverts.