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The following photos are of Black Saw-wing Psalidoprocne pristoptera - a species with as many as twelve races depending on the authority consulted. They were trapped and banded at the huge swallow roost in Ebbaken-Boje in eastern Nigeria where perhaps two taxa are regularly occurring: the widespread West African petiti, a brownish-bronze glossed form with very white underwing feathers (sometimes separated as the nominate form of Petit's Saw-wing Psalidoprocne petiti petiti), and the relatively poorly-known chalybea, a much more restricted greenish-glossed swallow with greyer underwings (sometimes treated as a form of Petit's Saw-wing P. p. chalybea).
To confuse matters other swallows found in the roost include Fanti Saw-wing Psalidoprocne obscura (an all-black green-glossed swallow with a deeply-forked tail with very long outer-tail feathers), and Mountain Saw-wing P. fuliginosa (a small drab swallow with matt-brown plumage and a shorter tail than Black saw-wing).
Figure 1: Black Saw-wing Psalidoprocne pristoptera petiti, January 2001
Figure 2: Black Saw-wing Psalidoprocne pristoptera petiti, January 2001
Figure 3: Black Saw-wing Psalidoprocne pristoptera petiti, February 2005
Figure 4: Black Saw-wing Psalidoprocne pristoptera petiti, February 2005
Figure 5: Black Saw-wing Psalidoprocne pristoptera chalybea?, February 2005
Figure 6: Black Saw-wing Psalidoprocne pristoptera chalybea?, February 2005
Figure 7: Black Saw-wing Psalidoprocne pristoptera chalybea?, February 2005
Figure 8: Black Saw-wing Psalidoprocne pristoptera chalybea?, February 2005
In a mail to Nik Borrow, Pierfrancesco Micheloni (the Italian bander/researcher working to protect the Ebbaken swallow roost) wrote:
"In January-February 2005, I caught many 'black swallows' in Ebbaken-Boje in Nigeria. I think that many of them are Black Saw-wing Psalidoprocne pristoptera petiti, but we also netted birds with the following characters:
- Black swallows with clear gloss green upperparts,
- both adult and young having grey and not white (= petiti) underwing cover feathers,
- and with the tail and tail-fork and tail like Mountain Saw-wing Psalidoprocne fuliginosa.
These birds have the following biometrics:
- wing: 92-102,5 (99,0)
- outer tail feathers:80-84 (82)
- fork: 41-46 (42)
- weight: 9,9-12,9 (10,2)
Could it be possible that in this area we are finding both P. p. petiti and P. p. chalybea or perhaps hybrids of these two forms?"
Nik replied as follows:
"Your swallows are interesting because the range of chalybea remains a real mystery. The type specimen came from Victoria (Limbe) Cameroon but the common saw-wing there (& throughout Cameroon I think) is petiti. In fact I have never confidently identified chalybea in Cameroon. Your photos show a great difference in underwing but the tail of the bird with the greyer underwing looks square not forked: chalybea should have a deeply forked tail.
Birds of Africa give measurements as follows:
Fork of the tail:
- petiti: 25-35
- chalybea: 38-54
- Pierfrancesco: 41-46
Outer tail:
- petiti: 70-82
- chalybea: 85-94
- Pierfrancesco: 80-84
Your birds therefore fall firmly within the measurements for chalybea with the fork but more or less within petiti for the outer tail feathers!
All very strange but if the plumage was glossed an oily green then I would say that you have chalybea as petiti is always brownish bronze to my eye & never green.
Because the type of chalybea came from Limbe it may be possible that chalybea performs some west - east migration.
If your birds were chalybea then it looks like this is a range extension. I'll be very interested in your conclusions."
Pierfrancesco also recieved the following email (Aug 04 2006) from hirundine expert Dr Angela Turner, which she has kindly given permission to reprint here:
"Judging by the size, the green gloss and the grey underwing coverts, the bird is chalybea, although if so, that would be an interesting range extension.
Outside the breeding season, I don't think tail length is always a good guide, because young birds and moulting birds may all have short outer tail feathers. In addition, relatively few saw-wings have been measured, so the possible range of tail length and moult patterns aren't very well known. I wouldn't put as much weight on that feature as on plumage colour."
Additionally Pierfrancesco and I are very grateful to Dr Chris Bell for sending images of a 'bog-standard' P.p.petiti for comparison with the birds shown above. This swallow was caught at Obudu Plateau in April 2006, about 50km north-east of Ebakken. It shows the typical whitish underwing coverts but dark flight feathers of petiti, and the tail appears to be about 70mm, with a fork of 25-30mm. As Chris says, the bird doesn't show much gloss but does show a bit of a brown/bronzy wash.
Figure 9: Black Saw-wing Psalidoprocne pristoptera petiti, April 2006
Figure 10: Black Saw-wing Psalidoprocne pristoptera petiti, April 2006
Figure 11: Black Saw-wing Psalidoprocne pristoptera petiti, April 2006
Figure 12: Black Saw-wing Psalidoprocne pristoptera petiti, April 2006
Figure 13: Black Saw-wing Psalidoprocne pristoptera petiti, April 2006
As a final question, is the small 'square-tailed' swallow in the image below (also photographed at the Ebbaken roost) a Square-tailed Saw-wing Psalidoprocne nitens (and if so why is it showing greyish underwings?) or a small Black Saw-wing in moult?
Figure 14, December 2000
Figures 1 - 8, 14 copyright Pierfrancesco Micheloni. Figures 9 - 13 copyright Dr Chris Bell
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