Mystery Bird: African Grey Hornbill, Tockus nasutus

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[Mystery bird] African Grey Hornbill, Tockus nasutus, photographed catching a dragonfly at the Pangani River Camp, Tanzania, Africa. [I will identify this bird for you in 48 hours]

Image: Dan Logen, January 2010 [larger view].

Nikon D300s, 600 mm lens, ISO 640, 1/2500 sec, f/5 0 exposure compensation.

Please name at least one field mark that supports your identification.

The photographer writes:

There seemed to be quite a lot of interest in the African Grey Hornbill's bill. Since it was partially obscured by shadow and wing, l thought I would send another image. You may post if you would like.

The main image shows the bird just after landing, with some dragonfly wing hanging in its bill. The inset shows the bill a little better. All images are of the same individual.

[Mystery bird] African Grey Hornbill, Tockus nasutus, photographed catching a dragonfly at the Pangani River Camp, Tanzania, Africa.

Image: Dan Logen, January 2010 [larger view].

Nikon D300s, 600 mm lens, ISO 640, 1/2500 sec, f/5 0 exposure compensation.

Review all mystery birds to date.

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The large bill without a trace of color: I'd say Grey Hornbill.
But there seems to be too much white in the tail.

Hello Jan, the tail is OK for your ID of African Grey Hornbill. Is this the most widespread Hornbill in Africa?

I agree with Jan's diagnosis (although the tail doesn't bother me). It looks like you can see a pale base on the lower mandible, suggesting a young bird.

It's surely an African Grey Hornbill. My clue is the sawtooth like inner edge on the beak.

I wonder what is meant by "widespread", range or how many countries it may be found in?

With regard to total countries, the African Grey is recorded as native to 39 countries, and a vagrant in an additional one...

by comparison, the Red-billed has a range estimate of 10,900,000 km2 (native to 31 countries and vagrant in an additional 2); then the Southern Ground with a range estimate fo 8,670,000 km2 (native to 16 countries); the African Pied with a range estimated at 5,530,000 km2 (native to 21, vagrant in 1); and the Trumpeter rounds out the top five with a range estimated at 4,070,000 km2 (native to 13 countries)

the smallest range is recorded for the Black-and-white Casqued Hornbill at 964,000 km2 but is recorded as native to 21 countries, whereas the Von der Drecken's is only recorded in 4 countries but has a range estimated at 1,150,000 km2

By David Hilmy (not verified) on 12 Mar 2010 #permalink

Nish -- is that saw-tooth edge specific to Gray Hornbill, or is it found in other hornbills?

Carel,

"It looks like you can see a pale base on the lower mandible, suggesting a young bird"

my Sasol Birds of Southern Africa describes the male of this species as "the only small hornbill with a dark bill, with a creamy stripe at the base" whereas the female has the upper part of the bill pale yellow and the tip maroon"... immature hornbills "resemble the male without a casque but with the same bill color"

By David Hilmy (not verified) on 12 Mar 2010 #permalink

Thanks for that David, I meant the largest range ( a more scientific definition). "widespread" comes from reading too many guide books which use this rather loose term.
As an example of convergent evolution don't the Neotropical Toucans have the same serrations for dealing with fruit? I seem to recall the Aracaris have this feature.

David, although young hornbills in general resemble adult males rather than females (I believe they are unique among birds in this respect), the juvenile Grays I've seen had bills rather different from either adult parent: without bold color or markings, but with a pale base.
Regarding distribution, variety of habitat could also serve as the metric for deciding "most widespread." Either way, I'd award the prize to T. nausutus. The Yellow-bill ventures but slightly into more arid habitat, where the Gray seems to extend its range into much heavier forests.
Another interesting point of toucan-hornbill convergence: the Malay word for hornbill is "Tucan." I've looked hard for a possible route for introduction of the word from the Tupis to the Malays or vice versa and come up empty-handed.

Thanks Carel,

I'm not quite sure what distinction you are making between juveniles and males- the adult male should be showing a light cream stripe towards the base of the bill and along the upper mandible but having super-enlarged this photo, I'm not sure I see the base of the bill anyway- it appears that the "elbow" of the wing covers that precise spot and that the bird's head is not "square" to the camera but slightly inclined away which allows the light to reflect slightly off the upper mandible and masks almost all of the casque- if you follow the top edge of the upper mandible towards the bird's head I think I can just make out the edge of a casque...

by the way, the range estimate for the Eastern Yellow-billed is slightly over 1,000,000 km2 (covering 9 countries) and after the Von der Drecken's, is actually the next smallest range out of the 11 species of hornbill recorded for Tanzania...

the possible linguistic "convergence" is interesting and I'd like to research that a little further, so please drop a comment when/if you find something more- funnily enough, one of the strangest things I experienced when I was in Belize (I did the independence thing in '81 with the British military) was the virtually identical facial structure and physiognomy between the Gurkhas I had attached to my platoon and the local Mayans...

By David Hilmy (not verified) on 12 Mar 2010 #permalink

I did come across a fascinating story about how the Helmeted Hornbill, Rhinoplax vigil, came to get it's Malay name of tebang mentua which means "kill your mother-in-law bird"!

"This name arose because of its strange call, consisting of a loud toks repeated increasingly faster and ending in wild laughter, which gave rise to an old legend. They say that the Helmeted Hornbill was once a Malayan who cordially disliked his mother-in-law, and finally chopped down the stilts that supported her hut when she was inside it, in order to get rid of her. As punishment for this misdeed the gods then changed him into this bird, and condemned him forever to re-live his crime by making the sound of the axe striking the foundation posts, followed by his outburst of unholy glee when the house came crashing down."

from: Cammann, S.V.R. 1950. The story of hornbill ivory. University Museum [University of Pennsylvania] Publication. 15:19-47.

By David Hilmy (not verified) on 12 Mar 2010 #permalink

Oops. Meant to say "Red-billed."
I remember reading that colorful story about Rhinoplax.
It's hard to say for sure, but it appears to me that you can see the dark corner of the bird's open gape right below its wrist, with a pale mandible base below that. There's a primary or something hanging down at a funny angle from the forward bend of the wing. I agree that you can see the point of the casque, but it's just a low one like you'd see on a youngster or a hen. I've never seen a young Gray Hornbill that showed the adult male's light stripe on the upper bill or the thin bars on the lower. Their bills are uniform gray with a lighter, buffy base. I've also never seen these birds in the south, only along the Sahel/forest belt transition zone. Perhaps there's a geographic difference.

You know, David, looking at that picture again, I think you're right. I think that "mandible base" I was looking at is the bird's wrist with the alula peeking out in front.
I still insist it's a youngster, though. An adult hen would show a rusty tip to the bill and an adult male's casque would be higher.

Carel,

Let's not forget that the bill on this bird seems to be slightly tilted away from the camera and not "square" to our view, but more importantly, the casque on this species is variable and very often relatively small with little projection- how much of this is due to geography or subspecies differences is not clear in the literature, however I have found a couple of probable nasutus ssp. and a couple of epirhinus ssp. that all demonstrate a relative smallness with this structure:

African Grey Hornbill (ssp. nasutus), Gambia

African Grey Hornbill (ssp. nasutus), Maritania

African Grey Hornbill (ssp. epirhinus), Tanzania

African Grey Hornbill (ssp. epirhinus), Kenya

By David Hilmy (not verified) on 13 Mar 2010 #permalink

I beg to differ Carel- if you enlarge this photo you'll see that the top edge of the upper mandible bisects the ridge on top so it therefore must be distal to the bill and therefore a part of the casque- if it was the tip of the alula, we would not see an unbroken top edge to the bill

close-up of male African Grey Hornbill beak

By David Hilmy (not verified) on 13 Mar 2010 #permalink

I really enjoy the picture. I like the color and the bird itself.