To the Sahara in quest of dinosaurs (living and extinct)

Several weeks ago, I and a group of colleagues from the University of Portsmouth (Dave Martill, Robert Loveridge and Richard Hing) set off on a trip to the Cretaceous exposures of Morocco. We were to be joined by Nizar Ibrahim from University College Dublin - our team leader - and by Samir Zouhri and Lahssen Baidder from the University of Casablanca. Our primary aim was to discover Cretaceous dinosaurs, pterosaurs and other fossil reptiles, but we were also interested in studying the region's geology, and to learn about the sedimentology, palaeoenvironment and taphonomic setting of the rocks that yielded the animals, particularly those of the famous Kem Kem Formation, source of Deltadromeus and Carcharodontosaurus. Morocco is an amazing country, and we experienced most of its extremes, from deep snow and blizzards in the Atlas Mountains to the aridity, heat and immense sand dunes of the Sahara. We experienced a day of sandstorms, crossed several rivers in flood, and saw the desert come to life after rain. The nights were usually clear and cold. Everywhere we went we were treated to the tremendous hospitality of the Moroccan people, whether they lived in the big, bustling cities likes Marrakesh or Casablanca, or in the small, rural villages in the south.

For me (and for some other members of the team, particularly Richard), this was also the chance to see a lot of amazing African wildlife for the first time. I'm pleased to report that we had the most extraordinary luck, eventually seeing most (though not all) of the creatures I hoped we might. If you're reading this article (and those that will follow) in the hope of hearing loads of stuff about rebbachisaurs, noasaurs and carcharodontosaurs, you're going to be somewhat disappointed I'm afraid. If you like passerines and waders however: woo-hoo, jackpot! Unless stated otherwise, the photos were taken by Bob - thanks Bob...

Distracted by Cyanopica

Before getting to Morocco, we drove through France and Spain. In Spain we stopped to watch Griffon vultures Gyps fulvus and Spotless starlings Sturnus unicolor and we also drove through areas where Azure-winged magpies were abundant. I cannot help but get a feeling of disbelief and wonder where a creature that I've always regarded as exotic and almost semi-mythical is suddenly commonplace and easy to see. Cyanopica is a very cool bird. Its disjunct distribution (Iberian Peninsula and eastern Asia, and nowhere in between) once resulted in the idea that it had been introduced to Iberia by Spanish or Portugese sailors during the 16th century, but genetic data and fossils (from Gibraltar) have shown that its modern distribution is relictual and that the populations have been separated for over a million years (Cooper & Voous 1999, Cooper 2000, Fok et al. 2002) [image below from wikipedia].

In fact morphological and genetic data indicate that the Iberian and Asian groups can be treated as distinct species: C. cyanus Pallas, 1776 is the Asian one and the Iberian one has to be called C. cooki Bonaparte, 1850 (Fok et al. 2002, Kryukov et al. 2004). In Asia, there are indications that Azure-winged magpies are able to quickly expand their range and to colonise new areas when conditions are right: this provides indirect support for the hypothesis that, during the Pleistocene at least, they were clearly so adaptable and mobile that they were able to colonise the entire breadth of Eurasia. But if this is so, why hasn't the European population gotten out of Iberia? Humans may be the answer: because Spanish farmers regard it as an agricultural pest, it has suffered from a long history of persecution (there is a tradition of destroying its nests), and this may have prevented eastwards expansion (Kryukov et al. 2004). Incidentally, the position of Cyanopica within Corvidae is kind of controversial: Ericson et al. (2005) found it to group weakly with the Perisoreus jays and to be near the base of a major clade that includes Old World 'core corvids' and New World jays. That rules out any close relationship with magpies proper, and also with the Asian magpies and treepies.

Anyway, back to the trip... after crossing the Strait of Gibraltar and staying overnight in Ceuta (a Spanish city located in north Africa) we were in Morocco proper, and almost immediately were treated to excellent views of White storks Ciconia ciconia and Cattle egrets Bubulcus ibis [shown here, image © Bob Loveridge]. I counted over 40 storks at a rubbish dump. Egrets were also hanging out at the dumps, as well as in any field with livestock. Little egrets Egretta garzetta were commonplace too, and it was easy to distinguish them from the far stockier, paler-billed Cattle egrets (or, it was for me anyway). Here in England, Little egrets are now common birds that don't deserve a second glance: they first bred here in 1996 (at Brownsea Island, Dorset) and in a 2003 survey more than 400 birds were counted at a single site (this was in Essex). Cattle egrets now seem to be doing the same thing. A load came over to southern England in 2007, and in 2008 they were reported breeding here for the first time (this was in Somerset). The Cattle egret is already probably the world's most widely distributed bird, having colonised all seven continents* from an African centre of origin.

* Yes, I said all seven: the Antarctic records are from the South Orkney, South Shetland and Argentine islands. White storks at a rubbish dump shown below [image © Bob Loveridge].

Also abundant and easy to spot were members of the highly distinctive African magpie subspecies Pica pica mauretanica. Its blue eye-ring is not really obvious at any distance, but it also differs from other Old World magpies in having less white on the wing and a tail that isn't iridescent green. Indeed it's distinct enough from other Old World magpies for some people to suggest that it should be regarded as a proper species, the so-called Maghreb magpie P. mauritanica.

Gulls, terns and waders

With a bit of time to kill - and keen to experience some of the region's wildlife - Dave, Bob, Richard and I visited one of the wetland regions in the north-east of the country (I failed to record the name of the exact place we visited: it was possibly Lac de Sidi Bourhaba). A local guide took us out on his boat and knew exactly where to take us to see all the local specialities: his identifications were generally excellent but sometimes off. Anyway, it proved pretty incredible, with multiple new species for all of us. Among the first birds we looked at were the gulls. Among a mixed group of Lesser black-back Larus fuscus (or is it L. graellsii?) and Yellow-legged gull L. cachinnans (or is that L. michahellis?) were several Audouin's gull Ichthyaetus audouinii, one of the rarest gulls in the world: it's restricted entirely to the Mediterranean region [Audouin's gulls at front of image shown at top, © Bob Loveridge]. Once you know what to look for, this species is highly distinctive, with dark eyes and bill, grey-green legs and a more elegant look than white-headed gulls. Slender-billed gulls Chroicocephalus genei were also present, though at times quite difficult to distinguish from winter-plumaged Black-headed gull C. ridibundus [Black-headed gull shown at bottom of adjacent image, © Bob Loveridge]. Seeing Slender-billed gulls and Audouin's gull in the same place was interesting, as one of my childhood memories from bird books was the inference that Audouin's might be an evolutionary intermediate between the Slender-billed gull and white-headed gulls like the Herring gull. Alas, this never stood the test of time, and the two are about as far apart as they could possibly be in modern phylogenies (Pons et al. 2005). Black-headed and Mediterranean gull C. melanocephalus stood obligingly together.

Caspian terns Hydroprogne caspia flew overhead [one is shown in the second image down in adjacent composite, © Bob Loveridge] and Sandwich terns Thalasseus sandvicensis [shown in third image down, © Bob Loveridge] were present on a sandbar (the taxonomy I've used for terns follows that suggested by Bridge et al. (2005)). We then moved on to the mudflats where Grey plovers Pluvialis squatarola, Ruddy turnstones Arenaria interpres and Ringed plovers Charadrius hiaticula were fairly abundant. This region is apparently the only place in the western Palaearctic where sightings of the extremely rare Slender-billed curlew Numenius tenuirostris can be essentially guaranteed, but we didn't have time to look around the whole area and didn't get to see any. One book on bird-watching in Morocco states that local guides often point to long-billed waders and identify them as Slender-billed curlews when they are in fact something else. Indeed our own guide did exactly this, claiming that what was clearly a Bar-tailed godwit Limosa lapponica was a curlew. I don't think this is deliberate deception as he didn't have the advantage of binoculars! We did see Greenshank Tringa nebularia [image below, © Bob Loveridge], Redshank T. totanus, Little stint Calidris minuta and Greater flamingo Phoenicopterus ruber. I discovered that I struggle to distinguish Kentish plover Charadrius alexandrinus from Ringed plover when the latter is in winter plumage. Marsh owls Asio capensis were also in the area but we didn't have time to see them. We would have encounters with other owls later on however.

After visiting Casablanca and meeting up with Nizar, we drove to Marrakesh. A weird sounding, noisy bird in a street tree turned out to be a Common bulbul Pycnonotus barbatus, the first I'd seen. Bulbuls (pycnonotids) are strange birds, at least if you're European and not from Africa or Asia. With robust bills and (usually) hair-like filo-plumes on the nape, they're short-winged frugivores of forests and scrublands. They seem to be sylvioid passeridans closely related to babblers and to a huge assortment of mostly warbler-like African passerines, though the long-tailed tits, bushtits and swallows are apparently part of the same major clade. Incidentally, bulbuls are able to eat large quantities of wax (Horne & Short 1990).

More next: Atlas birds and desert tetrapods...

Refs - -

Bridge, E. S., Jones, A. W. & Baker, A. J. 2005. A phylogenetic framework for the terns (Sternini) inferred from mtDNA sequences: implications for taxonomy and plumage evolution. Molecular Phylogenetics and Evolution 35,459-469.

Cooper, J. H. 2000. First fossil record of Azure-winged magpie Cyanopica cyanus in Europe. Ibis 142, 150-151.

- . & Voous, K. H. 1999. Iberian Azure-winged magpies come in from the cold. British Birds 92, 659-665.

Ericson, P. G. P., Jansén, A.-L., Johansson, U. S. & Ekman, J. 2005. Inter-generic relationships of the crows, jays, magpies and related groups (Aves: Corvidae) based on nucleotide sequence data. Journal of Avian Biology 36, 222-234.

Fok, K. W., Wade, C. M. & Parkin, D. T. 2002. Inferring the phylogeny of disjunct populations of the azure-winged magpie Cyanopica cyanus from mitochondrial control region sequences. Proceedings of the Royal Society of London B 269, 1671-1679.

Horne, J. F. M. & Short, L. L. 1990. Wax-eating by African common bulbuls. Wilson Bulletin 102, 339-341.

Kryukov, A., Iwasa, M. A., Kakizawa, R., Suzuki, H., Pinsker, W. & Haring, E. 2004. Synchronic east-west divergence in azure-winged magpies (Cyanopica cyanus) and magpies (Pica pica). Journal of Zoological Systematics & Evolutionary Research 42, 342-351.

Pons, J.-M., Hassanin, A., & Crochet, P.-A. 2005. Phylogenetic relationships within the Laridae (Charadriiformes: Aves) inferred from mitochondrial markers. Molecular Phylogenetics and Evolution 37, 686-699.