A week ago I went on a tetrapod-finding trip – with my good friends Mark North and Jon McGowan – to the Isle of Portland. Portland isn’t an island: it’s a promontory, sticking out from the south coast of Dorset into the English Channel. The plan with this post was to show off some of the neat photos that resulted, and perhaps accompany some of those photos with a little bit of text. As with previous attempts to produce ‘text-lite’ posts of this sort, I failed miserably…
What’s been happening at Tet Zoo lately I hear you ask? Besides that long-awaited British dinosaurs paper, I’ve had a few articles of mine appear on Mesozoic birds, pleurodires and lacertid lizards, and work on yet more British dinosaurs, stegosaurs and…. other stuff (nod to Dave Hone) sort of continues when my time isn’t being taken up by other things. The aetosaur ethics story continues to rumble on, with important and interesting contributions still coming in from many people. In blog news, I am pleased to announce that I’ve been awarded a ‘thinking blogger’ award, and have been tagged by Luca Fenu with the ‘Why do I blog?’ meme. Both of these events solicit a response, and I’ll produce those soon. Actually, I’d like to know how many people are interested in hearing me answer the question ‘Why do I blog?’. It always seems to me that things like this can be a bit self-indulgent. Please let me know.
As for Portland: if you can’t be bothered to read the long article I’ve penned here, feel free to scroll down and look only at the pictures (some of which were taken by Mark. Thanks Mark). First of all, given the photo that accompanied the teaser for this post, I have to explain that Veästa* is the sea monster that some people claim to have seen from Portland’s Chesil Beach (with the emphasis being on claim). Not exactly the most convincing marine cryptid I’ve learnt of.
Portland’s peninsular nature makes it a great place to see birds, and since 1961 it’s been home to the Portland Bird Observatory and Field Centre. They log all the birds that land on and pass Portland, and have accrued a ridiculously impressive list of vagrants and rarities. Within the grounds of the observatory is what is easily the best bookshop in the world, though going there when you haven’t got any money is not an enjoyable experience.
Regular readers might have noticed that I haven’t blogged on birds at all lately: this isn’t because I’ve suddenly stopped finding birds interesting; it’s because after analysing my subject coverage during 2006 (here) I found that birds were (in my opinion) unfairly over-represented, and I’ve therefore made a special effort to leave them alone for a while. Given recent news on the Large-billed reed warbler Acrocephalus orinus and Long-whiskered owlet Xenoglaux loweryi, the identification of a new crossbill in Idaho and a new frogmouth in the Solomon Islands, and news on the migratory habits of godwits, this has been particularly difficult. I’m going to stick at it a bit longer though.
Anyway, we didn’t see any particularly unusual or rare birds that day, in part because – bar a wryneck seen from the observatory – there weren’t really any there (though what might have been a Woodchat shrike Lanius senator had disappeared when we drove back to find it). Later on we spent time watching fulmars, shags, kestrels, rock pipits and wheatears. Both Jon and I thought that there was something not quite right about the male Wheatear Oenanthe oenanthe we spent time watching: the black on his ear coverts extended further back and further toward the throat than we were used to. There are in fact a few subspecies that possess pigmentation matching this, but we weren’t able to go further with the limited field guide I had to hand [adjacent image showing male wheatear is not one of our photos: from here].
Wheatears are one of those groups of passerines that are neither thrushes nor flycatchers, and are generally assumed to somehow be in-between these two groups. But given that many taxonomic systems classify both thrushes and flycatchers as ‘families’ (Turdidae and Muscicapidae respectively), where does that leave the wheatears and their relatives?
A recent supertree analysis of oscine passerines (Jønsson & Fjeldså 2006) concluded that wheatears were best supported as close relatives of anteater-chats (Myrmecocichla) and chats (Saxicola), and part of a larger clade that included rock thrushes (Monticola and Pseudocossyphus), redstarts and kin, and nightingales and kin. This chat-redstart-nightingale clade was found to be the sister-taxon to an African clade that included alethes, robin-chats, akalats and forest robins. The pied flycatchers and their relatives, and the Muscicapa flycatchers and their relatives, were more basal members of the same assemblage. True thrushes (including solitaires, bluebirds and ant-thrushes) were the sister-taxon to the entire chat-flycatcher clade. All of this means that wheatears and their friends and relatives belong in Muscicapidae, and it better reflects phylogeny to keep this clade separate from its sister-taxon, Turdidae. And, yes, I know that there are, like, another thousand studies on oscine phylogeny that I should be citing and discussing, but I don’t want to go too far off on a tangent. Incidentally, there are a ridiculous 15 wheatear species in the European field guide region.
Given that we spent a lot of time hanging around seaside cliffs, Jon wondered out loud why we hadn’t seen more of the several peregrine pairs that nest on the promontory. At exactly that point, a peregrine took off from the adjacent cliff edge, not more than 6 m from where we stood. Its flight style and posture showed that it was carrying something, and it was at that point that we noticed the white down feathers that were floating around us. They were drifting up from the region of cliff edge where the peregrine had just taken off from: it seemed that the kill had only just happened, and that we’d missed it entirely. This has happened to me before. On one recent occasion, a sparrowhawk flew off just as I (and the group I was with) entered a wood. When we got to where the hawk had been perched, we found a scattering of Great tit Parus major feathers. They were still warm to the touch so, again, the kill must have occurred just moments earlier.
With its rock piles, quarries, inland cliffs and crevasses and low scrubby vegetation, Portland is also excellent for lizards, and within minutes of arrival we’d seen two of the three species present there. The Viviparous or Common lizard Zootoca vivipara* is a northern specialist of temperate and even Arctic places, and it has a tremendously wide distribution, occurring from western Europe all the way east to the coast of the Pacific. It occurs throughout Britain, being most easily found in upland moors, heathland, cliff edges, sand dunes, and uncultivated field edges, roadsides, railway embankments and gardens. In gardens, they are heavily predated upon by domestic cats and, believe it or not, Blackbirds Turdus merula. They are variable in colour, usually have a brightly coloured underside, and are born black and – despite being born live – still bearing an egg-tooth. The individual pictured here was tremendously co-operative and remained resting on that stone even after I’d finishing photographing it.
* This species is usually termed Lacerta vivipara but recent phylogenetic work indicates that the traditional version of Lacerta is paraphyletic and deserves to be split up into multiple different genera.
Occurring in the exact same places as the Viviparous lizards were Wall lizards Podarcis muralis: they are rather longer-limbed and longer-tailed than Viviparous lizards, and tend to be more boldly patterned. They are actually tremendously variable across their range, with populations differing in their background colour, belly colour, and extent of spotting and striping (Arnold et al. 1978). Jon had heard that at least some of the wall lizards on Portland were of the green-backed form seen in parts of Spain and western Italy. Well, if wall lizards of this sort are there we didn’t see them: all the lizards we saw, at all the locations we visited, were brown wall lizards of the sort widely distributed in northern Europe. Quite why there are so many wall lizards on Portland no-one really seems to know, as this species is not thought to be native to Britain. Introductions are known to have occurred at Farnham Castle in Surrey, Shoreham in West Sussex and Ventnor on the Isle of Wight, and there are several colonies elsewhere (Lever 1977, Beebee & Griffiths 2000). The Portland colony might be introduced, or might have colonised the area itself by spreading from another centre of introduction. Again, I was lucky enough to get close to a particularly co-operative individual.
Molecular clocks indicate that Podarcis evolved late in the Miocene and the fact that some Podarcis species have ranges that virtually encircle those of some other European lacertid species has led to the suggestion that Podarcis has gradually been replacing older, more archaic lacertids over parts of their former range (Arnold 2004). This raises the question as to whether Viviparous lizards in Britain will become more restricted in distribution as alien Wall lizards become more common. At places where the two species occur together, such as on Portland and at Boscombe Cliffs in Bournemouth*, my impression is that Wall lizards are indeed more numerous and better at hogging the sunny walls and rock piles and so on. However, this might just be because they are less cryptic, and/or more prone to basking in full view.
* The location well known for its Western green lizard Lacerta bilineata colony (go here). I’ve just published an article on the subject of these lizards.
The third lizard species we encountered on Portland is the Slow worm Anguis fragilis, but this isn’t a sun-bathing diurnal animal, it’s crepuscular and fossorial, and to find it in the day-time you have to go rooting around in compost heaps, look under sheet metal, or dig around near ant’s nests. As mentioned before on the blog, everywhere I go I look for slow worms and I seem reasonably successful in finding them. There’s a lot of stuff I want to say about them, including on how they’re related to other anguids and on how big they get, but that’s another of those topics that I’m going to have to cover in future, not here. Update (added 20-5-2007): thanks to Mark, I’ve just added a video segment of me holding a Portland slow-worm. Not much happens I’m afraid, the highlight is the bit where the slow-worm flicks out its tongue.
And, finally, what about mammals? We explored caves and crevasses, looking for tracks, scat, hair, remains of kills, and evidence for den sites. And we found a ton of field sign… left by lynx. I’m talking about tracks, droppings and kills. If you know where to look, and what to look for, this stuff is easy to find, and I am not kidding [adjacent pic shows lynx scat]. However, I’ve written more than enough lately about British felids and don’t want to talk more about this subject right now.
Refs – -
Arnold, E. N. 2004. Overview of morphological evolution and radiation in the Lacertidae. In Pérez-Mellado, V., Riera, N. & Perera, A. (eds) The Biology of Lacertid Lizards. Evolutionary and Ecological Perspectives. Institut Menorquí d’Estudis. Recerca 8, 11-36.
- ., Burton, J. A. & Ovenden, D. W. 1992. Reptiles and Amphibians of Britain and Europe. Collins, London.
Beebee, T. & Griffiths, R. 2000. Amphibians and Reptiles. HarperCollins, London.
Jønsson, K. A. & Fjeldså, J. 2006. A phylogenetic supertree of oscine passerine birds (Aves: Passeri). Zoologica Scripta 35, 149-186.
Lever, C. 1977. The Naturalized Animals of the British Isles. Hutchinson & Co, London.