Tetrapod Zoology

i-59a78d18d5ce46709bdc95ab2e2a3671-camera-trapped-composite-genet-otter-muntjac-Dec-2010.jpg

ResearchBlogging.org

The increasing availability of automatic cameras (cameras set up to take photos on their own are known in the trade as camera traps) has been a great boon to field biologists, and to people interested generally in the documentation of obscure and elusive creatures. Many animals hardly ever photographed in living state have been documented by these tools, and quite a few taxa never photographed in living state at all have been captured by them too. A few examples of the latter include Lowe’s servaline genet Genetta servalina lowei (camera-trapped in 2002, shown at the top of the adjacent composite), Giant (or Large-antlered) muntjac Muntiacus vuquangensis (camera-trapped in 2007, shown at bottom of composite) and Hairy-nosed otter Lutra sumatrana (camera-trapped in July 2010, shown in middle of composite). Species have also been documented in entirely new areas thanks to camera traps: witness, as one example among many, the 2008 camera-trapping of Bush dogs Speothos venaticus in the Atlantic forest of São Paolo, Brazil (Besiegel 2009).

Most exciting of all, entirely new species have also been discovered thanks to camera traps. Examples include the Grey-faced sengi Rhynchocyon udzungwensis (covered on Tet Zoo back in March 2008) and a possible new species of brocket deer from Peru (Trolle & Emmons 2004). Every now and again things that look like sasquatches and thylacines are photographed by camera traps, but no real deal so far :)

A while ago I became interested in the fact that several ‘ethnoknown’ pigs from SE Asia have been documented by camera traps, yet remain the source of controversy. An ethnoknown animal, for those of you unfamiliar with the term, is one that’s recognised as a distinct entity by local people, but isn’t necessarily a distinct taxon: an ethnoknown animal could, say, be a distinct growth stage or colour morph of a certain species, or it might not be a real animal at all (but, rather, a mythological entity or such). On the other hand, it could be an animal wholly new to science.

i-c4e935633560539828eb25f8d62160f6-Vietnamese-pig-drawings-Meijaard-et-al-Dec-2010.jpg

In Tuyen Quang Province, northern Vietnam, local people report two distinct types of pig: a common, long-snouted, long-legged form with white cheek stripes, and a short-faced, black form [drawings of the two forms are shown here, from Meijaard et al. (2002)]. In southern Vietnam, people again report two distinct pigs. The heo bac (meaning ‘silver pig’) is a short-snouted, whitish animal with white cheeks, while the heo den is longer-snouter and blackish. While the reported snout lengths do not tally between these forms, it is plausible that the whitish pigs from both regions represent the same taxon, as do the blackish pigs from both regions.

What might the identity be of these ethnoknown animals, and are known or unknown taxa at the bottom of the reports? This is very difficult to answer, as a tremendous amount of variability and hybridisation within wild and feral pigs in SE Asia makes identification difficult (Groves 1981). Camera traps used in Na Hang Nature Reserve in Tuyen Quang Province succeeded in photographing wild pigs that seem to correspond to these different descriptions [a camera-trapped Na Hang pig is shown below; from Meijaard et al. (2002)]. The white-cheeked heo bac might represent Sus scrofa moupinensis Milne-Edwards, 1871, a small boar from China and Vietnam with a broad, high skull.

i-4f3a0f200b4e9d541f9e0b2b20b66241-Na-Hang-pig-Meijaard-et-al-Dec-2010.jpg

The possibility that the small, dark heo den might represent Heude’s pig S. bucculentus (also known as the Indo-Chinese warty pig) has been proposed (Meijaard et al. 2002). Named in 1892 for two skulls discovered in Vietnam, S. bucculentus remained enigmatic until 1995 when an additional skull discovered in the Annamite Mountains of Laos apparently rescued the species from oblivion, supposedly validating its existence as a distinct species (Groves et al. 1997). More recently, DNA analysis has shown that S. bucculentus fits within the range of variation present within Asian populations of S. scrofa, the widespread Eurasian wild boar, so separate species status is no longer thought likely (Robins et al. 2006). ‘S. bucculentus‘ might not be a distinct species, but there still seems to be a population that corresponds to our concept of this animal, and it might be that this is what people have been seeing and calling the heo den.

Please note the many caveats given in the text above: the assumption that the animals from northern and southern Vietnam are the same could well be erroneous (as suggested by conflicting details of snout length), and one could argue anyway that it might not be possible to arrive at firm conclusions based on the evidence to hand. Field studies and DNA sampling of the heo bac and heo den, and their northern Vietnamese equivalents, are needed.

i-83efae082728e74cd2b5f11ed99f1106-Allen-2002-Baliungan-island-pig-Dec-2010.jpg

Controversial pigs have also been photographed in the Philippines. While searching Tawi Tawi and adjacent islands between 1995 and 1999 for birds, Desmond Allen photographed an unidentified pig on Baliungan Island (just east of Tawi Tawi) [it's shown here; from Allen (2002)]. A separate visit to Tawi Tawi by Karen Rose in 1997 revealed that “a pig present was probably of an undescribed species and … pigs on some of the offshore islands such as Bilatan might be different again” (Allen 2002, p. 4). The high diversity of endemic pig taxa already known from the Philippines (something I plan to cover one day) renders it likely that further forms do await documentation there.

Thanks in part to the spread of feral colonies in parts of Europe and North America, the adaptability and versatility of the wild boar and its modified descendants are all too familiar. Less well known is that pigs as a whole are a surprisingly large, diverse group that have been very good at colonising islands, crossing barriers* and evolving new endemic forms, many of which are of high conservation priority. Many questions remain on the subject of pig systematics, evolution and diversity, and the documentation of local forms – aided by camera trapping techniques – remains an important (yet frequently unappreciated) area of investigation.

* Including Wallace’s line (Groves 1983).

For previous Tet Zoo articles on pigs, see…

Refs – -

Allen, D. 2002. Some poorly-known pigs in the Philippines: Tawi Tawi and Tablas. Asian Wild Pig News 2 (1), 4-5.

Besiegel, B. M. 2009. First camera trap records of bush dogs in the state of São Paulo, Brazil. Canid News 12.5 (online) [free pdf here].

Groves, C. P. 1981. Ancestors for the Pigs: Taxonomy and Phylogeny of the Genus Sus. Technical Bulletin 3, Department of Prehistory, Research School of Pacific Studies, Australian National University, pp. 96.

- . 1983. Pigs east of the Wallace Line. Journal de la Société des Océnistes 77, 105-119.

Groves, C., Schaller, G., Amato, G., & Khounboline, K. (1997). Rediscovery of the wild pig Sus bucculentus Nature, 386 (6623), 335-335 DOI: 10.1038/386335a0

Meijaard, E., Oliver, W. L. R., Martin, B. & Thanh, V. N. 2002. Records and reports of pigs in Vietnam. Asian Wild Pig News 2 (2), 40-42.

Robins, J. H., Ross, H. A., Allen, M. S. & Matisoo-Smith, E. 2006. Sus bucculentus revisited. Nature 440, E7.

Trolle, M. & Emmons, L. H. 2004. A record of a dwarf brocket from Madre de Dios, Peru. Deer Specialist Group Newsletter 19, 2-5.

Comments

  1. #1 farandfew
    December 16, 2010

    Hmm. Well I can report that people living in central Vietnam – between those two locations – do recognise two kinds of pigs which have different names in the local language, not just Vietnamese and they do recognise the white face stripe in the picture as being characteristic of the larger one. However they themselves readily state that this larger kind is just the solitary male. The smaller kind are the group-living females and younger males. All fits Sus scrofa. I haven’t read Meijaard et al yet, though.

  2. #2 Darren Naish
    December 16, 2010

    Ah.

  3. #3 She
    December 16, 2010

    LOL! I just knew I was gonna get to see flying pigs….:))

  4. #4 Dartian
    December 17, 2010

    The heo bac (meaning ‘silver pig’)

    Silver pig, silver pig,
    doing whatever a silver pig does…

    (Sorry, couldn’t resist.)

    DNA analysis has shown that S. bucculentus fits within the range of variation present within Asian populations of S. scrofa, the widespread Eurasian wild boar, so separate species status is no longer thought likely (Robins et al. 2006). ‘S. bucculentus‘ might not be a distinct species, but there still seems to be a population that corresponds to our concept of this animal

    That nicely illustrates just what kind of a taxonomic mess Sus scrofa sensu lato is…

  5. #5 Jerzy
    December 17, 2010

    Of course, pigs in SE Asia are understudied and in taxonomic mess.

    However, I guess, many populations were originally introduced by people. However, still they might be important for conservation and zoology, because source populations in the meantime might become endangered or extinct (see the story of Bornean/Javan elephants).

  6. #6 farandfew
    December 17, 2010

    Well actually, Jerzy, that’s what exactly what a Vietnamese scientist – I’m guessing the one who did the interviews – suggested to explain the situation at the site in Tuyen Quang province, according to the Meijaard et al paper (which i now have). I don’t know about the southern site but it’s a relatively well studied area. I’ll ask.

  7. #7 Darren Naish
    December 17, 2010

    I see that Meijaard et al. refer to the opinion of Le Xuan Canh, who seems to be suggesting that the two Tuyen Quang pigs are not distinct taxa, but feral domesticates (as per comment 1). I confess that I had largely missed this, having been most interested (understandably, I hope) in the suggestion that the two forms might instead represent S. scrofa moupinensis and ‘S. bucculentus‘. Would be great if there were more data. I can’t see any mention of translocation or introduction in Meijaard et al.: have I missed it? (for those interested, the article is here).

  8. #8 Nathan Myers
    December 18, 2010

    Do the Jumblies live in Viet Nam now?

  9. #9 melina
    April 27, 2011

    The camera traps is useful tool when tiring to get pictures but, can you use thoughts to follow animals that are set free for a reserve? The brocket deer that is from Peru look quite big. I’m for the one for a nice rack but that I like the idea of using them

The site is undergoing maintenance presently. Commenting has been disabled. Please check back later!