Recent research highlights:
With colleagues from the Netherlands, Germany and Iran I recently published a number of papers dealing with DNA barcoding. DNA barcoding is a taxonomic method that employs a short genetic marker to identify it as belonging to a specific species. The amount of genetic variation within species is normally considerably smaller than that between species and by focussing on this difference known species can be identified and unknown species can be recognised. We developed a simple and fast software utility –ExCaliBar- to calculate calculate intra- and interspecific distances from DNA barcodes (published in Contributions to Zoology), and we used this on two different avian datasets. The first one comprising a large set of sequences of owls, the analysis of which is detailed in a paper in Zoological Science, and the second comprising the most comprehensive DNA barcoding dataset of birds of the Netherlands, as can be read in a paper published in ZooKeys. The tree to the left is one of the warbler genus Sylvia with S. c. curruca and S. c. blythi standing out as two potentially distinct species.
Aliabadian M, Nijman V, Mahmoudi A, Naderi M, Vonk R, Vences M (2014). Excalibar: a simple and fast software utility to calculate intra- and interspecific distances from DNA barcodes. Contributions to Zoology 83: 79-83.
Aliabadian M., Beentjes KK, Roselaar CS, Nijman V, Vonk R (2013). DNA barcoding of Dutch birds. ZooKeys 365: article 25.
Nijman V, Aliabadian M (2013). DNA barcoding as a tool for elucidating species delineation in wide-ranging species as illustrated by owls (Tytonidae and Strigidae). Zoological Science 30: 1005-1009.
Living side by side with primates
With colleagues and former students from Nepal and England we recently published two papers on the perceptions of humans towards commensal primates. In Sri Lanka and Nepal we conducted interviews at a fairly large scale, involving several hundred of farmers in each of the two study sites. Managing the needs for primates and humans and mitigating conflict has to take into account the social aspects. Conflict between macaques and humans often starts with actual damage caused, but human relationships may result in more severe social conflict. For instance, increased crop protection on one farm (e.g. better fencing, active protection or repellents) may inadvertently lead to social conflict among farmers as macaques may simply shift their raids to unprotected fields or adjacent farms. An integrative approach to reducing macaque–human conflicts is needed, an approach which not only adjusts interactions among macaques, habitat and humans but which also mitigates interactions among humans faced with the challenges of crop-raiding
Nekaris KAI, Boulton A, Nijman V. (2013). An ethnoprimatological approach to assessing levels of tolerance between human and commensal non-human primates in Sri Lanka. Journal of Anthropological Sciences 91: 1-14.
Regmi GR, Nekaris KAI, Kandel K, Nijman, V. (2013). Crop-raiding macaques: predictions, patterns and perceptions from Langtang National Park, Nepal. Endangered Species Research 20: 217-226
Ivory trade in Laos – highlighting the role of China
Last year Chris Shepherd and I were in a position to properly survey the trade in ivory and other elephant products (skin, teeth, bones) in various parts of Laos. Prior to our survey only scant data were available and the Lao authorities had never filed a report on the ivory trade in their country to the Elephant Trade Information System, despite having been a Party to CITES for almost a decade. We found the trade in ivory to be large and open, with especially Vientiane emerging as a global hub for the ivory trade. The trade appears to be dominated by Chinese nationals or Lao national of Chinese decent, with a significant flow of ivory directed to China.
Nijman V, Shepherd CR (2012) The role of Lao PDR in the ivory trade. TRAFFIC Bulletin 24: 35-40.
Nijman V, Shepherd CR (2012) China’s role in trade in ivory and elephant parts from Lao PDR. Oryx 46: 172-173.
Forensic herpetology: Unsustainable trade in reptiles from Indonesia
With colleagues from Malaysia, Indonesia and Australia I recently published a paper on the exploitation and illegal trade of reptiles in Indonesia. The paper was the result of an invitation to contribute to a special issue focussing on herpetological forensics. Initially this was for the journal Applied Herpetology but when that ceased publication it was picked up by The Herpetological Journal, to which our thanks to the editors. We present several case studies but the one dealing with Tokay geckos is worth highlighting. The trade in this species, involving just 3 traders from Central and East Java, amounts to ~1.2 million individuals a year, greatly exceeding the national quota of 50,000 individuals for the entire year. This trade represents a monetary value for exporters of around one million USD / year. Export is permitted for the trade in live animals but the 1.2 million geckos are dead and dried when they are exported for the traditional Asian medicine markets.
Nijman V, Shepherd CR, Mumpuni, Saunders KL (2012). Over-exploitation and illegal trade of reptiles in Indonesia. Herpetological Journal 22: 83–89.
Population viability modelling of proboscis monkeys
With two of my (former) MSc students, Danika Stark and James Robins, and colleagues from Wales and the Czech Republic, I have published a paper modelling the population viability of proboscis monkey populations. Over ten years ago Erik Meijaard and I assessed the conservation status of the species for Kalimantan showing that while the distribution range was larger than previously assumed, several populations were under serious threat (pdf here). In the present study we zoomed in on two of the larger populations in Kalimantan (Danau Sentarum and Balikpapan Bay) and the largest population outside Indonesia (along the Kinabatangan River in Malaysian Sabah - see photo by Danika Stark to the left). Representing three distinct habitat types (inland lakes, coastal / mangroves and riverine forest) and facing different threat regimes the viability of these populations is distinctly different. The one in Danau Sentarum has a very high probability of becoming extinct within the next 30 years, largely due to a combination of hunting and, more importantly, habitat loss due to fires. Fires also will lead to a clear reduction of the population size in Balikpapan Bay, but the likelihood of extinction within the next 50 years is small. With virtually no hunting and or forest fires, in the different scenarios the population along the Kinabatangan showed a limited reduction.
Stark DJ, Nijman V, Lhota S, Robins JG, Goossens B (2012)Modeling population viability of local proboscis monkey Nasalis larvatus populations: conservation implications. Endangered Species Research 16: 31–43.
Discrepancies in wildlife trade from Thailand
Wide discrepancies in the numbers of live reptiles and amphibians reported in the pet trade to Thailand indicate misreporting or deliberate violation of international trade rules. With Chris R Shepherd of TRAFFIC Southeast Asia I examined how records supplied to the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) on the commercial trade in reptiles and amphibians exported to Thailand between 1990 and 2007 reflected changes in trends, species composition and numbers of wild-caught versus captive-bred specimens. Thailand is a key hub in the global wildlife trade, importing reptiles from Africa and South Asia for onward distribution within South-East Asia and East Asia. The ever increasing role of South-East Asia in the global pet trade has been attributed at least partly to the rising affluence in the region. Right a Panther Cameleon from the island of Nosy Mangabe of Madagascar's eastcoast as observed in Bangkok's pet market [Photo: Matthew Todd]
Nijman V, Shepherd CR 2011. The role of Thailand in the international trade in live CITES-listed reptiles and amphibians. PLoS One 6(3): e17825
Historic decline of orangutans on Borneo
With a team of researchers led by Erik Meijaard of People and Nature Consulting International in Indonesia, we have recently translated the records with orangutans of 59 Bornean expeditions into an encounter rate, and found a clear decline over time [the red circles on the map to the left are expeditions before 1965 (before large-scale deforestation started) and the black ones are more recent ones]. As reported in the journal PLoS One the odds of encountering an orangutan on any given day have fallen 3 to 6-fold over the last 150 years. This downward trend stayed the same even after accounting for the fact that expeditions have become shorter and involve fewer people. We conclude the decline is real and of a number of possible explanations we considered hunting to be the main reason for this decline. Our findings may force us to rethink the whole biology of orangutans. Much of our current ecological understanding is possibly based on field studies of animals living at densities below those that would be imposed by food availability. The question to ask is: "How would the species behave if natural densities were 5 or 10 times higher than those we currently observe?"
Meijaard E, Welsh A, Ancrenaz M, Nijman V, Wich SA, Marshall AJ. 2010. Orangutan encounter rates from Wallace to the present suggest the species was once more abundant. PLoS One 5(8): e12042.
Modelling crop-raiding by primates
With KAI Nekaris I present a model to predict crop-raiding by wild animals. The method relies on firstly assessing the risk that individual crops (e.g. papaya, rice, banana) are raided on any given farm, and secondly, based on crops grown, the risk that individual farms are subjected to crop-raiding. We tested the model using data from 2 species of primate and data from 273 farms in southern Sri Lanka. We found that the model worked well for predicting crop-raiding by the terrestrial toque macaque but less so for the arboreal purple-faced langur (seen right eating jackfruit in someone's garden).
Nijman V, Nekaris KAI 2010. Testing a model for predicting primate crop-raiding using crop- and farm-specific risk values. Applied Animal Behaviour Science 127: 125-129
Quantifying wildlife trade in and from Asia
Southeast Asia is a hub of the international wildlife trade, and globalization and the increased buying power of many countries in the region is increasing the demand for rare species — as pets and for medicines and food. The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), created to regulate the trade in protected species, went into force in 1975. Under the treaty, currently signed by 175 countries, including all of Southeast Asia, certain rare species can be exported legally only if the authorities can show that their trade is not adversely affecting animal populations in what is known as a nondetriment finding.
I recently analysed the international trade in CITES listed species resulting in two papers: one focussing on the export of all major taxa from Southeast Asia (seahorses, butterflies, reptiles, mammals, fish, birds, corals) and one highlighting the role of Asia in the global trade in poison arrow frogs.
Nijman V. 2010. An overview of the international wildlife trade from Southeast Asia. Biodiversity and Conservation 19: 1101-1114.
Nijman V, Shepherd CR. 2010. The role of Asia in the global trade in CITES II-listed poison arrow frogs: hopping from Kazakhstan to Lebanon to Thailand and beyond. Biodiversity and Conservation 19: 1963-1970.