About Dr. Wolfgang Dittus

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So far Dr. Wolfgang Dittus has created 31 blog entries.

IUCN Red List Update

26 April 2011.  Dr. Dittus is a member of the IUCN SSC Primate Specialist Group. At the invitation of the Biodiversity Secretariat, Ministry of Environment, Government of Sri Lanka, he participated in a workshop for the revision of the IUCN Red List for all the mammals of Sri Lanka.

There is high variance in the availability of field data for different mammalian taxa concerning their geographic distribution and abundance in Sri Lanka.  Earlier work by Dittus and colleagues (e.g.CAMP 2003), however, had provided sufficient detail about primates to allow assessments at the level of the 12 different subspecies of the 5 species of Sri Lankan primates.  This is important for conservation management considerations because IUCN Red List criteria applied at the level of subspecies would require a revision of earlier government assessments made at the level of the primate species only. It is hoped that the new finer grained focus would raise the level of protection afforded some of these taxa.

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Staff Achievements

10 May 2011. Research Coordinator, Sunil Gunathilake, completed 25 years of service on the Primate Biology Program. He also achieved the highest score (out of 140 candidates) in the National Tour Guides Training Program.

Our Research Coordinator, Sunil Gunathilake, completed his 25th year of service on the Smithsonian Primate Biology Program on 02 May 2011. Based at Polonnaruwa, he is a well know expert on primate behavior and activist in conservation and environmental education in Sri Lanka.

For the past year he had participated in a rigorous training program for Tourists Guides held by the Sri Lanka Institute of Tourism and Hotel Management. In the recent final set of examinations he had earned the highest score achieved by anyone over several years among some 500 candidates.

The ability to excel must run in the family, as his daughter, Sasanka (age 12 years), also achieved the highest academic score in the North Central Province in the several levels of competition held in the Junior Science Olympiad. In the upcoming run-offs, Sasanka hopes to represent Sri Lanka in the international arena of competiton.

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Air-rifles and monkey pest control

22 May 2001. Environmentalists, including Dr. W. Dittus and Sunil Gunathilake, argue against government plans to distribute air-rifles to farmers for the protection of their crops from raids by monkeys and squirrels.

From a telephone interview with reporter Malaka Rodgigo, published in the Sunday Times newspaper of 22 May 2011, Dr. Wolfgang Dittus and Sunil Gunathilake responded to plans by the Sri Lankan  government, Ministry of Coconut Development and State Plantations, to distribute air-rifles to farmers  to ward off monkeys and giant squirrels from damaging their crops.  They point out that shooting monkeys with air rifles, is by itself an inappropriate and inadequate response to prevent pest problems.  Instead, they pointed out that to prevent pest problems with monkeys  a more comprehensive approach is required whereby farmers (and others subject to monkey raids) take steps not to attract monkeys to their properties in the first place. The causes for attracting monkeys includes, for example,  the all too common littering of kitchen and other food scraps as well as easily accessible water sources, such as open water tanks and drains and leaky garden faucets.  They point out that removing all such attractions is an important prerequisite  to prevent pest raids on crops. In addition, Dr. Dittus indicated that personnel, who are specially trained to deal with monkey raids, would be a necessary component to prevent pest raids. Dr. Dittus and his team are negotiating with the Ministry of Economic Development of how best to address the monkey pest problems in affected areas (see news item of 8 March 2011).   Mr. Gunathilake pointed out that the encroachment of humans on monkey natural habitat, and the freely available human food scraps and water found there has stimulated unnatural […]

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Public Lectures

24th June 2011.  Dr. Dittus had been invited to address the “Conference of District Secretaries,” Ministry of Home Affairs and Public Administration, concerning solutions to human-monkey conflict. On 30th June, he also addressed “The National Trust – Sri Lanka” on his investigations concerning social evolution in primates.

24 June 2011.  At the invitation from the Ministry of Home Affairs and Public Administration, Dr. Dittus addressed a meeting of the country’s 25 Government Agents (District Secretaries) at the Sri Lanka Institute of Development Administration (SIDA). The purpose was to consider and discuss various options as solutions to the escalating problem of human-monkey conflicts in many areas of Sri Lanka.

30 June 2011.  The committee of the National Trust, Sri Lanka, had invited Dr. Dittus to address their members and the general public on discoveries of his 40 years of research on the primates of Sri Lanka.  The lecture and brief film clip were followed by a lively discussion

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Sri Lankan Airlines and Monkeys

July 2011. Polonnaruwa monkeys entertain and lure passengers on Sri Lankan Airliine flights.

Our primate studies were featured in the in-fight magazine Serendib.  For complete article see: Serendib

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Research Station now Education Center

19 November 2011. Our Research Station officially serves the local school community in nature education

The Department of Education, central government, and the North Central Provincial Education Department have recruited the facilities of our research station at Polonnaruwa, and expertise of our staff, in organizing and carrying out nature education programs in for school children between the 6th grade and A-levels. More than 300 children already have benefited from the program in 2011.

In the photograph, Mr. S. M. Saluwadana, Director of Science, North Central Province Education observes as our team, lead by Sunil Gunathilake, instructs about fish biology.

Our neighbors and collaborators, Mr. Nimal and Ms. Malani Perera, life-long fisher-folk, give pointers about the anatomy and habits of different fish species found in the Parakrama Samudra lake.

Here they show the “tilapia” Oreochromis mossambicus imported from East Africa in 1951 and used to stock dry-zone tanks. In the photo, the fish held by Mr. Perera is urinating.

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Rains flood grassland: elephants move

30 November 2011.  The monsoon rains have flooded the grasslands encircling dry-zone tanks. Deprived of their favorite feeding grounds, elephants move to higher ground.
Elephants swim our lake and visit our neighbor’s garden for better feeding opportunities.
For the past week, and elephant cow and her youngster (about 5 yr old) have come to our next door neighbor’s garden (100 m south of us) on nightly visits to snack on lush banana plants.  The villagers shouted, threw loud fire-crackers, and flashed their bright lights; but nothing could dissuade the pachyderms from giving up their meal. Eventually, after much hullabaloo, they did shift away from the village, but on their own terms it seems.  Luckily, both humans and elephants showed restraint, and there were no seriously threatening incidents.
Elephants take to the water (Photo: Palitha Handunge)The north-east monsoon has brought heavy rains to the area; the lake water level has risen fast and inundated the extensive grasslands surrounding the lake where elephants prefer to graze.  The elephants now seek forage elsewhere. In the lake at our doorstep, we have observed small herds of elephants swimming long distances in broad daylight by way of traveling between feeding areas. Although some victims of elephant raids may take a different view, we feel privileged that in this days and age, elephants are still free to roam.  These visits also indicate that man and elephants could co-exist peacefully if the proper precautions to prevent conflict were practiced.

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Asian Art, Culture and Heritage

Aug 2013, IAAH conference: Dittus & Gunathilake call to align the management of Sri Lanka’s heritage sites with ancient cultural values and UNESCO policy

The following presentation was delivered at the International Conference on Asian Art, Culture and Heritage organized in collaboration with the International Association for Asian Heritage (IAAH) and the Sri Lanka Ministry of Culture and the Arts,    held from 21st to 23rd of August 2013

Section:   Trends in Heritage Management, Museology and Tourism

Title:  A call to align the management of Sri Lanka’s heritage sites with ancient cultural values and UNESCO policy

Authors:  Wolfgang Dittus, Ph. D.1,2,3  and  Sunil Gunathilake3

Authors’ Institutional Affiliations:

1 Smithsonian Conservation Biology Institute, Washington, DC,  USA

2 National Institute of Fundamental Studies, Sri Lanka

3 Association for the Conservation of Primate Diversity, Polonnaruwa


The preservation of Sri Lanka ancient cultural heritage would benefit from a more balanced distribution of emphasis in management and conservation among the different elements that constitute this heritage.  The elements of the ancient civilization includes not only (a) the  physical remnants of monuments and artifacts, (b) the tanks and irrigation systems, but also (c) the  living forest gardens, and the natural  environment that buttressed the quality of ancient life.  Currently, most archaeological attention and resources are focused on the reconstruction and preservation of ancient stone monuments, infrastructural modernization and tourist management.  The ancient cultural heritage, however, extends far beyond monuments.

Forest gardens, for example, were an integral part of the ancient civilizations of South Asia.  In Sri Lanka, historical evidence for their existence is widespread being associated with at least 27 sites, the most prominent are known from Sigiriya, Mihintale, Sithulpawa. Rithigala and Polonnaruwa.   Their antiquity in Sri Lanka goes back to at least  King Mutasiva’s period ( 307-247 BC) (Mahavamsa: Geiger 1912), and […]

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Student Conference on Conservation Science

100 Presentations | 300 of Africa and Asia’s brightest conservation researchers

Demography: A Window to the Evolution of Primate Societies
Wolfgang Dittus

Wolfgang Dittus, Ph.D.
National Institute of Fundamental Studies, Sri Lanka
Smithsonian Conservation Biology Institute, USA
Date: 27th September, 2013
Time: 08:30 A.M
The basic assumption in studies of social evolution is that phenotypes, including behaviors, have been naturally selected to fine-tune an organism’s efficiency in surviving and passing on copies of its genes to future generations. The evolutionary honing of a phenotype relates to exogenous variables that influence its ability in making a daily living in a particular habitat, manipulating social partners to advance its own survival and reproductive success and other factors.  The challenge to students of such a system is to identify and measure key exogenous variables of social behavior (e.g., dominance hierarchical relations), ecology (e.g., feeding strategies) among others, and to relate them the measures of individual Darwinian fitness. In long-lived organism, like primates, such an inquiry demands a substantial investment of time and effort to test sociobiological hypotheses. Some salient findings of our 45 years of study of primates at Polonnarruwa will consider gender differences in life-history strategies, population genetic distributions, issues related to paternity (DNA studies) and inbreeding avoidance, and conservation.  The study also suggests that short-term cross-sectional demographic profiles of extant natural populations of primates could make an invaluable contribution to our understanding of social evolution.

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Fatness in primate evolution

Nov 2013: In the American Journal of Physical Anthropology Dr. Dittus considers changes in the anatomical distribution of body fat that were critical in the evolution from arboreal monkeys to terrestrial hominids.

Dittus, WPJ (2013).  Arboral adaptations of body fat in wild toque macaques (Macaca sinica) and the evolution of adiposity in primates. American Journal of Physical  Anthropology 152:333-344.
There is a paucity of information on body composition and fat patterning in wild nonhuman primates.  Dissected adipose tissue from wild toque macaques (Macaca sinica) (WTM), feeding on a natural diet, accounted for 2.1 % of body weight.  This was far less than fatness reported for nonhuman primates raised in captivity or for contemporary humans.  In WTM, fatness increased with age and diet richness, but did not differ by sex.  In WTM (none of which were obese) intra-abdominal fat filled first, and “excess” fat was stored peripherally in a ratio of about 6:1. Intermuscular fat was minimal (0.1%).  The superficial paunch held <15% of subcutaneous fat weight in contrast to its much larger proportions in obese humans and captive monkeys where most added fat accumulates subcutaneously.  With increasing total adiposity, accumulating fat shifted in its distribution among 8 different main internal and peripheral deposit areas – consistent with maintaining body balance and a low center of gravity.   The available data suggest that, in arboreal primates, adaptations for agile locomotion and terminal branch feeding set constraints on the quantity and distribution of fat.  The absence of a higher percentage of body fat in females and neonates (as are typical of humans) suggests that arboreal adaptations preclude the development of fat-dependent, large-brained infants and the adipose-rich mothers needed to sustain them. The lifestyle and body composition of wild primates represent a […]

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