Food Selection by Northern Yellow-Cheeked Crested Gibbons (Nomascus Annamensis)In Northern Cambodia

Food Selection by Northern Yellow-cheeked Crested Gibbons (Nomascus annamensis)in Northern Cambodia Naven Hon A thesis submitted to Victoria University of Wellington in partial fulfilment of the requirements for the degree of Master of Science in Ecology and Biodiversity School of Biological Sciences Victoria University of Wellington New Zealand 2016 i Abstract Tropical regions have extremely high plant diversity, which in turn supports a high diversity of animals. However, not all plant species are selected by animals as food sources, with some herbivores selecting only specific plants as food as not all plants have the same nutrient make up. Animals must select which food items to include in their diets, as the amount and type of nutrients in their diet can affect lifespan, health, fitness, and reproduction. Gibbon populations have declined significantly in recent years due to habitat destruction and hunting. Northern yellow-cheeked crested gibbon (Nomascus annamensis) is a newly described species, and has a limited distribution restricted to Cambodia, Laos and Vietnam. The northern yellow-cheeked crested gibbons play an important role in seed dispersal, yet little is currently known about this species, including its food selection and nutritional needs. However, data on food selection and nutritional composition of selected food items would greatly inform the conservation of both wild and captive populations of this species. This study aims to quantify food selection by the northern yellow-cheeked crested gibbons by investigating the main plant species consumed and the influence of the availability of food items on their selection. The study also explores the nutritional composition of food items consumed by this gibbon species and identifying key plant species that provide these significant nutrients. A habituated group of the northern yellow-cheeked crested gibbons with five members located in northern Cambodia was studied for 12 weeks during the dry season, and focal animal sampling was used to observe individual feeding behaviours. Four main activity categories were recorded including resting, feeding, travelling and socializing. Phenological data was recorded from transect lines, and plant densities from 20 vegetation plots inside the home range of this group of gibbons were also measured. Seventy-four plant samples from 20 tree and liana species that were consumed by this group of gibbons were collected for nutritional analyses. These samples were initially dried in sunlight, and then oven dried before levels of protein, total non-structural carbohydrates, lipids, fibres and condensed tannins were measured at the Nutritional Ecology Lab at Hunter College of the City University of New York, New York. i The northern yellow-cheeked crested gibbon individuals spent most of the time resting, followed by feeding, travelling and socializing. Their main diet was fruit, supplemented with young leaves, flowers, mature leaves, and occasionally insects. Individuals selected food from 37 plant species, but predominately fed on just 16 of these species. The three most-consumed species were fruit from Ilex umbellulata (tree), Ficus. sp (liana), and young leaves from Lithocarpus elegans (tree). There was a significant relationship between feeding time and the availability of flowers, indicating that flowers were actively selected for when present. However, there was no significant relationship between feeding time and the availability of fruit or young leaves. Only a small number of plants bore fruit, with very low densities in the home range of this gibbon study group, but these plants produced a large abundance of fruit. These findings clearly indicate that fruit is the main diet for northern yellow-cheeked crested gibbons in the dry season, with young leaves, flowers, mature leaves and insects acting as secondary food sources. The northern yellow-cheeked crested gibbons selected only a small number of specific plants in their territory for food sources, indicating that any selective logging targeting these plant species would reduce food availability, and restrict the diet of these animals. Fruits consumed by the northern yellow-cheeked crested gibbons were rich in carbohydrates and lipids, while young leaves were richest concentration of protein. Mature leaves had a high moisture content, whereas flowers contained condensed tannins more often than other plant tissues. All plant tissues consumed had similar amount of fibres. Generally, the food items consumed had higher concentrations of carbohydrate than protein or lipids. The overall diet of this group of gibbons was low in lipids. These results indicate that northern yellow-cheeked crested gibbon consumed food items with high concentrations of carbohydrate, and only selected a few food sources with high level of protein. Overall, these findings have contributed important knowledge that can be used for long-term conservation of this gibbon species. There are a small number of key food species in the home range which need special protection. The northern yellow-cheeked crested gibbons consumed food items from different plant species, and as a consequence, all plant species selected play an important role for nutritional requirements by this gibbon species. When considering feeding requirement by the northern yellow-cheeked crested gibbons for captive breeding programs, diets should include fruit, which is rich in carbohydrates, and young leaves, which have high levels of protein. ii Acknowledgements Firstly, I would like to thank New Zealand ASEAN Scholarship Program, and the New Zealand government through the New Zealand Aid Program for a three-year scholarship to study at Victoria University of Wellington (VUW), New Zealand. This has been a great opportunity to upgrade my knowledge in science and in particularly biodiversity research and conservation. I also would like to thank the Primate Conservation Incorporated (PCI) and Primate Action Fund (PAF) with Conservation International (CI) for supporting this project. Without the support of these agencies, I would not have chance to become involved in primate research and conservation. This thesis would not have been possible without the encouragement and support of my supervisors, Associate Professor Dr Ken Ryan (VUW) and Dr Alison Behie (Australian National University, Canberra, Australia). I highly appreciate what both of you have contributed to this thesis. Without both of you, I would not have had the chance to conduct the field work and laboratory analysis for this thesis. Ken, thank you very much for accepting me as your student. Your suggestion and reviews as well as the detail of your corrections of this thesis were always highly appreciated, and all of these have contributed to the quality of this thesis. Alison, I have no words to say besides thank you very much for your help during my study in New Zealand. Without your help, I might not have completed this Master’s degree smoothly in a country where the education system is so different from my own. More importantly, thank you very much for agreeing to be my supervisor, and for guiding me in this research. Although you are very busy with your lovely daughters and family, you always spent your time reviewing this thesis from the beginning until it was ready for submitting. I also thank Sonja Hampel and Dr Lisa Woods for their guidance in checking grammatical errors and statistical analyses through this thesis. I also extend my thanks to Assistant Professor Dr Jessica Rothman (Hunter College of the City University of New York) who allowed me to do plant nutritional analyses in her lab in New York, and helped to analyse the rest of my plant samples. I also thank Jenny Paltan, Ketti Barateli, Caley Johnson, Santiago Cassalett and all the people who helped me during iii the time I was working in the lab. I especially thank Ishmael Deen who drove and guided me around New York City. I also would like to thank Dr Ben Rawson and Dr Jackson Frechette for their expertise and guidance during and after my data collection. This research would not have been possible in the field without the contribution of my local assistants: Mr. Noy, Mr. Vath, Mr. Soulit, Mr. Sie and the local people from I-tube village. I thank Mr. Hieng and Mr .Poy for their help in data collection, climbing trees and lianas to get plant samples. Some local assistants rose early in the morning (4:00 am) with me and walked to the gibbon site (site A). Thanks again to Mr. Vath who was not only a local assistant, but also was the village volunteer doctor who helped me when I contracted malaria, and made sure I was taken to the hospital on time. The project would not have been completed without the collaboration of the Forestry Administration (FA), Ministry of Agriculture, Forestry and Fisheries of the Royal Government of Cambodia, and their permission to conduct the study and export plant samples to the United States of America. In particular, I would like to thank Mr. Vong Sokserey and Mr. Pov Samanak for coordinating these permission letters. I also thank CI, in particular Mr. Seng Bunra, Mr. Cheap Chanthon, and everyone at the Veun-Sai Siem Pang Conservation Area (VSSPCA) including Mr. Nget, Mr. Pheak, Mr. Earn, Mr. Puthy, and Mr. Pisey for your care and time in protection the forests as well as the gibbons at the study site. Lastly, I would like to thank my lovely parents and my wife, Lim Sotheary, for their love, care, and patience during the time I was studying in New Zealand. Your encouragement is an effective medicine that also encourage me to finish this study. I also thank my sisters and brothers, relatives and friends for your support and encouragement while I was away from home, and those friends who live and study in New Zealand. I also thank Wellington Khmer Association who always invited me during Khmer New Year and many special occasions, your warm welcome had reduced what we called “homesickness”.

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