INTRODUCTION
Species overview
Cat Ba langurs, also known as golden-headed langurs or „Cang den dau trang‟/„vooc Cat Ba‟ in Vietnamese (Nisbett and Ciochon 1993; Nguyen Cam pers comm
2014) are a Critically Endangered (Bleisch et al 2008a) leaf-eating monkey within the family Cercopithecidae and subfamily Colobinae of Old-World monkeys, endemic to a small Vietnamese island – Cat Ba Island
Early colobines moved into arboreal and folivorous niches by the late Pliocene
Around 10.9 to 15.39 million years ago, primates divided into two tribes: the African Colobini, which includes genera such as Procolobus, Piliocolobus, and Colobus, and the Asian Presbytini, comprising the odd-nosed monkeys (Nasalis, Rhinopithecus, Simias, and Pygathrix) and the langur or leaf monkeys (Trachypithecus, Presbytis, and Semnopithecus) Approximately 6.9 million years ago, the Asian group further split into odd-nosed and leaf-eating monkeys Notably, the Asian group has preserved more primitive features in their molars, premolars, jaw bones, feet bones, and thumbs compared to the more derived characteristics found in the African group.
Debate continues as to the relatedness of the Asian colobines (Karanth 2010), particularly between Rhinopithecus, Pygathrix, and Trachypithecus (Oates et al 1994;
Wang et al 1997), although each genus has been shown to be monophyletic (Sterner et al
The phylogenetic relationships among the langurs, specifically Presbytis, Trachypithecus, and Semnopithecus, remain unclear, with debates on whether Presbytis is a sister taxon to Trachypithecus and Semnopithecus or if Semnopithecus is related to the other two This complexity may stem from historical hybridization events or morphological convergence, leading to varying interpretations of their relatedness.
6 what is being tested (e.g morphology, nuclear vs mitochondrial DNA), although this does not change the true nature of their evolution and phylogeny
The genus Trachypithecus, previously classified into five species-groups—T obscurus, T cristatus, T Francois, T pileatus, and T vetulus—has been revised due to genetic findings Research indicates that T pileatus is a hybrid with Semnopithecus, while T vetulus is now recognized as part of Semnopithecus Consequently, Trachypithecus now comprises only three species-groups: T obscurus, T cristatus, and T francoisi.
The separation of the genus Trachypithecus occurred approximately 3.17 million years ago, as noted by Harding (2010) The exact number of species within this genus remains uncertain, with estimates varying between 17 and 20 species (Harding 2010) This study adheres to the latest taxonomic classification, acknowledging 20 distinct Trachypithecus species as identified by Roos et al (2014) Among these, the francoisi species-group of limestone langurs includes Delacour’s, Laotian, Hatinh, Indochinese black, and Franỗois’ langurs.
The francoisi species-group, which includes the northern langurs such as Franỗois’, Cat Ba, and white-headed langurs, as well as the southern varieties like Delacour’s and Laotian langurs, inhabits limestone karst mountains These unique habitats present similar ecological, locomotor, and nutritional challenges for all these species.
Hatinh, and Indochinese black langurs) groups (Roos 2003; Roos et al 2007), whose ranges are divided by the Red River (Groves 2007)
The Cat Ba langur, as highlighted by the Cat Ba Langur Conservation Project, features distinctive black skin and dark brown fur, with its head and shoulders exhibiting a striking golden to yellowish-white hue Notably, its long tail measures approximately 85 cm, significantly surpassing its body length of around 50 cm.
Cat Ba langurs are golden-orange at birth, with their fur changing color around four months Males and females are visually similar, and they typically live in groups led by one male, accompanied by several females and their young These diurnal primates thrive in limestone habitats, with each group maintaining a distinct territory defended by the adult male Females usually give birth to one baby every 2–3 years, reaching maturity at 4–6 years, and they have an average lifespan of 25 years Their diet primarily consists of leaves, along with fresh shoots, flowers, bark, and some fruits.
Vietnam has the richest diversity of primate taxa in Southeast Asia (Nadler 2010) Within the country‟s borders, there are two species of Lorisidae (both genus Nycticebus),
The Cercopithecidae family includes 18 species, comprising five Macaca, eight Trachypithecus, three Pygathrix, and one Rhinopithecus, while the Hylobatidae family features six Nomascus species (Roos et al 2014) Most of these primates are listed on the IUCN Red List, with classifications ranging from Vulnerable to Critically Endangered (Nadler 2010) Notably, two or three species, such as the Cat Ba and Delacour’s langurs, and possibly the gray-shanked doucs (Pygathrix cinerea), are strictly endemic to specific regions.
Vietnam is home to several primate species, including the near-endemic Cao-Vit gibbon (Nomascus nasutus) and the potentially endemic Tonkin snub-nosed langur (Rhinopithecus avunculus) due to local extirpations Political borders do not significantly influence the distribution of nonhuman primates; in the biogeographically significant area east of the Mekong River, over half of the primate species are endemic.
Trachypithecus occur across a large range both geologically and ecologically
They survive in moist and wet lowland forests, dry deciduous forests, mangrove swamps
8 along the coast, and broad-leaved forests in the mountains (Oates et al 1994)
Trachypithecus species coexist with Presbytis in Malaysia and Indonesia, Nasalis on Borneo, and Pygathrix in Indochina In Vietnam, there are eight species of Trachypithecus, including the gray langur, margarita, Indochinese lutung, Franỗois', Cat Ba, Hatinh, Delacour’s, and Indochinese black langurs.
Limestone langurs inhabit the limestone karst mountains of northern Vietnam, central and northern Laos, and southern China Among these, Franỗois’ langurs are found in the largest and northernmost region, primarily in southwest China and northern Vietnam In contrast, white-headed langurs have a more limited range, residing in Guangxi Province, China, and are parapatric with Franỗois’ langurs Delacour’s langurs are located in northcentral Vietnam, while Laotian langurs inhabit central Laos, just north of the Hatinh langurs, which extend into northcentral Vietnam and east-central Laos Lastly, Indochinese black langurs are found in east-central Laos and central Vietnam.
The Cat Ba langur is endemic to Cat Ba Island in northeastern Vietnam, with no evidence of its presence on the mainland due to the absence of suitable limestone habitats nearby It is believed that these langurs initially inhabited the limestone range during periods of lower sea levels, which later transformed into isolated islands Cat Ba Island, located at coordinates 20°42′-20°55′N and 106°54′-107°10′E, is the largest island in the Cat Ba archipelago.
2006, roughly half of the 140km2 island is devoted to the CBNP (Sterling et al 2006;
Schrudde et al 2010), a subset of which is part of a sanctuary (a strictly protected zone within the CBNP created for langur protection)
The map illustrates the distribution of Cat Ba langur populations across various locations on Cat Ba Island, Vietnam, specifically highlighting areas in Cua Dong (southeast), the sanctuary (east), and Hang Cai (northwest) This visual representation is provided with permission from Leonard (2014).
Cat Ba langurs exhibit a distinctive pelage, characterized by dark brown to black fur, complemented by a bright golden-brown to yellowish-white coloration on their head and shoulders Their back hair transitions from brown at the roots to a darker hue at the tips, with hair lengths ranging from 10-12 cm A notable feature is the V-shaped frosted gray band that extends from the thighs to above the tail root, where the roots match the body color and the terminal 5 mm are a striking silver-gray While there is minimal sexual dichromatism, females are identifiable by a pale pubic patch and irregular skin coloration on their inner thighs.
Infants are initially bright orange without a crest at birth, and their coloration begins to change as they grow older.
Figure 1.2: Male Adult Photo by Nguyen Huy Cam
Figure 1.3: Female Adult Photo by Nguyen Huy Cam
There have been some numbers of research on vocalization of trachypithecus since early such as:
"Calling patterns of Western purple-faced langurs (Mammalia: Primates: Cercopithecidea: Trachypithecus vetulus nestor) in a degraded human landscape in Sri
Conservation and threat of Cat Ba Langur
The Cat Ba langur, with only 53 individuals remaining in the wild and two in captivity at the Endangered Primate Rescue Centre in Cuc Phuong National Park, is critically endangered To address this alarming decline, the Cat Ba Langur Conservation Project was initiated in 2000 by Műnster Zoo and the Zoological Society for the Conservation of Species and Populations (ZGAP).
The primary goal of the Cat Ba Langur Conservation Project is to stop poaching and raise conservation awareness among the residents of Cat Ba Island This initiative has significantly decreased poaching-related deaths from 30 to just three in four years, with nine langurs born and thriving during this period The langurs are closely monitored in a dedicated sanctuary within the National Park, which is home to 20 individuals protected by a remarkable one-to-one ratio of rangers The sanctuary is clearly marked and off-limits to tourists Additionally, the project has established two new ranger stations, provided boats for patrols, and facilitated the voluntary relocation of local households to aid conservation efforts The project also receives support from Flora and Fauna International's Flagship Species Fund and the Cat Hai District Women’s Union, which promotes biodiversity conservation through community engagement.
In response to the decline of the white-headed black langur in China, significant conservation efforts have been initiated A survey funded by the Asian Development Bank in January 2003 indicated signs of recovery in the Fusui populations (Mittermeier et al, 2005) Since the start of Professor Pan Wenshi's research program at Peking University in 1996, the population in Chongzuo has increased from fewer than 100 to over 200 individuals.
2005) Tourism has become central to the economy of both Vietnam and China, and now must be controlled to prevent the disturbance of recovering habitats and species in the
Conservation International‟s Indo-Burmese Biodiversity Hotspot (Birdlife Indochina - Cat
1.2.2 Threat of Cat Ba Langur
Hunting of the Cat Ba langur used to be common The primary reason for hunting was to supply the traditional medicine industry Cat Ba langurs were used to make a
Monkey balm, derived from langurs, is believed to aid in treating erectile dysfunction and various health issues Due to the dwindling langur population, hunting them can take two to four weeks, and poachers can earn up to $50 for a single langur, a significant sum considering the average annual income is less than $350 (Ben, 2003) As langurs are difficult to locate, poachers typically capture them by chance while hunting other animals Between 1970 and 1986, it is estimated that 500 to 800 langurs were killed (Quan Nguyen, 2010).
The hunters of the langurs have been known to attack people who get in their way
To protect langurs, unarmed "bodyguards" have been implemented as part of a conservation initiative Unfortunately, these guards have faced severe violence from hunters, resulting in injuries such as lost teeth and stabbings This ongoing threat has led to a growing reluctance among the guards to continue their vital work.
Cat Ba Island is rapidly developing its tourism sector, with plans for luxury hotels, including a notable 17-story establishment To support the influx of visitors, a new road is under construction, linking the town to a northern village where a ferry service will transport tourists to the renowned Ha Long Bay However, this road's proximity to the park's border raises concerns about increased hunting activity in the region.
GOALS AND OBJECTIVE
Goal
To providing data on the characteristics and vocalization behavior of Cat Ba langur
(Trachypithecus poliocephalus) for the conservation of this rare species in Vietnam.
Objective
- Describing the vocal repertoire of Cat Ba Langur
- Identifying the calling pattern of Cat Ba Langur
- Give solutions to improve the conservation of Cat Ba Langur.
Study area
- This research focus on 3 locations in Cat Ba Island: Cua Dong, Gia Luan Communes and Sanctuary (a strictly protected zone within the CBNP created for langur protection)
Figure 2.1: Cua Dong Photo by Neahga Leonard
Figure 2.2: Hang Cai - Gia Luan Commune Photo by Neahga Leonard
Figure 2.3: Sanctuary Photo by Neahga Leonard
STUDY SITE
Natural conditions
Cat Ba Island is located 45 kilometers east of Hai Phong, 24 kilometers south of Ha Long City, and approximately 150 kilometers southeast of Hanoi It is bordered to the north by Ha Long Bay in Quang Ninh Province, to the west by Cat Hai Island in Hai Phong City, and is surrounded by the East Sea to the east and south.
Cat Ba island coordinates: 20°42' - 20°54' North latitude; 106°52' - 107°07' East longitude
Cat Ba National Park coordinates: 20°44'50'' - 20°55'29'' North latitude: 106°54'20''
Cat Ba island has an area of approximately 300 square kilometers
The region, situated in a tropical monsoon climate influenced by the oceans, experiences average temperature, humidity, and rainfall levels similar to its surroundings However, it features milder winters and cooler summers compared to inland areas Variations in topography, sea influence, altitude, mountain orientation, and forest vegetation contribute to distinct climate regimes across different areas within the region.
Precipitation: Average annual precipitation is 1,700 - 1,800 mm/year, seasonal fluctuations The rainy season begins from May to October, but focusing mainly in July
17 and August Precipitation during this season accounts for nearly 80 - 90% f the total annual rainfall
The annual average temperature is 23.6 °C, with July being the hottest month, averaging between 28 and 29 °C, peaking at 32 °C In contrast, January sees the lowest temperatures, averaging 16 to 17 °C, with a minimum of 10 °C, and occasionally dropping to as low as 5 °C The hot season extends from May to October, while the cold season lasts from November to April.
The average air humidity throughout the year is 85%, with January experiencing the lowest levels at 73% and April peaking at 91% Annual water evaporation is approximately 700mm, leading to frequent droughts and water shortages during the dry months.
The region experiences two types of winds: East-Northeast during the dry season and East-Southeast in the rainy season Storms typically occur from June to October, with an average of 2.5 hurricanes annually These storms often bring heavy rain, leading to flooding that significantly impacts the levee system and aquaculture areas.
Salinity of sea: from 0.930% (rainy season) to 3.111% (dry season);
Cat Ba is a limestone archipelago characterized by undeveloped river systems, where temporary water flows emerge only during rainfall and cease shortly after During the rainy season, water tends to stagnate in small areas and infiltrate through caves Despite its limited availability, this water source is essential for sustaining the island's flora and fauna.
Flora resources on Cat Ba Island abundant with statistics of 620 species belonging to 438 genera and 123 families The typical family: Myrtaceae, Moraceae, Rubiaceae, Lauraceae, Asteraceae
Dividing flora on Cat Ba Island, we have:
Medium and large wood trees: 68 species;
The composition of plant life in Cat Ba is not particularly abundant, yet it includes economically and scientifically valuable species such as Fagraea fragrans, Chukrasia velutina, Aglaia spectabilis, and Podocarpus fleuyi The island's most representative vegetation is the evergreen moist rainforests found on limestone, along with coastal mangrove forests near estuaries Additionally, certain areas feature unique and rare forest types, including submerged vegetation in high mountainous regions.
In addition to the forest vegetation, agriculture vegetation type also plays a key role in the region This vegetation including plantation forests, perennials, agricultural crops, fruits, aquaculture, and residential areas
The island's evergreen broadleaf tropical rainforest, shaped by various external factors like terrain, geology, climate, and hydrology, has flourished over the past few decades, covering most of the land area Despite recent impacts that have altered the forest's structure and canopy, Cat Ba's unique limestone forest remains a significant ecological treasure on the East coast of North Vietnam.
Cat Ba Island is home to a rich biodiversity, featuring 53 animal species across 18 families and 8 orders The island boasts 160 bird species from 46 families and 16 orders, alongside 46 reptile species belonging to 16 families and 2 orders Additionally, it hosts 21 amphibian species from 5 families within a single order.
Cat Ba Island is home to approximately 282 terrestrial animal species, including the critically endangered golden langur (Trachypithecus poliocephalus), which is found exclusively in Vietnam with an estimated population of only 50 to 60 individuals, according to the IUCN Red List.
The marine ecosystem around Cat Ba is rich in biodiversity, featuring 98 species of zooplankton, 196 species of marine fish (including 79 reef fish), 177 coral species, and 532 bottom-dwelling animals According to the Institute of Oceanography in Hai Phong, there are currently 900 fish species, 500 mollusk species, and 400 crustacean species in the region Notably, Cat Ba is home to rare species such as the large dolphin and its calves Overall, 21 rare marine species have been identified in Cat Ba, including two listed in the CITES database and seven that are protected under the Vietnam Red Book.
Cat Ba Island, recognized as a "Biosphere Reserve World," boasts remarkable biodiversity, unique geology, and rich cultural heritage, making it a captivating destination for both domestic and international travelers This designation will not only enhance economic and social development on the island but also promote international scientific research collaboration, support environmental management, and protect its diverse ecosystems.
Economy - Society
As of 1997, Cat Hai district had a population of 27,051, representing 1.6% of Hai Phong city's total population, with an average density of 80 people per square kilometer.
The number of people in labor age is 10,500 (1997), 12,000 (2000) and 15,000 people (2010)
As of 2011, Cat Ba Island's population reached 16,566, with a natural growth rate of 0.68% per year, which is lower than both Hai Phong city and national averages The population has remained relatively stable, with a notable trend of migration to the island Gender distribution has not significantly changed over the years, with women slightly outnumbering men, making up 50.69% of the population according to 2011 statistics.
Table 3.1: The population situation of the commune, town in Cat Ba island
(Source: People's Committees of communes, Cat Ba town and district Statistical Yearbook - 2011)
3.2.2.1 Production of industrial and handicraft
The small engineering works, repairing boats, stone production, mineral water, production of building materials, electricity, rapidly developing produce timely service and create Occupations for thousands of workers
In general, industry and handicraft development less powerful, scattered and focused in town
Cat Ba island limestone terrain, so largely lacks surface water The commune on the island with an area not exceeding 200 has of agriculture land The rice output is not
22 high, so do not meet people's demand for agriculture communes as well as people on the island
The agricultural production sector in the district constitutes a mere 1.5% of total production value and 2.3% of GDP, indicating its limited economic impact However, the industry is evolving towards more goods-oriented production, with key products including rice, corn, potatoes, cassava, beans, nuts, green vegetables, fresh fruits, and diverse animal and poultry farming Additionally, hill cultivation and animal husbandry models are gaining popularity in the region, demonstrating increased efficiency and productivity.
Livestock farming on the island is thriving, with local pig production contributing 4 to 5 tons of meat annually to the district Recent initiatives have promoted the development of lean pig breeding and chicken farming to meet the island's food demands and improve living standards The average growth rate of livestock production in the district is 4.75%, providing not only a source of income for families but also essential fertilizer for agricultural activities.
In recent years, the cultivation sector in the locality has consistently experienced an average growth rate, with crop yields increasing by 4.7% annually since 2001 According to the Cat Hai District People's Committee, rice productivity remains relatively low, while other crops such as corn, potatoes, cassava, beans, and groundnuts, despite covering only 61 hectares and producing 133.3 tons, significantly contribute to local food supply and household income Additionally, green vegetables are primarily cultivated in Tran Chau, Xuan Dam, and Viet Hai, occupying 20 hectares and yielding 31.2 tons The area also supports various fruit trees, including oranges, custard apples, peaches, jackfruit, apples, and pineapples, which are planted intermittently on residential land.
Irrigation: Irrigation systems have an important role in agricultural production
The irrigation system in the communes is inadequate, failing to meet the demand for irrigated agriculture Currently, the community's living and production activities depend solely on natural water sources, including rainwater, spring water, and wells The absence of effective irrigation schemes has restricted some agricultural land to rice cultivation only.
The majority of the forest area on Cat Ba Island falls under the management of the national park, resulting in limited forest land within the buffer zone To address this, the district's Forest Protection Unit (FPU) has collaborated with the national park's FPU to implement key initiatives, including focused reforestation, scattered plantations, forest restoration, and ongoing forest care.
Cat Ba Island boasts a total forest area of 15,200 hectares, with 9,800 hectares under the management of the National Park and the remaining 6,400 hectares overseen by a cooperative The island features approximately 293 hectares of natural wood forest, primarily consisting of shrub forests, alongside 126 hectares of resinous pine and additional areas of Acacia plantations.
The Cat Ba Island has successfully planted 121 hectares of trees in recent years, with significant areas dedicated to species such as Cunninghamia lanceolata (30 ha) and bamboo (40 ha) Ongoing investigations into land and forest planning have been effective, leading to limited deforestation across the island.
METHODOLOGY
Field surveys method
4.1.1 Determine the age/sex structure of Cat Ba langur
Age refers to the duration of an individual's life and is measured in various time units based on their lifespan Understanding the age distribution among different generations is crucial in ecological studies, as it can reveal the complexity or simplicity of age structures within populations or species, influenced by their average life expectancy.
In biology, sex refers to gender (male or female) and the process of gamete combination for gene mixing This cross-fertilization enhances fertility and promotes gene pooling among individuals The sex structure of a population plays a crucial role in reproductive efficiency, adapting to environmental changes The ratio of males to females is influenced by the species' genetic traits and environmental factors, including temperature and light conditions.
A group of Cat Ba langurs consists of numerous individuals across various age groups, forming a complex age structure within the herd Researchers determined this age/sex structure through linear and point surveys, allowing them to observe key characteristics such as morphology, vocalizations, and behavior This enables the identification of mature, near-mature, semi-adult, and juvenile langurs, as well as the determination of each individual's sex within the group.
To analyze the age and sex structure of the Cat Ba langur herds, I referenced Rebecca's 2014 study, which identifies the demographic composition as including adult males, adult females, juveniles, and infants (Table 4.1).
Table 4.1: The characteristic of Cat Ba Langur
Age Definition Photo reference Adult Golden-yellow to creamy-white heads, glossy black coat with the possibility of yellow markings around the shoulders
Males are generally more robust than females and typically reach maturity around 7 to 8 years old They feature a distinctive white-tipped penis and lack white patches on their inner thighs, with joined ischial callosities Access to females for mating may vary.
Females: Has given birth at least once, elongated nipples
Slightly smaller than adult males Over five years old White patches on inner thighs and ischial callosities are separated
Subadults Mostly adult pelage but with more orange around the neck and shoulders than the more white head of adults
Males: Penis is white-tipped; no white patches on inner thighs Testes have descended Does not have mating access to females Roughly 3-7 years old
Females: White patches on inner thighs Does not have offspring or elongated nipples Roughly 3-5 years old
Juveniles Yellow/orange on extremities, dark torso, brighter orange Figure 4.1,
26 head than subadults/adults Still hangs out around females, not fully weaned, 2/3 adult body size, is not carried by adults
Has characteristically large stomach Roughly 1-3 years old
Males: No white patches on thighs; undescended testes
Females: White patches on inner thighs
Infants exhibit a yellow to orange hue with a subtle dulling of orange across their bodies Although they are unweaned, they are beginning to consume some solid food These infants are often carried by adult females and typically remain close to them, rarely straying far.
Males: No thigh patches; undescended testes
Females: Thigh patches become visible during this age class
Newborns Bright orange/yellow without any darkening No crest
Unweaned langur infants, typically aged 0-3 weeks, rely entirely on their mothers for nourishment and do not consume solid foods These newborns are often held closely by their mothers, making it difficult to determine their sex Their dependence on maternal care makes them highly desirable to other group members, leading to frequent transfers among caregivers.
(Source: Cat Ba Langur Conservation Project)
Figure 4.1: Juveniles Photo by Nguyen Huy Cam Figure 4.2 Subadults Photo by Nguyen Huy Cam
Figure 4.3: Newborn Photo by Nguyen Huy Cam
Data collection
Data collected in 30 days, from 25th June to 24th July 2018 Focus on 3 locations in Cat Ba Island: Cua Dong, Gia Luan, and Sanctuary
I utilized a Handy Recorder (H4n), an IC recorder (ICD-Ux523), and a Sennheiser K6 to gather audio data on the Cat Ba langur species Data collection involved careful observation of the Cat Ba langur, ensuring that I maintained a safe distance throughout the process.
When observing langurs, maintain a distance of at least 50 meters, allowing them to approach naturally without human initiation It's essential to remain quiet, limiting conversation to soft tones, and avoiding loud noises, including phone calls and shouting Flash photography is prohibited, and any guests must receive prior permission before joining the observation Additionally, sharing content related to the langurs on social media requires prior clearance.
Daily observations of the Cat Ba langur were conducted for 8 hours, from 05:00 to 09:00 in the morning and 15:00 to 19:00 in the afternoon, when the langurs moved to their sleeping caves The research data was regularly updated on the computer to calculate the follow-up time and behaviors of the langurs, ensuring comprehensive data collection and supplementation.
28 resting, moving, foraging, social behavior (Isabell et al, 2010) Data on behavior patterns are analyzed in tables 4.2:
Table 4.2: The behavior of Cat Ba langurs
Table 4.3: Define the behavior of Cat Ba langurs
1 Moving Changing position or location on bamboo poles, on the cage wires, on the ground or in the trees
2 Resting Inactivity, where the animal is sitting or lying down that is not associated with eating, foraging or social activity
3 Foraging The active intake of food and searching for food items (examining vegetation)
4 Social behavior Included grooming activities and playing (running, jumping or play-fighting with one another or alone)
5 Vocal It is the activity of the individual protected from the conflict between the other herd by vocal of male adult
Semi - structure interviews survey
When I go to the field, to learn more about the information of Cat Ba langur, time vocal, and the probability of finding objects in the study area; I have conducted the interview focused on the local people who lived in this area and the forest ranger who directly monitored the langur to gather preliminary information on vocal characteristics and vocal behavior of Cat Ba Langur During the interview, I used the colors photos of Cat
In a study focused on identifying Ba langur species, I conducted interviews with eight individuals from June to July Prior to the interviews, I prepared a comprehensive questionnaire, and the information gathered was meticulously recorded for comparison during subsequent fieldwork.
Data analysis
Using Raven 1.5.0 software, we analyzed voice recording files to examine individual sound spectra, frequency, and vocal length The frequency between the spectra is crucial for understanding the pitch of each sound, measured in Hertz (Hz) Additionally, we determined the duration of each call in seconds (s) and counted the number of consecutive calls, which aids in identifying the unique sound characteristics of each species.
To conduct audio research with Raven software version 1.5.0, begin by collecting field noise using Sony ICD-UX560F and H4n Pro recorders Next, transfer the audio files to your computer Utilize Raven 1.5.0 to process each sound file, and finally, analyze the frequency spectrum of each recording based on frequency (Hz).
RESULTS AND DISCUSSION
Result
5.1.1 The status and the population size of Cat Ba langur
As of July 2018, Cat Ba Island is home to three populations of Cat Ba langurs, totaling 79 individuals The first population consists of 31 langurs residing in three groups within the sanctuary on the island's eastern side The second population, located in Cua Dong/Viet Hai on the southeastern side, comprises 24 langurs in four groups Additionally, four isolated langurs are found at Hang Cai in the far northwestern region, separated from the mainland due to mangrove destruction.
As of July 2018, only 64 Cat Ba langurs remain, comprising 59 individuals in the wild and a group of five langurs in captivity at the Endangered Primate Rescue Center (EPRC) in Cuc Phuong National Park since September 2014 Table 5.1 provides an overview of their status and population structure.
Table 5.1: Population size, age-sex classes for Cat Ba langurs as of July 2018
Cat Ba langur groups by area
Sanctuary Cua Dong Hang Cai EPRC
5.1.2 Vocalization of Cat Ba langur
Figure 3.1: The sound spectrum of the Adult male
The vocalizations of male adults exhibit a broad sound spectrum, characterized by a consistent "Oc Oc" sound in the field These vocal patterns show minimal variation, as detailed in the parameters calculated and presented in Table 5.1.
Table 5.2: The vocal frequency of adult males (n=6)
Time (s) Number of consecutive vocals Highest spectrum Lowest pectrum
The table 5.2 will provide the vocal frequency of adult male with n = 6 The result shows the maximum of the highest spectrum is 2904 Hz, the minimum of the highest is
1890 Hz and the average frequency in the highest spectrum is 2397 Hz In another hand, the maximum of the lowest spectrum is 774 Hz, the minimum of the lowest spectrum is 61
Hz and the average are 417.5 Hz The length of the vocal in the range from 2.9s to 3.2s
Figure 5.2: The sound spectrum of Juveniles
Juvenile vocalizations exhibit a broad sound spectrum, characterized by a consistent "Rit Rit" sound with minimal variation The parameters calculated for these vocalizations are detailed in Table 5.2.
Table 5.3: The vocal frequency of juveniles (n=3)
The table 5.3 will provide the vocal frequency of juveniles with n=3 The result shows the maximum of the highest spectrum is 15591 Hz, the minimum of the highest is
1114 Hz and the average frequency in the highest spectrum is 8352.5 Hz In another hand, the maximum of the lowest spectrum is 13030 Hz, the minimum of the lowest spectrum is
1225 Hz and the average are 7127.5 Hz The length of the vocal in the range from 0.54s to 0.747s
Figure 5.3: The sound spectrum of Infants
Infants produce a wide range of sounds, characterized by the distinct "Chit Chit" vocalization This sound exhibits two different shapes; one resembles a parabolic curve, while the other shows varying amplitude within the audio frequency spectrum Despite these variations, the vocal characteristics remain largely consistent, with minimal changes observed Detailed calculations of these vocal parameters are presented in Table 5.3.
Table 5.4: The vocal frequency of Infants (n=4)
Time (s) Number of consecutive vocals
The table 5.4 will provide the vocal frequency of infant with n=4 The results show the maximum of the highest spectrum is 21453 Hz, the minimum of the highest spectrum is
4380 Hz and the average of the highest spectrum is 12916.5 Hz In another hand, the maximum of the lowest spectrum is 13340 Hz, the minimum of the lowest spectrum is
The frequency range between the highest spectrum at 8885 Hz and the lowest at 4430 Hz is significantly large Additionally, the vocal length falls within the range of 1.31 seconds to 1.46 seconds.
5.1.3 Vocalization behavior of Cat Ba Langur
5.1.3.1 The rate of vocalization behavior in the day
The results of the monitoring of specific activities in Cat Ba Island area after the actual data collection has identified the operational time of the langur (figure 5.4) as follows:
Figure 5.4: The behavior of Cat Ba langur
The daily behavior of the Cat Ba langur reveals that foraging occupies the largest portion of their time at 34%, followed by moving at 29%, resting at 18%, social interactions at 13%, and vocalizations at a mere 5% This indicates that vocal activity is minimal, constituting only 5% of their total daytime activities.
5.1.3.2 The appearance of vocalization behavior is related to age and sex
MovingRestingForagingVocalSocial behavior
Table 5.5: The number of vocal by individual
Individual The number of vocals (times) Averages (%)
The data collected in the field, as illustrated in Table 5.4, reveals vocalization patterns among Cat Ba langurs Notably, adult males are the most vocal, accounting for 58% of the recorded sounds, followed by infants at 32% and juveniles at 11% However, no vocalizations were recorded from female adults, newborns, male subadults, or female subadults during the observation period.
5.1.3.3 The vocalization behavior of Cat Ba langur by time
During my field trip, I recorded vocalizations from three Cat Ba Langur individuals, specifically targeting male adults, juveniles, and infants Figure 5.5 illustrates the vocalization behavior of Cat Ba Langur throughout the day.
Figure 5.5: The vocalization behavior of Cat Ba langur by time
Figure 5.5 shows the vocalization behavior of Cat Ba langur by the time of the day
Male adults vocalize frequently throughout the day, notably between 5:00 - 7:00 AM to call the herd out of the cave for foraging, from 7:00 - 9:00 AM to guide them to the valley or warn of boundaries, and again from 5:00 - 7:00 PM to gather the herd back to the cave for sleep or to signal boundaries Infants also vocalize during the day, particularly between 7:00 - 9:00 AM and 5:00 - 7:00 PM, as they engage in social behaviors like jumping and playing with peers Additionally, juveniles vocalize during the evening hours of 5:00 - 7:00 PM, reflecting their social interactions within the herd.
Discussion
The study on Cat Ba Langur identified three primary types of vocalizations: "Oc Oc," "Rit Rit," and "Chit Chit." The "Oc Oc" call is typically heard during early mornings and evenings, with adult males often repeating it two to three times This vocalization serves as a warning to delineate the herd's boundaries.
The presence of invading herds signals the preparation for the animals to leave their cave for morning foraging or return for evening rest Juvenile members of the herd often communicate with a "Rit Rit" sound while playing, while infants emit a "Chit Chit" when seeking assistance during challenging movements or adverse weather conditions In the mornings, as the herd navigates rocky terrain and descends to forage, the male adults also vocalize, contributing to the group's communication.
Male adults use a warning sound, "Oc Oc," to alert the herd of potential danger and to stop all activities They frequently emit this sound to deter other herds from entering their territory Additionally, when two males encounter each other, they produce a continuous sound until one is forced to leave, or they engage in a fight, which can result in one of them being injured or driven away.
Research limitations hinder the ability to study primate vocalizations effectively, resulting in many unrecorded vocal forms from adult males, females, subadults, and newborns.
5.2.1 Solutions to improve the conservation and development of Cat Ba Langur
To ensure the conservation of Cat Ba langurs on Cat Ba Island in Hai Phong city, it is essential to enhance collaboration between forest rangers and local communities Joint patrols will help effectively monitor and combat illegal hunting activities in the region.
The study area faces significant challenges, including firearms use, hunting, trapping, wildlife trade, and the exploitation of forest products To address these issues, it is essential to enhance patrolling efforts by forest rangers in critical zones of the national park and habitats of langurs Additionally, a voluntary weapon surrender program should be established, along with strict enforcement of penalties for violations to protect wildlife and preserve the ecosystem.
To enhance the protection and education of local communities, particularly those residing in the buffer zone surrounding the live langur population, it is essential to strengthen propaganda measures Implementing a variety of extracurricular activities aimed at educating children about the biodiversity within Cat Ba National Park will foster a deeper understanding and appreciation for these unique species.
Encourage further intensive research into the characteristics of Cat Ba species in the future for zoologists, students, and interns
PART VI CONCLUSION AND RECOMMENDATIONS
Conclusion
This thesis investigates the vocalization behaviors of the Cat Ba Langur across three locations in Cat Ba Islands: Cua Dong, Gia Luan Commune, and the Sanctuary It identifies three distinct vocal types—"Oc Oc," "Rit Rit," and "Chit Chit"—across three age groups: male adults, juveniles, and infants The study provides detailed data on the frequency, number of beeps, and varying vocal lengths for each individual Notably, the findings reveal that the frequency of vocalizations is highest in infants, followed by juveniles, with adult males exhibiting the lowest frequency.
Vocal activity among Cat Ba Langurs is minimal, representing only 5% of their total behavioral activities, with adult males vocalizing the most at 58%, followed by infants at 32% and juveniles at 11% Notably, male adults primarily vocalize during two peak times: from 5:00 to 7:00 AM and 5:00 to 7:00 PM, while juveniles and infants are most vocal between 5:00 and 7:00 PM To enhance the conservation of Cat Ba Langurs in their habitat, it is crucial to implement protective measures such as habitat preservation, reducing human disturbances, and increasing awareness of their vocalization patterns to aid in monitoring their social interactions and overall health.
Recommendations: 40 REFERENCES
Fieldwork conducted on Cat Ba Island in Hai Phong City faced challenges due to limited research time and prolonged rainy weather The study area, which includes both marine and forest ecosystems, made access to the langur population difficult As a result, the findings are considered relative The herd's natural movement patterns also affected the consistency of voice recorder operations, leading to variability in the recorded sounds.
41 individual in the vocal is difficult to obtain due to the relatively high mountain terrain with low recording ability
Therefore, we should have a long time for this research, need to collect data of Cat
The Ba Langur at the Endangered Primate Rescue Center (EPRC) in Cuc Phuong National Park requires extensive data collection on the vocalizations of individual Cat Ba langurs to enhance the understanding of their unique voice characteristics Conducting thorough surveys in both natural habitats and the EPRC is essential for improving research outcomes on this species.
1 "The Cat Ba Langur: a primate walks the razor's edge of extinction" Mongabay Environmental News
2 Ben, S (5 March 2003) "Experts Say Viet Tourism Overtaking Conservation, as Monkey Nears Extinction" San Jose Mercury News
3 BirdLife Indochina – Cat Ba National Park (April, 2006)
4 Bleisch B, Le Xuan Canh, Covert B, Yongcheng L (2008a) Trachypithecus poliocephalus The IUCN Red List of Threatened Species Version 2015.2
5 Bleisch B, Nguyen Manh Ha, Le Khat Quyet, Yongcheng L (2008c) Trachypithecus francoisi The IUCN Red List of Threatened Species Version 2015.2
6 Brandon-Jones D (1995) A revision of the Asian pied leaf monkeys (Mammalia: Cercopithecidae: Superspecies Semnopithecus auratus), with a description of a new subspecies Raffles Bull Zool 43:3–43
7 Cat Ba Langur Conservation Project (April, 2006)
8 Cat Ba Langur Conservation Project News
9 Delson E (1994) Evolutionary history of the colobine monkeys in paleoenvironmental perspective In: Davies G, Oates JF (eds) Colobine monkeys: Their ecology, behavior and evolution Cambridge University Press, New York, pp 11–43
10 Fooden, J 1996 Zoogeography of Vietnamese primates Int J Primatol
11 Groves CP (1989) A theory of human and primate evolution Clarendon Press, Oxfor
12 Groves CP (2001) Primate taxonomy Smithsonian Institution Press, Washington D.C
13 Groves CP (2007) Speciation and biogeography of Vietnam’s primates Vietnam J Primatol 1:27–40
14 Isabell Schneider, Inge H.M Tielen, Johanna Rode, Pieter Levelink and Daniela Schrudde 2010 "Behavioral Observations and Notes on the Vertical Ranging Pattern of the Critically Endangered Cat Ba Langur (Trachypithecus Poliocephalus Poliocephalus) in Vietnam"
15 Jablonski NG (2002) Fossil Old World monkeys: The late Neogene radiation In: Hartwig WC (ed) The primate fossil record Cambridge University Press, Cambridge, pp 255–299
16 Karanth KP (2010) Molecular systematics and conservation of the langurs and leaf monkeys of South Asia J Genet 89:393–399
17 Kirkpatrick RC (2007) The Asian colobines: Diversity among leaf-eating monkeys In: Campbell CJ, Fuentes A, Mackinnon KC, et al (eds) Primates in perspective Oxford University Press, New York and Oxford, pp 189–201
18 Li Z, Wei Y, Rogers E (2003) Food choice of white-headed langurs in Fusui, China Int J Primatol 24:1189–1205
19 Lippold, L K., and Vu Ngoc Thanh 1998 Primate Conservation in Vietnam In: The Natural History of the Doucs and Snub-nosed Monkey, N G Jablonski (ed.)
20 Mark H (2009) Karst landscapes in the Bay of Ha Long, Vietnam Geogr Rundsch Int
21 Meyer D, Rinaldi ID, Ramlee H, et al (2011) Mitochondrial phylogeny of leaf monkeys (genus Presbytis, Eschscholtz, 1821) with implications for taxonomy and conservation Mol Phylogenet Evol 59:311–319
22 Mittermeier, R.A., Valladares-Pádua, C., Rylands, A.B., Eudey, A.A., Butynski, T.M., Ganzhorn, J.U., Kormos, R., Aguiar, J.M and Walker, S (2005) Primates in Peril: The World’s 25 Most Endangered Primates 2004–2006 IUCN/SSC Primate Specialist Group (PSG), International Primatological Society (IPS), and Conservation International (CI), Arlington, VA
23 Nadler T (2010) Status of Vietnamese primates-complements and revisions In: Nadler
T, Rawson BM, Van Ngoc Thinh (eds) Conservation of primates in Indochina Frankfurt Zoological Society, Hanoi, pp 3–16
24 Nadler T, Ha Thang Long (2000) The Cat Ba langur: Past, present, and future The definitive report on Trachypithecus poliocephalus, the world’s rarest primate Frankfurt Zoological Society, Hanoi
25 Nadler T, Momberg F, Nguyen Xuan Dang, Lormee N (2003) Vietnam primate conservation status review 2002 Part 2: Leaf Monkeys Fauna & Flora International, Frankfurt Zoological Society, Hanoi
26 Nisbett RA, Ciochon RL (1993) Primates in northern Viet Nam: A review of the ecology and conservation status of extant species, with notes on Pleistocene localities Int J Primatol 14:765–795
27 Oates JF, Davies AG (1994) What are the colobines In: Davies AG, Oates JF (eds) Colobine monkeys: Their ecology, behaviour, and evolution Cambridge University Press, Cambridge, pp 1–10
28 Osterholz M, Walter L, Roos C (2008) Phylogenetic position of the langur genera Semnopithecus and Trachypithecus among Asian colobines, and genus affiliations of their species groups BMC Evol Biol 8: DOI: 10.1186/1471-2148-8-58
29 Pan R, Groves C (2004) Cranial variation among the Asian colobines In: Anapol F, German RZ, Jablonski NG (eds) Shaping primate evolution: Form, function, and behavior Cambridge University Press, Cambridge, pp 45–65
30 Perelman P, Johnson WE, Roos C, et al (2011) A molecular phylogeny of living primates PLoS Genet 7:e1001342
31 Phan Duy Thuc, Bosch OJ, Nguyen Cam Nam, Tuyen Thanh C (2014) Dynamics and viability of the Critically Endangered Cat Ba Langur: A new perspective for conservation actions In: Proceedings of the 57th Annual Meeting of the ISSS-2013 Haiphong, Vietnam, pp 1-27
32 Quan Nguyen (March 2010) Translated by Van; Duc, Thanh; Van "Landscapes and
Ecosystems of Tropical Limestone: Case Study of the Cat Ba Islands, Vietnam" Journal of Ecology and Field Biology
33 Roos C (2003) Molecular phylogeny and systematics of Vietnamese leaf monkeys Vietnam Primate Conserv Status Rev 2002-Part 2 Leaf Monkeys 19–23
34 Roos C, Boonratana R, Supriatna J, et al (2014) An updated taxonomy and conservation status review of Asian primates Asian Primates J 4:2–38
35 Roos C, Nadler T, Walter L (2008) Mitochondrial phylogeny, taxonomy and biogeography of the silvered langur species group (Trachypithecus cristatus) Mol Phylogenet Evol 47:629–636
36 Roos C, Zinner D, Kubatko LS, et al (2011) Nuclear versus mitochondrial DNA: Evidence for hybridization in colobine monkeys BMC Evol Biol 11:1–13
37 Roos C., Vu Ngoc Thanh, L Walter, and T Nadler 2007 Molecular systematics of Indochinese primates Vietnam J Primatol
38 Schneider, Isabell; Tielen, Inge H.M.; Rode, Johanna; Levelink, Pieter; Schrudde, Daniela (2010-12-01) "Behavioral Observations and Notes on the Vertical Ranging Pattern of the Critically Endangered Cat Ba Langur (Trachypithecus Poliocephalus Poliocephalus) in Vietnam"
39 Schrudde D, Levelink P, Raffel M (2010) Protection of the Cat Ba langur (Trachypithecus [poliocephalus] poliocephalus) through the ―Cat Ba Langur Conservation Project.‖ In: Nadler T, Rawson BM, Van Ngoc Thinh (eds)
Conservation of primates in Indochina Frankfurt Zoological Society, Hanoi, pp 237–
40 Sterling EJ, Hurley MM, Le Duc Manh (2006) Vietnam: A natural history Yale University Press, New Haven
41 Sterner KN, Raaum RL, Zhang Y-P, et al (2006) Mitochondrial data support an odd- nosed colobine clade Mol Phylogenet Evol 40:1–7
42 Strasser E, Delson E (1987) Cladistic analysis of cercopithecid relationships J Hum Evol 16:81–99
43 Ting N, Tosi AJ, Li Y, et al (2008) Phylogenetic incongruence between nuclear and mitochondrial markers in the Asian colobines and the evolution of the langurs and leaf monkeys Mol Phylogenet Evol 46:466–474
44 Trouessart E-L (1911) XXXIII —On a new species of Semnopithecus (Semnopithecus poliocephalus) from Tonkin J Nat Hist 8:271–272
45 Van Ngoc Thinh, A R Mootnick, Vu Ngoc Thanh, T Nadler and C Roos 2010 A new species of crested gibbon, from the central Annamite mountain range Vietnam J Primatol
46 Wang W, Forstner MR, Zhang Y, et al (1997) A phylogeny of Chinese leaf monkeys using mitochondrial ND3-ND4 gene sequences Int J Primatol 18:305–320
47 White-headed langur (Trachypithecus poliocephalus) ARKive Accessed 2008-07-15
48 Zhang Y, Ryder OA (1998) Mitochondrial cytochrome b gene sequences of Old-World monkeys: With special reference on the evolution of Asian colobines Primates 39:3
Nguyen Manh Ha's 1999 thesis examines the primate fauna and ecology of the Hatinh langur (Trachypithecus francoisi hatinhensis) within the Phong Nha – Ke Bang Nature Reserve, located in Quang Binh Province, Vietnam Conducted at the Forestry University of Vietnam, this research provides valuable insights into the habitat and conservation needs of this endangered species.
Table 1: The vocal frequency of Juveniles
Table 2: The vocal frequency of Infant
Table 3: The vocal frequency of male adult
Table 4: List of people interviewed
ID Name Study area Job
1 Vu Duc Tang Cua Dong Fishermen
2 Tran Van Lenh Cua Dong Fishermen
3 Pham Van Day Viet Hai/ Cai Minh Tu Fishermen
4 Vu Van Chau Hang Cai/ Gia Luan Fishermen
5 Vu Van Chu Hang Cai/ Gia Luan Fishermen
6 Pham Ngoc Son Ranger Station of Van Ta/ Sanctuary Forest Ranger
7 Nguyen Van Thiet Ranger Station of Gio Cung/ Sanctuary Forest Ranger
8 Pham Van Man Ranger Station of Ang Ke/ Gia Luan Forest Ranger