Detecting the presence of nocturnal birds in cat tien national park using bioacoustics method

Distribution of some bird species and favorite habitat for the detected birds in each forest types Cat Tien NP ..... The thesis detected 5 bird species divided into 2 orders and 2 famili

MINISTRY OF AGRICULTURE AND RURAL DEVELOPMENT

VIETNAM NATIONAL UNIVERSITY OF FORESTRY

STUDENT THESIS

DETECTING THE PRESENCE OF NOCTURNAL BIRDS IN CAT TIEN

NATIONAL PARK USING BIOACOUSTICS METHOD

Major: Natural Resources Management

Code: D850101

Faculty: Forest Resources and Environmental Management

Student: Vũ Huyền Linh Student ID:1453092355 Class: K59B_ Natural Resources Management Course: 2014 - 2018

Advanced Education Program Developed in collaboration with Colorado State University, USA

Supervisor: Assoc.Prof.Vu Tien Thinh

ACKNOWLEDGMENT

Firstly, I would like to express my sincere gratitude to my supervisor Assoc.Prof.Vu Tien Thinh for his great support, patience, motivation, and immense knowledge His guidance was really helpful so this thesis has been finished I am very grateful to him for enlightening me the first glance of the thesis

Besides, I would like to extend my thanks to Ms Nguyen Thi Hoa, member of the Department of Wildlife in the Vietnam National University of Forestry for guiding me to apply RAVEN software on the process of analyzing data There are no words to show my appreciation to her for assisting and helping me during the period of two months when I did my thesis in the office of the Department of Wildlife

I also would like to thank my fellow labmates Ms Lan Tran for the stimulating discussions, for the sleepless nights we were working together before deadlines, and for all the fun we have had in the last years Also, I want to send my thank to my friend, Mr An

Le for his insightful comments, encouragement and hard questions which incented me to widen my thesis from various perspectives

Last but not least, I would like to thank my family: my parents, my brothers, and sisters for supporting me spiritually throughout writing this thesis and my life in general

ABSTRACT

LIST OF FIGURE

LIST OF TABLE

ABBREVIATIONS

CHAPTER 1: INTRODUCTION 1

CHAPTER 2: STUDY GOALS, OBJECTIVES 4

2.1 Goals 4

2.2 Objectives 4

CHAPTER 3: STUDY SITES 5

3.1 Natural condition 5

3.1.1 Geographical location 5

3.1.2 Geography conditions 6

3.1.3 Hydrology Soil 8

3.1.4 Climate 8

3.1.5 Flora 10

3.1.6 Fauna 11

3.1.7 Forest type 11

3.2 Social features 13

CHAPTER 4: METHODS 15

4.1 Study site selection 15

4.2 Data Collection 15

4.3 The locations recorders in Cat Tien National Park 18

4.4 Sound Analysis 21

4.5 Pre-analysis of results 24

CHAPTER 5: RESULTS 26

5.1 Determining the presence of nocturnal birds in Cat Tien NP 26

5.1.1 Nocturnal bird detected species from the recording in the study site 26

5.1.2 The comparison between the spectrograms of detected birds and the spectrogram of sample targeted birds in Cat Tien NP 27

5.1.3 Determining the frequency of appearance of the nocturnal bird in Cat Tien NP 33

5.2 Determining the distributions of some bird species and favorite habitat for the targeted bird in Cat Tien NP 36

5.2.1 Distribution of nocturnal bird species of them at 7 location in Cat Tien NP 36

5.2.2 Distributions of detected bird species and their favorite habitats in Cat Tien NP 39

CHAPTER 6: DISCUSSION 42

6.1 Detected the presence of the nocturnal bird in Cat Tien NP 42

6.2 Distribution of some bird species and favorite habitat for the detected birds in each forest types Cat Tien NP 44

CHAPTER 7: CONCLUSION 47

REFERENCE 48

APPENDIX 49

ABSTRACT

Detection and recognition of birds are important to reduce bird mortality and, thereby, in order to protect endangered species Consequently, we need to find out exactly what their presence and habitats are When a bird sings, it's telling you what it is and where

it is Especially, determining of bird sound from nocturnal birds is difficult to study Researching the nocturnal bird species is a painstaking process, with every piece of data collected to understand their habitats However, surveying for nocturnal birds by the traditional method had many limitations and often did not give accurate information, which causes many difficulties for conservation Some methods can hurt the birds, as well as the researchers, could have trouble if they researched in bad conditions or in the dark In this thesis, the utility of automated bioacoustics recorders was examined and the associated classification by RAVEN software which was used as a way to survey for the nocturnal bird species The survey was conducted at 7 study sites which belong to three communes in Cat Tien National Park, Dong Nai province from August 17th to October 4th, 2018 The thesis detected 5 bird species divided into 2 orders and 2 families in the total of 9 targeted bird species at the 7 locations with different habitat types in Cat Tien National Park The data obtained from the recorders revealed that nocturnal bird was most active just at midnight and before dawn, and least active during the dusk As a result, the study found that recording at both midnight and dawn or only at dawn would give reasonably high levels of detection The study also pointed out that their frequencies of occurrence of bird vary among species Moreover, some bird species sing many times in the recordings On the contrary, some birds species sing only one in recordings The thesis also found that almost detected birds live in Bang Lang Da Co forest and Tuong mountain and a small number of them live in Bau Sau, Rang stream and Cat Tien center which are mainly evergreen forests

LIST OF FIGURE

Figure 4.1: Map of study site in Cat Tien National Park 15

Figure 4.2: An automatic recorder was attached to a tree 16

Figure 4.3: The location of 30 automatic recorders in Cat Tien National Park 18

Figure 4.4: The interface of the RAVEN software 21

Figure 4.5: The process of converting spectrogram’s frequency by Audacity software 22

Figure 4.6: The interface of correlation configuration 23

Figure 5.1: The detection of percentage nocturnal bird in 7 locations in Cat Tien NP 27

Figure 5.2: The percent of the active time during surveying time of Oriental Scops Owl 33

Figure 5.3: The percent of the active time during surveying time of Asian Barred Owlet 33 Figure 5.4: The percent of the active time during surveying time of Spot-bellied Eagle-Owl 34

Figure 5.5: The percent of the active time during surveying time of Brown Hawk-Owl 34

Figure 5.6: The percent of the active time during surveying time of Great Eared-Nightjar 35 Figure 5.7: Map of nocturnal bird detected species in the study site 37

Figure 5.8: Forest types of recorded locations in Cat Tien 41

LIST OF TABLE

Table 3.1: Area according to forest status and land types in Cat Tien National Park 6

Table 3.2: Climate of Cat Tien National Park 9

Table 3.3: The species recorded in Cat Tien National Park 11

Table 4.1: List of targeted bird species in Cat Tien National Park 17

Table 4.2: Characteristics of 30 automatic recorders in study sites in Cat Tien National Park 19

Table 4.3: Birdsong detected at location … in … from… 23

Table 4.4: List of nocturnal bird species detected in the study site 24

Table 4.5: The most active time during surveying time of nocturnal bird 24

Table 4.6 Distribution of nocturnal bird species of them in Cat Tien NP 25

Table 4.7: Characteristics of 30 automatic recorders in study sites in Cat Tien National Park 25

Table 5.1: List of nocturnal bird species detected in the study site 26

Table 5.2: Comparison between the spectrogram of Great Eared-Nightjar and the sonogram of sample Great Eared-Nightjar 28

Table 5.3: Comparison between the spectrogram of Asian Barred Owlet and the sonogram of sample Asian Barred Owlet 29

Table 5.4: Comparison between the spectrogram of Brown Hawk-Owl and the sonogram of sample Brown Hawk-Owl 30

Table 5.5: Comparison between the spectrogram of Spot-bellied Eagle-Owl and the sonogram of sample Spot-bellied Eagle-Owl 31

Table 5.6: Comparison between the spectrogram of Oriental Scops-Owl and the sonogram of sample Oriental Scops-Owl 32

Table 5.7: The most active time during surveying time of nocturnal bird 35

Table 5.8 Distribution of nocturnal bird species of them in Cat Tien NP 38

Table 5.9 Distributions of bird species detected and favorite habitat of them in Cat Tien NP 40

CHAPTER 1: INTRODUCTION

For centuries, deforestation, farming, urbanization, and other human activities have wreaked bird species generally and wild animal species in particular and sent them to the verge of extinction That's also why management of endangered bird species requires detailed information on the distribution and abundance of the species that are often hard to obtain Thesis understands the importance of detection and recognition of birds’ species to reduce bird mortality and protect endangered species, which is the aim of the thesis In this thesis, bioacoustics method with high-end sound recorders and advanced RAVEN software were used to detect the presence of the nocturnal bird in Cat Tien NP to and provide base data for conservation purposes.(

Birds (Aves) are some of the most amazing animals on earth They are very diverse groups of animals with amazing characteristics They are a group of endothermic vertebrates, characterized by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a lightweight but strong skeleton Their bodies are covered with feathers and they have wings Feathers have three functions: flight, temperature regulation, and display (wikipedia.org) Nocturnal birds are quite different from their diurnal (daytime) relatives Physically, these birds have a number of traits different from more familiar daytime birds They have dull plumage colors because bright colors which are difficult to see at night, most nocturnal bird species lack red, blue, orange or other bold colors Instead, these birds have more muted plumage with shades of brown, gray, black and white Males and females typically look very similar Moreover, camouflaged patterns are common among nocturnal birds When these birds are roosting during the day, strongly camouflaged plumage helps them blend into their surroundings and keeps them safe from predators Nocturnal birds often have eyes that are exceptionally large in relation to their head and body size These oversized eyes help collect what limited

light is available to enhance their vision In addition to larger eyes for better vision, other senses, such as hearing and smell, maybe acuter in nocturnal birds than in diurnal birds For example, owls have facial disks that help enhance their hearing Birds that are active at night also behave differently than daytime birds When they are spotted during the day, they may seem relatively tame and calm, but that is a defense mechanism rather than a sign

of mellow behavior These birds will instinctively freeze and remain immobile when they feel threatened in the daylight, hoping that their camouflage conceals them and trying not

to attract additional attention by moving (Melissa mayntz, 2018) In the thesis, I have chosen which 9 species are the most popular bird species to research include: Barn Owl

(Tyto-Alba -Scopoli 1769), Oriental Scops-Owl (Otus-sunia - Hodgson, 1836), Spot-bellied Eagle-Owl (Bubo nipalensis - Hodgson, 1836), Brown Fish-Owl (Ketupa zeylonensis -

Gmelin, 1788), Asian Barred Owlet (Glaucidium cuculoides - Vigors, 1831),Brown

Hawk-Owl (Ninox scutulata - Raffles, 1822), Collared Scops Hawk-Owl (Otus bakkamoena -

Pennant,1769), Great Eared-Nightjar (Lyncornis macrotis - Vigors,1831). (birdlist.org)

The thesis was studied in Cat Tien National Park, which covers 71,920 hectares (278 square miles) of lowland forests and swamps in southern Viet Nam and is home to numerous birds and mammals It is approximately 160 km (100 miles) northeast of Ho Chi Minh City There are many mammals including a number of primate species such as the endemic Golden-cheeked gibbon, Bears, Elephant, and Gaur Many birds can be found such as Germain's Peacock Pheasant, Bar-bellied Pitta, and the rare endemic Orange-necked Partridge The diversity of the Park has been recognized by WWF when this international organization selected the Park as one of 200 global ecological zones including the land and its water area with its well-known biological diversity In 2001 Cat Tien National Park has been listed by UNESCO as the 411th biosphere Reserve Zone in the world However, determining of bird sound from nocturnal birds are very difficult to study

Researching the nocturnal is a painstaking process, with every piece of data I need to understand the habitat it requires and its landscape Surveying for nocturnal birds by the traditional method has many limitations and often do not give accurate information, cause many difficulties for conservation Some methods can hurt the bird and the researchers could have trouble if they research in bad conditions and in the dark So, the method used

in the thesis is the bioacoustics method with high-end sound recorders automatic and advanced RAVEN software help easily to identify the sounds of each species at different points in Cat Tien NP Acoustic communication in birds is rich and lends itself to one of the primary ways in which birds make their presence is known to each other, as well as one

of the most direct ways for humans to detect them, often at times when they are difficult to see Further, the vast majority of birds have songs or calls that serve as a species-specific acoustic signature that readily announces their presence This abundance of sound provides

a readymade source of information that can be used to explore the composition of bird diversity in particular regions of interest Moreover, electronic developments and subsequent miniaturization of the equipment have opened up new horizons for bioacoustics

in recent years Today, it is easy and cheap to obtain basic equipment for bio-acoustical research, and even powerful laptops can now be used in the field along with high-end sound recorders and advanced software These new technologies have transformed the way sounds can be sampled, analyzed, stored and accessed As a consequence, currently, the collections of animal sounds produced by insects, amphibians, mammals, and birds for

communication, are widely used and applied for research (Gianni Pavan, 2008)

I hope this thesis will give the best results in the detected of nocturnal birds through the use of the bioacoustics method in Cat Tien National Park

CHAPTER 2: STUDY GOALS, OBJECTIVES

2.1 Goals

This thesis aims to use bioacoustics method with high-end sound recorders and advanced RAVEN software to detect the presence of the nocturnal bird in Cat Tien NP to and provide base data for conservation purposes

2.2 Objectives

The study has 2 main objectives as follows:

Objective 1: Determining the presence of nocturnal birds in Cat Tien NP

Objective 2: Determining the distribution of 9 target bird species and favorite

habitat for the targeted bird in Cat Tien NP

CHAPTER 3: STUDY SITES

- North Latitude: From 11 20'50 "to 11 50'20"

- East Longitude: From 107 009'05 "to 107 035'20"

The area of Cat Tien National Park is 82,637.3 ha, including:

- Lam Dong Province is 27,374.7 ha

+ Cat Loc area: 27,317.9 ha

+ Dao Tien area: 56.8 ha

- Binh Phuoc province is 4,382.8 ha

- Dong Nai province is 50,879.7 ha

+ Nam Cat Tien area: 39,527.1 ha

+ Dac Lua protection forest: 1,418.0 ha

Table 3.1: Area according to forest status and land types in Cat Tien National Park

- Mixed woodland (Wood– Bambusa procera

- High mountain with slope side: It mainly locates in the North of Cat Tien

National Park The elevation is 200m – 600m above sea level, slope 150 - 200 with some areas are over 300 The topography is mostly sloping at the mountainsides, the areas in the center of river, stream and at the top are flat The division grade is complex and is the beginning of small streams flowing into the DongNai river

- Medium-high mountain with slope side: Locating at the West South of Cat Tien

National Park with an elevation of 200m - 300m, slope 150 - 200, high division Big streams as Dac Lua, Da Tapok are formed by this hilly midland and finally pour into Dong Nai river

- Low and flat hill: Locating at the East South of Cat Tien National Park with an

elevation of 130m - 150m, the slope of 50 - 70, little division

- Dong Nai river bench and hill connecting to the swamp: At the West South of

Cat Tien National Park, with a mean elevation of 130m.The gradient is 5-7° and partial separation

- Stream bench mixed with lake and swamp: This type of terrain includes small

streams, scattering flooded lands, lakes and ponds in the branch of Dac Lua stream and the central area in the north of the Park It is often in lack of water in the dry season but flooded in the rainy season In the dry season, the water exists only in big swampy areas such as Bau Sau, Bau Chim, Bau Co, The elevation of this area is less than 130m

The National Park grade is down from the North to the South and West to East, elevation of 626m in Loc Bac and 115m in, Nui Taong

3.1.3 Hydrology Soil

Cat Tien National Park consists of three main structures: Sediment, Bazal, and Jatropha have developed into four main soil types:

- Land developed in Bazal (Fk): This type of land has the largest area( nearly 60%

of the natural area of the NP) and is mainly distributed in the South of the Cat Tiên National Park It is one of the richest nutrient soils, good soil, deep, thick (red or reddish brown and dark brown) and has many rocks from the volcano are not fully weathered On this land, the forest grows well, there are many species of precious trees and the ability of forests to recover quickly

- Land developed on sandstone (Feldspar Stone) (Fq): occupying the second

largest area of the NP about 20% is distributed mainly in the area of Cat Loc

- Land developed on clay (Fs): the area is not large, mainly in the south,

alternating with Bazal land The soil here is fertile but the mechanical components are so heavy so when deforestation that leads the soil root degradation quickly

- Land developed on ancient alluvium (Fo): (gray soil on ancient alluvium ):

including the types of soil deposited along streams and along the Dong Nai River also occupy a large area in the north and southeast of Cat Tien National Park This soil is poor

in nutrients The water level is quite shallow to help the growth and development of forest trees during the dry season

3.1.4 Climate

Cat Tien National Park is located in the tropical monsoon climate with two distinct rainy and dry seasons Rainy season is usually from May to October, dry season usually from November to April next year

The climate of the two regions is also quite different between the North and the South of Cat Tien National Park Because of the terrain of Cat Tien National Park is located in two areas: mountains and hills of different heights

Data collected from two hydro-meteorological stations:

- Cat Tien Station (Lam Dong): collecting rainfall data and Bao Loc station (Lam

Dong province) for collecting data on temperature and humidity (Cat Loc area)

- Ta Lai station (Dong Nai): collect data on precipitation and Ben Cat (Binh

Duong) to collect data on temperature and humidity (Cat Tien area)

Table 3.2: Climate of Cat Tien National Park

2 The highest average temperature (oC) 23,0 ( 6 month) 28,6 (6month)

3 Lowest average temperature (oC) 21,1 (12 month) 20,5 (1month)

4 The average amount of rain per year (mm) 2.675 2.175

5 The highest monthly rainfall (mm) 494,8 (9month) 368 (9month)

6 The lowest monthly rainfall (mm) 23,8 (2month) 11 (2month)

7 An average number of rainy days per year

9 The average time for rain in the rainy season

10 Rainfall in rainy season / Annual rainfall (%) 97,4 88,3

As such, Cat Loc area has low average annual temperature and annual average rainfall and humidity are higher than in the South Cat Tien and West Cat Tien So, Plants also have a different distribution of vegetation and vegetation composition

3.1.5 Flora

Cat Tien NP is known with 3 main vegetation covers: Closed evergreen tropical humid rain forest; closed semideciduous tropical humid rain forest; closed deciduous tropical humid rainforest

According survey results show that the plant composition of Cat Tien National Park

is 1,618 species of plant, belonging to 706 genera, 167 families, 57 orders, and 10 classes

of 06 different plant species

Including endemic species, rare species of plants in Vietnam, IUCN results are as follows:

There are 25 species belonging to 25 genera, 17 families, 13 families are discovered in Dong Nai (collected according to species name in "Vietnamese Herbs" by Pham Hoang Ho, 2003)

Big trees: 176 species; small trees: 335 species; Mini plants: 345 species, floristic composition: 311 species; vine: 238 species; Epiphyte, phytoparasite plants: 143 species; Semi-plant: 62 species

Specious plants: 38 species of 13 families such as Afzelia Xylocarpa, Dalbergia sp., Pterocarpus macrocarpus, Sindora siamensis, Dispyros martima, Xylia xylocarpa, that have listed in Vietnamese Red Book

The endemic gene and local endemic trees: 22 species of 12 families such as Thien Thien Dong Nai, Ve Tuyen Ngot of Thien Ly family

3.1.6 Fauna

According to the research, there are 1,498 species of wildlife belonging to 216 families, 51 in CT National Park The number of species in the animal classes (show in Table below)

Table 3.3: The species recorded in Cat Tien National Park

Cat Tien National Park is divided into 5 types of forest as follows:

- Evergreen broad-leaved forest: mainly in the southwest and northwest of Cat

Loc and southeast of the area of Nam Cat Tien, are cut into small flats, usually good land

areas The majority is trees of Dipterocarpaceae such as Dipterocarpus alatus,

Dipterocarpus intricatus, Dalbergia alatus, Dalbergia mammosa, Afzelia xylocarpa, pterocargus macrocarpus

- Deciduous forest (Often green leaves with half fallen forest): in the North East

of Cat Tien, near the Dong Nai River often green leaves with half fallen forest The land is shallow and drier than evergreen broadleaved forest Mainly are trees with fallen leaves in

the dry season as Lagerstroemia calyculata, Tetrameles nudiflora, Anogeissus acuminate

- Bamboo forest: distributed in the east and south of the park This is also affected

by human beings After the rice fields made by destroying the forest and be ignored creating favorable condition for the growing of bamboos The two popular bamboos are

Bambusa procera and Gigantochloa sp Forming big parts of the forest There is only La Nga bamboo exists in the flooded area

- Trees mixed with bamboo forest (mixed forest): This is affected by the human

beings, the forest often green with half of which have leaves fallen by a forest fire, toxic chemicals, the forest canopy is opened and bamboos have occupied Popular trees are

Mesua sp, Eagerstoernia calyculata, Xylia xylocarpa, and two main bamboos are Bambusa procera; Gigantochloa sp

- Floodplains, wetlands, and lakes: Cat Tien National Park has large areas of

swampland and unpolluted water resources In the rainy season, the flooded area may exceed 2,500 ha - especially near the lakes (Bau Sau, Bau Chim, and Bau Co) The area may also include relatively small (down to <1 ha) areas of forest swamp clearings in depressions of forest land Besides, Flooded plantation area is a favorable location for Crocodylus siamensis, aquatic plants, and animals, water birds, freshwater grasses Big

animals such as Sus Scrofa, Cervus Unicolor, Bos Gaurus, often gather here in dry

season The popular water trees are Dai Phong Tu, Loc Vung,

Besides forest, the Park contains:

- Grassland: often as a result of previous cultivation Although 'degraded', these

zones can provide good viewing of mammals and birds

- Other land use includes plantation (including cashew in the south of the park),

settlement cultivation (now greatly reduced), scrub, etc De-forested land may become infested with immigrant invasive species

3.2 Social features

Cat Tien National Park is also especially significant to the socio-economy of the region as its ecosystem takes an active part in the control of flood, at the same time it is also forest protecting for the water source of Tri An Hydro electrical Power Plant, a freshwater source supplied for Dong Nai province, Ho Chi Minh city, and Ba Ria - Vung Tau province

The buffer zone of Cat Tien National Park has 36 communes and 8 districts of 4 provinces: Dong Nai, Binh Phuoc, Lam Dong and Dak Lak with around 17,000 inhabitants

- At present, there are 9 residential clusters in Cat Tien National Park Cat Loc area in Lam Dong province has:

+ Phuoc Cat Commune: There are 3 clusters living along the Dong Nai River with

about 80 households, of which 28 are S'Tieng ethnic and 12 households are Chau Ma ethnic

+ Tien Hoang Commune: There are 2 residential clusters, about 230 households

are mainly Chau Ma ethnic

+ Gia Vien Commune: These include 12 households of the Chau Ma ethnic

minorities

- These ethnic groups live along the banks of the Dong Nai River from Ta Lai and Tan Phu in Dong Nai province to Dak Lak and Lam Dong provinces for generations and are members of the Khmer ethnic group

Tay Cat Tien Area in Binh Phuoc Province: There are 232 communities of Tay,

Nung and Dao ethnic minorities living in Cat Tien National Park since 1990-1991

Nam Cat Tien area of Dong Nai province has:

+ Ta Lai Settlement area: There are 292 households are S'Tieng and Chau Ma

CHAPTER 4: METHODS

4.1 Study site selection

The study covered some areas in Cat Tien National Park including

- Bang Lang Da Co forest

- Rang Stream in South Cat Tien

- Dang Ha commune

- Bau Sau station

- Cat Tien center

- Da Bong Kua station area belonging Dak Lua commune

- Tuong Mountain area belonging Dak Lua commune

Figure 4.1: Map of study site in Cat Tien National Park

4.2 Data Collection

At the first phase of the process, the recorders were installed at survey locations in Cat Tien NP with a time period when their calling activity usually happened during the

night (from 5 p.m to 6 a.m) Besides, GPS was used to determine the exact survey locations in Cat Tien NP Totally, 7 sites were surveyed These locations were determined based on favorable topographic conditions and follow instructions of an experienced staff

in Cat Tien NP

Figure 4.2: An automatic recorder was attached to a tree

In each survey location, two to four full-spectrum recorders were placed The recorders had a microphone on both left and right sides and were attached to a tree The recorders were set to record throughout the night time between 5 p.m and 6 a.m Recordings were saved to disk at 30-minute intervals to prevent the loss of an entire evening’s recordings in case the batteries ran out These 30 min segments were saved in a compressed format Each recorder continued to record until the batteries ran out of power This resulted in an average recording period of three or four nights Battery and memory card would be changed when moving the recorders to other areas

Many automatic recordings were used at the same time The location of the birds in the area between the recorders will be accurately determined The distance from the recorders to the birds was determined by the software ArcGIS 10.3, based on the coordinates of the machine and coordinates emitted sound calculation

Sound data was analyzed using the RAVEN (Cornell Lab of Ornithology) software

to detect the sound of targeted bird species Raven is “a software program for the acquisition, visualization, measurement, and analysis of sounds” List of targeted bird species consists of 11 bird species, divided into 3 families and 2 orders in Cat Tien

National Park that was shown below (Table4.1)

Table 4.1: List of targeted bird species in Cat Tien National Park

4 Spot-bellied

Eagle-Owl

Bubo nipalensis (Hodgson, 1836) Dù dì Nêpan Strigidae Strigiformes Stable (LC)

5 Brown

Fish-Owl

Ketupa zeylonensis (Gmel

in, 1788)

Dù dì Phương đông Strigidae Strigiformes

Decreasing (LC)

Cú Vọ Strigidae Strigiformes Increasing

(LC)

7 Brown

Hawk-Owl

Ninox scutulata (Raffles, 1822)

Cú vọ lưng nâu Strigidae Strigiformes

Decreasing (LC)

8 Collared

Scops Owl

Otus bakkamoena (Pennant, 1769)

Cú mèo khoang cổ Strigidae Strigiformes Stable (LC)

9 Great

Eared-Nightjar

Lyncornis macrotis (Vigors, 1831)

Cú muỗi mào Caprimulgidae Caprimulgiformes Stable (LC)

4.3 The locations recorders in Cat Tien National Park

During the period from August 17th to September 30th, 2016, 7 areas were surveyed within the boundary of Cat Tien National Park, Dong Nai Province Each area was surveyed for 3-4 days The survey areas were mainly located in the eastern part of Cat Tien

NP This area had evergreen forests and suitable habitats of the bird species The locations

of 30 automatic recorders in Cat Tien National Park were described in this map below:

Figure 4.3: The location of 30 automatic recorders in Cat Tien National Park

Recorders in study sites were distributed on three forest types include evergreen forest, bamboo forest, and mixed wood-bamboo forest In particular, the evergreen forest has is further divided to the rich evergreen broad-leaved forest, medium evergreen broad-leaved forest, poor evergreen broad-leaved forest, regrowth evergreen broad-leaved forest

Table 4.2: Characteristics of 30 automatic recorders in study sites in Cat Tien National Park

Number ID of

recorders

1 CT304785 1267459.981 467120.24

Bang Lang Da Co Forest I 18-21/July

Regrowth evergreen broad-leaved forest Txp

4 CT304785 1267554.907 463224.39

Bang Lang Da Co Forest II 21-22/July

Medium evergreen broad-leaved forest Txb

7 CT304785 134973.7626 462165.65

Bang Lang Da Co Forest III 23-25/July

Medium evergreen broad-leaved forest Txb

11 CT304785 1263760.697 464318.14

Cat Tien core zone 28/July

Medium evergreen broad-leaved forest Txb

15 CT304785 1270954.836 448945.23

DaBongKua - Thanh Sơn 2-6/August

Trees mixed with bamboo forest Hg2

19 CT304785 1276543.77 440416.99

Dang Ha 7-9/August

Bamboo forest (Bambusa balcooa) Loo

23 CT304785 1267550.613 459449.96 Tuong Mountain

17/September- 30September

Regrowth evergreen broad-leaved forest Txp

25 CT304785 1268665.737 439915.93

Rang stream - Thanh Son 10-13/ August

Rich evergreen broad-leaved forest Txg

29 CT304785 1265285.189 456953.81 Bau Sau - Tuong

Mountain 17-19/August

Medium evergreen broad-leaved forest Txb

4.4 Sound Analysis

The sound of nocturnal birds was recorded with the multi-spectral recording machine SM3 All sound data files of about 4Tb were stored in removable drives Sound data were analyzed by software RAVEN (Cornell Lab of Ornithology) to detect the sound

of the nocturnal bird species The interface of the RAVEN software is shown in Figure 4.4

Figure 4.4: The interface of the RAVEN software

Before analyzing the sound, I set up the process of the recognizers: For each compressed “ wac” file the two channels were saved as separate files and converted into a

“.wav” file Moreover, the results were chosen with a score above 40.0% and a quality above 0 The score values were on a scale from 0.00% to 100.0% and represented the statistical fit of the candidate nightjar vocalization to the bird recognizer model The quality values were on a scale from 0.00 to 99.99 and reflected how well a set of secondary parameters of the candidate bird vocalization match with the training data used to build the recognizer (Mieke et al, 2014)

Between species, there is variation in birdsong signals along various dimensions including frequency range, a speed of pitch modulation, vocabulary size, syllable duration, song duration Different birds will sing at different times of day, and the amount and type

of singing will vary throughout the year according to the needs of territory and mating These factors mean that time, date and location could serve as useful information in a recognition system, reducing the effective number of possible species (Dan Stowell and Mark D Plumbley,2011)

I used Audacity software to convert the frequency of the recordings on the same frequency values, the spectrograms between two correlating recordings must have the same frequency (24000 Hz) The interface of the Audacity software is shown in Figure 4.5 below:

Figure 4.5: The process of converting spectrogram’s frequency by Audacity software

Next step, I compared two recordings between a 30-minute interval recording and a recording of the targeted bird by correlation configuration tool used to compare these spectrograms with the available spectrogram of these bird species based on the characteristic of the frequency range, the speed of pitch modulation, vocabulary size, syllable duration of each spectrogram to detect nocturnal bird The standard audio samples

of this species were referenced from the document Scharringa (2005)

Figure 4.6: The interface of correlation configuration

The process of analysis sound will detect the spectrogram of each species I tried to listen and analyze that interval and the determined name of the nocturnal bird species After that,

I could know where they live base on the locations I put the automatic recorders Name and place detected of bird will be listed in the table below

Table 4.3: Birdsong detected at location … in … from…

No Species name Day Time of detection Time Periods Data of recorder

4.5 Pre-analysis of results

Determining the composition of detected bird species

Base on the IUCN Red List of Threatened Species program to know the assessment

of the status of nocturnal birds Besides, I compared nocturnal species detected with a list

of the bird at Cat Tien NP through the document "Checklist of birds Vietnam", (Vo Quy Nguyen Cu,1995) to determine exactly that they live in Cat Tien The result listed in the following below

Table 4.4: List of nocturnal bird species detected in the study site

Species

Name

Scientific name

Vietnames

e name

Family name

Determining the frequency of appearance of the nocturnal bird in Cat Tien NP

To find out what time was the most activity of song nocturnal birds, I divided the time into 3 periods as follows: dusk (18.00–19.00), middle of the night (22.00–03.00), dawn (04.00–06.00) The most active time is shown in the table below

Table 4.5: The most active time during surveying time of nocturnal bird

Name

The most active time during surveying time (6.00-6.00 AM)

Determining the distribution of some bird species and favorite habitat for the

targeted bird in Cat Tien NP

Table 4.6 Distribution of nocturnal bird species of them in Cat Tien NP

Species Da Co

Forest

Cat Tien Center

Da Bong Kua station

Dang Ha Commune

Tuong Mountain

Rang Stream

Bau Sau station

From data of recorders in 30 locations with different habitat types, I identified where bird species appeared I fully defined ecological variables of each habitat that impact

on the presence of bird species After that, the results listed in the following table:

Table 4.7: Characteristics of 30 automatic recorders in study sites in Cat Tien

Bamboo forest

Rich

Evergreen

forest

Medium Evergreen forest

Poor Evergreen poor forest

Regrowth Evergreen forest