Journal of Threatened Taxa | www.threatenedtaxa.org | 26 March 2024 | 16(3): 24973–24978

ISSN 0974-7907 (Online) | ISSN 0974-7893 (Print)

https://doi.org/10.11609/jott.8732.16.3.24973-24978

#8732 | Received 29 September 2023 | Final received 01 December 2023 | Finally accepted 08 March 2024

Breeding of the ‘Critically Endangered’ White-rumped Vulture Gyps bengalensis in the Shan Highlands, Myanmar

Sai Sein Lin Oo ¹, Nang Lao Kham ², Marcela Suarez-Rubio ³ & Swen C. Renner ⁴

¹ Sao Hsur Wai Library, 06151, Ke Hsi Township, Shan State, Myanmar.

² No.288, Aye Chan Thar, 06301, Lashio Township, Shan State, Myanmar.

³ Institute of Zoology, Department of Integrative Biology and Biodiversity Research, University of Natural Resources and Life Sciences Vienna, Gregor-Mendel-Straße 33/I 1180 Vienna, Austria.

⁴ Ornithology, Natural History Museum Vienna, Burgring 7, 1010 Vienna, Austria.

¹ seinlinu@gmail.com, ² laokham01@gmail.com, ³ marcela.suarezrubio@boku.ac.at,

⁴ swen.renner@nhm-wien.ac.at (corresponding author)

Editor: H. Byju, Coimbatore, Tamil Nadu, India. Date of publication: 26 March 2024 (online & print)

Citation: Oo, S.S.L., N.L. Kham, M. Suarez-Rubio & S.C. Renner (2024). Breeding of the ‘Critically Endangered’ White-rumped Vulture Gyps bengalensis in the Shan Highlands, Myanmar. Journal of Threatened Taxa 16(3): 24973–24978. https://doi.org/10.11609/jott.8732.16.3.24973-24978

Copyright: © Oo et al. 2024. Creative Commons Attribution 4.0 International License. JoTT allows unrestricted use, reproduction, and distribution of this article in any medium by providing adequate credit to the author(s) and the source of publication.

Funding: The APC was funded through the Open Science Strategy of the NHM Wien Museum. Sai Phone Aung and Sai Sai Peanut Oil supported the study with a travel grant.

Competing interests: The authors declare no competing interests.

Author details: Sai Sein Lin OO is a retired associate professor of Department of Zoology, University of Mandalay and he is currently a researcher and working at Sao Hsur Wai Library. He has extensive experience of undertaking research on bat diversity in Myanmar. He has been collaborated with international institutions for the academic sector in research training and conservation in Myanmar, research on biodiversity and wild life of Myanmar. Nang Lao KHAM is a retired associate professor of Department of Zoology, Lashio University and she is currently a freelance researcher for working on vulture for several years in the northern Shan State, Myanmar. Marcela Suarez-Rubio is interested to understand the interconnection between landscape patterns and ecological processes. Specifically, she is involved in how birds and bats respond to global change, in particular, land use/land cover changes, to inform conservation, management and mitigation strategies.

Swen C Renner focuses on biodiversity research and how birds respond to land use change, conservation biology, and avian malaria.

Author contributions: Study design: SSLO, SCR; fieldwork: SSLO, NLK; data analysis: SSLO, NLK, MSR, SCR; writing: SSLO, SCR; revisions: all authors.

Acknowledgements: We are grateful to Sai Phone Aung, Pu Tao Khae, Sai Phoe Sein, and their families for accommodation and logistic support. Our thanks also go to Sai Khay Aon, Sai Kyaw Oo, and Sai Lao for logistics during the surveys.

Abstract: Recent studies have shown the importance of Myanmar for the conservation of three ‘Critically Endangered’ vulture populations. From November 2022 to March 2023, we carried out rapid surveys on vulture nests and nesting tree characteristics in Ke Hsi Township, Shan Highlands. We recorded 10 nests of White-rumped Vultures, Gyps bengalensis, on five nesting trees from four different localities. Six nests were active, and six nestlings were observed; four nests were inactive or abandoned. Most of the nests were recorded on Ficus spp. and the mean nest height was 13.6 m (SD ± 4.1) above ground. This represents the first confirmed record of the breeding success of White-rumped Vultures from Shan Highlands and confirms the ongoing presence of the species in Shan States. The population of G. bengalensis in Shan Highlands is small, but the confirmed breeding is significant in the wider context for this species.

Keywords: Breeding success, Ficus spp., nestlings, Shan states, viable population, vulture nest.

Introduction

In Myanmar, each year new records of birds and range extensions are published (Zöckler et al. 2010, 2020; Oo et al. 2022), or records of species, which have been declared locally extinct, re-emerge (Oo et al. 2019). Myanmar hosts five vulture species: The White-rumped Vulture Gyps bengalensis, Red-headed Vulture Sarcogyps clavus, Slender-billed Vulture Gyps tenuirostris, Cinereous Vulture Aegypius monachus, and Himalayan Vulture Gyps himalayenis (Robson 2008; Hla et al. 2011), and three of these are classified as ‘Critically Endangered’ by the IUCN Red List of Threatened Species. Among these, the White-rumped Vulture has a widespread distribution across Bangladesh, Bhutan, Cambodia, India, Myanmar, Nepal, and Pakistan (BirdLife International 2021a,b,c) but has also suffered the most drastic declines of over 99.9% across India (Prakash et al. 2012). Literature records suggest that vultures were once widely distributed throughout Myanmar, mainly the northern half of the country with records from Kachin State, Shan State, Chin State, and Sagaing Region (Hla et al. 2011). Also Gyps bengalensis was recorded 78 times from Myanmar, most of these records are sights of non-breeding birds in Kachin (68), while only nine records are from the two Shan states (GBIF 2023). The Shan records are all from 2009 to 2023, which indicates a rare visitor to the Shan Highlands (Image 1).

All but the Himalayan Vulture have been considered relatively common throughout these areas in the past (Tordorf et al. 2007; Hla et al. 2011; Shwe & Aung 2016; Oo et al. 2019). The earliest record of the White-rumped Vulture dates back to the late 19^th Century for Southern Shan State, where it was once a common species (Rippon 1901). The Shan states remained relatively unexplored by ornithologists due to political instability, security issues, and inaccessibility of the region (Smythies 2001).

In the early 20^th Century, White-rumped Vultures were abundant and considered the most common vulture throughout Myanmar’s central plains (Smythies 2001; Naing et al. 2012). However, their population has declined across their historical range because of food shortages, breeding-habitat loss, chemical poisoning, habitat loss, and anthropogenic impacts (Bildstein 2017). This decline was so severe in the region that the White-rumped Vulture population crashed by almost 95% between the 1990s and 2000s (Bildstein 2017).

Hla et al. (2011) estimated a population of 62 White-rumped Vultures based on observations at vulture feeding sites in all of Myanmar for 2006 and 2007. The first White-rumped Vulture survey in northern Shan State documented 31 individuals, including juveniles (Oo et al. 2019). While the two studies had different temporal and spatial scales as well as methods, we assume that the stronghold of the White-rumped Vulture population of Myanmar is likely located in Shan today, while another hotspot for the species within Myanmar is found in the Hukaung Valley, Kachin State (Thet Zaw Naing pers. comm. 2023).

White-rumped Vultures typically build their nests in tall trees (Khan 2013; Ghimire et al. 2019; Samson & Ramakrishnan 2020; Jha et al. 2021), as these trees reduce predators’ access and support mobility for the vultures.

Methods and survey sites

Fieldwork was conducted in Ke Hsi Township (alternatively spelled Kehsi), located in the southern region of Shan State, with specific localities and coordinates detailed in Table 1 and Image 1. Our team undertook surveys of vulture nests, leveraging local knowledge to identify these sites. Nesting trees were identified using GPS coordinates, and these sites were subsequently revisited on a bi-weekly basis. Ke Hsi Township is situated on the elevated plains of southern Shan State, at an approximate altitude of 1,000 m.

The vulture survey covered 35 days, from 15 November 2022 to 31 March 2023. During this period, we collected data on the characteristics of nesting trees, adopting the nest categorization framework established by Jha et al. (2020), which delineates nests as active (housing adults along with juveniles, chicks, or eggs), inactive (only occupied or frequented by adults), or abandoned (without any occupants).

Measurements of tree height and nest elevation were taken using a clinometer, while the diameter at breast height (DBH) was measured with a tape measure, and canopy density was assessed with a densitometer. The relative canopy cover of each nesting tree site was evaluated using the “CanopyApp” (University of New Hampshire), where a photograph taken beneath the tree provided the percentage of canopy coverage as an output.

We also recorded the proximity of nesting trees to the nearest water bodies, which, within the study area, averaged 11.7 hectares in size (N = 4). Observations of nests were conducted from a non-intrusive distance of 100–200 m using Kowa Japan YF30-8 binoculars (8 × 30), to minimize disturbance for the birds. Documentation of birds and their nests was accomplished with a Nikon P1000 digital camera, with results presented in Images 2–6. Each site visit lasted approximately 15 minutes, during which we assessed the breeding status of the nests. Observation periods were conducted from 0800 h to 1600 h.

The climate of Ke Hsi Township is predominantly subtropical, characterized by a mean annual temperature of approximately 23°C and an average annual rainfall of about 1,100 mm (General Administration Department 2020).

Results

During our research period, we identified and monitored 10 nests of White-rumped Vultures, situated within five nesting trees across four distinct locations. Within these locations, three were categorized as loose colonies, notably with one tree hosting four nests. The nesting trees were, on average, 10.4 km apart, with a range from 0.4 to 25.0 km. All nests, discovered in November 2022 at the onset of our survey, exhibited vulture activity during our initial inspection. Throughout our study, six nests remained active, while the remaining four exhibited signs of inactivity or abandonment. Of the five nesting trees, three were positioned within agricultural fields (specifically, corn and peanut farms), and the other two were adjacent to religious sites (a pagoda and a monastery). Ficus trees emerged as the preferred nesting choice, representing four of the five identified nesting trees (Table 1). The average height of these nesting trees was 20.7 m, with nests situated at an average height of 13.6 m (Table 1). The canopy cover of these trees averaged 39.9% (SD ± 10.59, N = 5).

By January 2023, all active nests were home to six vulture chicks, with observations typically noting chick presence alongside at least one adult until late March 2023 (Table 2).

Our observations also included five colonies of White-rumped Vultures, each comprising two to 20 individuals (N = 5), and vulture groups ranging 29–57 individuals, with an average of 41 individuals (N = 4), feeding on carcasses. These groups encompassed three vulture species: White-rumped Vulture, Slender-billed Vulture, and Himalayan Vulture. Throughout the study, we located three cattle and one buffalo carcasses, with three in cropland and one in a paddy field. Near each carcass, two to three stray dogs were observed feeding alongside the vultures. The cause of livestock mortality was undetermined, and no information was collected on the availability of diclofenac, a veterinary drug causing casualties in vultures, in the area. According to the local veterinarian, diclofenac was not utilized for treating cattle within the township. No deceased vultures were discovered during our research period.

Despite observing Slender-billed and potentially Himalayan Vultures feeding on carcasses, nesting sites for the Slender-billed Vulture were not identified. Himalayan Vultures are noted as winter visitors to Myanmar. Moreover, Red-headed Vultures were not observed throughout the duration of this study.

Discussion

With this survey, we documented the breeding success of the ‘Critically Endangered’ White-rumped Vulture in Myanmar’s Shan Highlands, representing the first confirmed breeding record in the eastern part of the country. It also sheds light on their nesting site preferences and food availability. Between November 2022 and March 2023, we observed nestlings in six nests, and all six nestlings successfully fledged. This is a positive sign for vulture conservation in Myanmar (Hla et al. 2011). Our findings suggest that these vultures have sufficient food sources in the study areas, as evidenced by frequent observations of vulture flocks and recorded carcasses. The availability of food is crucial for vulture presence, especially considering their role as obligate scavengers. This is further supported by the presence of a substantial cattle population in the region, as has been found in southern India (Manigandan et al. 2023).

Although Slender-billed Vultures were observed feeding on carcasses, we could not locate their nests. Similarly, Red-headed Vultures were not observed during the study, suggesting their rarity compared to the other vulture species.

The preference of White-rumped Vultures in our study was for large, tall trees, often Ficus spp., while others reported that Terminalia arjuna, and Spondias mangifera were utilized for nesting by White-rumped Vultures in India (Majgaonkar et al. 2018; Samson & Ramakrishnan 2020). The average nesting tree height in India was 25.4 m (Majgaonkar et al. 2018) and 26.7 m (Samson & Ramakrishnan 2020), respectively.

Since the study areas are located outside of protected areas (compare Image 1), it is needed to introduce conservation awareness and management practices to local communities. In addition, it is required to raise awareness for protecting nesting trees. The vulture colonies we recorded, as well as the flocks attending domestic livestock carcasses, indicate that these birds continue to play an essential role in the ecosystem by cleaning up carrion. Hla et al. (2011) had previously postulated, but not observed, the presence of viable populations of Gyps bengalensis and G. tenuirostris in Myanmar, and our current findings confirm this claim at least for G. bengalensis.

Majgaonkar et al. (2018) emphasized that nesting and reproductive success serve as indicators of specific site-use by the vultures. Therefore, it is demonstrated that habitats and food availability for Gyps species still exist in the Shan Highlands of Myanmar. While the population of G. bengalensis in Shan State may be relatively small, its breeding success is of significance, indicating that these populations are healthy and successfully reproducing. Based on the study results, Ke Hsi Township emerges as particularly crucial for White-rumped Vulture populations due to its large open habitats, food availability, low disturbance levels, and relatively low human density. Vultures can find and detect carcasses and feed in such open areas, making these habitat characteristics vital for nesting choices. In conclusion, the findings of this study offer promising insights into vulture conservation opportunities in Myanmar.

Table 1. Locations and records of trees with White-rumped Vulture Gyps bengalensis nests in the Shan Highlands. Note: * one out of the four nests was in the crown of the tree and we could not confirm the presence of nestling.

Place	Tree species	Tree height m	# nests	Nest height m	DBH cm	Altitude m	Roosting individuals	Number of nests	Number of chicks	Fledged	North	East
Wan Mut	Ficus tinctoria	23.9	2	19.1; 17.6	980	830	5	2	n/a	n/a	22.0	98.1
Wan Mut	F. tinctoria	20.3	2	11.3; 7.6	1,210	870	7	2	1	1	22.0	98.1
Wan Narr	Schima wallichii	18.3	1	16.5	245	1,000	2	1	1	1	21.7	98.1
Kone Mont	F. tinctoria	21.3	1	19.5	1,100	1,030	2	1	1	1	21.8	98.0
Nam Linn	F. lacor	20.1	4	16.5; 16.5; 12.6; 6.6	750	1,040	14	4*	3	3	21.8	98.0

Table 2. Records of White-rumped Vulture Gyps bengalensis nestling found in nests of the study area. 1 observed, 0 not observed.

Date	Kone Mont	Nam Linn	Wan Mut	Wan Narr
8 Jan 2023	0	0	1	1
13 Jan 2023	1	1	1	1
5 Feb 2023	1	1	0	1
11 Mar 2023	1	1	1	1
15 Mar 2023	0	0	1	1

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