Institutional Repository of Xishuangbanna Tropical Botanical Garden
| 缅甸地区缅甸湾鳄 (Crocodylus porosus) 分布、种群大小、栖息地及居民态度研究 | |
| Alternative Title | Occupancy, population size, habitat connectivity of and locals’attitudes on saltwater crocodiles (Crocodylus porosus) in Myanmar |
| KAY ZIN THAN | |
| Thesis Advisor | 马友鑫 |
| 2020 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 中国科学院西双版纳热带植物园 |
| Degree Name | 理学博士 |
| Degree Discipline | 生态学 |
| Keyword | 伊洛瓦底江三角洲，连通性，栖息地，人与鳄鱼共存，景观，湄公河野生动物保护区，缅甸，占领，人的态度，种群规模，保护区，湾鳄，物种分布模型 |
| Abstract | 缅甸的湿地，特别是沿海地区红树林边缘的滩涂，是鳄鱼的栖息地。湾鳄(Crocodylus porosus)是缅甸《野生动物和自然保护区法》所保护的爬行动物物种。由于鳄鱼皮交易驱动的捕获行为、湾鳄养殖场的捕获、湿地转化为农业用地导致的栖息地流失，使得湾鳄的数量急剧减少。虽然在伊洛瓦底三角洲的湄公河流域野生动物保护区仍有少数个体，但这是东南亚大陆现存的少数种群之一。鉴于政府已经授权保护湾鳄，要成功地就地保护这种顶级捕食者，就需要跨学科的方法，通过了解当地人对湾鳄的复杂态度，使人与鳄共存，共享伊洛瓦底三角洲的栖息地。根据2000 年在湄公河流域野生动物保护区的调查，伊洛瓦底三角洲的湾鳄数量估计不足100 只。由于在Tanintharyi和Rakhine沿海地区有少数分散的个体，湄公河野生动物保护区的受保护生境对湾鳄的生存至关重要。有效保护和管理缅甸境内的湾鳄，需要了解适宜生境的范围、种群状况、环境参数以及人为因素对其生境的影响。同时，考虑海岸线沿线生境的可用性，适合性和连通性极其重要，因为生境的隔离和碎片化会对种群数量产生负面影响，例如导致近交或遗传多样性丧失。根据栖息地大小、栖息地碎片化程度及其分布或栖息地格局，适当调节栖息地斑块的连通程度，可以支持保护区管理，保护小种群，以应对缅甸物种区域灭绝的风险，所以我们迫切需要了解栖息地分布或栖息地格局相关的关键信息。这项研究旨在评估伊洛瓦底三角洲地区湾鳄的栖息面积，种群状况和季节性栖息地使用模式，并确定合适的栖息地斑块，并在缅甸范围内建立湾鳄零散生境的联系。此外，还评估了影响当地人态度的因素，以促进缅甸人鳄共存。2018 年至2019 年，我们在湄公河野生动物保护区和附近的两个保留森林进行了标准化重点调查(每条水道重复调查4 次)、相机陷阱调查和环境变量调查。我们使用层次混合模型、空间计数模型和相对丰度指数来估计伊洛瓦底三角洲湾鳄的栖息地使用情况和种群大小。我们收集了1999年至2018 年期间咸水鳄鱼出现的684 个地点的坐标，其中雨季(5 月至6 月)444 个，旱季(12 月至1 月)240 个。此外，我们从文献、缅甸林业部报告和在线数据集中收集了物种出现的数据。根据现有的在线数据集，选取与湾鳄（Crocodylus porosus）种群分布相关的13 个变量，包括11个环境变量和2个生物气候变量。为了确定该物种在一个地区的生存状态，我们通过对17 个村庄中244 户居民的问卷调查研究了当地居民对环境、湾鳄、栖息地和威胁的了解，对人鳄冲突的认识，以及对湾鳄保护的好处和影响的认识。湄公河流域野生动物保护区内的河道中，湾鳄在保留森林、狭长低盐度河道比宽阔高盐度河道更易栖息和繁殖。但是，在有人居住的地区，湾鳄的数量会比没有人居住的地区减少。我们发现，湄公河流域野生动物保护区有中等盐度的小溪，没有人类聚居活动，因此，它被认为是伊洛瓦底三角洲最后一个适合湾鳄的栖息地。我们观察到，在雨季和旱季之间，湄公河野生动物保护区和Kadonkani保留森林的栖息地使用有明显重叠（426.96km2）。这项研究结果表明，新开发的Khaing Thaung岛是Kadonkani和Pyindayae 保留森林的新的潜在海洋保护区和发展缓冲区，非常适合湾鳄鱼居住，保护伊洛瓦底三角洲的盐水鳄鱼的季节性栖息地。除季节性栖息地外，我们还选定了6 个栖息地斑块（若开邦2 个栖息地斑块，伊洛瓦底三角洲2 个栖息地斑块，莫塔马湾附近1 个栖息地斑块，坦因塔里地区1 个栖息地斑块）和1 条连接缅甸境内栖息地斑块的湾鳄生境走廊。此外，目前地图显示了七个区域性的瓶颈区域，用于将湾鳄分散到其潜在的栖息地斑块上。在缅甸沿海的几个地方发现了适合于咸水鳄鱼的栖息地，可以考虑用于未来的保护计划。我们发现当地居民对环境、湾鳄及其栖息地非常了解。依靠湄公河流域野生动物保护区自然资源维持季节性生计的人们对鳄鱼保护持消极态度。如果当地人认为在湄公河流域野生动物保护区保护鳄鱼没有任何好处，他们可能会有消极的态度。通过限制资源获取来执行法律并不能提高保护成功率，反而会导致对物种保护的怨恨。当地人建议，了解湾鳄带来的风险是管理的基础，是在伊洛瓦底三角洲地区促进人类和鳄鱼共存的最佳途径。我们的研究向管理者和政策制定者提供了湾鳄数量上明确的估计，优先考虑受保护的、未受保护的栖息地和潜在的扩散走廊，这在土地和基础设施的规划、分配和开发中有不容忽视的作用。作为缅甸的首次尝试，我们探索了伊洛瓦底江三角洲湾鳄栖息地和丰度的重要环境参数，并通过解决众所周知的野外鳄鱼检测偏差提供了健全的种群规模数据。此外，我们强调必须采取以利益为基础的办法，确保当地人民对保护的积极态度。我们鼓励整合和推广当地人民的生态知识，以社区为基础的保护方法，制定可行的冲突解决措施，保护和管理缅甸的湾鳄。湾鳄的连通地图不仅可以为湾鳄提供关于连通性和潜在瓶颈区域的信息，还可以使其他物种受益，因为湾鳄是湿地生态系统的关键物种。因此，为包括湾鳄在内的野生动物维持生境连续性是一项具有挑战性的任务，但是，这项研究采用了稳健的分析方法，量化了景观的连通性，这可能有助于缅甸湾鳄的保护决策。 |
| Other Abstract | Wetlands in Myanmar, particularly mangrove-fringed mudflats in coastal areas, are the habitats for crocodiles. The saltwater crocodile (Crocodylus porosus) is a protected reptile species under the Conservation of Wildlife and Natural Areas Law in Myanmar. The population of saltwater crocodiles in Myanmar has declined precipitously as a result of commercial hunting for skins, collecting for crocodile farms and loss of habitats through the conversion of wetlands to agriculture. Although a few individuals persist in Meinmahlakyun wildlife sanctuary in the Ayeyarwady Delta, this represents one of few extant populations in mainland Southeast Asia. Given that the government already mandated to protect saltwater crocodiles, successful in-situ conservation of such an apex predator species requires interdisciplinary approaches to enable human-crocodile coexistence through understanding the complex attitudes of local people on saltwater crocodiles, and their shared habitat in the Ayeyarwady Delta. According to surveys in Meinmahlakyun wildlife sanctuary in 2000, the population of saltwater crocodiles was estimated at less than 100 individuals in the Ayeyarwady Delta. Given the few scattered individuals in Tanintharyi and Rakhine coastal regions, the protected habitats in Meinmahlakyun wildlife sanctuary are of the utmost importance for the continued survival of saltwater crocodiles in Myanmar. The effective conservation and management of saltwater crocodiles within their range of Myanmar requires information on the extent of suitable habitats, population status and the influence of environmental parameters as well as the anthropogenic factors on their habitats. The extent of connectivity of suitable habitat patches in terms of habitat size, degree of fragmentation of habitats in relation to their dispersal or home range pattern are urgently needed to know not only for supporting protected area management but also for conservation of small population of saltwater crocodiles to combat the risk of regional extinction of this species in Myanmar. This study aims to estimate occupied areas, population status, and seasonal habitat-use patterns of saltwater crocodile in the Ayeyarwady Delta and identify suitable habitat patches and build connections of potential habitats throughout its range in Myanmar. Additionally, factors affecting local people’s attitudes were assessed to promote human-crocodile coexistence in Myanmar. We conducted standardized spotlight surveys (4 repeated surveys per sampling waterway), camera trap surveys and environmental variables surveys along the rivers inside the Meinmahlakyun wildlife sanctuary, and two nearby reserved forests during 2018 to 2019. We used Hierarchical N-mixture models, Spatial Count models, and the relative abundance index to estimate site use by and population sizes of saltwater crocodiles in the Ayeyarwady Delta. We compiled coordinates of 684 locations of saltwater crocodiles’ encounters, 444 for wet season (May to June) and 240 for dry season (December to January) between 1999 and 2018. Moreover, we gathered data on species occurrence from the literature, forest department of Myanmar reports, and online datasets. A total of 13 variables related to the distribution of Crocodylus porosus were selected based on the available online data set, including 11 environmental variables and the two bioclimatic variables. To determine local attitudes in the one area the species persists, we examined local knowledge about the environment, crocodiles, habitats and threats, awareness of human-crocodile conflict, perceptions of benefits, and impacts of saltwater crocodile conservation through questionnaires at 244 households in 17 villages. Saltwater crocodiles were more likely to occupy and abundant in the waterways inside Meinmahlakyun wildlife sanctuary than the reserved forests, narrow and low salinity waterways than the wide and high salinity ones. But, the abundance of saltwater crocodiles is reduced in areas with the human disturbance than in areas with no disturbance. We found Meinmahlakyun wildlife sanctuary having creeks with moderate salinity and no human settlement and therefore, it was suggested as the last remaining optimal saltwater crocodile habitat of the Ayeyarwady Delta. We observed significant overlap (426.96 km2) in habitat use which fall into the areas of Meinmahlakyun wildlife sanctuary and Kadonkani reserved forest between the wet and dry seasons. This study results suggest Khaing Thaung Island, a newly explored island with high suitable habitat for saltwater crocodiles, as a new potential marine protected area and developing buffer areas in Kadonkani and Pyindayae reserved forests to safeguard the seasonal habitats of saltwater crocodiles in the Ayeyarwady Delta. Aside from the seasonal habitats, we identified 6 habitat patches (2 habitat patches in Rakhine, 2 habitat patches in the Ayeyarwady Delta,1 habitat patch near the Gulf of Mottama and 1 habitat patch in the Tanintharyi region) and 1 corridor for saltwater crocodiles connecting habitat patches across its range of Myanmar. Moreover, the current maps indicate seven regional bottleneck areas for the dispersal of saltwater crocodiles across its potential habitat patches. Suitable habitat for saltwater crocodiles was identified in several locations along the coast of Myanmar that could be considered for future conservation programs. We found that local people were highly knowledgable about the local environment, saltwater crocodiles, and their habitats. People with seasonal livelihoods which rely on natural resources from Meinmahlakyun wildlife sanctuary had negative attitudes towards crocodile conservation. Local people were likely to have negative attitudes if they perceived no benefits from crocodile conservation in Meinmahlakyun wildlife sanctuary. Law enforcement through restricting resource access does not enhance conservation success and actively builds resentment towards the conservation of the species. Local people suggested understanding risks posed by crocodiles as a basis for management was the best approach to facilitate human-crocodile coexistence in the Ayeyarwady Delta. Our study informed manager and policy maker with spatially explicit quantified population size estimates of saltwater crocodiles to prioritize the protected, unprotected habitats and the potential corridor for their dispersal that should not be neglected in planning, allocation, and development of land and infrastructure. As a first attempt in Myanmar, we explored important environmental parameters on saltwater crocodile occupancy and abundance in the Ayeyarwady delta and provided robust population sizes by addressing wellknown detection bias of crocodiles in the wild. Moreover, we highlight the need for benefit based approaches to secure local people’s positive attitudes towards conservation. We encouraged integrating and promoting ecological knowledge of local people, communitybased conservation approaches to develop feasible conflict resolution measures in the conservation and management of saltwater crocodiles in Myanmar.The connectivity map could be used not only to provide the information on the potential habitat and bottleneck dispersal areas for saltwater crocodiles but also to benefit on other species as crocodiles are keystone species of the wetland ecosystems. Therefore, maintaining landscape connectivity for wildlife including crocodiles is a challenging task, however, this study with robust analytical method quantifying the landscape connectivity could serve promising findings to assist the conservation decisions of saltwater crocodiles in Myanmar. Keywords: Ayeyarwady Delta, connectivity, habitats, human-crocodile coexistance, landscape, Meinmahlakyun wildlife sanctuary, Myanmar, occupancy, people’s attitudes, population size, protected area, saltwater crocodile, species distribution modelling |
| Pages | 177 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | https://ir.xtbg.ac.cn/handle/353005/11709 |
| Collection | 西双版纳热带植物园毕业生学位论文 |
| Recommended Citation GB/T 7714 | KAY ZIN THAN. 缅甸地区缅甸湾鳄 (Crocodylus porosus) 分布、种群大小、栖息地及居民态度研究[D]. 中国科学院西双版纳热带植物园. 中国科学院大学,2020. |
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| File Name/Size | DocType | Version | Access | License | ||
| KAYZINTHAN.pdf（74382KB） | 学位论文 | 开放获取 | CC BY-NC-SA | Application Full Text | ||
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