Species with wide ranges often require extensive habitat patches to enable populations to remain viable. Furthermore, if species are to remain viable over extended periods, there is a need to mitigate habitat-fragmentation driven loss of population connectivity and gene flow. As a case in point, saltwater crocodiles (Crocodylus porosus) have experienced significant habitat loss in certain parts of their territory in Myanmar. Within Myanmar, the species is currently only found in a single protected area—the Meinmahla Kyun Wildlife Sanctuary, an island in the Ayeyarwady Delta. Its population in the Ayeyarwady region was estimated to be no more than 80 individuals in 2019, and this number continues to decline under unprecedented socioeconomic pressures on their mangrove habitats.
Yet, despite the decline in population over recent decades and inadequate habitat protection in the Ayeyarwady region, no recent assessments have investigated the range-wide habitat patterns, occupancy conditions and population status of saltwater crocodiles in Myanmar. Therefore, there is an urgent need to obtain such critical information to effectively manage and conserve its populations.
Through a comprehensive analysis using 20 years of data, we identified suitable habitats, range-wide corridors and regional pathways that facilitate saltwater crocodile dispersal, thereby enhancing connectivity between habitat patches. The optimal dispersal corridors were identified based on expert-driven landscape resistance surface modelling. This method reflects the level of difficulty saltwater crocodiles face while moving through different geographical landscape features, allowing for the mapping of the most efficient routes to reconnect fragmented habitats.
The study identified extensive habitat patches in the Rakhine, Ayeyarwady, Yangon, Mon and Tanintharyi regions—approximately 1247 km2 along the coastline, with only 12 percent aligning with the IUCN-defined extent of occurrence of saltwater crocodiles in Myanmar. The Ayeyarwady Delta boasts more extensive and suitable habitat coverage compared to the Rakhine and Tanintharyi regions, where marginal habitats are highly fragmented and largely unprotected. We also identified bottleneck areas where the movement of saltwater crocodiles will be constrained due to high landscape resistance and few alternative routes. Notably, while several suitable patches of habitat exist, many are currently unconnected, and dispersal may not be possible between such habitats.
Myanmar currently designates less than one percent of the country’s total area as marine and coastal protected areas, which includes two internationally important wetland sites—Nanthar Island and Mayyu Estuary, and Meinmahla Kyun Wildlife Sanctuary. Expanding legally designated protected areas to include important wetland sites, such as the Gulf of Mottama (GOM), identified habitat corridors and dispersal bottlenecks, is vital for increasing this percentage and boosting conservation efforts of the saltwater crocodile ecosystem. To this end, we identified five key priority areas for protection, restoration and monitoring. These five areas align with the Key Biodiversity Areas within four coastal zones, namely Ramree Island and Kyeintali (Rakhine), Ngapudaw-Phone Taw, Dedaye-Kungyangon (Ayeyarwady Delta), GOM-Bilugyin-Kyaikkhami (Mon) and Myeik Archipelagos (Tanintharyi).
Mangrove restoration and biodiversity monitoring programmes along those habitat corridors and dispersal pathways could enable population recovery, and in turn, improve population resilience to future environmental changes. Our study emphasises the pivotal role of habitat connectivity, particularly in Myanmar’s overlooked coastal wetlands, and provides a complement to the 30×30 global biodiversity target. This habitat connectivity framework offers valuable insights for conservation practitioners and scientists seeking effective measures to safeguard biodiversity through facilitating conservation planning to better reflect connectivity.
Our study lays the groundwork for establishing a protected areas network in Myanmar’s coastal regions, utilising saltwater crocodiles as an umbrella species to facilitate comprehensive conservation planning and connectivity efforts for the region’s’ biodiversity and ecosystems.
Further Reading:
Than, K. Z., Z. Zaw, R. C. Quan and A. C. Hughes. 2024. Biodiversity conservation in Myanmar’s coastal wetlands: Focusing on saltwater crocodile habitats and connectivity. Biological Conservation 289: 110396.
