Thailand protects 156 formally designated national parks, 58 wildlife sanctuaries, 67 non-hunting areas, and 12 forest parks, totaling approximately 21 percent of the country's land area under some form of conservation designation as of 2024. The Department of National Parks, Wildlife and Plant Conservation, established in 2002 under the Ministry of Natural Resources and Environment, administers this network. Khao Yai National Park, established in 1962 as Thailand's first national park, covers 2,168 square kilometers across the Sankamphaeng Range and forms part of the Dong Phayayen-Khao Yai Forest Complex, inscribed as a UNESCO World Heritage Site in 2005. This complex encompasses four adjacent protected areas totaling 6,155 square kilometers and contains one of mainland Southeast Asia's largest intact monsoon forest blocks.
The country's protected areas span six distinct biogeographic zones from montane forests in the north to coral reef ecosystems in the south. Kaeng Krachan National Park, Thailand's largest at 2,914 square kilometers along the Myanmar border, protects watershed forest feeding the Phetchaburi and Pranburi river systems and contains populations of Asian elephants, clouded leopards, and Indochinese tigers. The International Union for Conservation of Nature documented 73 mammal species within Kaeng Krachan during surveys conducted between 2009 and 2013. Doi Inthanon National Park, surrounding Thailand's highest peak at 2,565 meters, contains the northernmost extent of several Southeast Asian montane species and protects 362 bird species, including 14 species endemic to the northern highlands.
Thailand's marine protected areas cover approximately 6,200 square kilometers across both the Gulf of Thailand and the Andaman Sea. Tarutao National Marine Park, established in 1974, encompasses 51 islands totaling 1,490 square kilometers, of which 1,260 square kilometers is marine area. The park forms the northern portion of a transboundary protected area with Malaysia's Langkawi archipelago and contains seagrass beds supporting dugong populations estimated at 30 to 50 individuals based on surveys conducted by the Department of Marine and Coastal Resources in 2019. The Similan Islands National Park, designated in 1982, protects nine granite islands 70 kilometers northwest of Phuket and closes annually from mid-May to mid-October to reduce tourist impact on nesting sea turtles and coral recovery.
The country provides habitat for 265 mammal species, 982 bird species, 313 reptile species, and 150 amphibian species according to the 2022 checklist published by Thailand's Biodiversity-Based Economy Development Office. Khao Sok National Park in Surat Thani Province contains Cheow Lan Lake, a 165-square-kilometer reservoir created in 1982 by the Ratchaprapha Dam, surrounded by limestone karst formations up to 960 meters high. The park protects populations of sun bears, Malayan tapirs, and banteng, with camera trap surveys in 2018 recording 48 mammal species. The Rafflesia kerrii, a parasitic flower reaching 70 centimeters in diameter, occurs in Khao Sok and blooms unpredictably between January and March in lower montane forest between 400 and 700 meters elevation.
Indochinese tigers persist in Thailand's western forest complexes, with the Department of National Parks documenting 160 to 189 individuals across five landscape units in a 2020 report compiled using camera trap data from 2018 to 2019. The Western Forest Complex, spanning 18,730 square kilometers across 17 protected areas along the Myanmar border, contains the largest contiguous tiger habitat. Huai Kha Khaeng Wildlife Sanctuary, part of this complex and a UNESCO World Heritage Site since 1991, recorded 77 individual tigers through camera trap analysis conducted during the 2019 survey period. The sanctuary protects 2,574 square kilometers of predominantly dry deciduous forest and is one of two sites in Southeast Asia where all three Asian wild dog species—dhole, Asiatic jackal, and golden jackal—occur sympatrically.
Asian elephants number between 3,000 and 4,000 individuals in Thailand, split roughly equally between captive animals and wild populations according to surveys conducted by the National Parks Department in 2021. Wild populations concentrate in the Western Forest Complex, the Dong Phayayen-Khao Yai complex in the east, and the Northern Forest Complex. Kui Buri National Park, covering 969 square kilometers in Prachuap Khiri Khan Province, contains Thailand's highest density of wild elephants, with approximately 300 individuals regularly visible at salt licks and open grasslands during the dry season from December through April. The park recorded zero human-elephant conflict fatalities between 2008 and 2020 through a buffer zone management program separating agricultural land from core elephant habitat.
Thailand contains six species of hornbills, with the great hornbill and helmeted hornbill occurring in lowland and hill evergreen forests in the western and southern regions. Budo-Sungai Padi National Park in Narathiwat Province, designated in 1999 and covering 315 square kilometers, protects the northernmost breeding population of helmeted hornbills, a species listed as Critically Endangered on the IUCN Red List due to ivory casque poaching. Camera trap surveys in 2017 recorded helmeted hornbills at 14 locations within the park, representing approximately 20 breeding pairs. The hornbill nesting season from January to May coincides with fruiting periods of Ficus species, with females remaining sealed inside tree cavities for 120 to 150 days while males provision them with fruit.
The country's freshwater ecosystems contain 850 fish species, including 120 species endemic to Thailand according to the 2019 taxonomic database maintained by Kasetsart University's Faculty of Fisheries. The Mekong River system along Thailand's northern and northeastern borders contains the world's largest inland fishery by catch volume, though the river itself lies primarily beyond national park boundaries. Phu Chong-Na Yoi National Park in Ubon Ratchathani Province protects 686 square kilometers of Mekong tributary streams containing populations of Jullien's golden carp, a species reaching 30 kilograms that migrates upstream during July and August floods. The Chao Phraya River basin contains fewer protected areas, with wetland conservation focusing on the Bung Khong Long Non-Hunting Area in Nong Khai Province, which protects 2,234 hectares of seasonal marshland supporting resident and migratory waterbird populations exceeding 50,000 individuals during December and January.
Thailand's coral reef ecosystems cover approximately 315 square kilometers along 3,148 kilometers of coastline, with the Andaman Sea containing 66 percent of reef area. The Department of Marine and Coastal Resources conducts annual reef surveys at 234 monitoring stations, recording a national average live coral cover of 31 percent in 2022, down from 43 percent in 2004. Mu Ko Surin National Park, 60 kilometers offshore in Phang Nga Province, contains 16 square kilometers of fringing and patch reefs with live coral cover averaging 52 percent in 2022 surveys. The park protects populations of manta rays and whale sharks, with seasonal aggregations of whale sharks occurring from February through May at Richelieu Rock, a submerged limestone pinnacle reaching to within 18 meters of the surface.
The Moken people, a traditionally sea-nomadic ethnic group also called Chao Le, inhabit areas around Mu Ko Surin during the monsoon season and maintain traditional knowledge of marine resource cycles. Approximately 400 Moken individuals hold Thai citizenship and reside within or adjacent to national park boundaries in the Surin and Similan island groups, with contested access rights to traditional fishing grounds resolved through Ministry of Natural Resources permits issued annually since 2010. Moken fishing practices use hand lines and spears rather than nets, and ethnographic research published in 2018 documented Moken ability to distinguish 87 fish species by Thai, Moken, and scientific names, indicating detailed ecological knowledge relevant to marine conservation.
Mangrove forests in Thailand cover 2,445 square kilometers, concentrated in Ranong, Trat, and Nakhon Si Thammarat provinces, according to the Department of Marine and Coastal Resources 2021 survey data. Mu Ko Ranong National Park protects 526 square kilometers in Ranong Province, of which 90 square kilometers consists of mangrove forest dominated by Rhizophora apiculata and Avicennia alba. These forests provide nursery habitat for commercial fish species and breeding sites for milky storks, with 17 nesting pairs recorded in 2020 representing a recovery from local extinction in the 1980s. Mangrove reforestation programs initiated by the Royal Forest Department in 2004 added 148 square kilometers of replanted mangroves by 2020, though ecological function studies published in 2019 show replanted stands support 40 percent fewer fish species than old-growth mangroves of equivalent area.
Gibbons inhabit forests across northern and western Thailand, with four species present including the pileated gibbon, white-handed gibbon, yellow-cheeked gibbon, and endangered cao-vit gibbon. Khlong Lan National Park in Kamphaeng Phet Province contains populations of both pileated and white-handed gibbons in adjacent habitat zones, with pileated gibbons preferring evergreen forest above 600 meters and white-handed gibbons occupying mixed deciduous and evergreen forest below that elevation. Acoustic surveys conducted in 2017 recorded 47 gibbon groups across 300 square kilometers of Khlong Lan, with territorial calling occurring primarily between dawn and 9 a.m. Gibbon song bouts average 14 minutes and carry up to 1.5 kilometers through forest, serving as acoustic markers for territory mapping.
Thailand's limestone karst landscapes contain cave ecosystems with distinct endemic fauna. Khao Sok contains more than 40 mapped caves, several exceeding one kilometer in length. Tham Nam Talu Cave System extends 6.2 kilometers through karst formations and contains populations of cave-adapted fish in the genus Nemacheilus and cave-dwelling bats including Lyle's flying fox and wrinkle-lipped free-tailed bats. Wrinkle-lipped bat colonies in southern Thailand can exceed one million individuals, with nightly emergence flights at Khao Chong Pran Cave in Ratchaburi Province creating visible columns on weather radar. Bat guano supports cave ecosystems including specialized invertebrates, with 23 troglobitic species documented in southern Thailand caves, of which 14 occur nowhere else.
Saltwater crocodiles historically occurred throughout coastal Thailand but are now functionally extinct in the wild, with the last confirmed wild individual captured in 2004 in Ranong Province. The Department of National Parks maintains breeding populations at the Phuket Crocodile Farm and releases captive-bred juveniles into Mu Ko Ranong National Park mangrove channels, with 380 individuals released between 2015 and 2022. Monitoring data shows 12 percent survival to adulthood, with predation by feral dogs and entanglement in fishing gear causing most mortality. Siamese crocodiles, a separate species endemic to Southeast Asia, persist in Kaeng Krachan National Park and the Cardamom Mountains complex extending into Cambodia, with Thailand's population estimated at fewer than 200 adults based on 2018 surveys.
Clouded leopards occur throughout Thailand's forested regions, with camera trap surveys documenting the species in 42 protected areas between 2010 and 2020. Population density estimates derived from camera trap analysis indicate 2.4 to 3.8 individuals per 100 square kilometers in optimal habitat. Kaeng Krachan National Park recorded 18 individual clouded leopards identified through spot pattern analysis of camera trap images collected during a 2019 survey covering 850 square kilometers. Clouded leopards occupy altitudinal ranges from sea level to 2,200 meters, overlapping with Indochinese leopards in montane forests. Indochinese leopards occur at lower densities, estimated at 0.8 individuals per 100 square kilometers in the Western Forest Complex based on surveys conducted in 2018.
Bird conservation in Thailand focuses on winter habitat for migratory species using the East Asian-Australasian Flyway. The Inner Gulf of Thailand contains coastal wetlands supporting more than 200,000 shorebirds during December and January, including endangered spoon-billed sandpipers and Nordmann's greenshanks. Laem Phak Bia Environmental Research and Development Project in Phetchaburi Province, operated by the Electricity Generating Authority of Thailand since 1990, uses constructed wetlands for wastewater treatment that incidentally provide 312 hectares of shorebird habitat. Surveys in January 2022 recorded 38 shorebird species and 14,200 individual birds using these wetlands. Don Hoi Lot in Samut Songkhram Province, a mudflat area covering 10,000 hectares at low tide, supports populations of great knots and sharp-tailed sandpipers, with peak counts exceeding 5,000 individuals in January 2021.
Thailand contains populations of Gurney's pitta, a ground-dwelling bird endemic to Myanmar and southern Thailand and listed as Endangered due to lowland forest loss. Khao Nor Chuchi Non-Hunting Area in Krabi Province protects the largest remaining Thai population, estimated at 800 to 1,000 pairs in 2020 surveys conducted by the Bird Conservation Society of Thailand. The species requires closed-canopy lowland forest below 300 meters elevation with dense understory, and breeding occurs from March through June. Males perform elaborate courtship displays involving log-top singing posts and territorial chases. Nest success rates average 34 percent based on monitoring data from 2015 to 2019, with nest predation by monitor lizards and snakes causing most failures.
The giant Mekong catfish, reaching lengths exceeding 2.7 meters and weights up to 293 kilograms, spawns in tributaries of the northern Mekong River but is not directly protected within Thai national parks due to its migratory range extending into Laos and China. The Chiang Khong Fisheries Station in Chiang Rai Province maintains a captive breeding program that released 16,000 juvenile giant Mekong catfish into the Mekong between 2010 and 2020. Wild adult captures have declined from 60 to 70 individuals annually in the 1990s to fewer than five per year after 2015, indicating population collapse. The Mekong giant catfish is listed as Critically Endangered, with dam construction blocking access to spawning tributaries identified as the primary threat.
Green peafowl, distinct from the widely distributed Indian peafowl, occur in open deciduous forests in northern and western Thailand. Huai Kha Khaeng Wildlife Sanctuary contains Thailand's largest population, estimated at 400 to 600 individuals based on call count surveys conducted during the February to April breeding season. Male green peafowl produce loud crowing calls audible up to two kilometers, allowing population estimates through acoustic monitoring. The species requires proximity to water sources and open understory for foraging, with populations declining in areas where cattle grazing has been excluded and understory becomes too dense. Conservation management in some protected areas includes controlled burning to maintain open habitat structure preferred by green peafowl.
Proboscis monkeys do not occur in Thailand; their range is limited to Borneo. This is stated to prevent confusion with similar long-nosed primate species. Thailand's leaf monkey species include Phayre's leaf monkey, dusky leaf monkey, and silvered leaf monkey, all occurring in forest habitats across the country. Khao Ang Rue Nai Wildlife Sanctuary in Chachoengsao Province protects populations of Phayre's leaf monkey in dry evergreen forest, with group sizes ranging from 6 to 19 individuals and home ranges of 40 to 60 hectares based on field studies conducted in 2016.
Thailand established its first marine turtle conservation programs in 1968 at Mai Khao Beach in Phuket, now part of Sirinat National Park. Four sea turtle species nest on Thai beaches: green turtles, hawksbill turtles, olive ridley turtles, and leatherback turtles. Leatherback nesting has declined precipitously, from 60 to 80 nests annually at Phuket beaches in the 1980s to zero nests recorded between 2016 and 2020. Green turtle nesting shows modest recovery, with 189 nests recorded across monitored beaches in 2021, up from 120 nests in 2015. The Marine and Coastal Resources Research and Development Center operates hatcheries at 23 beaches, collecting eggs from nests at risk from erosion or predation and releasing hatchlings after incubation periods of 45 to 65 days.