Mangrove forests, creeks and intertidal mudflats are the main habitats in and around Pulau Kukup. At least 18 true mangrove species grow on the island; a relatively high figure compared to other larger mangrove sites. In this protected area, mangrove trees are able to grow undisturbed to their full potential. As such, the island boasts some very large living specimens, including a 20-m high perepat (Sonneratia alba) that is currently the tallest on record in the country for the species.
The forest supports seven species of mammals, including the flying fox (Pteropus vampyrus), smooth otter (Lutra perspicillata) and Asian palm civet (Paradoxurus hermaphroditus). The flat-headed cat (Prionailurus planiceps), an elusive wetland specialist that is listed as Endangered on the IUCN Red List of Threatened Species, has also been recorded on the island, as well as the bearded pig (Sus barbatus), whose present distribution in Peninsular Malaysia is largely limited to Johor. Pulau Kukup is also an important route for dolphins transitioning between the island and mainland.
Six species of reptiles are present on Pulau Kukup, i.e. the mangrove skink (Emoia atrocostata), Asian water monitor (Varanus salvator), saltwater crocodile (Crocodylus porosus), dog-faced water snake (Cerberus rynchops), mangrove pit viper (Cryptelytrops purpureornaculatus) and mangrove snake (Boiga dendrophila).
Pulau Kukup forms part of the South-west Johor Coast Important Bird & Biodiversity Area (IBA); one of 55 IBAs across Malaysia identified by Birdlife International to be of international significance for the conservation of the world’s birds and other wildlife. The island is home to a number of rare and globally-threatened birds, including the Lesser Adjutant (Leptoptilos javanicus), Milky Stork (Mycteria cineria) and Chinese Egret (Egretta eulophotes), as well as mangrove specialists such as the Mangrove Pitta (Pitta megarhyncha), Mangrove Whistler (Pachycephala cinerea) and Mangrove Blue Flycatcher (Cyornis rufigastra).
The park is also an important stopover site for migratory waterbirds travelling along the East Asian – Australasian Flyway (EAAF), such as the Common Redshank (Tringa totanus) and White-winged Tern (Chlidonias leucopterus). The mudflats on the northern side of the island are productive grounds for these birds to feed during low tide while the mangroves provide them with a safe place to roost.
The mangroves are habitats for many species of marine fishes such as the siakap (Lates calcarifer), ikan merah (Lutjanus argentimaculatus) and senangin (Eleutheronema tetradactylum). The mudflats below hold an array of marine invertebrates including commercially-important species such as oysters (Crassostrea spp.), blood cockles (Tegillarca granosa) and sentinel crabs (Macrophthalmus sp.).
While walking along the boardwalks, all manner of creepy-crawlies may be seen scuttling across the mud including tree-climbing crabs (Episesarma spp.), fiddler crabs (Uca spp.) and mudskippers. As their name suggests, the tree-climbing crabs do climb up the mangrove trees. They will stay just above the water level in order to escape from fishes that come in with the incoming tide. To complicate matters, these crabs also have to stay very still to avoid the attention of other predators that lurk above the tides such as kingfishers, monitor lizards and long-tailed macaques (also known as crab-eating macaques).
Male fiddler crabs are blessed with one normal sized claw and one humongous claw. The oversized claw is used to attract females and fend off rival males, while the normal sized claw is used to put food in its mouth. Can you guess why it is called a “fiddler crab”?
While mud lobsters (Thalassina anomala) are rarely seen, the mounds that they build protrude like mini volcanoes between the stilt roots of the mangrove trees. These mounds are an important habitat for many other creepy-crawlies, including the tree-climbing crab.