ENIDDENL
Wildlife of Borneo

Irrawaddy dolphin

Orcaella brevirostris

Orcaella brevirostris has a rounded forehead and no pronounced beak.

Endangered
Species details & taxonomy
Species
Orcaella brevirostris
Genus
Orcaella
Family
Delphinidae
Order
Artiodactyla
Class
Mammalia
Irrawaddy dolphin (Orcaella brevirostris); see the caption for the photograph’s location.
Orcaella brevirostris in Kiên Giang, Vietnam; a species portrait, not a Mahakam observation.Long Vu · Wikimedia Commons · CC BY 4.0 · Original

Identification

Orcaella brevirostris has a rounded forehead and no pronounced beak. Its range includes coastal and estuarine waters as well as some freshwater populations. It is not a Borneo-endemic species; “Mahakam dolphin” refers to a particular local population, not a separate species record.

Sources & references · 3University of Michigan Animal Diversity Web · Orcaella brevirostrisIUCN SSC Cetacean Specialist Group · Red List status of cetaceansYayasan Konservasi RASI · Freshwater dolphin surveys

Forest and habitat

The Mahakam population lives in freshwater reaches documented by RASI’s monitoring programme. Boat noise, entanglement and habitat pressures form its conservation context. Do not infer dolphin presence along every urban riverbank from the broader river relationship.

Sources & references · 1Yayasan Konservasi RASI · Freshwater dolphin surveys

Feeding

The species feeds on fish, cephalopods and crustaceans. This general description is not a quantified diet for Mahakam individuals.

Sources & references · 1University of Michigan Animal Diversity Web · Orcaella brevirostris

Mothers and young

Females usually bear one calf and nurse it over an extended period. A precise local breeding calendar is not established by the sources used here.

Sources & references · 1University of Michigan Animal Diversity Web · Orcaella brevirostris

Range on Borneo

The selected sources document Orcaella brevirostris at Mahakam River. These are place-specific published records, not current population estimates or evidence for every protected area in the province.

Sources & references · 1Yayasan Konservasi RASI · Freshwater dolphin surveys

Conservation

The species is globally Endangered; the Mahakam River subpopulation is Critically Endangered. These assessments have different scopes and must not be combined into one population claim.

Sources & references · 1IUCN SSC Cetacean Specialist Group · Red List status of cetaceans

Life in the Mahakam

In the Mahakam, the freshwater population is known as pesut. Its survival depends on connected river and lake habitats with sufficient fish. Dolphins surface briefly, so a rounded head and low dorsal fin may be all that appears. Conservation surveys have identified gillnet entanglement as a major cause of death, alongside collisions and declining habitat quality. Heavy vessel traffic, underwater noise, pollution and damage to fish-spawning wetlands can affect the same river reaches. Protecting dolphins consequently also means protecting fish habitat and the livelihoods that depend on it.

Sources & references · 2Yayasan Konservasi RASI · Freshwater dolphin surveysUniversity of Michigan Animal Diversity Web · Orcaella brevirostris

Where to look

A recorded occurrence does not guarantee a sighting or visitor access. Read the area and experience guides for habitat, responsible observation, guiding and current access before choosing a trip. Keep wildlife at a distance and follow local restrictions.

Places with documented occurrence

Related wildlife trips

Related discoveries

Habitats

Nature areas

The Mahakam River at Samarinda.
Nature areas

Mahakam River

The Mahakam is a working river landscape in East Kalimantan, connecting urban waterfronts, settlements and inland wetlands. It is not one protected area or a single wildlife cruise. Samarinda and Tenggarong reveal its transport and cultural roles, while inland journeys require a more specific route and local host. The river is also important for the threatened Mahakam population of Irrawaddy dolphins, but that does not make an urban boat trip a dolphin-viewing trip. Choose between a city river experience and a longer community or conservation journey before deciding where to stay. There is no single Mahakam entrance, park ticket or visit duration.

ShaaShaRS · Wikimedia Commons · CC BY-SA 4.0 · Cropped · Original

Destinations

Sekonyer River in Tanjung Puting National Park, Central Kalimantan.
Destinations

Kalimantan

Kalimantan is the Indonesian part of Borneo, where five provinces invite five different starting decisions. Choose rivers and peat forests around Palangka Raya or Pangkalan Bun, city food and upper-Kapuas journeys in the west, Banjar river life and Meratus hills in the south, Mahakam heritage and Berau islands in the east, or coastal and highland travel in the north. The most useful question is which corridor deserves your time, not how many provinces can fit on a map. Travel usually combines an arrival city with separate road, river or island stages. Use the province summaries below to choose a starting point, then open its destination and activity pages for the actual visit.

Nanosanchez · Wikimedia Commons · CC BY-SA 4.0 · Cropped · Original

Activities

The Mahakam River at Samarinda.
Activities

Mahakam river experiences: city waterfront or inland village?

The Mahakam is both a working river and a route into East Kalimantan's inland landscapes. Near Samarinda, boats, waterfront buildings and the scale of the river create an urban experience. Farther inland, a village-based visit around Pela brings a different pace and a closer relationship with local livelihoods and river ecology. These are distinct choices, not stages automatically included in one sightseeing ticket. This guide helps you decide whether you want a short city outing, a cultural stop in the wider river region or time with a locally organised inland programme. The most useful first question is where the boat actually goes. Once the stretch is clear, the transfer, accommodation and amount of time you need become much easier to judge.

ShaaShaRS · Wikimedia Commons · CC BY-SA 4.0 · Cropped · Original

Sources & references

IUCN SSC Cetacean Specialist Group · Red List status of cetaceansAccessed: 2026-10-01

University of Michigan Animal Diversity Web · Orcaella brevirostrisAccessed: 2026-10-01

Mammal Diversity Database · Orcaella brevirostrisAccessed: 2026-10-01

Yayasan Konservasi RASI · Freshwater dolphin surveysAccessed: 2026-10-01

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