Also known as the marbled teal, this species was once native across the Mediterranean and beyond. Its dwindling habitat currently encompasses fragmented pockets in Asia, across the levant to southern Europe, where remaining European populations nest in the Iberian Peninsula. In this article, we learn more about the marbled duck – another species in decline.
Species History
Fossil records of the marbled duck trace back millions of years ago to the Upper Pliocene. Earliest deposits were found in Spain, Italy, Malta, and Türkiye. The species was first described in the early 1800s but was placed in the Anas genus, to be reclassified under the monospecific genus Marmaronetta—from the Greek marmaros and netta, meaning “marbled” and “duck,” respectively.
Field Identification
The marbled duck is a fairly small and slender member of the Anatidae family, named for the pale spotting across its gray-brown plumage. It has a prominent, dark eye patch—sans speculum unlike similar species—and a narrow black bill. Its wings are long with pale secondaries, white underwings, and dark wing tips visible in flight. It has a longish tail that points upward while swimming.
Sounds and Vocalisations
While mostly silent, adults have a squeaky, nasal courtship call, while juveniles give contact calls similar to other ducklings, and alarm calls when disturbed or threatened.
Habitat and Ecology
Marbled ducks inhabit temporary wetlands, preferring brackish and saline waters, with plentiful emergent, halophilic, and submerged vegetation. They also take to slow rivers and human-made reservoirs, fish ponds, and paddies, with shallow areas surrounded by dense vegetation—protective oases in otherwise dry regions.
Range and Movements
The marbled duck is found in the Palearctic, where it breeds in southern Europe, North Africa, and across Asia from western China to Türkiye, with significant populations in Iraq and Iran.
Somewhat nomadic, marbled ducks are partial migrants that move in response to the seasonal availability of suitable breeding habitat—typically wetlands—moving south after the breeding season and returning north in the spring. Some birds, however, remain at the breeding grounds over winter. Vagrant birds have been recorded as far south as southern India and north as Switzerland.
Diet and Feeding
Marbled ducks feed by dabbling in the shallow waters of their habitat. In deeper waters, they upend to forage beneath the surface. Their diet is mainly comprised of seeds, but they also eat invertebrates and aquatic plants. Prey includes insect larvae, tiny crabs, and even ants—an uncommon menu item for ducks.
Lamellae along the edges of their bills allow them to filter zooplankton from the water. Ducklings feed mainly on invertebrates until their gizzards are fully developed, enabling them to process seeds and other plant foods.
Breeding and Rearing
During courtship, several males swim around near one or more hens. Displaying and other courtship behaviour may be initiated by either sex. Monogamous pairs form each season. The hens construct the nests, typically on the ground amid the reeds or under some shrubbery at the water’s edge. Clutches are large, with hens laying up to fourteen eggs. Larger clutches result from brood amalgamation, whereby some eggs in the nest are laid by other hens in the colony.
Most drakes leave shortly after the young hatch, but some remain with the hen and ducklings. Typical of ducks, the young are precocial and can leave the nest and feed themselves shortly after hatching, but remain dependent on the hen for protection. They are fully fledged within sixty days.
Important breeding sites include the Mesopotamian Marshes in southern Iraq and the Shadegan Ponds—a series of wetlands of international importance, protected under the Ramsar Convention.
Behaviour
Marbled ducks are gregarious—year-round, although they tend to disperse during the breeding season. They form flocks during the winter, ranging from just a few birds to thousands strong.
Marbled ducks are strong flyers, able to cover great distances in a short time, despite their gentle wingbeats and low quiet flights. They are also good swimmers, although they need not cover long distances in water.
The marbled duck is not territorial, nor is it aggressive. It is an even-tempered bird, albeit nervous and flighty, yet commonly kept in captive collections.
Status and Conservation
Once an abundant species, marbled duck populations have been in decline since the 20th century. In Europe, the historical range of this species spanned from the south of France to the Balkans to southwestern Russia. They were also found in the Canary Islands, as well as Crete, Cyprus, and other islands in the Mediterranean Sea. Most island populations have since disappeared. In 2014, the species was reported extinct in Türkiye.
In Central Asia, the breeding range of the marbled duck diminished in the 1900s, as rivers, lakes, and deltas dried up following the diversion of water from the Amu Darya and Syr Darya Rivers to irrigate agricultural fields.
Since the early 1990s, several conservation measures have been implemented and habitat management techniques were employed to protect and restore populations. This includes the release of birds bred in captivity, the acquisition of protection of wetlands, habitat restoration efforts, and the implementation of hunting bans and restrictions in key areas within their range.
The destruction and degradation of wetlands pose an ongoing threat, forcing birds in Spain and other parts of their range to adopt artificial breeding sites such as fish farms. Marbled ducks are also impacted by unsustainable hunting, lead poisoning, and competition for food with invasive species encroaching into their habitat.
The marbled duck is currently classified as “near threatened” according to the International Union on the Conservation of Nature (UCN) Red List of threatened species.
Final Thoughts
Many gaps exist in our understanding of this enigmatic bird. Much of its breeding activity, migratory routes, stopover sites, life span, and survivorship remain unknown. We do know, however, of its ecological value. For instance, the marbled duck is an important disperser of seeds, partially those of sedges, between wetlands. Along with other species, marbled ducks are a food source for badges, foxes, and boars.
While the numbers of breeding pairs in some areas have marginally increased, the effects of conservation measures—particularly the release of captive-bred birds into wild populations—are poorly known.
More research and detailed censuses are needed to understand the full scale of risk this species faces and whether conservation efforts have so far been successful.
