The fulvous whistling duck (Dendrocygna bicolor) and black-bellied whistling duck (Dendrocygna autumnalis) are two species of whistling duck found in North America. While they are similar in appearance and behavior, there are some key differences between these two bird species.
Appearance
The most noticeable difference between fulvous and black-bellied whistling ducks is in their plumage.
The fulvous whistling duck has tawny brown plumage over most of its body, with a whitish belly. The breast is a rich chestnut color. The head is a lighter brown with a dark crown. The bill is blue-gray, long, and slightly decurved. The legs and feet are bluish-gray.
The black-bellied whistling duck has a more striking plumage pattern. The head and neck are chestnut with a black crown and cheek patch. The back and wings are grayish brown. As the name suggests, the belly is black from the chest to the undertail coverts. The chest is a bold chestnut color that abruptly transitions to black underparts. The bill is long, broad, and black. The legs and feet are bright pink.
In flight, the fulvous whistling duck shows mostly brown wings, while the black-bellied whistling duck has prominent white markings on the wings and a white tail.
Juveniles of both species have a duller, gray-brown plumage overall with little contrast between the back and belly.
Size
The fulvous and black-bellied whistling ducks are very similar in size.
Fulvous whistling ducks measure 17-24 inches (43-61 cm) in length and weigh 1.1-2.2 pounds (0.5-1 kg). Their wingspan is around 30-38 inches (76-97 cm).
Black-bellied whistling ducks are slightly larger at 19-26 inches (48-66 cm) in length. They weigh 1.2-2.6 pounds (0.5-1.2 kg) and have a wingspan of 32-40 inches (81-102 cm).
So while fulvous whistling ducks tend to be on the lower end of the size range, there is considerable overlap with black-bellied whistling duck sizes.
Voice
The whistling ducks get their name from their distinctive vocalizations. However, the calls of the two species differ.
The call of the fulvous whistling duck is a high-pitched, squeaky whistle. It is rendered as “piew-piew” or “peeh-peeh.” They may also make barking and soft clucking sounds.
Black-bellied whistling ducks have loud, clear whistles. Their call is written as “who-kee” or “who-chuch.” The last note tends to slur down in pitch.
The whistles of the black-bellied duck are lower-pitched and more nasal compared to the thin, squeaky whistles of the fulvous duck.
Range and Habitat
The ranges and habitat preferences of fulvous and black-bellied whistling ducks differ considerably.
Fulvous whistling ducks are native to the southern United States and Mexico. In the US, they occur in southeast Texas, Louisiana, and southern Florida. They also range through much of Mexico and down into Central America. This species occupies shallow wetlands, flooded agricultural fields, rice paddies, ponds, and sluggish rivers.
Black-bellied whistling ducks occupy a larger range extending from the southern US through Mexico, Central America, the Caribbean, and into northern South America. In the US, these ducks occur along the Gulf Coast, throughout Florida, and into the southwestern states like California and Arizona. Black-bellied whistling ducks frequent ponds, lakes, marshes, estuaries, and wet agricultural areas, often in open or semi-open habitats.
So while the fulvous whistling duck is more localized in coastal southeastern states, the black-bellied whistling duck occupies a broader range including inland areas west of the Mississippi River.
Behavior
The behavioral patterns of these duck species are generally similar, with a few subtle differences.
Both species feed mainly at night or early morning and roost during midday. They walk and swim when foraging, often dipping their heads underwater or tipping forward to feed. Their diet consists of plant material like seeds of grasses and aquatic vegetation as well as aquatic invertebrates.
Fulvous and black-bellied whistling ducks are highly social and gather in flocks, often associating with other duck or wetland species. They may congregate in high numbers at prime roosting or feeding sites.
Nesting takes place between March and June depending on the region. Nests are built on the ground or in holes in trees. Unlike many ducks, whistling duck pairs exhibit long-term pair bonds and cooperate in incubating eggs and rearing young. Fulvous whistling duck clutches tend to be slightly smaller on average.
Black-bellied whistling ducks are perhaps more willing to occupy urban and suburban areas with man-made ponds and residential canals. But both species adapt readily to human-altered wetland habitats.
Conservation Status
Both species of whistling ducks remain widespread and abundant. They are considered species of Least Concern by the IUCN.
Fulvous whistling ducks suffered declines in the late 19th century due to overhunting and wetland loss or degradation. With protection from hunting and more actively managed wetlands, their populations increased over the 20th century. They are common and increasing throughout their range today.
Black-bellied whistling ducks also adapted well to habitat changes from agriculture and urbanization. Their populations expanded northward in the 1900s. They are now one of the most common breeding duck species in places like Florida and southeastern Texas.
Neither species is under immediate threat, although localized impacts from wetland destruction or disturbance may affect some populations.
Key Differences Summary
Here is a quick overview of the main differences between fulvous and black-bellied whistling ducks:
- Fulvous whistling ducks have brownish plumage with a chestnut breast; black-bellied ducks have gray-brown plumage with a black belly and chestnut chest.
- Fulvous ducks are slightly smaller on average.
- Fulvous ducks make a high, squeaky whistling call; black-bellied ducks make a lower, nasal whistling call.
- Fulvous ducks occur along the Gulf coast and into Mexico; black-bellied ducks range more widely from the southwest US through Central America.
- Fulvous ducks prefer natural wetlands; black-bellied ducks also occupy urban and suburban wetlands.
- Both species have adapted well to habitat changes and have Least Concern conservation status.
Conclusion
In summary, the fulvous and black-bellied whistling ducks possess similar behaviors as highly social, ground-nesting ducks that frequent shallow wetland habitats. However, they differ significantly in their geographic ranges, preferred habitats, vocalizations, and plumage characteristics. Fulvous whistling ducks are smaller and more localized in the southern coastal US, while black-bellied ducks occupy a broader American range. Understanding the similarities and differences between these species can help birders properly identify them in the field based on location, appearance, and calls. Despite some population declines historically, both species remain common and widespread throughout their respective ranges.
