Tadorna ferruginea

Tadorna ferruginea

The ruddy shelduck (Tadorna ferruginea Pallas, 1764) is a species of bird belonging to the Anatidae family.

Systematics –
Domain Eukaryota,
Kingdom Animalia,
Phylum Chordata,
Class Aves,
Order Anseriformes,
Family Anatidae,
Subfamily Anatinae,
Tribe Tadornini,
Genus Tadorna,
Species T. ferruginea.
The following terms are synonymous:
– Anas casarca Linnaeus, C, 1768;
– Anas ferruginea Pallas, 1764;
– Ruddy shelduck Linnaeus, C, 1768;
– Ruddy shelduck (Pallas, 1764);
– Tadorna shelduck (Linnaeus);
– Tadorna rutila (Pallas).

Geographic Distribution and Habitat –
The Tadorna ferruginea is a bird of the order Anseriformes and the family Anatidae. It is a monotypic species, meaning it is not divided into recognized subspecies, characterized by a predominantly Central Asian-North African distribution. Its range includes northwest Africa, southeastern Europe, Asia Minor, and central-southern Asia.
Migratory behavior varies considerably depending on the area. In some parts of its range, especially in Asia, the common shelduck is migratory, while in other areas it may be erratic, making irregular movements that are not necessarily linked to a true seasonal migration. In some regions, however, it is sedentary. In Italy, its presence is described as sporadic.
During the winter season, the species winters mainly in North Africa, Asia Minor, and the Middle East. A smaller number of individuals also spend the winter in Europe, particularly in Greece and Spain. Regarding European sightings, the notes emphasize the need to interpret them with caution: many could refer to individuals escaped from captivity, as the shelduck is a species commonly bred and reproduced by amateur breeders.
The ferruginous shelduck displays a remarkable adaptability in its choice of habitat. It frequents both coastal wetlands, such as lagoons, river mouths, deltas, and salt marshes, as well as inland aquatic environments, including lakes of various sizes, rice paddies, marshes, and ponds. It is therefore not exclusively tied to large bodies of water and, in inland areas, can also make do with small streams.
However, its presence is not limited to areas immediately adjacent to water. The species also frequents inland environments, such as countryside, steppes, plateaus, and mountainous regions. Its ability to reach high altitudes is particularly notable: in the Himalayas, it can be observed up to approximately 5,000 meters above sea level. This wide variety of habitats is consistent with the adaptability of the species.
The ferruginous Tadorna also has gregarious habits, allowing it to frequent favorable environments even in groups. The variety of habitats it uses, along with its ability to live both near large wetlands and inland areas with small streams, is one of the characteristic features of its ecology.

Description –
The Tadorna ferruginea belongs to a group of ducks with a fairly uniform shape and medium size, but its appearance is a cross between a duck and a goose. This particular shape has led to its being described as a duck with a “goose-like” appearance.
Its coloration is the most easily recognizable feature. The body has a characteristic orange-brown or rusty-orange hue, while the head is generally lighter, with a color described as cinnamon-honey. Thanks to this distinctive plumage, the species is generally unmistakable, although from a distance it can be confused with the Egyptian goose (Alopochen aegyptiacus).
The Tadorna ferruginea has a total length of approximately 58-70 cm, a wingspan of approximately 115-145 cm, and a weight ranging from approximately 920 to almost 2000 grams. Similar in size to the common shelduck (Tadorna tadorna), there are some morphological differences: the shelduck’s neck and legs are slightly longer, its wings are longer and relatively narrow, and its beak is smaller.
The beak measures approximately 39–45 mm and is completely black. Its rather high and vertical attachment helps give it a similar appearance to a geese’s beak. The two rhamphothecae, the horny structures that cover the beak, have numerous teeth; those of the upper rhamphotheca protrude slightly. The legs are black, and the tarsi measure approximately 54–62 mm. The iris is dark brown.
The male, especially during the breeding season, has a distinctive black collar that encircles the neck approximately halfway along its length. This feature is particularly useful for distinguishing it from the female. The primary and secondary feathers, at least in the areas indicated in the notes, are black, as are the tail and rump. The lower belly and undertail are a darker brick red.
On the dorsal region, in front of the black uppertail, the feathers are finely vermiculated, characterized by a dense pattern of thin streaks, in shades of light red and blackish-brown. The secondary feathers, viewed dorsally, are brownish-black-purple and form a green wing mirror, particularly evident when the bird is in flight. The dorsal wing coverts are white, with a very slight tawny-yellow tinge, while those on the underwing are white. The black uppertail may also have dark green highlights.
The female is similar to the male in overall coloration, but has less intense orange tones. The most obvious difference is the absence of the black collar. Around the eyes, it also has white feathers that form a characteristic periocular patch, more or less extensive but always clearly visible. During the post-breeding period, the female does not show significant changes in appearance, while in the male, the black collar may disappear or be significantly reduced.
Juveniles resemble the female, but have an overall duller coloration and darker upperparts. The crown and back of the neck are dark gray-brown, while the beak and legs are similar in color to those of adults.
Their voices are also recognizable. The two sexes produce different vocalizations: the male produces a more blunt, breathy call, while the female produces a higher, squawking call. The calls are described as distinctive and nasal, similar to honking, and in some ways reminiscent of those of the greylag goose (Anser anser). From a great distance, they can even resemble the braying of a donkey.
The scientific name reflects one of the most striking characteristics of the species. The genus name Tadorna derives from the Latin and means “pied waterfowl,” referring to the distinctly colored plumage of many species within the genus. In the case of the shelduck, however, this definition is less appropriate, as the species exhibits a predominantly dominant coloration. The specific term ferruginea, also of Latin origin, refers to the characteristic orange-rust colour of the livery.

Biology –
The Tadorna ferruginea is a species characterized by its distinctive and easily recognizable flight pattern. It flaps its wings vigorously but slowly and widely, a characteristic that allows it to be identified even when in flight. It is also often capable of flying at considerable altitudes.
Throughout the year, it undergoes a gradual and complete post-breeding molt. During this phase, it temporarily loses the ability to fly for about four weeks. The period indicated in the notes is from mid-July to September. The mating plumage is then complete between March and April.
From a dietary perspective, the common shelduck has a very varied and adaptable diet and is described as omnivorous. This characteristic allows it to exploit different food resources depending on its environment. Animal-based components of its diet include mollusks, crustaceans, small fish, aquatic worms, amphibians, and insects.
Its diet also includes numerous plant resources. The shelduck feeds on algae, aquatic plants, shoots, seeds, cereals, and agricultural crops, as well as berries and other resources. This combination of animal and plant foods further highlights the opportunistic and adaptable nature of the species.
Breeding can occur in a wide variety of environments. The shelduck breeds on the banks of rivers and lakes and in salt marshes, but it can also nest in hills and mountains, even in places relatively far from water. Despite this flexibility in choosing its breeding environment, the pair bond is described as very strong and generally long-lasting.
The choice of nesting site is also particularly interesting. The nest is preferably placed in tree or rock cavities, in abandoned burrows, near riverbanks, or in ruins. Consequently, the nest does not necessarily have to be on the ground: it can also be located at a certain height, up to about 10 meters above the ground.
In some nature reserves, the species has benefited from the installation of closed artificial nests, or nest boxes. These interventions have favored the increase of the species in the affected areas, demonstrating how the availability of suitable nesting sites can be an important factor for its presence.
The female generally lays 7-12 white, smooth-shelled eggs. Incubation is carried out exclusively by the female and lasts about 30 days. After hatching, however, both parents participate in caring for the clutch and tend it with determination.
The ducklings have a characteristic black and white pied coloration and may closely resemble common shelduck (Tadorna tadorna) chicks. Compared to the latter, however, they have a slightly more diluted crown and dark upperparts. They generally lack the white eyebrow patch, or this feature is less evident and extensive. The iris is brown, the beak is gray-black, and the legs are blackish.
Regarding conservation, notes indicate an estimated population of approximately 170,000-220,000 individuals. The species is currently considered not particularly threatened and, according to the source, will be listed on the IUCN Red List as Least Concern (LC) starting in 2025.
This does not mean, however, that the ferruginous shelduck is free of threats. The main risk factors include hunting, especially in southeastern Europe, the loss of wetlands, urban development, pollution, and the introduction of non-native fish species.
Another concern is the possibility of hybridization. The common shelduck can interbreed quite easily with other species belonging to the Tadorna genus. For this reason, the notes emphasize the importance of preventing the escape of non-native shelducks into natural areas where resident species of the same genus are present. Hybridization could, in fact, lead to genetic pollution.

Ecological Role –
The Tadorna ferruginea occupies a central role within aquatic and wetland ecosystems, frequenting extremely diverse environments, from coastal lagoons to salt marshes, from river mouths to lakes, from marshes to ponds and rice paddies. Its presence in the countryside, steppes, plateaus, and mountainous areas also highlights how its relationship with the environment is not limited exclusively to wetlands.
From a feeding perspective, the common shelduck is an omnivorous consumer. It feeds on numerous aquatic organisms, including mollusks, crustaceans, small fish, aquatic worms, amphibians, and insects, but also consumes algae, aquatic plants, sprouts, seeds, cereals, agricultural crops, and berries. Its diet thus allows it to exploit resources from different ecosystem components.
Its remarkable dietary and environmental adaptability allows the species to utilize available resources in different contexts. In inland areas, for example, it can also live near small streams, without necessarily relying on large bodies of water, thus contributing to its ability to inhabit diverse habitats.
Reproduction also demonstrates close interaction with the environment. The species uses natural cavities in trees and rocks, abandoned burrows, riverbanks, and ruins as nesting sites, thus establishing a relationship with different structural elements of the habitat. The possibility of also using artificial nests also highlights the importance of the availability of suitable cavities for the local presence of the species.
Finally, the shelduck is also of interest in the management and conservation of Anatidae communities. Its ability to hybridize with other species of the Tadorna genus makes it important to monitor the possible presence of non-native individuals from captivity, in order to prevent potential genetic contamination of wild populations.
Overall, the shelduck is distinguished by a remarkable capacity for adaptation, which allows it to exploit a wide variety of habitats and food resources. Its ecological role is therefore closely linked to the aquatic and terrestrial environments it frequents and its position as an omnivorous consumer within natural communities.

Guido Bissanti

Sources
– Wikipedia, l’enciclopedia libera.
– GBIF, the Global Biodiversity Information Facility.
– C.Battisti, D. Taffon, F. Giucca, 2008. Atlante degli uccelli nidificanti, Gangemi Editore, Roma.
– L. Svensson, K.Mullarney, D. Zetterstrom, 1999. Guida agli uccelli d’Europa, Nord Africa e Vicino Oriente, Harper Collins Editore, Regno Unito.

Photo source:
– https://www.inaturalist.org/observations/336243638
– https://creazilla.com/media/traditional-art/7195938/tadorna-ferruginea-1921