Ducula is a genus of imperial pigeons (Columbidae). Big to huge pigeons with medium to long tails. Fruit Eaters Ptilinopus is the dove’s genus. It is arboreal, eats mostly fruit, and is closely related to the other fruit-eating dove genera. Each species features contrasting purple, orange, or red underparts and green upperparts. Imperial pigeons have big ceres.
They eat whole seeds and have wide gaps for seed dispersion. Southern Asia, New Guinea, northern Australia, and the Pacific islands have imperial pigeons. Some animals travel long distances in pursuit of seasonal fruits. They all fly well and migrate. Imperial pigeons are among the world’s most endangered birds owing to habitat loss and predation.
Taxonomy Of Imperial Pigeons:
The Imperial pigeons were named after the English scientist Brian Houghton Hodgson in 1836. Taxonomic status: mountain imperial pigeon subspecies (Ducula Badia). The Latin word Ducula means “leader.”
The taxonomy of the imperial pigeon is unclear, with reports of 34-36 species under the genus Ducula.] Derek Goodwin’s 1959 study on Ducula taxonomy divides 36 species into seven groupings based on distribution and phenotype. This categorization is used by Gibbs et al.
Habitat And Range:
A distribution from the Himalayas (D. Badia) to Tahiti (D. Badia) is all that exists for Imperial pigeons (D. Aurorae). New Guinea has the most bird variety. Imperial pigeons can fly across seas and have successfully colonized islands and archipelagos.
Only one Ducula species breeds on the continent of Australia (D. spilorrhoa). No one knows why more Ducula species did not traverse the Torres Strait islands to mainland Australia. Before European arrival, Lopholaimus, with just one species, may have been highly represented across the Australian continent, excluding Ducula.
Imperial pigeons are arboreal and only found in forest and woodland environments with fruit-bearing trees. About half of the species live in 2500m alpine forests—islands and coastal woods, with a few species living on forest margins or mangroves.
The Appearance Of Imperial Pigeons:
Tropical pigeons have a wide range of colours, perhaps to aid in species identification. The seed-eating Columbidae have drab brown or grey plumage. Imperial pigeons have a black dorsum and iridescent green wings. Their breasts are lighter, ranging from grey to pink to dark grey. Birds confined to islands have less noticeable markings. Most animals lack sexual dimorphism.
Imperial pigeons are big to huge pigeons with medium to long tails. The Marquesan imperial pigeon is the biggest arboreal pigeon in the family, Columbidae, measuring 50 cm.
- Bicolor and D. sialorrhea have fat quills. Fat quills are modified feathers that generate a fatty material comparable to preen gland secretions. D. bicolour and other Columbidae species have fat quills on their rump. The yellow-coloured lipid causes D. bicolour’s head and shoulders to change colour from cream to yellow. Due to the variation in colouration across individuals and moult stages, it is difficult to identify taxa. The fat quills’ purpose is debated, with theories ranging from sexual signal to antibacterial to olfactory. A fractured rachis may exude a yellow lipoid material.
The Behaviour Of Imperial Pigeons:
Most Imperial pigeons are timid and dwell in isolated locations, making observation difficult. The breeding and nesting behaviour of animals is unknown. Despite their size and numbers, birds may be camouflaged under dense vegetation.
Ducula may travel long distances to obtain fruit. They may fly across islands to exploit irregular food supplies. Small islands with inadequate vegetation may temporarily feed migratory birds. Some Imperial pigeons live alone or in pairs, but many form flocks of 30-50 birds. They like offshore islands or mangroves to breed. Large colonies of D.
Sialorrhea flies to fruit-bearing woods during the day and roosts together at night. 20,000-25,000 birds bred on Low Isles in North Queensland in 1971-1973. A volunteer census in December 2014 found over 22,000 pied imperial pigeons (pipwatch.net). 100,000 D. Sialorrhea flew from the mainland to their roosting grounds on Dunk Island, North Queensland, in 1908. Pigeons drink by pumping or sucking, keeping their beak submerged in water. Consumption of fruit by pigeons reduces water needs.
Diet Of Imperial Pigeons:
Imperial pigeons live in tropical woods and mangroves, including seasonal fruit trees, palms, vines, and shrubs. Most birds climb up twigs and trees to obtain food, leaning or hanging upside down. The bill twists fruit off stems and swallows it whole. Their 40mm gapes enable them to consume big fruits. D. Galatia can consume 70mm seeds. Flowers, leaves, and insects may be added to their diet.
Ducula has thin-walled gizzards and short, broad guts, enabling big seeds to pass. They empty the seeds intact after digesting the fleshy portions, thereby acting as seed dispersers.
Other Columbidae genera have grinding gizzards that either destroy or regurgitate seeds. The Nicobar pigeon (Colaenesa nicobarica) eats big seeded fruits, whereas the imperial pigeon excretes them whole.
Imperial pigeons are big frugivores that can spread seeds from fruit that most other species cannot manage. A 30 mm fruit size would exclude all vertebrates except Bucerotidae and Ducula. Big pigeons eat large fruit, whereas medium pigeons feed on medium fruit. Pacific pigeons (D. Pacifica) are efficient seed dispersers in Tonga and are important in forest management.
Reproduction Of Imperial Pigeons:
Imperial pigeons build fragile nests of loosely braided twigs in tree forks. Mangrove roosting species build larger nests from mangrove branches. They usually deposit just one egg with a brief incubation time. It is a joint effort of both sexes. Pigeons generate nutritious crop milk that enables chicks to fledge and leave the nest, decreasing vulnerability quickly. The short breeding cycle allows for several broods to be raised during a long summer breeding season.
Crop milk is a thick cheesy fluid made from squamous cells shed from the crop of both male and female pigeons. There is no Ducula-specific crop milk composition research. In contrast, crop milk from domestic pigeons (Columba livia) contains lipids, proteins, and enzymes and promotes maternal antibodies to squabs.
Prolactin, like in animals, regulates crop tissue hypertrophy and milk production. Fruit availability is essential for frugivorous bird nesting success. Large breeding colonies need unexplored forests for daily feeding.
Typical pigeon family ‘coo’ and ‘woo-woo cries, to resonant ‘whoops’ sudden booming sounds or barking notes, to disyllabic deep booming calls.
Columbidae can fly across oceans to obtain seasonal food sources. D. bicolour’s spread shifts with food availability.
Ecology And Aildlife:
About one-third of extant Columbidae pigeons are endangered, making it one of the world’s most endangered families. Nearly two-thirds of Columbidae species are found in Asia, Australasia, and Oceania, yet three-quarters are endangered.
Loss of habitat, human hunting, and foreign predators are the main challenges to Columbidae species. Other concerns include illness and invasive species competition. Vast flocks of Ducula are nomadic and may exploit large regions for food but are susceptible to forest degradation.