Indian Spot-billed Duck

The Indian Spot-billed duck or Spot bill with the scientific name of Anas Poecilorhyncha is one among the three Spot-billed duck species found commonly in various parts of India. The Spot bill is commonly called as Grey duck. These duck species are the residents of India and various other countries like Pakistan, Southern Japan and South East Asia. The quick classification of Indian Spot-billed duck is as below,

Kingdom	Animalia
Scientific Name	Ardeola grayii
Class	Aves
Order	Anseriformes
Family	Anatidae
Genus	Anas
Species	Anas Poecilorhyncha
Sub species	Anas poecilorhyncha poecilorhyncha

Physical Characteristics:

Spot bill is a commonly breeding bird with dark brown or grey colored body. Their body is heavily scaled. The bill of this species is black with an orange spot on the top of the bill and yellow spots on the base of the bill. Their head and neck is whitish or pale grey colored with light black streaks over this area and black colored broad line around the eyes. The lower neck area is usually pale grey with black spots throughout.

They possess pale grey feathers with black spots at the lower neck and breast and dark feathers as they graduate to the edge. The feathers are dark at the abdomen, ventral region, tail and rumps. The tail is usually covered with black brown colored feathers. The upperparts are blackish with pale grey at the edges. Wings are colored with the grey and black combination and white at the tip of wings.

The wings have a speculum which is green in between black and white bands. The speculum can be best noticed during their flight. The terminal half of the inner tertials are white colored. Legs are orange-red in color. Females look slightly duller than the males.

The species measures around 22–25 in (55–63 cm) in length and 33–37 in (83–95 cm) across the wings, with a body weight ranging from 790 to 1,500 g (1.7–3.3 lb). The wingspan ranges from a minimum of 83 cm to a maximum of 95 cm. The incubation period is at a minimum of 24 days to a maximum of 28 days. The fledging period ranges between 50 days and 55 days. The clutch eggs ranges from 6 to 12.

Behaviour:

These ducsk are gregarious species always found in flocks around various wetlands of India. The call of drake is a bit hoarse and wheezy but the duck makes a loud quacking sound.

Habitat:

These birds prefer living in areas where the vegetation contains water in surplus. They are found in wetlands, freshwater vegetation containing reservoirs, lakes, rivers, etc. They can be spotted as flocks at the coast, various types of wetlands and inland. They prefer being in shallow water with vegetation.

Migration:

The Indian Spot-billed Duck belongs to a highly mobile family. These species are migratory as individuals or small flocks. Migration occurs seasonally in search of water and rain availability.

They are usually vegetarian and feed on seeds, sedges, grains like rice, parts of grasses and aquatic plants. At times they feed on water insects, larvae, molluscs, worms and water snails. Like the dabbling ducks they are the surface feeder and get its food by dipping its head and up-ending in the shallow water.

When it dips its head to grab a food the tail of the bird stays up the water surface providing it a balance. On marshlands they walk and grab the food.

Places found

The species Anas poecilorhyncha poecilorhyncha is found all over the Indian subcontinent. They are widely seen in various states like Tamilnadu, Assam, West Bengal, Karnataka, Andhra Pradesh, Madhya Pradesh, Uttar Pradesh, Jammu and Kashmir, Sikkim and Delhi. Other than India they are found in Korea, Japan, Russia, Taiwan, Thailand, Cambodia and Laos.

Mating and Nesting:

The breeding season of Indian spot bill is throughout the year and to be specific the mating happens during July-October in northern India and November-December in south India. Both male and female attain sexual maturity at its first year. During this season they can be found in pairs or they may form small colonies. The female builds a nest under water with a pad of grass and weeds in between water plants.

Occasionally they build nest in trees. They lay 7 to 14 eggs which are greenish-white or grey in color. The incubation period is 4 weeks and the fledging happens between 50 and 55 days. The female tend to top its ducklings and at times the male assists them. The hatched ducklings have blackish yellow markings over their upper parts and the under parts are yellow in color. They have a broad black eye stripe. The egg is 56 x 41mm in size and weighs around 55g.

Threats and conservation

Indian Spot bill have been categorized as "least concern bird " by IUCN.

Studies reveal that these birds occur in the range of about 20,000 square km. Despite having an extremely large range their population seems to be decreasing in the recent days, which may reach to vulnerable state if left unnoticed. The population statistics in the recent studies states that there has been more than 30% decline in these species.

The numbers couldn't be quantified as they tend to appear in various ranges and also it is believed that the population decline is not so rapid such that they would be categorized as a vulnerable species. Hunting is one of the major threat faced by this species.

Subspecies of Spot-billed Duck

There are three recognized subspecies of Spot-billed Duck or Grey duck found all over the world. They are as below, • Indian Spot-billed Duck (A. poecilorhyncha poecilorhyncha)
• Eastern Spot-billed Duck (A. poecilorhyncha zonorhyncha)
• Burmese Spot-billed Duck (A. poecilorhyncha haringtoni).
Anas poecilorhyncha zonorhyncha and Anas poecilorhyncha poecilorhyncha are the common species compared to Anas poecilorhyncha haringtoni.

Interesting facts about Indian Spot-billed Duck:

1. The flocks have ducks containing a maximum of fifty birds.
2. These species are commonly hybridized with mallard type ducks.
3. These species breed easily and it is easy to maintain them in domestic environment.
4. They build nest boxes majorly in the low or close ground with a pad of grasses and weeds.