Freckled duck
| Freckled duck | |
|---|---|
 | |
| Male | |
 | |
| Female | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Anseriformes |
| Family: | Anatidae |
| Subfamily: | Stictonettinae |
| Genus: | Stictonetta L. Reichenbach, 1853 |
| Species: | S. naevosa |
| Binomial name | |
| Stictonetta naevosa (Gould, 1841) | |
The freckled duck (Stictonetta naevosa) is a waterfowl species endemic to Australia and is considered to be amongst the rarest waterfowl in the world. The freckled duck has also been referred to as the monkey duck or the oatmeal duck (in English), Punktchenente (in German), canard mouchete (in French) and pato manchado (in Spanish) (21). These birds are usually present in mainland Australia, but disperse to coastal and subcostal wetlands in the dry period. During such times it is common for the freckled duck population to congregate in flocks inhabiting the same environment, giving the impression that they are more common than they really are. (16).
The freckled duck population is at risk of further reduction from habitat destruction, droughts and game hunting. Often habitat destruction and drought can lead to an increase in hunting, as the freckled duck is forced to disperse into more coastal ranges where they may not be recognised as a protected species. (23).
In the past few decades, several institutions have established breeding programs to aid in supplementation of the freckled duck population. Such establishments included, but are not restricted to the Hunter Wetlands Australia, Slimbridge Wetlands, Melbourne Zoo, Bronx Zoo, Adelaide Zoo, Healesville Sanctuary and Tidbinbilla Nature Reserve. (28). The success of these institutes has been variable, with some failing to establish self-maintaining colonies of this species.
Description
The freckled duck has a distinctive visage, which is characterised by dark grey to black plumage in adults which is covered by small white flecks, which gives the duck the ‘freckled’ appearance. The feet, legs and bill of both sexes is of a slate grey colour. Hatchlings and juveniles are distinguished by a uniform light grey plumage, which they will lose around their 32nd week when they undergo a full body moult to assume the adult plumage. (26).
The adult freckled displays a few sexual dimorphisms, the first being size. On average, males are the larger sex with average weight ranging between 700 - 1200g. Not to be outdone, females have an only slightly lower range between 600 – 1200g. Both sexes have a length of 50 – 60 cm. During the breeding season particularly, the males are characterised by the base of their culmen which takes on various shades of red. Those which are in prime reproductive condition will take on a deep red colouring, while other males may only develop lighter shades of red, or in some instances, no colouring at all. Deep red colouring of the culmen is also associated with dominance, and those with the deepest red are those likely to breed with the females of the group. (28).
Distribution and Habitat
Endemic to Australia, the freckled duck is mainly situated throughout inland regions of the Eastern section of the country – including New South Wales, Victoria and Queensland. This species also has known populations in South Australia and Western Australia (24). Due to habitat requirements, the distribution of the freckled duck is directly correlated to river flow and rainfall in both river catchments and wetland systems. (10). Because of this, main populations of this species are located within the Paroo-Warrego catchment (Currawinya Lakes), Eyre-Georgine-Mulligan catchment (Lake Torquinie) and potentially at Lake Galilee. High numbers of this species have also been recorded at the Cooper’s Creek catchment, wetlands within the Barkley Tablelands, the Bulloo River catchment and Lake Gregory in central north Western Australia (24).
Habitat preference for the freckled duck can be split into two distinct categories: breeding and non-breeding habitat. While this species does not appear to have any sort of distinct migratory pathway, there does appear to be seasonal migration in order to find suitable habitat for breeding purposes (1). The freckled duck will sometimes travel long distances in order to find a suitable breeding location, and they seem to have a preference for large bodies of fresh water with thick vegetation. Usual contenders are recently flooded wetland systems and swamps (10). After breeding, the freckled duck will disperse to more coastal areas which have more permanent bodies of water such as lakes, reservoirs and ponds. These areas are often more exposed and contain little vegetation (25).
Diet
The diet of the freckled duck has been subjected to a degree of controversy and disagreement over the years, potentially due to the versatile diet of different populations and distributions of this duck. Despite this, it is widely agreed that the freckled duck is a resilient, specialist filter feeder that consumes a range of aquatic vegetation, insects, algae, larvae and crustaceans. (27 & 6). Studies have found that the freckled duck prefers to feed in shallow water, using its bill to strain food particles from the mud or sand. (8).
Social Behaviour
A highly gregarious species, the freckled duck is known to have flock sizes ranging from 10-100 individuals, especially outside of breeding season. During breeding season, these flocks often break up into smaller sub-units, scattered throughout wetland and swamp systems. (7).
Despite these large flock sizes, this species is lacking in demonstrative displays towards one another, with only cryptic gestures and few interactions towards fellow flock mates. The rare interaction that is observed within this species is usually of a quarrelsome nature. (15).
Bathing
While there has been little research into the bathing behaviour of the freckled duck, it is known that a body of water (e.g. a swamp or dam) is essential for many natural behaviours such as feeding, mating and bathing (2). Freckled ducks have been observes preening both within water and after emerging from water while in a roosting position (12). There is no evidence that the freckled duck dust bathes or requires any other substrate for bathing.
Reproductive Behaviour
The freckled duck is a polygamous species that undertakes short term, seasonal monogamous pairings in the wild. (7). This short term pair will see the male defend the receptive female during the pre-egg laying stage of the breeding season. During this time, the male will also assist in the construction and defence of the nest site, but will leave before the female lays her clutch and plays no further role in the rearing or defence of his offspring. (9).
The freckled duck has few pre or post copula
tory behaviours. Copulation occurs in the water with the male approaching a receptive female who will adopt a semi submerged orientation, with her head stretched outwards and tail raised. The male will then mount the female and clutch the feathers on the lower neck of the female during copulation. After dismounting, both sexes will display bathing and preening behaviours. (15).
Timing of Breeding
The breeding season of the freckled duck is basically regular, with a generic breeding season existing between September and December. However, the freckled duck retains the ability to breed out of season. Breeding out of season is highly correlated with periods of heavy rainfall and flooding (20).
Sexual Maturity
Both male and female freckled ducks reach sexual maturity at around 12 months of ages when the first breeding occurrence can commence (7). The freckled duck has been known to continue breeding annually throughout their life, with records suggesting successful breeding in birds in excess to 10 years of age. (28).
Incubation Period
The freckled duck has a standard incubation period ranging between 26–28 days, although some sources have recorded incubation periods lasting up to 35 days. (14) The female is solely responsible for egg incubation and will only leave the eggs for short periods in order for her to feed.
Clutch Size
The average clutch is seven eggs, but can range between four to 14 eggs. (4). Clutches of up to 14 eggs can occur naturally, although this occurrence mainly appears to be the result of females ‘dumping’ additional eggs into another female’s nest. This occurrence is common within freckled duck populations as it enables the offending females to pass on their genetic material while not expending energy to raise their hatchlings. (19).
The eggs of the freckled duck are glossy, smooth and almost perfectly oval in shape. They are white in colour, ranging from shades of cream to ivory. The freckled duck egg is unique, having an exceptionally thick but soft shell unlike that of any other species. Egg measurements usually fall between 60-65mm by 45-48mm and weigh an average of 66g (13).
Fledging
Freckled duck hatchlings are precocial, meaning upon hatching they are fully functional and are able to feed themselves. Despite this, the mother is still necessary in order for the best chance of survival. Apart from protection, the mother is essential for learning important social cues and behaviours that will see the hatchlings will use throughout their life (22).
The ducklings fledge late compared with other waterfowl species, at 9 weeks of age when they no longer need the protection from their mother. At this point, the mother and fledglings are likely to re-join a larger flock. (Flinchum, 2005).
Suitability to Captivity
Historically, the freckled duck has been kept with limited success in captivity and ironing out the issues with captive life is still an ongoing issue. Issues with stress, breeding and mortality rates of chicks are amongst the biggest issues with keeping these ducks in captive environments. In recent years some of these concerns have been mitigated with establishments such as the Hunter Wetlands Australia and Slimbridge Wetlands UK implementing successful breeding programs, with chicks surviving to adulthood (28).
The freckled duck is a highly compatible species, with various establishments holding this species in groups of various sizes, sex ratios and species with no interspecific or intraspecific aggression. However, there has been limited success with breeding programs when housed in mixed exhibits. (3).
Behavioural considerations are another consideration to take into account when holding a captive population of freckled ducks. The most important of these considerations is the possibility of imprinting on a subject other than the mother. Imprinting is an instinctual phenomenon that occurs early on in life whereby the juvenile establishes a long lasting behavioural response to the parent (or another animal, person or thing that is present during the crucial imprinting period). (17). Imprinting on human keepers is a serious consideration, as hatchlings require the mother in order for them to learn important behaviour traits including vocalisations and feeding amongst other important attributes.
References
- ↑ BirdLife International (2012). "Stictonetta naevosa". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
1. Blakers, M., Davies, S. & Reilly, P. N., 1984. The Atlas of Australian Birds. Melbourne: Melbourne University Press.
2. Braithwaite, L. W., 1976. Notes on the breeding of the Freckled Duck in the Lachlan River Valley. Emu, 76(3), pp. 127–132.
3. Briggs, S. V., Hodgson, P. F. & Ewin, P., 1994. Changes in populations of waterbirds on a wetland following water storage. Wetlands (Australia), 13(2), pp. 36–48.
4. Briggs, S. V., 1982. Food habits of the Freckled Duck and associated waterfowl in North-western New South Wales. Wildfowl, Volume 33, pp. 88–93.
5. Christidis, L. & Boles, W. E., 2008. Systematics and Taxonomy of Australian Birds. Collingwood, Australia: CSIRO Publishing.
6. Corrick, A. H., 1980. Freckled Ducks on lakes in the Western District, Victoria. Australian Bird Watcher, 8(1), pp. 254–255.
7. Craig, M., 1994. Captive species management plan for freckled duck: Stictonetta naevosa. Parkville, Victoria: Zoological Board of Victoria.
8. Crome, F. H., 1985. An Experimental Investigation of Filter-Feeding on Zooplankton by Some Specialized Waterfowl. Australian Journal of Zoology, 33(6), pp. 849 – 862.
9. Delacour, J., 1964. The Waterfowl of the World. 4th ed. s.l.:Country Life.
10. Department of Environment and Heritage NSW, 2016. Freckled Duck (Stictonetta naevosa). [Online] Available at: http://www.environment.nsw.gov.au/savingourspeciesapp/project.aspx?ProfileID=10771 [Accessed 16 March 2016].
11. Environment Australia, 2001. A directory of important wetlands in Australia. Third ed. Canberra: Environment Australia.
12. Frith, H. J., 1964. The downy young of the Freckled Duck, Stictonetta naevosa. Emu, 64(1), pp. 42–47.
13. Frith, H. K., 1965. Ecology of the Freckled Duck Stichonetta naevosa (Gould). CSIRO Wildlife Research, 10(1), pp. 125–139.
14. Frith, H. J., Braithwaite, L. W. & McKean, J. L., 1969. Waterfowl in an inland swamp in New South Wales. Wildlife Research, 14(1), pp. 1–16
15. Fullagar, P. J., Davey, C. C. & Rushton, D. K., 1990. Social behaviour of the Freckled Duck Stictonetta naevosa with particular reference to the Axle-grind. Wildfowl, Volume 41, pp. 53–61.
16. Garnett, S., 1992. The Action Plan for Australian Birds. Canberra: Australian National Parks and Wildlife Service.
17. , E. H., 1958. Scientific American. "Imprinting" in animals, 198(3), pp. 81–90.
18. IUCN, 2013. Stictonetta naevosa. [Online] Available at: http://www.iucnredlist.org/details/22679836/0 [Accessed 16 March 2016].
19. Jaensch, R., 2003. Breeding by freckled Duck Stictonetta naevosa in the Diamantina Channel Country. Sunbird: The Journal of the Queensland Ornithological Society, 33(1), pp. 24–28.
20. Johnsgard, P. A., 1965. Handbook of waterfowl behaviour: Tribe Stictonetti. In: Handbook of waterfowl behaviour. s.l.:s.n., pp. 60–61.
21. Johnsgard, P. A., 2010. Ducks, Geese, and Swans of the World: Tribe Stictonettini (Freckled Duck). In: Ducks, Geese, and Swans of the World. s.l.:s.n., pp. 97–100.
22. Kear, J., 2005. Ducks, Geese and Swans: Volume 2 Species Accounts (Cairina to Mergus). Oxford: Oxford University Press.
23. Loyn, R. H., 1991. Assessing and managing the impact of duck hunting in Victoria - a new approach. Wildfowl, Volume 42, pp. 155–161.
24. Maher, M. T. & Braithwaite, L. W., 1992. Patterns of waterbird use in wetlands of the Paroo, A river system of inland Australia. The Rangeland Journal, 14(2), pp. 128–142.
25. Martindale, J., 1986. The Freckled Duck. Moonee Ponds, Victoria: Royal Australasian Ornithologists' Union.
26. Norman, F. I. & Norris, K. C., 1982. Some notes on Freckled Duck shot in Victoria, Australia, 1981. Wildfowl, Volume 33, pp. 81–87.
27. Norman, F. I. & Brown, R. S., 1985. Gizzard grit in some Australian waterfowl. Wildfowl, Volume 36, pp. 77–80.
28. Wilson, S. & Silcocks, S., 2001. The husbandry and breeding of the freckled duck at Melbourne Zoo. Australian Birdkeeper, 14(9), pp. 524–527.
- "Chance to visit freckled friends", Callaghan, F. (16 April 2008). Newcastle Herald
External links
Media related to Stictonetta naevosa at Wikimedia Commons