The Blue-billed Duck (Oxyura australis) is a small Australian  stiff-tailed duck, with both the male and female growing to a length of 40 cm (16 in). The male has a slate-blue bill which changes to bright-blue during the breeding season, hence the duck?s common name (see photo). The male has deep chestnut plumage during breeding season, reverting to a dark grey. The female retains black plumage with brown tips all year round. The duck is endemic to Australia's temperate regions, inhabiting natural inland wetlands  and also artificial wetlands such as sewage ponds in large numbers. It can be difficult to observe due to its cryptic nature during its breeding season through autumn and winter. The male duck exhibits a complex mating ritual. The blue-billed duck is omnivorous, with a preference for small aquatic invertebrates. BirdLife International  has classified this species as Near Threatened. Major threats include drainage of deep permanent wetlands, or their degradation as a result of introduced fish, peripheral cattle grazing, salinisation and lowering of ground water.
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/43603415@N08">Richard Ashurst</a>
CC BY 2.0
<p><a rel="nofollow" class="external text" href="https://www.flickr.com/photos/-wichid/4738192538/">Blue Billed Duck</a>
</p>
<ul><li>Uploaded by <a href="//commons.wikimedia.org/wiki/User:Berichard" title="User:Berichard">berichard</a></li></ul>