This species breeds in small, shallow, fresh to brackish wetlands with dense submerged vegetation and extensive reedbeds (Tucker and Heath 1994). Breeding begins in April with broods hatching mostly in June and July (Billerman et al. 2020). Nests are a platform of reed stems and leaves sparsely lined with down and are built in dense vegetation, on the ground or over water, often in old nests of other waterbirds. They are sometimes sited within gull and tern colonies, and birds will use specially constructed nest-boxes. Clutches are usually four to nine white eggs and females may re-lay if the first clutch is lost. As a diving duck, its diet consists of midge larvae and other aquatic invertebrates. Seeds and the vegetative parts of aquatic plants are also taken (Billerman et al. 2020). Most birds are migratory, wintering in Europe from further east in Russia and Kazakhstan. Breeding in Europe is mostly concentrated in Spain where the population is resident but also occurs in Russia and Turkey (Tucker and Heath 1994).

Although the generation length for both EU and Europe regional assessments were calculated using the same methodology, new information arriving after the EU assessments were undertaken gave rise to an update in the generation lengths. This new information was then used for the Europe level assessments giving rise to a difference between the generation lengths used for the EU and Europe regions.

In Europe, this species breeds primarily in Spain, where it is resident, and Russia, but also notably in Turkey, with a smaller population also present in Armenia. 
It occurs on passage and in winter primarily in Azerbaijan, with smaller populations present in the eastern Mediterranean, the Caucasus and the Black Sea.

Concurrently, breeding populations have become extinct in Italy, France, and in many countries in central and eastern Europe (Snow and Perrins 1998, Billerman et al. 2020).

Conservation Actions Underway
CITES Appendix II. CMS Appendix I and II. The species is legally protected in many range countries and occurs in a number of protected areas. A conservation programme in Spain has resulted in a significant population increase (J. Criado in litt. 1999). Ruddy Ducks (O. jamaicensis) are controlled in 15 western Palearctic countries, including Spain, Portugal and France. A programme was started in 2005 to eradicate the U.K. population of Ruddy Ducks and by 2009, over 6,200 ducks had been culled, resulting in a suggested decrease in the U.K. population of almost 90% (Henderson 2009). Reintroduction schemes are operational in Majorca and Italy (B. Hughes in litt. 1999, A. J. Green in litt. 2012). A European action plan was published in 2006 (Hughes et al. 2006). Sport hunting has been banned on two primary wintering lakes (Burdur Gölü and Yarisli Gölü) in Turkey where hunting from speedboats was threatening the White-headed Duck (Green et al. 1996).

Conservation Actions Proposed
Survey breeding and wintering grounds and migration sites. Enforce strict protection from hunting. Conduct comprehensive winter monitoring and tracking studies to improve knowledge of migration routes and phenology (Li and Mundkur 1993). Protect and manage key sites and their catchments, including monitoring of hydrology and water pollution (M.A. Tabur in litt. 2005). Reduce disturbance by fisheries. Ensure legislative protection for this species in all range states (Li and Mundkur 1993). Alleviate hunting pressure and ban lead shot throughout its range. Prevent drowning in fishing nets by regulating fisheries. Promote policies to control O. jamaicensis and hybrids.