This study was focused on the ecology and behavior of the White-headed Duck (Oxyura leucocephala) at Garaet Hadj Tahar (Guerbes-Sanhadja, North East of Algeria). Sampling was carried out during two wintering seasons (2017-2018 and 2018-2019). High number of this duck was recorded in 2018/19 (350 individuals). We observed two Oxyura population, the first sedentary, and the second, hosted the Garaet during the wintering season. Diurnal time budget was dominated by the comfort activities the sleeping with a rate of 39.13%. Following by swimming (37.76%), feeding (17.59%) grooming (4.58%), courtship ritual (0.56%) and flying (0.38%). The feeding of white-headed duck is done exclusively by diving. Beside, this waterbird associated between Feeding by diving and grooming in order to minimized energy. The accessory activities such as: courtship ritual, flying were done by this duck at the end of wintering. This results confirm that Garaet Hadj Tahar is considered as wintering site for this threatened species. Biological Conservation plan (BCP) must be applied at level of this wetland in order to manage bioressources and threatened waterbirds.