Surviving amid the Saharan sands: first breeding record and nesting ecology of the Mallard in the Algerian Sahara

We report the first breeding occurrence of Mallard (Anas platyrhynchos) in the northern Algerian Sahara, focusing on nesting ecology in the Kef Doukhane wetland. We analyzed the influence of different environmental factors on nesting outcomes and breeding success. Our results indicate that the timing of egg laying is a critical factor influencing both breeding outcomes and the number of fledged chicks. Specifically, our results indicate that nest outcomes become less favorable as the season progresses, with later clutches having a lower probability of success. In addition, the number of successfully fledged chicks is significantly lower for later clutches. Interspecific parasitism was documented in five mixed clutches, involving Ferruginous Duck (Aythya nyroca) in four cases and Moorhen (Gallinula chloropus) in one case. Our study highlights the challenges that the hyperarid environment of the Sahara poses for breeding waterbirds. It also highlights the selection pressures exerted by both biotic factors and environmental factors, with temperature, solar radiation, and the presence of protective vegetation playing important roles. Comparative analyzes show that the timing of egg laying has similar effects in other regions, as observed at Lake Tonga further north, where Mallard breeding performance declines as the season progresses. This research not only contributes to our understanding of the nesting ecology of mallards in this unique Saharan wetland but also underscores the urgency of conservation action, especially in the face of ongoing environmental change. It also improves our understanding of waterbird breeding dynamics in the region and highlights the challenges faced by these bird populations in a demanding, arid environment.