Threats listed in assessment
Within the UAE the main threats to the species are likely from land-use changes and possibly oil pollution, but the severity of these threats are essentially unknown.Across its global range the species faces a large number of threats, outlined below; but it is highly uncertain to what extent such threats impact individuals that visit the UAE.The species is threatened by the degradation and destruction of well-vegetated shallow pools and other wetland habitats(Vinicombe 2000,;del Hoyo et al. 1992,;Kear 2005, Robinson and Hughes 2006)(e.g. changes to the vegetation community, disruption of water regimes, siltation, and increased water turbidity [Robinson and Hughes 2006]) as a result of excessive drainage and water abstraction(Vinicombe 2000,;Grishanov 2006, Robinson and Hughes 2006), peat extraction(Grishanov 2006), eutrophication (from inadequate sewage treatment and nutrient run-off [Robinson and Hughes 2006]), oil pollution(Grishanov 2006), dam and barrage construction, the building of infrastructure on flood-plains (Vinicombe 2000, Robinson and Hughes 2006) and river canalisation(Kear 2005). Changing land management practices such as reed cutting and burning during the breeding season (Petkov 2006), over-grazing (Robinson and Hughes 2006) decreased grazing and mowing of wet meadows(Grishanov 2006), and abandonment (causing succession to scrub) or intensification (causing reversion to open water) of extensively managed fishponds(Vinicombe 2000,;Kear 2005, Petkov 2006, Robinson and Hughes 2006) also threatens the species. The introduction of non-native species has caused further habitat degradation. For example the stocking of lakes with and accidental introduction of Grass Carp Ctenopharyngodon idella has resulted in reductions in macrophyte biomass and corresponding reductions in invertebrate biomass(Kear 2005, Robinson and Hughes 2006), and in Bulgaria an introduced shrub (Desert False Indigo Amorpha fruticosa) is changing the ecological character of wetlands (Robinson and Hughes 2006). Introduced predators such as the Wels Catfish Silurus glanis (Kazakhstan) that predate ducklings, and the Muskrat Ondatra zibethicus (Aral Sea region) have also caused population declines (Robinson and Hughes 2006). Increased drought due to global climate change may pose a threat to the species in part of its range(Vinicombe 2000, Robinson and Hughes 2006). Disturbance by fishing boats and anglers alongside fringe vegetation could cause abandonment of the breeding sites or disrupt the timing of breeding (N. Petkov in litt. 2008). Hunting is another serious threat to the species(Vinicombe 2000,;del Hoyo et al. 1992, Robinson and Hughes 2006). Large numbers are shot on passage in the autumn (e.g. through the Volga delta) and on some wintering grounds<sup>;</sup>(Kear 2005, Balmaki and Barati 2006). Other lower-level threats include lead poisoning (from ingestion of discarded lead shot), fires in areas of reed thickets, peat bogs and woods (Grishanov 2006), entanglement and drowning in fishing nets (Robinson and Hughes 2006<strong style="""">)<strong style=""""> and hybridisation with native species (e.g. Tufted Duck Aythya fuligula and Common Pochard Aythya ferina in Switzerland [Leuzinger 2010]).
