International importance of Extremadura, Spain, for overwintering migratory dabbling ducks: a role for reservoirs

Abstract

SummaryMany migratory waterbird populations are in decline and loss of natural wetlands is one of the main causes. However, some species may respond positively to artificial wetland recreation. In Extremadura (south-west Europe), several large reservoirs were created for irrigation since the 1960s and some comparatively small reservoirs were built from the late 1990s onwards close to rice fields. Here we analyse the abundance of wintering dabbling ducks (Anas spp.) in Extremadura before (1991–1994) and after (2007–2010) the creation of these new reservoirs in order to address the current importance of the area for this guild within the East Atlantic Flyway (EAF). A mean of 25,277 dabbling ducks wintered in the study area during 1991–1994, increasing to 46,163 individuals during 2007–2010. After controlling for environmental variables, Northern Pintail Anas acuta, Common Teal A. crecca and Northern Shoveler A. clypeata experienced significant increases in the area between both periods, and only Eurasian Wigeon A. penelope suffered a significant decrease. Mallard A. platyrhynchos and Gadwall A. strepera populations did not show any significant trend. The large older reservoirs experienced overall population decreases between the two periods, with four new reservoirs holding more than 35,000 wintering dabbling ducks. Our results reflect an overall improvement in habitat conditions, driven by the creation of reservoirs near to rice fields that could have resulted in a partial redistribution of wintering dabbling ducks in the EAF. The area emerges as one of the most important wintering sites for dabbling ducks in southern Europe, regularly exceeding two of the Ramsar Convention criteria for the conservation of several populations. The protection of these new reservoirs by legal mechanisms would guarantee the existence of a large functional wetland area, which could also mitigate the loss of natural wetlands for populations using the EAF.

Assembly processes of waterbird communities across subsidence wetlands in China: A functional and phylogenetic approach

“…Therefore, waterbirds are an ideal species group to explore assembly processes and assess effects of habitat changes on biotic communities. Moreover, in the context of global losses and degradations of natural wetlands (Butchart et al, 2010;Kar, 2013), waterbirds have been increasingly found to use artificial wetlands as complementary habitats, such as paddy fields, aquaculture ponds and water reservoirs (Elphick, 2015;Navedo et al, 2012;Petchey, Evans, Fishburn, & Gaston, 2007). An understanding of waterbird responses to environmental variables and assembly processes in human-dominated landscape can increase the success of management and conservation actions of waterbirds (Thompson & Starzomski, 2007;Tscharntke et al, 2012).…”

Geographical origin of dabbling ducks wintering in Iberia: sex differences and implications for pair formation

“…), including dabbling ducks (Navedo et al . ). Our study site was located at Vegas Altas del Guadiana (Fig.…”

“…The anthropogenic wetlands of Extremadura (SW Spain) are a key site for many migratory waterbirds (S anchez-Guzm an et al 2007, Masero et al 2009), including dabbling ducks (Navedo et al 2012). Our study site was located at Vegas Altas del Guadiana (Fig.…”

“…Our study site was located at Vegas Altas del Guadiana (Fig. 1), where several large reservoirs provide roosting areas for waterbirds (Navedo et al 2012). These reservoirs, together with adjacent rice fields (25 000-30 000 ha), create an environmental mosaic that has promoted the populations of anatids and other wintering waterbirds in the area (S anchez-Guzm an et al , Masero et al 2011, Navedo et al 2012.…”

“…(Scott & Rose 1996, Rend on et al 2008, SEO/BirdLife 2012. Recently, other anthropogenic habitats such as rice fields and the reservoirs of Extremadura, inland Iberia, have emerged as key international sites for the populations of several dabbling ducks, such as Northern Pintail Anas acuta and Eurasian Teal Anas crecca (Navedo et al 2012). Available information on the geographical origin of dabbling ducks in Iberia comes from ringing recovery data (SEO/BirdLife 2012).…”