Population Decline of Anatidae Species in the Parishan Wetland (SW Iran) Resulting from a Decreasing Water Level

The Parishan freshwater wetland is the most important wintering site for waterbirds among the inland wetlands of Iran. Using annual wintering waterbird census data collected from 1967 to 2022, we analysed the population trends of wintering Anatidae species. Of the 19 species of Anatidae, only ten species were recorded during at least 20 years, and statistical trend analysis was possible for seven species. The average population of Anatidae over 31 years (1988–2018) was more than 5430 individuals. In the first 21 years it was 7854 individuals, while in the last ten years (2009–2018) it decreased to about 340 individuals. Since 2018, no waterbirds have been counted and recorded in the wetland. The largest number of Anatidae was observed in 1989 and 1990 by counting 32,271 and 26,200 individuals, respectively. The Anatidae family accounted for an average of more than 39% of the waterbird populations and 29% of the species diversity. Results showed that the population of Greylag Goose Anser anser decreased with a slope of –17.9% per year, Ruddy Shelduck Tadorna ferruginea decreased with a slope of –10.4%, Common Teal Anas crecca –10.9% and Common Pochard Aythya ferina –10.7%. The decrease in the abundance and diversity of Anatidae is directly related to the decrease in the water level of wetlands and water bodies. Currently, the Parishan Wetland is completely dry and there are no longer any areas that are permanently flooded. Protection and restoration of the wetland requires the allocation of water resources to wetland, choosing an effective governance method and participation of the stakeholders.