A comparison of wintering duck numbers among European rice production areas with contrasting flooding regimes

Abstract

Agricultural lands can provide suitable habitat for birds under some conditions. 25In particular, waterfowl sometimes rely on ricefields as nocturnal foraging habitat during 26 winter if post-harvest practices make food accessible. To assess whether the winter flooding 27 of ricefields could be a major driver of duck regional abundance in Europe, we relied on a 28 combination of spatial and temporal analyses. In the former, five of the most important 29western European rice growing regions in Spain, Italy and France were compared in terms of 30 habitat composition over the 2002-2012 period. The relative importance of natural wetlands 31 and ricefields (either dry or flooded) in determining the abundance of wintering ducks was 32 then established. In the second approach, the trends in duck numbers before and after 33 implementation of winter-flooding Agri-Environment Schemes (AES) were compared in two 34 of the study regions. Both approaches highlighted the role of winter ricefield flooding in 35 explaining wintering duck numbers and complementing the natural wetlands; flooding 36 harvested ricefields improves habitat attractiveness by enhancing food resource accessibility. 37In Europe, the proportion of ricefields flooded during winter varies considerably between 38 countries (0.17 to 62%), owing to differences in policy initiatives such as Agri-Environment 39Schemes. Promoting such schemes more widely across the European rice production area 40 could make a big difference in terms of waterfowl habitat quality at the scale of their 41 wintering range. 42

Seed density and waterfowl use of rice fields in Camargue, France

“…This apparent increase in wintering bird nocturnal density is consistent with the increased importance of rice and rice weed seeds in the diets of Camargue teal and mallard compared to that in the 1960s and 1970s (Brochet et al ). Because the majority of the 9% of Camargue rice fields that are flooded are done so for hunting purposes (Pernollet et al ), it is possible that limited flooded area (∼1,000 ha) and habitat management practices dedicated to increasing duck numbers are responsible for the high concentrations we observed during nocturnal surveys.…”

“…This is consistent with earlier results in Japan (Shimada et al , Tajiri and Ohkawara ), Europe (Lourenço and Piersma ) and North America (Day and Colwell ; Elphick and Oring , ; Strum et al ), and can be explained by the need for ducks foraging for seeds on dry land to rely on water for handling their food (Guillemain et al ). Beyond the local scale, ducks are reportedly more numerous in a given wintering ground when flooding is greater (Toral et al ) and can distribute among wintering grounds at the flyway scale depending on the intensity of rice field flooding (Pernollet et al ). Elphick and Oring () reported that 14–22‐cm water depth was ideal for ducks; in our study duck numbers were greatest in fields under 5–10 cm of water, owing perhaps to the relative abundance of small teal in our duck community and because ducks were here foraging and not resting on the fields.…”

“…In addition, foraging habits are likely more difficult to determine in European rice‐growing regions because limited field size, waterfowl hunting, and other disturbances shift foraging activity to occur at night (McNeil et al , Tamisier and Dehorter ). Furthermore, the variability of post‐harvest management practices (e.g., the extent to which rice field are flooded during winter) may cause food accessibility and field use to greatly fluctuate at the flyway scale, complicating estimates regarding the importance of rice field management practices to migratory waterbirds (Pernollet et al ). This knowledge is important because rice fields represent approximately a third of the waterbird habitats in southern Europe (Toral and Figuerola ), and their use of these habitats in winter has been underestimated (Tourenq et al ).…”

Focal Species Candidates for Pesticide Risk Assessment in European Rice Fields: A Review

“…In addition, the period of flooding generally corresponds to the period when pesticide exposure is most likely to occur, i.e., during rice cultivation. Consequently, flooded rice fieldsindependent of growth stage and assuming minimum pesticide usage-could function as a compensation for the loss of natural wetlands and are considered as a valuable conservation tool particularly during migration and winter periods (Pernollet et al 2015;Toral and Figuerola 2010). For risk assessment of specific pesticides applied outside this period or on dry soil before flooding (e.g., seed treatments), the focal species selection likely has to be re-evaluated on a case-by-case basis.…”

Waterfowl foraging in winter-flooded ricefields: Any agronomic benefits for farmers?

“…Up until now, winter flooding after rice harvest is done mainly to attract waterfowl for hunting and thus is used relatively little at the regional scale (ca. 9 % of rice area, Pernollet et al 2015) in spite of the opportunities that this practice could represent in terms of biodiversity and agronomic issues.…”