No abstract

Rice fields are an important habitat for waterbirds. Knowledge of the availability of this habitat is important since the reduction in the area of natural wetlands has converted rice fields into vital refuges. This paper presents a method for mapping habitat availability in rice fields according to different waterbirds' habitat preferences and examining its phenology during the crop cycle. Data from bird censuses carried out in the Doñana rice fields were analysed to determine the habitat preferences of 22 species of waterbird at different stages in the rice production cycle. Discriminant function analysis of seven Landsat images was used to classify paddy field stages. The phenology of habitat availability in rice fields during autumn and winter was examined. Waterfowl and waders preferentially used the 'flooded' and 'mudflats with water' paddy field stages, respectively, and the 'rice growing' and 'dry' stages were rejected by waterbirds. The area of preferred habitats within rice fields increased during autumn; subsequently, the area of the 'flooded' paddy fields decreased in January, whereas that of 'mudflats with water' remained available until March. The automatic classification of paddy field stages with Landsat images allowed habitat availability for different species of waterbirds to be monitored and provides relevant information for understanding behavioural and population responses in waterbirds that use rice fields. After examining the phenology of the availability of habitat and comparing it with dates of arrival and departure of migrant waterbirds, best crop practices could be defined to favour waterbirds (i.e. adjusting harvest, ploughing and flooding dates). Taking into account climatic change and loss of wetlands this method could help in the integration of agriculture and conservation, in particular in areas where there is no remaining natural wetland habitat.

Rice fields are an alternative habitat for waterbirds and provide food and shelter for many avian species, but there is a lack of information about how the use of rice fields translates into population level effects. The aim of this study was to test the relationship between the use of rice fields by European waterbirds and trends in their populations. We tested this relationship during the autumn migration season and during the breeding season. Based on counts conducted over the last 23 years in natural marshes and areas of rice fields in Doñana (SW Spain), an index of rice field use was constructed for 76 bird species, which was then compared to these species' European population trends obtained from the literature. A positive relationship was found between waterbird population trends and the use of rice fields during autumn migration season. Our study suggests that changes in the Common Agriculture Policy in Europe leading to reductions in areas of rice cultivation may have important effects on waterbirds. The restoration of former marsh areas and the maintenance of rice cultivation would seem to be more environmentally friendly approaches than the use of these areas to grow alternative crops or solar farms.

No abstract

We monitored nests of Kentish Plover Charadrius alexandrinus and Blackwinged Stilt Himantopus himantopus breeding in rice fields near the Doñana National Park (southwest Spain) during the breeding seasons 2005-2007. We used a logistic-exposure method to calculate nest success and examined daily nest survival as a function of year, locality, nest age, and date. Nest success was also calculated using a model assuming constant nest survival through time (equivalent to the Mayfield method). Daily nest survival increased during incubation in Black-winged Stilt, probably due to a higher predation risk during the first days of incubation. Daily nest survival in Kentish Plover showed little variation in relation to nest age, suggesting a constant but lower predation rate. Nest survival also varied with date in Kentish Plover and showed higher values in the middle of the nesting season. The nest success of Black-winged Stilt and Kentish Plover breeding in rice fields (50% and 45%, respectively, based on the Mayfield method) was within the range of nest success reported in stable populations breeding in natural habitats. The observations suggest that rice fields adjacent to the marshes of the Doñana National Park are an important additional breeding habitat for the two wader species studied.