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Many wild species, like waterbirds, are exploited for their economic interests. At present, the annual western Palearctic duck bag is at least 17 million birds. From a sustainable management perspective, wetland users and managers request predictions of spatial distribution and abundance variations of these bird populations. The objective of this study was to analyze local factors potentially influencing the diurnal distribution and population size of wintering ducks and coots, the main game species, in Camargue (southern France). First, we showed that marshland surface area, salinity and hunting disturbance were the principal variables explaining the duck and coot distribution. Secondly, we tested the hypothesis that hunting disturbance would reduce the carrying capacity of the Camargue with two analyses: the effect of creating a protected area and the change of the hunting closing date. This hypothesis was not validated. Our study therefore led us to reconsider the research orientations on the carrying capacity in this wetland. The surface of protected day roosts seems presently sufficient in the Rhone delta. Consequently, to increase the population size with the same level of hunting disturbance at the scale of the Camargue, alternative strategies should be envisaged, such as the creation of nature reserves on nocturnal feeding ground or the creation of large management units with limited disturbance.

The eastern portion of the Camargue in southern France is divided into two parts: a natural wetland area of 2800 ha and an agricultural area of 5045 ha. In 1984 and 1989, a new protected area (1000 ha) was created on two contiguous former hunting estates. Analysis of aerial photographs (1968–1998) in conjunction with a field survey revealed, from 1984 to 1998, an increase of management for waterfowl hunting in natural wetlands located on the periphery of the new reserve, and a similar increase in the agricultural area amongst residual wetlands and former rice fields. Based on monthly aerial censuses, the size of the waterfowl population in the winter increased in this part of the delta by a factor of 3.8 following the creation of the reserve. Our results suggest that the creation of a reserve on former hunting estates resulted in greater attractiveness for ducks but also in the development of commercial hunting activity around the edge. This development increased fragmentation and uniformity of natural areas, including the loss of the unique Cladium mariscus habitat in the Camargue and resulted in the spatial expansion of waterfowl hunting areas in agricultural areas. It is associated with an increase in financial profit from waterfowl hunting. Our study highlights unexpected costs for nature conservation associated with the creation of a reserve. It illustrates the need for new models of wetland conservation where protection goals are not restricted to reserves, but also integrate conservation and economic development outside the protected areas.