Waterbird demography as indicator of wetland health: The French-wintering common snipe population

The population dynamics of waterbirds constitute an indicator of wetland conservation status. However, waterbird population censuses are difficult to implement because the individuals are very mobile within their range, and some species are elusive or breed in remote areas. Therefore, demographic models based on the estimation of survival and breeding success appear as a reliable alternative to population censuses. Here we present this model-based approach in the case of the French-wintering snipe population (Gallinago gallinago), which breeds mainly in Northern and Eastern Europe. Using a multi-state model to accommodate the mobile nature of waterbirds, we estimate snipe survival using a joint analysis of capture-recapture and ring-recovery data. Then, we use matrix population models to estimate the minimum recruitment rate required to maintain the population at its current size and derive a chart for using age-ratio of ringed birds as indicator of population trend. Although we call for more data collection in order to reduce uncertainty, we conclude that occasional declines are likely after years with poor breeding success, but that the French-wintering snipe population is on average stable. Individual-based monitoring data and population modeling make it possible to use waterbirds as indicator species at the flyway scale.