This study showed that protective measures did not halt the decline of the lapwing in Europe. The productivity of the population remained insufficient due to a high mortality among chicks.
By comparing the dynamics of two subpopulations of lapwings monitored at different spatial and temporal scales, I showed that the low productivity was the main cause for the decline of the European lapwing. I demonstrated that a mean productivity of 0.8 fledglings per couple would be needed to reverse the decline. I highlighted that despite the positive impact of implemented nest protections on egg survival, the impact at the population level was not sufficient to reverse the decline. Protective measures should prioritize the reduction in predation and the improvement of chick habitat by promoting heterogeneous habitats combining tall vegetation for hiding and short and open vegetation for foraging.
Context
The Northern lapwing vanellus vanellus is a good illustration of the recent strong decline of waders in Europe. While it used to be a common agricultural bird up to the 1980s, this bird has obtained the status Near-Threatened since 2015. This migratory species spends its winters in South-West Europe and in North Africa where it is hunted. However, a study suggested that hunting was not the main driver of population decline. In some breeding populations, costly protective measures have been implemented and aim for direct protection of lapwing nests. A robust analysis was thus needed to assess if these measures were sufficient for halting the population decline at large spatial scales. A group of researchers from the Netherlands, Germany and Switzerland working on wader populations called on me to complete this analysis.
Challenge
What are the causes of the decline of the Northern lapwing in Europe? Are protective measures sufficient and efficient?
Approach & Results
Taking advantage of monitoring data from the populations of lapwings in the Netherlands (NL) and one region in Germany [Schleswig-Holstein (SH)], I built two integrated population models describing the dynamics of these two subpopulations. Each monitored subpopulation combined survival data, reproductive data and count data: monitoring of nests, count of breeding couples, recapture of ringed birds… Despite the spatial and temporal heterogeneity of the data, the results obtained from the two integrated population models showed similar mean demographic parameters (survival, productivity) between the subpopulations.
To unravel which demographic parameters contributed the most to the decline, I performed retrospective analyses. They showed that variation in productivity had the largest impact on the dynamics of both subpopulations. These results also confirmed that hunting had a weak influence on population dynamics. The low productivity (0.55 and 0.46 fledglings per couple in SH and NL, respectively) was the main cause of the decline in both subpopulations. By implementing a population viability analysis, I demonstrated that a productivity of 0.76 (SH) and 0.91 (NL) fledglings per couple would be needed to reverse the decline.
To evaluate the efficiency of protective measures, I compared conservation scenarios with and without the existing protective measures. Nest protection had a positive effect on egg survival but not on chick survival. As a consequence, protective measures had restricted and insufficient impacts at population scale. For instance, I highlighted that even if all nests in the Netherlands would be protected, the population growth rate would increase by 2% only.
By modeling the environmental variability and the observed variation in annual productivity, I showed that years of high productivity (0.8 fledglings per couple) that had currently occurred once in twenty years were needed to occur in three quarters of next years to halt the decline of the European lapwing.
Project leader and Collaborators
- Michael Schaub & Marc Kéry: Swiss Ornithological Institute, Sempach, Switzerland
- D. V. Cimiotti, A. Helmecke, H. Jeromin, H. A. Bruns, H. Hötker: Michael-Otto Institut im NABU, Bergenhusen, Germany
- M. Roodbergen, H. Schekkerman, W. Teunissen: SOVON Vogelonderzoek Nederland, Nijmegen, The Netherlands
- H. van der Jeugd: Netherlands Institute of Ecology – Dutch Centre for Avian Migration and Demography, Wageningen, The Netherlands
Floriane Plard 