The editor’s choice is the article by Zbinden et al. Long-term trends of reproductive success of black grouse Lyrurus tetrix in the southern Swiss Alps in relation to changes in climate and habitat
Climate change and the associated habitat changes affect numerous wildlife species. Particularly in Arctic and mountainous regions, warming-induced range shifts along latitudinal and elevational gradients have been reported. Predictive models are commonly used to assess how projected climate changes will modify the distribution patterns of wildlife species, and what this means for their conservation status. However, the mechanisms behind species distributions may be complex, and models based on a few simple available variables, may not be sufficient to describe species-habitat relationships adequately.
The paper by Zbinden et al. uses 40 years of monitoring data on the number of chicks observed per adult female black grouse in the southern Swiss Alps, to assess reproductive success in relation to changes in climate and habitat. Bird atlas data had suggested that Alpine black grouse as well as rock ptarmigan responded to climate by shifting their distribution towards higher elevations. Indeed, the work by Zbinden et al. revealed that black grouse breeding sites increased by around 100 m over the 40 years, but only at the edge of the distribution range, where black grouse occur at lower elevations.
Here, also reproductive rates had declined. Reproductive success was correlated with weather variables and habitat; however, year and region explained considerable amounts of the variance.
The study is another example of why long-term data are so valuable. They make it possible to detect and analyse shifts in range, and to investigate the driving factors behind. The work also shows that simple equations of the type “temperature change equals change in breeding success” are not to be expected in wildlife ecology. Often it is not the climate or one of its components per se that limits or enables the occurrence or reproduction of a species, but a complicated web of interactions throughout the ecosystem.