Comparison of breeding bird trends between the Netherlands and Europe

Bird trends in the Netherlands are explained by habitat type rather than by rarity. Inger et al. (2015. Common European birds are declining rapidly while less abundant species’ numbers are rising. Ecol. Lett. 18: 28–36) concluded that in the period 1980–2009 populations of common European birds declined while less abundant species increased in number. The main aim of this paper is to test if this also holds for the Netherlands. Our first hypothesis proposes the opposite effect; namely that: (1) common birds have become more common and rare birds more rare. We tested three additional hypotheses: (2) that in the Netherlands, habitat type plays an important role in population change, with a strong decline of farmland species, (3) that larger birds have increased more than small birds; and (4) that insectivorous birds have decreased more than birds of other feeding guilds. We used the same methodology as used by Inger et al. (2015) for 110 of the investigated 144 bird species that breed in the Netherlands. We found no significant effect on population change of rarity of the bird species in the Netherlands. So, neither the conclusion of Inger et al. (2015) nor our own contrasting hypothesis was supported. However, in line with our second hypothesis, we found a strong effect of habitat type, with a large decline of farmland species. In addition, we found an increase of forest and inland wetland species. These trends can mainly be attributed to agricultural intensification and a decrease in agricultural area, and to an increase of forest and inland wetland area and quality, respectively. Our third hypothesis was not supported. We found a non-significant positive effect of body weight on population trends. Finally, we found no support for our fourth hypothesis that insectivorous birds had declined. We recommend further in-depth comparative analyses of bird trends in Europe, its regions and countries, as a basis for better-targeted conservation measures at different spatial scales.