Sierdsema, H. | bioRxiv Science

bioRxiv2024

The future abundance of key bird species for pathogen transmission in the Netherlands

Wild birds serve as reservoirs and vectors for many different pathogens and changes in their distribution and abundance due to environmental change will influence disease risk. We study three species which are highly abundant in north-western Europe and which can transmit a wide range of diseases including avian influenza and West Nile virus: blackbirds, mallards and house sparrows. Using the Netherlands as a case study, we created random forest models for predicting the distribution and abundance of these species, both now and in the future. Climate, land use and vegetative cover were all important predictors of bird abundance. The three species had different spatial distributions, largely related to their preferred habitat and food availability. In the future, mallard and house sparrow populations were predicted to increase, while there was little change for blackbirds. Quantifying the consequences of these abundance changes is complicated as there are many factors to consider, however increased pathogen reservoirs will likely increase disease risk and changes in distribution may affect local outbreak risk. The future abundance maps created in this study, and the methods used to create them, will be useful tools for disease modellers and policymakers to estimate future disease risk and to plan accordingly.

ecology↗

bioRxiv2022

A country-wide examination of effects of urbanization on common birds

Urbanization forms one of the most drastic alterations of the environment and poses a major threat to wildlife. The human-induced modifications of the landscape may affect individuals fitness and thereby result in population declines. Research on how urbanization affects fitness traits has shown mixed results, but typically contrasted data from few urban and non-urban sites collected over short time frames from single species. It thus remains unknown whether we can generalize across species, whereas such knowledge is crucial for population predictions that are needed for conservation management. Here, we use data from a nation-wide citizen science project to examine variation in survival and body mass and size of common passerine birds, collected along an urbanization gradient in the Netherlands over an 8-year period. Although the overall association between urbanization and survival was slightly negative, there was strong support for lower survival in three species, and higher survival in two of the 11 species examined. Effects of urbanization on body mass and size also varied but were far less strong and there was no evidence that they mediated the impacts on survival. Our results imply that body mass and size cannot be used as indicators for urban-associated patterns of survival. Furthermore, the species-specific survival responses indicate that care should be taken when predicting the effects of ongoing urbanization for communities, because even closely related species can show different responses. Moreover, the contrasting survival successes among species suggests that ongoing urbanization may lead to shifts in community structure and loss of biodiversity.

ecology↗