Relationships between ergodic indicators of dispersal intensity, IUCN Red List values, and selected environmental variables in connection with European birds whose foraging and flying behavior is associated to roads and highways

Abstract

Displaying an appropriate dispersal intensity (DI) in response to environmental fluctuations may determine if a given species goes extinct or not. Thus, developing indicators of the DI necessary to harness a given ecological niche breadth is urgent due to the changing latitudinal boundaries between the Earth’s great climate belts because of global warming. So, a better assessment of extinction risk should require DI as a complementary indicator. However, the IUCN Red List, indirectly linked to niche assessments, does not take into account DI, and its values are expressed on an ordinal scale. In contrast, there is a theoretical consensus about the link between DI and extinction risk, as well as about the continuous nature of species extinction, which therefore should be measured on a ratio scale. This paper proposes solutions to the above-mentioned issues. Assuming the trait of ergodicity, successfully applied in several publications in ecology so far, measurements of the average values of recent indicators of DI of birds at the species level as well as at the plot level were performed starting from 52 samplings of roadkill events, in eight European countries. DI values were correlated with the respective values of extinction risk reported by the IUCN Red List. Collaterally, a comparative study between DI and two key environmental variables (traffic intensity, and average temperature over land areas) was performed. Inverse and significant correlations between DI and the ordinal scale of IUCN Red List values were obtained, indicating that higher DI values seem to reduce extinction probability. Our results also show that birds seem able to display rapid adaptive behaviors to the increase of traffic intensity. It was found that DI peaks of European birds are associated with deviations of only half a degree Celsius above the general background of temperature over land areas. This set of results, based on a new theoretical framework (Organic Biophysics of Ecosystems –OBEC–; see references and explanatory notes in the main text), is in favor of the appropriateness to rescue the classical foundations of ecosystem ecology based on interdisciplinary links between ecology and physics to promote a better management of the Anthropocene challenges, all of them typified by interdisciplinary traits that require holistic approaches.