Rubel, F. | bioRxiv Science

bioRxiv2024

Range of Ixodes laguri, a nidicolous tick that parasitizes critically endangered rodents, with details on its western distribution limit in Austria

The nidicolous tick Ixodes laguri is a nest-dwelling parasite of small mammals that mainly infest rodents of the families Cricetidae, Gliridae, Muridae and Sciuridae. There is no proven vectorial role for I. laguri, although it is suggested that it is a vector of Francisella tularensis. In this study, a first map depicting the entire geographical distribution of I. laguri based on geo-referenced locations is presented. For this purpose, a digital data set of 141 georeferenced locations from 16 countries was compiled. Particular attention is paid to the description of the westernmost record of I. laguri in the city of Vienna, Austria. There, I. laguri is specifically associated with its main hosts, the critically endangered European hamster (Cricetus cricetus) and the European ground squirrel (Spermophilus citellus). These two host species have also been mapped in the present paper to estimate the potential distribution of I. laguri in the Vienna metropolitan region. The range of I. laguri extends between 16-108{degrees} E and 38-54{degrees} N, i.e. from Vienna in the east of Austria to Ulaanbaatar, the capital of Mongolia. In contrast to tick species that are expanding their range and are also becoming more abundant as a result of global warming, I. laguri has become increasingly rare through-out its range. However, I. laguri is not threatened by climate change, but by anthropogenic influences on its hosts and their habitats, which are typically open grasslands and steppes. Rural habitats are threatened by the intensification of agriculture and semi-urban habitats are increasingly being destroyed by urban development.

zoology↗

bioRxiv2024

Hamster (Cricetus cricetus) and ground squirrel (Spermophilus citellus) in the metropolitan area of Vienna, Austria: Urban development vs. species protection

Although European hamsters and European ground squirrels are listed as critically endangered on the IUCN Red List of Threatened Species, their habitats are becoming increasingly smaller due to the rapid expansion of the city of Vienna. The distribution of both species over the period 2000-2023 was documented by compiling a map based on georeferenced data from scientific monitoring and citizen science collections. Based on this, the population sizes in the metropolitan area of Vienna were estimated at 4000 hamsters and 16000 ground squirrels. An overview map was also created for each of the two species, which contains the names of the most important local occurrences. Satellite images were used to document populations that became extinct during the study period or in which animals lost large parts of their traditional habitat due to new urban development. This is considered particularly important in terms of conservation, as future generations would otherwise see the absence of wildlife in cities as normal, an effect known as shifting baseline syndrome. The Court of Justice of the European Union clarified key concepts for strict species protection. These also include eco-offsetting, i.e. creating habitats to replace ones lost to development, which was already applied before a recent construction project was implemented. On the occasion of this project, the application of eco-offsetting to protect the local ground squirrel population was documented and critically discussed.

ecology↗