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17 March 2020 Variability of daily space use in wild boar Sus scrofa
Franz Johann, Markus Handschuh, Peter Linderoth, Marco Heurich, Carsten F. Dormann, Janosch Arnold
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Abstract

Wild boar space use and the determinants of its variation are crucial information for understanding wild boar Sus scrofa (L.) ecology and for wild boar management. Wild boar space use has mostly been investigated on broad temporal scales such as annual or seasonal home ranges. Ranges can vary depending on the observed timespan and on the temporal scales considered. The factors that affect space use variation can also depend on temporal scales.

In this study, we present an analysis of time series of daily ranging behaviour in wild boar. Using GPS-telemetry, we tracked 46 collared wild boars in southwest Germany. With the collected data, we calculated 6716 daily ranges of individuals based on at least 18 daily locations with near hourly location intervals. We compared three home range estimation methods and fitted multivariate models to assess the effects of the landscape, temporal and climatic factors or individual traits on the daily range size.

The daily range size varied significantly in the course of the year. The smallest daily ranges were covered from April to July, whereas the largest were covered in November and December. However, if the same days of the year are compared, lower temperatures reduced the size of daily ranges. Additionally, individual variation, social class, snow height, land use and elevation had a significant effect on the size of daily ranges.

Our results may be useful for planning protected areas, for monitoring wild boar populations, attributing agricultural damages to wild boar groups and for searching wounded or escaped animals. Moreover, the knowledge of daily used space may help to identify African swine fever (ASF) infection paths or design measures to reduce ASF risk including carcass removal, fencing projects or demarcation of management zones.

Wild boars Sus scrofa (L.) thrive under a wide range of environmental conditions (Podgórski et al. 2013) and the species is widely distributed around the world (Sjarmidi and Gerard 1988). The physical presence of wild boar is largely unnoticed by the public, because of their concealed lifestyle and mostly nocturnal activity (Keuling et al. 2008a, Brivio et al. 2017). Nevertheless, this large mammal influences ecosystems in many ways and is considered an ecosystem engineer (Barrios-Garcia and Ballari 2012, Genov et al. 2017).

In the last decades, wild boars have become a focus of wildlife managers, as their populations have increased in many parts of the world (Massei et al. 2015, Bengsen et al. 2017, Pesendorfer et al. 2020). Climate change has led to fewer harsh winters and also favours boar foraging, for example, by causing more frequent tree mast years (Nussbaumer et al. 2018). Therefore, climate change is seen as a major driver in wild boar population development in Europe (Bieber and Ruf 2005, Melis et al. 2006, Massei et al. 2015, Vetter et al. 2015).

Human–wild boar conflicts are on the rise in spite of hunting (Frackowiak et al. 2013, Massei et al. 2015). Undesired economic effects arise due to wild boar activities such as their use of agricultural areas, private gardens and public greenspaces, accompanied by crop or property damage (Barrios-Garcia and Ballari 2012). Moreover, the function of wild boar as a vector of diseases and the current cases of African swine fever (ASF) in Europe and other parts of the world stress the importance of wild boar management. A spread of ASF into domestic pig farming causes severe economic losses (Gortázar et al. 2007, Meng et al. 2009, De la Torre et al. 2015, European Commission 2018). Managing wild boar populations is considered a challenging task (European Food Safety Authority 2014). Detailed knowledge of the behavioural biology is needed for developing tailored wild boar management frameworks (Vicente et al. 2019). Therefore, a better understanding of factors which drive the spatio–temporal variation of wild boar behaviour is crucial (Nathan et al. 2008).

The area used by an animal during a specific timespan is of great interest to wildlife managers and ecologists as it is a key indicator for describing the relationship between an animal and its environment (Burt 1943). Moreover, wildlife ranges can easily be related to management units by comparing the respective areas. Wild boar home ranges have been estimated on different temporal scales (Keuling et al. 2008b, Podgórski et al. 2013, Jánoska et al. 2018). However, the factors which determine animal movement and the resulting range sizes are still not fully understood (Börger et al. 2008).

Space use is the result of many movement decisions which are determined by the interplay of individual traits, the internal state of an animal and the external environment (Börger et al. 2008, Nathan et al. 2008). There is already evidence for effects of numerous factors on movement of wild boar (Morelle et al. 2015). However, movement patterns of animals can be shaped by fine- and broad-scale movements, for example, daily patterns resulting from the locations of resting sites and feeding areas versus seasonal range shifts resulting from climatic factors and the emerging vegetation changes (Forester et al. 2007). The drivers of range size may vary on different temporal scales (Börger et al. 2006, Van Beest et al. 2011). Hence, for a comprehensive understanding of wild boar space-use patterns and the