Erik Versluijs

• Versluijs, Erik; Tofastrud, Morten; Hessle, Anna; Serrouya, Robert; Scasta, Derek & Wabakken, Petter [Show all 7 contributors for this article] (2024). Virtual fencing in remote boreal forests: performance of commercially available GPS collars for free-ranging cattle. Animal Biotelemetry. 12(1). doi: 10.1186/s40317-024-00389-8. Full text in Research Archive Show summary

  Background The use of virtual fencing in cattle farming is beneficial due to its flexibility, not fragmenting the landscape or restricting access like physical fences. Using GPS (Global Positioning System) technology, virtual fence units emit an audible signal and a low-energy electric shock when crossing a predefined border. In large remote grazing areas and complex terrains, where the performance of the GPS units can be affected by landscape structure, increased positioning errors can lead to unnecessary shocks to the animals leading to animal welfare concerns. This study aimed to explore factors affecting the GPS performance of commercially available virtual fence collars for cattle (NoFence©), both using static tests and mobile tests, i.e., when deployed on free-ranging cattle. Results The static tests revealed generally high fix success rates (% successful positioning attempts), and a lower success rate at four of 30 test locations was most likely due to a lack in GSM (Global System for Mobile communications) coverage. On average the GPS precision and accuracy errors were 3.3 m ± 2.5 SD and 4.6 m ± 3.2 SD, respectively. We found strong evidence that the GPS precision and accuracy errors increased errors under closed canopies. We also found evidence for an effect of the sky-view on the GPS performance, although at a lesser extent than canopy. The direction of the accuracy error in the Cartesian plane was not uniform, but biased, depending on the aspect of the test locations. With an average of 10.8 m ± 6.8 SD, the accuracy error of the mobile tests was more than double that of the static tests. Furthermore, we found evidence that more rugged landscapes resulted in higher GPS accuracy errors. However, the error from mobile tests was not affected by canopy cover, sky-view, or cattle behaviors. Conclusions This study showed that GPS performance can be negatively affected by landscape complexity, such as increased ruggedness and covered habitats, resulting in reduced virtual fence effectiveness and potential welfare concerns for cattle. These issues can be mitigated through proper pasture planning, such as avoiding rugged areas for the virtual fence border.

• Wikenros, Camilla; Nordli, Kristoffer; Amato, Giulia; Persson, Jens; Ausilio, Giorgia & Versluijs, Erik [Show all 9 contributors for this article] (2024). Carnivore guild utilization of hunter-provided food sources in boreal forest. Wildlife Biology. ISSN 0909-6396. 2024(6). doi: 10.1002/wlb3.01249. Full text in Research Archive Show summary

  Scavenging is an alternative foraging strategy to predation for many carnivore species, as they shift between predation and scavenging in response to changes in resource availability. The use of carrion may lead to interspecific competition and is thus influenced by a risk–reward trade-off to balance coexistence with guild-members, where smaller species are expected to be more vigilant due to their vulnerability to larger competitors. We used cameras to investigate the utilization of viscera from the annual moose Alces alces hunt by four sympatric carnivore species: wolf Canis lupus, wolverine Gulo gulo, red fox Vulpes vulpes and pine marten Martes martes in south–central Scandinavia, in relation to body size and habitat. Red foxes had highest probability of visiting viscera sites in both open and forested habitats. Visits by both red foxes and pine martens were longer in open habitats, while number of visits or activity did not differ between habitats. For pine martens, the probability of visiting viscera sites was twice as high in forest compared to open habitat; consequently, red foxes showed the highest overall use of viscera. Red foxes were most vigilant, especially in open habitat, whereas wolverines and pine martens spent a higher proportion of time feeding. Increased vigilance of red foxes facilitates extended resources use in open habitat, while for pine martens, the risk–reward decision occurs before leaving forest cover and entering open habitats. Viscera were not used to a large extent by wolves or wolverines. Wolves are generally less prone to scavenging and wolverines probably use other food resources, more suitable for caching. Overall, competition did not prevent use of viscera, probably due to small-scale temporal segregation and limited use by the larger carnivores. Consequently, this pulse of human-subsidized food resources before winter may have important implications for the smaller facultative scavengers.

• Versluijs, Erik; Niccolai, Laura Jeanne; Spedener, Mélanie; Zimmermann, Barbara; Hessle, Anna & Tofastrud, Morten [Show all 8 contributors for this article] (2023). Classification of behaviors of free-ranging cattle using accelerometry signatures collected by virtual fence collars. Frontiers in Animal Science. 4, p. 1–13. doi: 10.3389/fanim.2023.1083272. Full text in Research Archive Show summary

  Precision farming technology, including GPS collars with biologging, has revolutionized remote livestock monitoring in extensive grazing systems. High resolution accelerometry can be used to infer the behavior of an animal. Previous behavioral classification studies using accelerometer data have focused on a few key behaviors and were mostly conducted in controlled situations. Here, we conducted behavioral observations of 38 beef cows (Hereford, Limousine, Charolais, Simmental/NRF/Hereford mix) free-ranging in rugged, forested areas, and fitted with a commercially available virtual fence collar (Nofence) containing a 10Hz tri-axial accelerometer. We used random forest models to calibrate data from the accelerometers on both commonly documented (e.g., feeding, resting, walking) and rarer (e.g., scratching, head butting, self-grooming) behaviors. Our goal was to assess pre-processing decisions including different running mean intervals (smoothing window of 1, 5, or 20 seconds), collar orientation and feature selection (orientation-dependent versus orientation-independent features). We identified the 10 most common behaviors exhibited by the cows. Models based only on orientation-independent features did not perform better than models based on orientation-dependent features, despite variation in how collars were attached (direction and tightness). Using a 20 seconds running mean and orientation-dependent features resulted in the highest model performance (model accuracy: 0.998, precision: 0.991, and recall: 0.989). We also used this model to add 11 rarer behaviors (each< 0.1% of the data; e.g. head butting, throwing head, self-grooming). These rarer behaviors were predicted with less accuracy because they were not observed at all for some individuals, but overall model performance remained high (accuracy, precision, recall >98%). Our study suggests that the accelerometers in the Nofence collars are suitable to identify the most common behaviors of free-ranging cattle. The results of this study could be used in future research for understanding cattle habitat selection in rugged forest ranges, herd dynamics, or responses to stressors such as carnivores, as well as to improve cattle management and welfare.

• Neby, Magne; Andreassen, Harry Peter; Milleret, Cyril Pierre; Pedersen, Simen; Tamayo, Ana-Maria Peris & Sanchez, David Carricondo [Show all 8 contributors for this article] (2023). Small rodent monitoring at Birkebeiner Road, Norway. Biodiversity Data Journal. ISSN 1314-2836. 11. doi: 10.3897/BDJ.11.E105914. Full text in Research Archive Show summary

  Northern small mammal populations are renowned for their multi-annual population cycles. Population cycles are multi-faceted and have extensive impacts on the rest of the ecosystem. In 2011, we started a student-based research activity to monitor the variation of small rodent density along an elevation gradient following the Birkebeiner Road, in southeast Norway. Fieldwork was conducted by staff and students at the University campus Evenstad, Inland Norway University of Applied Sciences, which has a long history of researching cyclic population dynamics. The faculty has a strong focus on engaging students in all parts of the research activities, including data collection. Small rodents were monitored using a set of snap trap stations. Trapped animals were measured (e.g. body mass, body length, sex) and dissected to assess their reproductive status. We also characterised the vegetation at trapping sites.

• Versluijs, Erik; Eriksen, Ane; Fuchs, Boris; Wikenros, Camilla; Sand, Håkan & Wabakken, Petter [Show all 7 contributors for this article] (2022). Wolf Responses to Experimental Human Approaches Using High-Resolution Positioning Data. Frontiers in Ecology and Evolution. 10. doi: 10.3389/fevo.2022.792916. Full text in Research Archive Show summary

  Humans pose a major mortality risk to wolves. Hence, similar to how prey respond to predators, wolves can be expected to show anti-predator responses to humans. When exposed to a threat, animals may show a fight, flight, freeze or hide response. The type of response and the circumstances (e.g., distance and speed) at which the animal flees are useful parameters to describe the responses of wild animals to approaching humans. Increasing knowledge about behavioral responses of wolves toward humans might improve appropriate management and decrease conflicts related to fear of wolves. We did a pilot study by conducting 21 approach trials on seven GPS-collared wolves in four territories to investigate their responses to experimental human approaches. We found that wolves predominantly showed a flight response (N = 18), in a few cases the wolf did not flee (N = 3), but no wolves were seen or heard during trials. When wolves were downwind of the observer the flight initiation distance was significantly larger than when upwind, consistent with the hypothesis that conditions facilitating early detection would result in an earlier flight. Our hypothesis that early detection would result in less intense flights was not supported, as we found no correlation between flight initiation distances and speed, distance or straightness of the flight. Wolves in more concealed habitat had a shorter flight initiation distance or did not flee at all, suggesting that perceived risk might have been affected by horizontal visibility. Contrary to our expectation, resettling positions were less concealed (larger horizontal visibility) than the wolves’ initial site. Although our small number of study animals and trials does not allow for generalizations, this pilot study illustrates how standardized human approach trials with high-resolution GPS-data can be used to describe wolf responses at a local scale. In continuation, this method can be applied at larger spatial scales to compare wolf flight responses within and between populations and across anthropogenic gradients, thus increasing the knowledge of wolf behavior toward humans, and potentially improving coexistence with wolves across their range.

• Eriksen, Ane; Versluijs, Erik; Fuchs, Boris; Zimmermann, Barbara; Wabakken, Petter & Ordiz, Andres [Show all 15 contributors for this article] (2022). A Standardized Method for Experimental Human Approach Trials on Wild Wolves. Frontiers in Ecology and Evolution. 10. doi: 10.3389/fevo.2022.793307. Full text in Research Archive Show summary

  As wolves recolonize areas of Europe ranging from moderate to high anthropogenic impact, fear of wolves is a recurring source of conflict. Shared tools for evaluating wolf responses to humans, and comparing such responses across their range, can be valuable. Experiments in which humans approach wild wolves can increase our understanding of how wolves respond to humans, facilitating human-wolf coexistence. We have developed the first standardized protocol for evaluating wolf responses to approaching humans using high-resolution GPS data, and tested it on wild wolves. We present a field protocol for experimentally approaching GPS-collared wolves, a descriptive comparison of two statistical methods for detecting a measurable flight response, a tutorial for identifying wolf flight initiation and resettling positions, and an evaluation of the method when reducing GPS positioning frequency. The field protocol, a data collection form, and the tutorial with R code for extracting flight parameters are provided. This protocol will facilitate studies of wolf responses to approaching humans, applicable at a local, national, and international level. Data compiled in a standardized way from multiple study areas can be used to quantify the variation in wolf responses to humans within and between populations, and in relation to predictors such as social status, landscape factors, or human population density, and to establish a baseline distribution of wolf response patterns given a number of known predictors. The variation in wolf responses can be used to assess the degree to which results can be generalized to areas where GPS studies are not feasible, e.g., for predicting the range of likely wolf behaviors, assessing the likelihood of wolf-human encounters, and complementing existing tools for evaluating reports of bold wolves. Showing how wolves respond to human encounters should help demystify the behavior of wild wolves toward humans in their shared habitat.

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• Versluijs, Erik (2026). Free-Ranging Cattle in the Boreal forest: A story about wolves, conflicts, and solutions? Full text in Research Archive
• Versluijs, Erik; Zimmermann, Barbara; Niccolai, Laura Jeanne; Tofastrud, Morten; Hessle, Anna Karin & Scasta, John Derek [Show all 9 contributors for this article] (2025). How Advances in Livestock Technology Can Aid Wildlife Coexistence: a Case Study on Free-Ranging Cattle in the Boreal Forest. Full text in Research Archive Show summary

  In the last decade, technological advances have soared, both within wildlife research and livestock production. Within livestock farming, there has been a significant increase in technological applications to measure and monitor animal health, with the main focus on increasing production and maintaining high animal welfare standards. These precision livestock farming (PLF) techniques can be utilized beyond highly modernized barns. One such example is the use of accelerometers, i.e. activity sensors from which behaviours or certain activity states can be derived. For example, in an earlier study, we have successfully used accelerometers in free-ranging cattle in large, extensive forest areas in Norway to study cattle behaviours at high spatio-temporal resolution. However, interactions between livestock and wildlife bring multifaceted societal challenges of high complexity, such as livestock depredation. For example, repeated livestock depredation negatively affects animal welfare, is economically and emotionally straining to farmers, and leads to lower acceptance level for wildlife, such as carnivores, at a societal level. Studying wildlife species requires considerable effort, often using invasive techniques, and generally results in lower sample sizes due to lower population densities. Increasing focus on studying livestock within wildlife conflicts offers the opportunity to understand how different species, breeds, and age classes are affected by interactions with wildlife. At the same time, this provides valuable information about wildlife species. We have successfully used accelerometers on free-ranging cattle in large, extensive forest areas in Norway to study cattle behaviours at high spatio-temporal resolution. In our study, all adult cattle in the herds were equipped with virtual fence collars, recording both GPS and acceleration data. By using a behavioural classification model, we predicted behaviours and examined how different environmental, climatic, and topographic drivers relate to these behaviours. Ultimately, this can be used to study changes of behaviours, and potentially increased stress and vigilance behaviour in response to carnivore presence or other perceived risks. Furthermore, high livestock abundance and lower effort required for tagging livestock can increase the understanding of differences between breeds, ages, farming systems, etc., and therefore aid in coexistence with wildlife and reducing wildlife conflicts.

• Versluijs, Erik; Zimmermann, Barbara; Hessle, Anna Karin & Tofastrud, Morten (2025). Living with wolves: A new framework to enhance coexistence with wolves by studying livestock behaviours. Full text in Research Archive Show summary

  Coexisting with wolves brings multifaceted societal challenges of high complexity, such as livestock losses due to depredation. Countries often support farmers with economic compensation of livestock losses. However, farmers affected by repeated depredation events might not only suffer economically, but also emotionally. The resulting increase in stress and worry can impact their daily life, which in turn can negatively effect animal welfare. Furthermore, repeated livestock depredation will negatively effect animal welfare, as individuals which are not attacked who might have higher stress levels. In the meantime, many studies related to wolf management and coexistence are focussing directly on wolf behaviour and preventive measures to alleviate conflicts. These efforts are of great importance. However, in addition to this, we propose a new framework for studying livestock behaviours using precision livestock farming (PLF) techniques to enhance coexistence with wolves. Within livestock farming there is a strong increase in technological applications to measure and monitor animal health, with the main focus on increasing production and maintaining high animal welfare standards. These PLF techniques can reach further than only be used in highly modernized barns. One such example is the use of accelerometers, i.e. activity sensors from which behaviours or certain activity states can be derived. We have in an earlier study successfully used accelerometers in free-ranging cattle in large extensive forest areas in Norway to study cattle behaviours at high spatio-temporal resolution. Based on these experiences, we propose creating a broader network of cattle behaviour studies that consider different herd compositions, pasture types, breeds, ages, and management practices. Therefore, creating a wide knowledge base about breed specific livestock behaviours and responses towards wolf presence gives the opportunity to 1) inform farmers and suggest adjustments of management practices in specific situations, such as changing to breeds or herd compositions with a lower probability of depredation. And 2) developing tools to better monitor livestock behaviour, for example to detect sudden changes in behaviour suggesting towards wolf presence. In this presentation we will outline this interdisciplinary framework, discuss the technology and methods, and use a practical case to show how this might be implemented.

• Eriksen, Ane; Lorand, Charlotte Muguette Renée; Versluijs, Erik; Chimienti, Marianna; Devineau, Olivier & Bouet, Lea [Show all 10 contributors for this article] (2024). Studying wolf flight responses during experimental approaches using fine-scale GPS and accelerometer data. Full text in Research Archive
• Eriksen, Ane; Lorand, Charlotte Muguette Renée; Versluijs, Erik; Chimienti, Marianna; Devineau, Olivier & Bouet, Lea [Show all 10 contributors for this article] (2024). Eksperimentelle nærmøter med ulv – oppdatering og framtidige planer. Full text in Research Archive
• Zimmermann, Barbara; Niccolai, Laura Jeanne; Versluijs, Erik; Spedener, Mélanie; Evans, Alina & Tofastrud, Morten [Show all 7 contributors for this article] (2024). How can electronical tags for livestock facilitate livestock production in areas with large carnivores? Full text in Research Archive
• Versluijs, Erik (2024). Sharing the forest with wolves: can studying livestock behaviours enhance wolf coexistence? Full text in Research Archive
• Versluijs, Erik (2024). Open science: How make your research more FAIR? Full text in Research Archive
• Niccolai, Laura Jeanne; Wulff, Saskia H.; Versluijs, Erik; Spedener, Mélanie; Zimmermann, Barbara & Hessle, Anna [Show all 9 contributors for this article] (2024). Forest Cows Secrets: Cracking the Code With Movement Sensors. Frontiers for Young Minds. doi: 10.3389/frym.2024.1305706. Full text in Research Archive Show summary

  Have you ever wondered how we can watch animals in the wild without actually being near them? In Norway, cows roam freely in the deep forest during summer. While the cows enjoy the freedom, it can be tricky to keep them safe from carnivores like wolves and bears, as no shepherds or dogs protect the herds. Keeping an eye on the cows is important! Farmers and researchers use GPS to track animals, just as we do for phones or cars. However, GPS does not tell us much about what the animals are doing. That is where movement sensors come in. These sensors store information about the tiniest body movements and reveal what the animal is doing at any time. Is the cow’s head up or down? Is it walking or running? Based on the data, we could distinguish 20 different behaviors! Now we can spy on cows, see what they are up to in the forest, and help farmers better care for them.

• Versluijs, Erik (2024). Towards a shared forest: Effects of external stressors on space use and behavior of free-ranging cattle in the boreal forests. Full text in Research Archive
• Versluijs, Erik; Zimmermann, Barbara; Tofastrud, Morten; Hessle, Anna; Scasta, John Derek & Serrouya, Robert [Show all 7 contributors for this article] (2024). Behavioural dependent habitat selection of free-ranging cattle in the boreal forest. Full text in Research Archive Show summary

  During the 20th century, when large carnivores were subject to eradication in Norway, farmers started to release their livestock unsupervised in the forests during summer. Since 1970, Norway has committed to conserve large carnivores, which led to high losses in domestic sheep herds. Therefore, farmers are encouraged to use cattle instead, as cattle have a hundred times lower depredation rate. However, farmers report increased stress in cattle, and income loss. We GPS collared all adult cattle (N = 125) in four herds and two areas in the Innlandet County of SE-Norway. The collars included accelerometer sensors and were equipped with virtual fencing technology to retain the animals inside areas up to 25 km2. We registered GPS positions of cattle using 15-minute intervals and predicted common behaviours such as grazing, walking, vigilance, and resting, using accelerometry signatures. We used multi-state step-selection analyses to study effects of environmental variables (habitat, weather) on cattle behaviours,body condition, and seasonal variability. Preliminary results indicated that cattle used mostly forest roads for walking, as previously shown. Our results provide novel insights about cattle’s space-use in boreal forests, and the potential to study the compatibility of free-ranging cattle with carnivores and effects on animal welfare.

• Versluijs, Erik (2023). Change point analysis and animation of movement data in R. Full text in Research Archive
• Adamski, Genevieve; Versluijs, Erik; Zimmermann, Barbara & Tofastrud, Morten (2023). Outstanding in their field: factors influencing cattle habitat selection in Norwegian summer ranging areas. Full text in Research Archive
• Versluijs, Erik; Zimmermann, Barbara; Tofastrud, Morten; Hessle, Anna; Evans, Alina & Adamski, Genevieve [Show all 9 contributors for this article] (2023). Towards a shared forest: Studying the compatibility of free-ranging cattle and carnivores in boreal forests. Full text in Research Archive
• Zimmermann, Barbara; Wikenros, Camilla; Mathisen, Karen Marie; Ausilio, Giorgia; Sand, Håkan & Hellbaum, Paige [Show all 12 contributors for this article] (2023). Elgforvaltning i grenseland. Full text in Research Archive
• Zimmermann, Barbara; Mathisen, Karen Marie; Ausilio, Giorgia; Sand, Håkan; Wikenros, Camilla & Eriksen, Ane [Show all 13 contributors for this article] (2022). Motsatte norske og svenske mål for felles elgbestand. Hjorteviltet. ISSN 1502-3729. Full text in Research Archive
• Versluijs, Erik (2026). Free-Ranging Cattle in the Boreal Forest: Predicting behaviours and exploring behavioural drivers with virtual fencing technology. Universitet i Innlandet / University of Inland Norway. ISSN 9788283805819. Full text in Research Archive Show summary

  Befolkningsvekst og intensivert husdyrproduksjon bidrar til miljøforringelse, tap av biologisk mangfold og økende bekymringer for dyrevelferd. På verdensbasis varierer landbrukssystemer fra småskala til storskala drift, men alle står overfor utfordringer knyttet til dyrevelferd. Presisjonsteknologier for husdyrhold (PLF) kan forbedre forvaltning av husdyr og muliggjøre fjernstyring av beite ved hjelp av automatisert veiing og virtuelle gjerder. Dette kan fungere som et alternative til fysiske gjerder. Frittgående systemer møter utfordringer som rovdyr og miljømessige stressfaktorer. I Norge, hvor frittgående husdyr møter fornyede utfordringer fra tilbakevendende rovdyr, gir kombinasjonen av tradisjonelle frittgående husdyrsystemer og virtuell gjerdeteknologi en unik mulighet til å studere kvegatferd i seminaturlige miljøer, fremme forskning på dyrevelferd og redusere konflikter mellom husdyr og vilt, noe som kan styrke sameksistens i flerbrukslandskap. Jeg undersøkte hvordan miljømessige, klimatiske og tidsmessige faktorer påvirker atferden til frittgående storfe ved hjelp av virtuelle gjerdehalsbånd utstyrt med GPS og triaksiale akselerometersensorer. Først vurderte jeg ytelsen til de virtuelle gjerdehalsbåndene i avsidesliggende landskap (artikkel I) og fant at landskapskompleksitet kan påvirke GPS-ytelsen negativt. Disse problemene kan imidlertid reduseres ved å plassere de virtuelle gjerdegrensene utenfor ulendte områder. Deretter utviklet jeg en atferdsklassifiseringsmodell som identifiserte opptil ti av de vanligste atferdene (artikkel II), og som ble brukt til å klassifisere atferd, samt undersøke hvordan ulike faktorer påvirker storfeatferd (artikkel III). Jeg fant at storfeatferd var relatert til tid på dagen, hvor beiting, gange og sosial atferd var vanligere i dagslys, mens hvile dominerte om natten. Høyere temperatur-fuktighetsindeks (THI) økte beite under tettere kronedekke i løpet av dagen, mens vindhastighet og kronedekke hadde blandede effekter på beiting og hvile. I denne avhandlingen viser jeg hvordan høyoppløselige akselerometerdata muliggjør detaljert innsikt i frittgående storfeatferd, noe som potensielt kan støtte tidlig handling ved helseproblemer, gi bedre forståelse av individuell og gruppedynamikk, og informere strategier for sameksistens mellom husdyr og dyreliv. Videre fremhever avhandlingen hvordan integrering av GPS- og akselerometerteknologi med en tverrfaglig tilnærming kan forbedre forståelsen av frittgående storfeatferd, interaksjoner mellom husdyr og ville dyr, og menneskelige forstyrrelser. Den tilbyr også praktiske rammeverk for å forbedre dyrevelferd, overvåke flokkdynamikk og optimalisere landbrukspraksis, samtidig som konflikter i delte landskap håndteres.

• Zimmermann, Barbara; Mathisen, Karen Marie; Ausilio, Giorgia; Sand, Håkan; Wikenros, Camilla & Eriksen, Ane [Show all 20 contributors for this article] (2022). Elgvandringer i grenseland med følger for skogbruk, jakt og rovdyr. Sveriges Lantbruksuniversitet. ISSN 9789157699411. Full text in Research Archive
• Wikenros, Camilla; Aronsson, Malin; Nordli, Kristoffer; Amato, Giulia; Ausilio, Giorgia & Versluijs, Erik [Show all 7 contributors for this article] (2022). Interaktioner mellan järv, varg och människa – nyttjande av vargdödade klövdjur och slaktrester från älgjakten. Sveriges Lantbruksuniversitet. ISSN 9789157699466. Full text in Research Archive

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