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Predation is an unavoidable and dangerous fact in the lifetime of prey animals and some sign of the proximity of a predator may be enough to trigger a response in the prey. We investigated whether different degrees of predation risk by red foxes (Vulpes vulpes) evoke behavioural and physiological stress responses in wood mice (Apodemus sylvaticus). We examined the variation in mice responses due to individual factors (sex and reproductive status) and related them to the concentration of the volatile compounds from fox faeces over time. In our experiment, we introduced predation cues into four plots, each subjected to a different concentration treatment (0, 10, 50 and 100% concentration of fresh faeces of red fox), based on the following outline: initial odourless phase 0, phase1 in which predation treatment was renewed daily, and phase 2 in which we renewed the treatment only on the first day. Wood mice were live trapped during all three phases and the physiological response was measured non-invasively by analysing faecal corticosterone metabolites (FCM) in freshly collected faeces. Data were analysed by Generalized Linear Mixed Models. Overall, males were trapped less often than females, and reproductively active individuals from both sexes avoided traps more than non-reproductively active individuals, especially in medium- and high- concentration plots. Variations in FCM concentrations were explained by plot, the interaction between plot and treatment phase, and the interaction between the treatment phase and the reproductive status. During phase 1, we detected a significant rise in FCM levels that increased with predator faecal odour concentration. Additionally, reproductively active individuals showed a strong physiological response during both phases 1 and 2 in all plots, except the control plot. Our results indicated that wood mice are able to discriminate different degrees of predation risk, which allows them to trigger gradual changes in their behavioural and physiological stress responses.

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Landscape disturbance by roads may increase abundance of prey in verges 20 (i.e., strips of terrain adjacent to roadways) or create other features that can attract carnivores 21 and expose them to a higher risk of mortality by vehicle collision. We studied a system that 36 linear transects within the study area, 18 along motorways and 18 in control zones ( Fig. 1). 119We defined control zones as those with the same habitat structure and ≥4 km from habitat effect. We double-checked transects for habitat similarity; first we inspected habitat . We calculated the index value as the sum of all pellets counted in each transect. 142We estimated a carnivore abundance index as the number of scats detected in each 143 transect (Long et al. 2008 of the raw data in each transect type followed the same pattern for almost all the taxa, with 240higher mean values in motorways than in control sites (Fig. 2). Global carnivore abundance 241 increased with rabbit abundance (β = 0.103 ± 0.044, P = 0.019) and carnivore abundance was 242 higher in motorway transects than control sites (β = 0.400 ± 0.175, P = 0.022). 243The red fox showed higher abundance in motorways (β = 0.469 ± 0.197, P = 0.017) 244 but no significant response to rabbit abundance (P = 0.129; Fig. 3). The non-synanthropic 245 species showed the opposite response, with abundances positively related to rabbit abundance 246(β = 0.119 ± 0.044, P = 0.007) but no differences in abundance due to the proximity of the 247 motorway (P = 0.084; Fig. 3). 248Cascading Effects: Rabbit Abundance, Carnivore Abundance, and Roadkills 255In the analyses for the global carnivore community, roadkills were positively and numbers. For carnivores related closely to prey abundance, high prey abundance in verges 275 creates a local cascading effect that leads to carnivore roadkills. 276The increased abundance of the global carnivore community near motorways is 277 probably due to higher fox abundance in these areas, as foxes comprised almost half of the 295On the other hand, our group of non-synanthropic carnivores followed a different carnivores that prey on them will follow rabbit distribution. we controlled for by conducting DNA analysis to assess the accuracy of scat identification. 332We controlled for other potential sources of bias by choosing areas that were comparable in 333 habitat characteristics, which can affect fecal persistence and scat detectability (Long et al. are necessary to make informed management decisions that favor conservation objectives. 364Understanding wildlife responses to human-modified landscapes provides us with better 365 knowledge of the communities and identifies which processes should be the focus of our 366 conservation efforts. 367 MANAGEMENT IMPLICATIONS 368When prey are abundant near motorways, carnivores increase their abundance in those areas. 369Higher abundances of carnivores were strongly related to higher mortality by vehicles. 370Therefore, the design and management of verges could be a key aspect for conservation of 371 wil...