Do Roads Alter the Trophic Behavior of the Mesocarnivore Community Living Close to Them?

Abstract

Roads have impacts on the fauna arising from habitat fragmentation, roadkill and the barrier effect. Furthermore, roads lead species to change their activity with repercussions on predator–prey interactions and trigger indirect effects that are currently unknown. This study analyzes the effect of a motorway on the trophic behavior of the terrestrial carnivore community of its surroundings. Monthly scat sampling was conducted over a year at three distances from a motorway (0–50 m, 500–550 m and 1000–1050 m). We collected 498 scats, these originating from red fox (39.16%), cat (24.50%), stone marten (24.09%) and badger (12.25%). The relative abundance of the trophic resources in them was estimated together with the trophic diversity and niche overlap of the carnivore species. The results showed a distinct effect of distance from the road on trophic behavior of carnivores, as well as differences between species and seasons. The scats nearest the road had 10–20% more biomass of small mammals, equivalent in relative terms to a 21–48% increase in small mammals’ biomass when compared with scats collected further from the road. This finding indicates changes in predator–prey interactions near the road and shows that the human-generated structural and functional changes to ecosystems spread throughout trophic networks.

Interspecific interactions disrupted by roads

“…Ruiz‐Capillas et al . (2021) found that carnivore scats near a road included 10–20% more biomass from small mammals, likely related to increased numbers of micromammals along road verges (see Section III.1. a ).…”

“…Fourth, roads can result in dietary modifications. Ruiz-Capillas et al (2021) found that carnivore scats near a road included 10-20% more biomass from small mammals, likely related to increased numbers of micromammals along road verges (see Section III.1.a). Fifth, road proximity may force small mammals to reduce their time spent foraging (Giordano, Hunninck & Sheriff, 2022) in response to the increased predation risk perceived due to the proximity of the road (Gonzalez-Olimon, St Juliana & Sparks, 2016).…”

Mesocarnivore sensitivity to natural and anthropogenic disturbance leads to declines in occurrence and concern for species persistence

“…We predicted red fox would occupy areas near roads, but our models indicated that red fox were more likely to be found far from roads initially. Red fox are known to benefit from edge habitat near roads and they hunt in other edge habitat that would be related to low cover areas where we also expected occupancy to be more stable (Ruiz‐Capillas et al., 2021 ). Occupancy dynamics related to anthropogenic disturbance were mediated by seasonal variation, where shifts in distributions related to zone size and cover occurred primarily in the autumn transition period.…”

“…Although roads can be risky for animals (e.g., vehicular strike), roads can also provide beneficial food sources incidentally via roadkill. Road edges and infrastructure provide habitat for abundant small mammal communities that mesocarnivores, like gray fox ( Urocyon cinereoargenteus ), red fox ( Vulpes vulpes ) and coyote ( Canis latrans ) are known to benefit from (Adams & Geis, 1983 ; Gompper, 2002 ; Ruiz‐Capillas et al., 2021 ). Natural disturbance can also provide incidental food sources for mesocarnivores as storm events and natural tree mortality can create habitat for invertebrate and small mammal communities that support mesocarnivore diets (Carey & Johnson, 1995 ; Kirkland, 1990 ).…”

“…We hypothesized that forest dynamics related to moth damage and succession would influence fisher the most as they prefer high canopy cover (Kordosky, Gese, Thompson, Terletzky, Neuman‐Lee, et al., 2021; Kordosky, Gese, Thompson, Terletzky, Purcell, & Schneiderman, 2021; Sauder & Rachlow, 2015). We anticipated that the effects of anthropogenic disturbance in the form of roads would have the most impact on the fox species with gray fox avoiding roads and red fox benefiting from roads (Adams & Geis, 1983; Carroll et al., 2019; Riley, 2006; Ruiz‐Capillas et al., 2021). Additionally, we expected seasonal variation in site occupancy related to differences in seasonal home range size and movement for all species (Cypher, 2003; Hersteinsson & Macdonald, 1982; Mayer et al., 2021; Powell, 1993) except coyote, since home ranges of coyotes living near urbanization remains constant across seasons (Crête et al., 2001; Gehrt et al., 2009).…”