Relative Importance of Habitat Characteristics and Interspecific Relations in Determining Terrestrial Carnivore Occurrence

Abstract

Carnivores act as top-down regulators in terrestrial ecosystems, and their occurrence and relative abundance is a result of complex interactions between food and habitat availability, human pressure (e.g., trapping, hunting, roadkill), and intraguild interactions (competition, predation). Eastern United States has a long history of human impact, which resulted in an altered carnivore community. Specifically, Ohio presents an interesting case for evaluating the relative roles of interspecific relations and habitat characteristics for shaping the carnivore community, as its carnivore community has a unique dynamics and composition: invasive coyote and red fox (Vulpes vulpes), and native bobcat (Lynx rufus), currently recovering and expanding its range, gray fox (Urocyon cinereoargenteus) declining at a fast pace, and the generalist raccoon (Procyon lotor) and Virginian opossum (Didelphis virginiana). We used 50 camera traps to collect presence/absence data in southeastern Ohio, USA. We hypothesized potential interactions between the six carnivores, and used land cover variables, as well as occupancy probabilities of interacting species, to parameterize to single-species occupancy models. We found that landscape composition at three different scales (500 and 1000 m buffer around camera locations, and 3 × 3 km grid cell) had little effect on species occurrence. We identified strong negative interspecific relations between carnivores, with bobcat occurrence being influenced by presence of coyotes, red fox occurrence by gray foxes, and raccoon occurrence by Virginia possums. While these findings cannot discriminate between habitat partitioning (spatial or temporal) and competition (direct or interference), they lend support to complex dynamics between invasive coyotes and red foxes and recovering (bobcat) and declining (gray fox) native carnivore species. In particular, the negative relation between the apex predator in our system, C. latrans, and L. rufus, raise further questions on whether direct competition from coyotes has the potential to slow bobcat population recovery. In the context of regulated trapping (ongoing for gray fox and potential season for bobcat), a better understanding of the carnivore intraguild relations can inform management and conservation actions targeted at minimizing the impact of competition on at-risk native species from non-native species.

Limitations of current knowledge about the ecology of Grey Foxes hamper conservation efforts

“…In a rare experimental study, Henke & Bryant (1999) found that RAB of Grey Foxes in western Texas increased following removal of Coyotes. However, negative effects of Coyotes were often weak or not statistically significant (Borchert 2012;Lombardi et al 2017;LeFlore et al 2019) and two studies reported positive effects (Rota et al 2016;Rich et al 2018). Showing similar contrasts, LeFlore et al ( 2019) reported near complete temporal overlap between Coyotes and Grey Foxes (Figure 5) while Lesmeister et al (2015) found that these foxes were detected less frequently during nights when Coyotes were also detected.…”

“…Other studies evaluating temporal variation in RAB or occupancy of this species were conducted over relatively short (<3 year) periods (Chamberlain et al 1999;Cunningham et al 2006;Gallina et al 2016). In contrast, Bauder et al (2020) found evidence of declines in Grey Foxes in Illinois over 43 years and two studies in the midwestern USA found that they were the least prevalent species in the native carnivore community (Lesmeister et al 2015;Rich et al 2018). Lesmeister et al (2015) found that site extinction rates for these foxes were higher than site colonization rates, and other studies have suggested declines of Grey Foxes in the midwestern USA (Cooper et al 2012).…”

“…For example, Grey Foxes in California and Oregon were often positively associated with chaparral or shrub-scrub habitats (Fedriani et al 2000;Farias et al 2012;Erikson et al 2019). Several studies found weak or no association with forest-related covariates including forest cover (Rich et al 2018), canopy cover (Davis et al 2011;Reed 2011), distance to nearest forest (LeFlore et al 2019), or basal area (Barrett et al 2012) perhaps reflecting insufficient covariate variability within the study area or regional variation in habitat associations. Results from several studies suggest that these foxes may use more open forest environments (Barrett et al 2012;Borchert 2012), edge habitats (Davis et al 2011;Deuel et al 2017;Harmsen et al 2019;Pearman-Gillman et al 2020), and heterogenous landscapes (Cooper et al 2012;Lesmeister et al 2015; but see Constible et al 2006).…”

The influence of spatial and temporal scale on the relative importance of biotic vs. abiotic factors for species distributions

“…We selected variables that were known or suspected to influence species distribution based on previous studies on the species from the region (e.g. lynx—Maletzke et al., 2008; bobcats—Clare et al., 2015; cougars—Koehler & Hornocker, 1991; black bear—Long et al., 2007; wolves—Fuller et al., 2003; coyote—Rich et al., 2018; badgers—Apps et al., 2002). Variables representing similar processes were grouped into distinct models for testing to reduce the total number of models tested.…”

Spatial and temporal overlaps of top predators: Dhole, tiger and leopard, and their potential preys in Huai Kha Khaeng Wildlife Sanctuary, Thailand

“…The coexistence of large carnivores in an ecosystem according to the spatial-temporal overlap and niche overlap of different species of prey depends on the reaction towards each other (Pereira et al 2012). The complex environment also defines the ecology of population both wild carnivores and wild preys (Qi et al 2020), and the dynamics of habitat (Rich et al 2018). Understanding the spatio-temporal occurrence of large carnivores along with their preys could be used for conserving the species and populations (Davis et al 2018) in this changing world's environment (Frey et al 2017).…”