Spatial segregation of sympatric marten and fishers: the influence of landscapes and species‐scapes

Abstract

Co-occurring species are rarely considered as a factor infl uencing habitat selection. However, niche theory predicts that sharing resources, predators, and other interspecifi c interactions can limit the environmental conditions under which a species may exist. How does the spatial distribution of one species aff ect that of another within shared landscapes? We tested whether sympatric marten Martes americana and fi shers M. pennanti in a mountain landscape in Alberta, Canada exhibit local-scale spatial segregation, beyond diff erential habitat selection. We modelled marten and fi sher distribution in relation to remotely-sensed habitat data and species co-occurrence, using generalized linear models and informationtheoretic model selection. Marten and fi shers selected diff erent habitat types and showed diff erent responses to habitat fragmentation. Even after accounting for these diff erences, the absence of one species signifi cantly explained the occurrence of the other. We conclude that the spatial distribution of marten and fi shers infl uences habitat selection by each other at landscape scales, and hypothesize that this pattern may result from competition in a spatially heterogeneous environment. Species-habitat models that consider only resources may fail to capture key predictors of species ' occurrence. Reliable prediction and inference requires that ecologists expand from landscapes to also include species-scapes: a spatial plane of species interactions that combines with resources to drive species ' distributions.

A multi-method hierarchical modeling approach to quantifying bias in occupancy from noninvasive genetic tagging studies

“…Examination of dominance relationships and spatiotemporal partitioning is possible by analyzing photographs, and may help elucidate these mechanisms. Observed variation in θ is possibly related to other unmeasured differences among sites, such as habitat, although this seems unlikely based on existing data (see Fisher et al ). Excepting this possibility, sympatric heterospecifics appear to negatively or positively affect error in NGT hair‐trapping studies in a non‐trivial way.…”

“…Noninvasive genetic tagging data inform estimates of population size (Williams et al ), density (Gardner et al ), habitat selection (e.g., Fisher et al ), and landscape genetics—the landscape‐scale analysis of population connectivity and gene flow (Manel et al ). Noninvasive genetic tagging has been used successfully for these purposes in many mammal species including grizzly bears ( Ursus arctos ; Mowat et al , Kendall et al ), marten ( Martes americana ), fisher ( Pekania pennanti ; Mowat and Paetkau , Fisher et al ), and wolverines ( Gulo gulo ; Hedmark and Ellegren , Fisher et al ). Noninvasive genetic tagging is an important tool for ecological inquiry, and resulting data are frequently used in conservation decisions (e.g., Alberta Grizzly Bear Recovery Plan ).…”

Empirical evaluation of the strength of interspecific competition in shaping small mammal communities in fragmented landscapes

“…Removal experiments, however, are logistically difficult to conduct at the large scale required to investigate fragmentationrelated processes. For this reason, the few studies that have examined interspecific interactions in fragmented landscapes have done so by looking at distribution patterns (Nupp and Swihart 2001;Brown 2007;Kath et al 2009;Youngentob et al 2012;Fisher et al 2013;Robertson et al 2013a). Nevertheless, inferring competition processes from pattern-based studies can lead to misleading conclusions.…”

Abiotic conditions mediate intraguild interactions between mammalian carnivores

“…Despite the long history of observations regarding marten–fisher interactions and general acceptance of the idea that fishers limit marten populations through IG interactions, unless they are themselves limited by deep snowpack (Krohn et al, ), this potential exemplar of how asymmetrical IG interactions can lead to species coexistence or competitive exclusion remains poorly documented. In particular, the distributions of marten and fisher have not been assessed at a fine enough spatial resolution across large enough spatial scales to quantify their presence and/or coexistence across broad gradients in abiotic and biotic conditions (but see Fisher et al, ; Zielinski, Tucker, & Rennie, ). Here, we assess the biotic and abiotic drivers of the distribution of these two mesocarnivores and infer relative abundance using spatially explicit used–unused location, age and harvest data across an ecoregional scale (~30,000 km 2 ) that includes areas where fishers and martens co‐occur as well as areas where only fishers are present.…”