How will the greening of the Arctic affect an important prey species and disturbance agent? Vegetation effects on arctic ground squirrels

Abstract

Increases in terrestrial primary productivity across the Arctic and northern alpine ecosystems are leading to altered vegetation composition and stature. Changes in vegetation stature may affect predator-prey interactions via changes in the prey's ability to detect predators, changes in predation pressure, predator identity and predator foraging strategy. Changes in productivity and vegetation composition may also affect herbivores via effects on forage availability and quality. We investigated if height-dependent effects of forage and non-forage vegetation determine burrowing extent and activity of arctic ground squirrels (Urocitellus parryii). We collected data on burrow networks and activity of arctic ground squirrels across long-term vegetation monitoring sites in Denali National Park and Preserve, Alaska. The implications of height-specific cover of potential forage and non-forage vegetation on burrowing behaviour and habitat suitability for arctic ground squirrels were investigated using hierarchical Bayesian modelling. Increased cover of forbs was associated with more burrows and burrow systems, and higher activity of systems, for all forb heights. No other potential forage functional group was related to burrow distribution and activity. In contrast, height-dependent negative effects of non-forage vegetation were observed, with cover over 50-cm height negatively affecting the number of burrows, systems and system activity. Our results demonstrate that increases in vegetation productivity have dual, potentially counteracting effects on arctic ground squirrels via changes in forage and vegetation stature. Importantly, increases in tall-growing woody vegetation (shrubs and trees) have clear negative effects, whereas increases in forb should benefit arctic ground squirrels.

Wildlife species benefitting from a greener Arctic are most sensitive to shrub cover at leading range edges

“…Understanding species population dynamics may aid projection of long‐term change in such species (Anderson et al., ; Keith et al., ). Source‐sink dynamics may render a species with relatively wide distribution dependent on core populations in optimal habitat (as for arctic ground squirrels: Gillis, Hik, Boonstra, Karels, & Krebs, ; Donker & Krebs, ; Werner, Krebs, Donker, Boonstra, & Sheriff, ; Wheeler, ; Wheeler, Chipperfield, Roland, & Svenning, ), particularly in areas of high topographic variation. If habitat conversions to more woody vegetation become contiguous such that source populations are lost, rapid distributional changes could occur in these species.…”

“…Contingency arose where species only responded to specific attributes of shrub cover, effects were landscape‐dependent, or were determined by multiscale shrub characteristics. Some species are sensitive to shrub cover over a certain height, or are affected by overhead but not lateral visibility (Miller, Nol, Nguyen, & Turner, ; Wheeler et al., ). For some species, local shrub cover may influence prey survival and foraging efficiency by providing cover from predators where vegetation structure is open and prey exposed, but once shrub cover becomes denser, benefits of local increases in shrub cover may be lost or reversed (e.g.…”

EcoClimate: a database of climate data from multiple models for past, present, and future for macroecologists and biogeographers

“…This suite of methods and ideas has been applied to diverse research purposes: guiding discovery of populations of known (Bourg et al, 2005;Guisan et al, 2006) and unknown (Raxworthy et al, 2003) species; understanding distributional dynamics under past (Banks et al, 2008a;2008b) and future (Dormann, 2007;Anderson, 2013) climates; anticipating climate change impacts on agricultural (Fraga et al, 2013) and natural (Nabout et al, 2011) extraction; mapping invasion risk (Peterson, 2003;Jiménez-Valverde et al, 2011), pest distributions (Venette et al, 2010;Estay et al, 2014), and disease trasmission (Peterson, 2014); estimating population parameters (Tôrres et al, 2012;Lima-Ribeiro and DinizFilho, 2013;Thuiller et al, 2014), species richness (Wisz and Rahbeck, 2007;LimaRibeiro et al, 2013b), and community composition (Pellissier et al, 2012); analyzing biotic interactions (Anderson et al, 2002;Wheeler et al, 2015); illuminating patterns and processes of diversification and speciation (Silva et al, 2014); characterizing dispersal (Génard and Lescourret, 2013;Saltré et al, 2015); highlighting extinction (Nogués-Bravo et al, 2008;Lima-Ribeiro et al, 2013a); testing niche conservatism (Martínez-Meyer et al, 2004;Peterson and Nyári, 2007;Jakob et al, 2010) and phylogeographic hypotheses (Collevatti et al, 2013b;Alvarado-Serrano and Knowles, 2014); establishing historical refugia (Waltari et al, 2007;…”

Dietary Plasticity in a Specialist Predator, the Gyrfalcon (Falco rusticolus): New Insights into Diet During Brood Rearing

“…For instance, under some climate change scenarios ptarmigan may become functionally less available to Gyrfalcon through two mechanisms: (1) increases in the height, density, and distribution of shrub cover could increase the number of refugia from predation; and (2) range shifts or reductions could alter the distribution of ptarmigan within the range of the Gyrfalcon (Virkkala et al 2008, Mossop 2011, Lehikoinen et al 2014. Climate change is also predicted to impact the distribution of Arctic ground squirrels through a multitude of factors related to its habitat associations (Barker andDerocher 2010, Wheeler andHik 2012), where effects may be negative (e.g., increases in shrub cover) or positive (e.g., increases in forbs; Wheeler et al 2015). Thus, although our results provide important information on the phenology and role of each important prey type in Gyrfalcon breeding ecology, the effects of climate change on the relationship between these three important ecosystem members remain uncertain.…”