An uncertain future for woodland caribou (Rangifer tarandus caribou): The impact of climate change on winter distribution in Ontario

Abstract

Habitat alteration and climate change are two important environmental stressors posing increasing threats to woodland caribou, Rangifer tarandus caribou, in Ontario. Our first objective was to identify the importance of linear features, habitat, and climate on the occurrence of woodland caribou during the winter season using over 30 years of records . Our second objective was to forecast the impacts of climate change on the future occurrence and range of woodland caribou. Woodland caribou occurrence and environmental data collected during 1980 to 2012 were obtained from the Ontario Ministry of Natural Resources (OMNR). Logistic regression models were used to identify the importance of linear features, habitat, and climate on woodland caribou. We then forecast future caribou occurrences using 126 future climate projections. Woodland caribou preferred coniferous forests and mixed forests that tended to be associated with increased lichen coverage, and regions with colder winters. Woodland caribou also avoided anthropogenically disturbed regions, such as areas associated with high road density or developed areas. Caribou range extent was projected to contract by 57.2-100% by 2050 and 58.9-100% by 2070. Furthermore, all 126 climate change scenarios forecast a range loss of at least 55% for woodland caribou in Ontario by 2050. We project complete loss of woodland caribou in Ontario if winter temperatures increase by more than 5.6°C by 2070. We found that woodland caribou in Ontario are sensitive to changes in climate and forecasted that an average of 95% of Ontario's native woodland caribou could become extirpated by 2070. The greatest extirpations were projected to occur in the northernmost regions of Ontario as well as northeastern Ontario, while regions in western Ontario were projected to have the lowest rates of extirpation. This underscores the importance of mitigating greenhouse gases as a means to protect this iconic species.

From climate to caribou: How manufactured uncertainty is affecting wildlife management

“…These changes could have significant effects on boreal caribou range distribution (e.g., warming in combination with increases in natural disturbances could support the northward progression of other ungulates, such as white‐tailed deer, thereby increasing boreal caribou predation as well as transmission of disease and pathogens (e.g., brainworm [ Paralaphostrongylus tenuis ], which is carried by white‐tailed deer). Climate change could very well exacerbate effects of industrial development and human activity (Vors and Boyce , Masood et al ).…”

Global change risks a threatened species due to alteration of predator–prey dynamics

“…In particular, the increase in deciduous vegetation is consistent with observations following increasing forest harvest rates in eastern Canada (Boucher et al, 2014) and increased fire disturbance rates in western North America (Wang et al, 2020). Such climate‐mediated changes in forest composition have already been shown as deleterious for caribou populations using species distribution models (SDMs) (Masood et al, 2017). While SDMs bring information on species occurrence, our approach using combined models improves projections of the indirect effects of global changes by including biotic interactions, changes to forest composition, alterations to disturbance regimes (e.g., fire), and the interactions between CC and LUC.…”

Climate change alone cannot explain boreal caribou range recession in Quebec since 1850

“…Moreover, other factors of uncertainty could become particularly detrimental to caribou if cumulated over an already deteriorated habitat. For example, a northward displacement of isotherms could negatively affect caribou thermoregulation capacities within its current range (Masood et al, 2017; Racey, 2005; see also Williamsen et al, 2019 for Svalbard reindeer) as well as the distribution of parasites, pathogens, predators and competitors (Barber et al, 2018; Latham et al, 2011; Pickles et al, 2013), further intensifying the northward recession of its southern limit. Nevertheless, many compound effects from the ongoing amplification of climate change will need to be further identified and assessed, as they can have serious consequences on the survival of caribou.…”

“…We built these variables using the following data: 2 m air temperature (i.e. above ground level), total (liquid and solid) precipitation and ground surface snow depth, in order to fit what was considered most important according to literature when studying a large herbivore such as caribou (Mallory & Boyce, 2018; Masood et al, 2017; Weladji et al, 2002) (see Table S1.1 for detailed description of variable extraction).…”