Boreal Caribou Research Articles

One Health, One Forest: Harnessing Reclaimed Wood as a Sustainable Solution

Deforestation is a multifaceted and wicked problem characterized by its complexity and resistance to straightforward solutions. The issue is driven by human activities and has severe ecological, socio-economic, and climatic consequences. Between 1990 and 2015, approximately 129 million hectares of forest were lost globally, a trend contributing to biodiversity loss, increased carbon dioxide emissions, and climate change. In Canada, deforestation due to logging significantly impacts the boreal forests, with consequences such as habitat fragmentation affecting species like the threatened boreal caribou. The Canadian logging industry aims to provide essential raw materials while fostering economic growth and employment, supplying critical resources for sawmills, planing mills, shingle mills, and pulp and paper industries. Despite economic benefits, logging, particularly clearcutting, disrupts natural forest regeneration, soil composition, and water cycles, leading to long-term ecological consequences. The One Health approach, integrating human, non-human animal, and environmental health, is proposed to address this issue sustainably. Actions like those by Forests Ontario and Evergreen focus on reforestation and urban greening, while companies like Consolidated Pallet Co. promote wood recycling. This action plan showcases the potential for community-driven solutions to reduce environmental footprints, enhance sustainability, and foster economic and social well-being.

The 2023 wildfire season in Québec: an overview of extreme conditions, impacts, lessons learned and considerations for the future

The 2023 wildfire season in Québec set records due to extreme warm and dry conditions, burning 4.5 million hectares and indicating persistent and escalating impacts associated with climate change. This study reviews the unusual weather conditions that led to the fires, discussing their extensive impacts on the forest sector, fire management, boreal caribou habitats, and particularly the profound effects on First Nation communities. The wildfires led to significant declines in forest productivity and timber supply, overwhelming fire management resources, and necessitating widespread evacuations. First Nation territories were dramatically altered, facing severe air quality issues and disruptions. While caribou impacts were modest across the province, the broader ecological, economical, and social repercussions were considerable. To mitigate future extreme wildfire seasons, the study suggests changes in forest management practices to increase forest resilience and resistance, adapting industrial structures to changes in wood type harvested, and enhancing fire suppression and risk management strategies. It calls for a comprehensive, unified approach to risk management that incorporates the lessons learned from the 2023 fire season and accounts for ongoing climate change. The studyunderscores the urgent need for detailed planning and proactive measures to reduce the growing risks and impacts of wildfires in a changing climate.

Habitat alteration or climate: What drives the densities of an invading ungulate?

Anthropogenic habitat alteration and climate change are two well-known contributors to biodiversity loss through changes to species distribution and abundance; yet, disentangling the effects of these two factors is often hindered by their inherent confound across both space and time. We leveraged a contrast in habitat alteration associated with the jurisdictional boundary between two Canadian provinces to evaluate the relative effects of spatial variation in habitat alteration and climate on white-tailed deer (Odocoileus virginianus) densities. White-tailed deer are an invading ungulate across much of North America, whose expansion into Canada's boreal forest is implicated in the decline of boreal caribou (Rangifer tarandus caribou), a species listed as Threatened in Canada. We estimated white-tailed deer densities using 300 remote cameras across 12 replicated 50 km2 landscapes over 5 years. White-tailed deer densities were significantly lower in areas where winter severity was higher. For example, predicted deer densities declined from 1.83 to 0.35 deer/km2 when winter severity increased from the lowest value to the median value. There was a tendency for densities to increase with increasing habitat alteration; however, the magnitude of this effect was approximately half that of climate. Our findings suggest that climate is the primary driver of white-tailed deer populations; however, understanding the mechanisms underpinning this relationship requires further study of over-winter survival and fecundity. Long-term monitoring at the invasion front is needed to evaluate the drivers of abundance over time, particularly given the unpredictability of climate change and increasing prevalence of extreme weather events.

The umbrella value of caribou management strategies for biodiversity conservation in boreal forests under global change

Single-species conservation management is often proposed to preserve biodiversity in human-disturbed landscapes. How global change will impact the umbrella value of single-species management strategies remains an open question of critical conservation importance. We assessed the effectiveness of threatened boreal caribou as an umbrella for bird and beetle conservation under global change. We combined mechanistic, spatially explicit models of forest dynamics and predator-prey interactions to forecast the impact of management strategies on the survival of boreal caribou in boreal forest. We then used predictive models of species occupancy to characterize concurrent impacts on bird and beetle diversity. Landscapes were simulated based on three scenarios of climate change and four of forest management. We found that strategies that best mitigate human impact on boreal caribou were an effective umbrella for maintaining bird and beetle assemblages. While we detected a stronger effect of land-use change compared to climate change, the umbrella value of management strategies for caribou habitat conservation were still impacted by the severity of climate change. Our results showed an interplay among changes in forest attributes, boreal caribou mortality, as well as bird and beetle species assemblages. The conservation status of some species mandates the development of recovery strategies, highlighting the importance of our study which shows that single-species conservation can have important umbrella benefits despite global change.

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

The contraction of species range is one of the most significant symptoms of biodiversity loss worldwide. While anthropogenic activities and habitat alteration are major threats for several species, climate change should also be considered. For species at risk, differentiating the effects of human disturbances and climate change on past and current range transformations is an important step towards improved conservation strategies. We paired historical range maps with global atmospheric reanalyses from different sources to assess the potential effects of recent climate change on the observed northward contraction of the range of boreal populations of woodland caribou (Rangifer tarandus caribou) in Quebec (Canada) since 1850. We quantified these effects by highlighting the discrepancies between different southern limits of the caribou's range (used as references) observed in the past and reconstitutions obtained through the hindcasting of the climate conditions within which caribou are currently found. Hindcasted southern limits moved ~105 km north over time under all reanalysis datasets, a trend drastically different from the ~620 km reported for observed southern limits since 1850. The differences in latitudinal shift through time between the observed and hindcasted southern limits of distribution suggest that caribou range recession should have been only 17% of what has been observed since 1850 if recent climate change had been the only disturbance driver. This relatively limited impact of climate reinforces the scientific consensus stating that caribou range recession in Quebec is mainly caused by anthropogenic drivers (i.e. logging, development of the road network, agriculture, urbanization) that have modified the structure and composition of the forest over the past 160 years, paving the way for habitat-mediated apparent competition and overharvesting. Our results also call for a reconsideration of past ranges in models aiming at projecting future distributions, especially for endangered species.

Genomic population structure and inbreeding history of Lake Superior caribou.

Caribou (Rangifer tarandus) have experienced dramatic declines in both range and population size across Canada over the past century. Boreal caribou (R. t. caribou), 1 of the 12 Designatable Units, has lost approximately half of its historic range in the last 150 years, particularly along the southern edge of its distribution. Despite this overall northward contraction, some populations have persisted at the trailing range edge, over 150 km south of the continuous boreal caribou range in Ontario, along the coast and nearshore islands of Lake Superior. The population history of caribou along Lake Superior remains unclear. It appears that these caribou likely represent a remnant distribution at the trailing edge of the receding population of boreal caribou, but they may also exhibit local adaptation to the coastal environment. A better understanding of the population structure and history of caribou along Lake Superior is important for their conservation and management. Here, we use high-coverage whole genomes (N = 20) from boreal, eastern migratory, and barren-ground caribou sampled in Manitoba, Ontario, and Quebec to investigate population structure and inbreeding histories. We discovered that caribou from the Lake Superior range form a distinct group but also found some evidence of gene flow with the continuous boreal caribou range. Notably, caribou along Lake Superior demonstrated relatively high levels of inbreeding (measured as runs of homozygosity; ROH) and genetic drift, which may contribute to the differentiation observed between ranges. Despite inbreeding, caribou along Lake Superior retained high heterozygosity, particularly in genomic regions without ROH. These results suggest that they present distinct genomic characteristics but also some level of gene flow with the continuous range. Our study provides key insights into the genomics of the southernmost range of caribou in Ontario, beginning to unravel the evolutionary history of these small, isolated caribou populations.

Incorporating mechanism into conservation actions in an age of multiple and emerging threats: The case of boreal caribou

AbstractConservation strategies for imperiled species are frequently based on identifying and addressing the probable causes of population decline, an approach known as the declining population paradigm. Causes, however, are frequently linked to demographic outcomes by multiple mechanisms, and failing to target the primary mechanisms can reduce the effectiveness and efficiency of conservation actions. Increasingly, conservation strategies also need to consider emerging threats, such as climate change. Here, we use boreal caribou (Rangifer tarandus caribou), a threatened ecotype of woodland caribou, as a case study to illustrate how landscape disturbance and climate change can each exert negative demographic effects on caribou through multiple and complex mechanisms. We reviewed the extensive literature focused on woodland caribou to identify and assess the relative importance of each putative mechanism. While disturbance‐mediated apparent competition, the expansion of novel predators, and altered predator behavior appear to be primary mechanisms dictating past and current declines of caribou, climate change has increasing potential to exert strong direct and indirect effects now and in the future. Predicted climate effects may prevent some populations from regaining self‐sustaining status, despite local conservation actions. Our review revealed several knowledge gaps, notably a lack of clarity on the spatial extent of undisturbed habitat required for caribou populations to be stable. We used outcomes from our review to demonstrate how a mechanistic understanding of population decline can inform habitat‐based conservation strategies for caribou. For populations residing within highly disturbed ranges, habitat restoration is a key recommendation of current conservation strategies, yet the large spatial extent of disturbances will require prioritization of areas for restoration. Maximizing the conservation return‐on‐investment for caribou will require a mechanistically informed prioritization process that targets conservation actions toward the primary mechanisms underlying population decline.

Climate-informed forecasts reveal dramatic local habitat shifts and population uncertainty for northern boreal caribou.

Most research on boreal populations of woodland caribou (Rangifer tarandus caribou) has been conducted in areas of high anthropogenic disturbance. However, a large portion of the species' range overlaps relatively pristine areas primarily affected by natural disturbances, such as wildfire. Climate-driven habitat change is a key concern for the conservation of boreal-dependent species, where management decisions have yet to consider knowledge from multiple ecological domains integrated into a cohesive and spatially explicit forecast of species-specific habitat and demography. We used a novel ecological forecasting framework to provide climate-sensitive projections of habitat and demography for five boreal caribou monitoring areas within the Northwest Territories (NWT), Canada, over 90 years. Importantly, we quantify uncertainty around forecasted mean values. Our results suggest habitat suitability may increase in central and southwest regions of the NWT's Taiga Plains ecozone but decrease in southern and northwestern regions driven by conversion of coniferous to deciduous forests. We do not project that boreal caribou population growth rates will change despite forecasted changes to habitat suitability. Our results emphasize the importance of efforts to protect and restore northern boreal caribou habitat despite climate uncertainty while highlighting expected spatial variations that are important considerations for local people who rely on them. An ability to reproduce previous work, and critical thought when incorporating sources of uncertainty, will be important to refine forecasts, derive management decisions, and improve conservation efficacy for northern species at risk.

Setting a foundation for Indigenous knowledge systems‐guided boreal caribou (tǫdzı) conservation planning in the Western Boreal Region of Canada: A systematic map protocol

Abstract In recent years, researchers have increasingly recognized the need to bridge Western and Indigenous knowledge systems to strengthen research in wildlife conservation. Historically, this arena has not made space for Indigenous knowledge holders to share components of their knowledge systems with agency and to support their own self‐determination as equal partners. Since time immemorial, Indigenous Peoples have been developing, maintaining and refining their own knowledge systems, based on intimate knowledge and relationships with the lands, airs, and waterways. There remains enormous potential for Western scientists to engage in equitable knowledge exchange and co‐production with Indigenous Peoples. This applies to species such as boreal caribou Rangifer tarandus caribou, known by the Dene name, tǫdzı; which hold ecological value and cultural importance for both Indigenous and non‐Indigenous people in the boreal region of Canada. To gain an overarching perspective of this species, we will create a systematic literature map that will examine peer‐reviewed and grey literature involving spatial mapping of all species of caribou Rangifer tarandus based on Indigenous knowledge. This map will (a) characterize available data and previously engaged knowledge holders and (b) identify positive experiences that exemplify best practices for knowledge co‐production. Searches will be conducted in English in selected databases. Search strings will be tested against a collection of benchmark papers of documents previously chosen to determine strings with maximum sensitivity and specificity. Results will be reviewed through the: (1) title and abstract; and (2) full text. All screening decisions will be recorded in a database, with 10% of full‐text screening decisions validated. Items retained for inclusion in the systematic map will be coded using a list of coding questions. Ten percent of coding outcomes will be validated by a second reviewer. The systematic map will employ a narrative synthesis approach that will compare retained studies against a list of best practices from the current proposal. It will examine case studies that performed well according to the list and contribute to a repository of previously documented Indigenous knowledge about caribou to support projects involving Indigenous and Western knowledge co‐production.

Widespread Exposure to Mosquitoborne California Serogroup Viruses in Caribou, Arctic Fox, Red Fox, and Polar Bears, Canada.

Northern Canada is warming at 3 times the global rate. Thus, changing diversity and distribution of vectors and pathogens is an increasing health concern. California serogroup (CSG) viruses are mosquitoborne arboviruses; wildlife reservoirs in northern ecosystems have not been identified. We detected CSG virus antibodies in 63% (95% CI 58%-67%) of caribou (n = 517), 4% (95% CI 2%-7%) of Arctic foxes (n = 297), 12% (95% CI 6%-21%) of red foxes (n = 77), and 28% (95% CI 24%-33%) of polar bears (n = 377). Sex, age, and summer temperatures were positively associated with polar bear exposure; location, year, and ecotype were associated with caribou exposure. Exposure was highest in boreal caribou and increased from baseline in polar bears after warmer summers. CSG virus exposure of wildlife is linked to climate change in northern Canada and sustained surveillance could be used to measure human health risks.

Science‐informed policy decisions lead to the creation of a protected area for a wide‐ranging species at risk

AbstractProtected areas are needed to conserve nature and biodiversity worldwide. The province of Québec (Canada) recently established a large wilderness area affording significant habitat protection for boreal woodland caribou (Rangifer tarandus caribou), a wide‐ranging species at risk. We describe a decision support framework combining ecological modeling with socioeconomic constraints that ultimately led to the creation of this protected area. Multiple criteria were used to identify candidate protected areas for boreal caribou. These had to be large in size (>10,000 km2) and located in regions where available high‐quality habitat was threatened by development pressures. Candidate areas also had to contribute substantively to the maintenance of functional habitat connectivity, be exempt from major industrial developments and recent fires, and required evidence of recent use by caribou. Five candidate protected areas emerged from this exercise. Key regional stakeholders were consulted, thereby strengthening advocacy for land designation, and boundaries were refined through their input, which helped further reduce socioeconomic conflicts. This process involved difficult compromises, but eventually led to the legal designation on March 4, 2021 of a new protected area for boreal caribou known as the Caribous‐Forestiers‐de‐Manouane‐Manicouagan. We show how our science‐informed decision support framework was instrumental in the success of this endeavor, and describe the obstacles overcame in the process, so that other jurisdictions may draw from this experience in their efforts to achieve similar conservation goals.

Nested population structure of threatened boreal caribou revealed by network analysis

Delineating relevant local populations of widely distributed species is a common challenge in conservation ecology. Caribou and reindeer (Rangifer tarandus) are in general decline throughout their global range, despite ongoing conservation efforts. In Canada, recovery actions for the threatened boreal population of woodland caribou (Rangifer tarandus caribou) are stratified by ‘local population units’ (LPUs) on ranges distributed across 2.4 × 10 km2 of the species’ geographic range. To estimate local population dynamics, LPUs are assumed to be geographically closed, though supporting evidence varies widely. We assembled an exceptionally large database of GPS telemetry locations (891,306 telemetry days, 1998–2020) from 1586 adult female caribou across the 19 northwesternmost LPUs. We generated a many-to-many Gaussian Bayesian Network to identify candidate local populations at range-level extents, as well as subpopulations, termed ‘communities’ in network analysis. We detected local population boundaries that in some cases were consistent with accepted LPUs and consistent with the assumption of geographic closure. In other cases, local population boundaries did not map well to currently delineated LPUs. Several communities at smaller spatial extents were consistent with expert and local knowledge of caribou movements and support recovery planning and actions “stepped down” from entire ranges. Evidence consistent with population fragmentation was confirmed along the southern and southwestern boundaries of the species’ geographic range within the study area, as were more continuous distributions confirmed to the north. We suggest that network analysis can help to inform conservation planning for boreal caribou and other wide-ranging species that would benefit from data-driven characterizations of multiscale population spatial structure.

There is still time to reconcile forest management with climate-driven declines in habitat suitability for boreal caribou

Many boreal populations of woodland caribou in Canada are declining, mainly due to the prevalence of anthropogenic disturbances which alter predator-prey dynamics. Climate change is expected to exert an additional negative influence on caribou populations in coming decades, but it is unclear whether or how human activities and climate change will interact to influence habitat suitability for caribou, and how important these agents of change will be relative to each other. In this study, we used the LANDIS-II forest landscape model to forecast boreal caribou habitat suitability across its distribution within the harvestable boreal forest in Québec for the period 2020–2100, under three increasing anthropogenic radiative forcing scenarios (baseline, Representative Concentration Pathways [RCP] 4.5 and 8.5), and two contrasting harvest scenarios (with and without harvest). Our simulations revealed that harvesting was the dominant agent explaining future variations in caribou habitat suitability, although climate change also decreased habitat suitability, especially under RCP 8.5. Climate-induced decreases in habitat suitability mostly originated from increases in wildfires that burned mature conifer-dominated forests, i.e., high-quality habitat for caribou. Habitat suitability by 2100 was also predicted to vary spatially, with the northeastern and northwestern parts of the study area supporting better caribou habitat conditions regardless of scenarios. We show that reducing harvest activities in areas where habitat suitability is currently high could help maintain high-quality caribou habitat even under the most intense climate change scenario. Our results also suggest that highly-disturbed regions which currently provide low-quality habitat may not improve in the future unless active habitat restoration is performed. Our study helps disentangle the potential future effects of forest management and climate change as threats to caribou habitat, emphasizing the urgency of reconciling forest management with the conservation of this species at risk in Canada.

Protecting boreal caribou habitat can help conserve biodiversity and safeguard large quantities of soil carbon in Canada

Boreal caribou require large areas of undisturbed habitat for persistence. They are listed as threatened with the risk of extinction in Canada because of landscape changes induced by human activities and resource extraction. Here we ask: Can the protection of habitat for boreal caribou help Canada meet its commitments under the United Nations Convention on Biological Diversity and United Nations Framework Convention on Climate Change? We identified hotspots of high conservation value within the distribution of boreal caribou based on: (1) three measures of biodiversity for at risk species (species richness, unique species and taxonomic diversity); (2) climate refugia or areas forecasted to remain unchanged under climate change; and, (3) areas of high soil carbon that could add to Canada’s greenhouse gas emissions if released into the atmosphere. We evaluated the overlap among hotspot types and how well hotspots were represented in Canada’s protected and conserved areas network. While hotspots are widely distributed across the boreal caribou distribution, with nearly 80% of the area falling within at least one hotspot type, only 3% of the distribution overlaps three or more hotspots. Moreover, the protected and conserved areas network only captures about 10% of all hotspots within the boreal caribou distribution. While the protected and conserved areas network adequately represents hotspots with high numbers of at risk species, areas occupied by unique species, as well as the full spectrum of areas occupied by different taxa, are underrepresented. Climate refugia and soil carbon hotspots also occur at lower percentages than expected. These findings illustrate the potential co-benefits of habitat protection for caribou to biodiversity and ecosystem services and suggest caribou may be a good proxy for future protected areas planning and for developing effective conservation strategies in regional assessments.

A cautionary tale comparing spatial count and partial identity models for estimating densities of threatened and unmarked populations

Population monitoring is critical to wildlife conservation, but density estimation is difficult for wide-ranging, unmarked species inhabiting remote habitats. Furthermore, recent investigations into density estimation with camera trap data has revealed unmarked models to be potentially unreliable, prompting cautious application and continued model development. Two related approaches with increasing appeal include spatial count (SC), which infer latent identities from the spatial pattern of detections, and spatial partial identity models (SPIM), which additionally leverage partial identity covariates (e.g., sex, antler point count, and presence of GPS/radio collar). To assess the performance of unmarked density models, we applied SC and SPIM to camera trap data of threatened boreal caribou in Canada, which are declining but have few rigorous density estimates across their broad distribution to inform conservation efforts. In particular, we focused on two spatially proximate caribou ranges in northern Alberta, Canada that differ in estimated caribou demographic trends, disturbance histories, and abundances of caribou predators and apparent competitors. Estimates of caribou density varied over a 4 year period (2016 – 2019), and were higher in the region with more stable reported growth rates and less anthropogenic disturbance (mode SPIM estimates: 155 – 225/1000 km 2 vs. 19 – 96/1000 km 2 ). However, density estimates differed by modeling approach and had low and variable precision, hindering inferences about population status and trajectories. Simulations suggest that SPIM estimates may have been less biased and more precise. SC models likely underestimated density by mistaking detections of neighboring individuals as recaptures of a single individual, although SPIM may also have overestimated density by inflating assignment probabilities of detections to non-existent individuals. Findings highlight the need to explore how grouping dynamics and non-independent movement violate assumptions and reduce the ability to distinguish individuals. We advocate continued investigation into the accuracy of unmarked density estimation approaches, the ecological and sampling conditions appropriate for different unmarked density models, and coordination across sampling efforts and analyses to improve population inferences.

End of the road: Short-term responses of a large mammal community to forest road decommissioning

Anthropogenic disturbances are increasing worldwide, causing wildlife habitat loss, alteration, and fragmentation. In Canada, the decommissioning of linear anthropogenic structures is identified as a promising tool to restore the habitat of threatened populations of boreal caribou (Rangifer tarandus caribou) by reducing food availability for alternate prey and decreasing encounter probabilities with predators. In this study, we monitored the use of 40 km of decommissioned forest roads by caribou, gray wolves (Canis lupus), black bears (Ursus americanus), and moose (Alces americanus) 1–3 years after reclamation, using 232 motion-activated camera traps. We compared four additive treatments (meaning that each successive treatment included the treatment prior): closing the road to human access, decompacting its soil, planting black spruce (Picea mariana) trees, and adding enriched soil. We assessed the influence of treatments, use by other large mammals, and characteristics of the surrounding environment on road use by the four species. Caribou used the planted treatment (which also included closing and decompacting) more than the closed-only (reference) treatment, but treatments did not influence the use of decommissioned roads by bears and moose. We could not assess the use of treated roads by wolves because of low sample size. Road use by caribou declined with local moose density, but increased with local bear density. Caribou were observed more frequently on roads surrounded by regenerating and mature coniferous stands; caribou also preferentially used roads surrounded by wetlands. Our results suggest that the treatment combining road closure, soil decompaction, and tree planting could be beneficial to caribou, highlighting the relevance of including active restoration efforts in caribou conservation programs. We recommend that such a treatment be added to road decommissioning protocols for the conservation of caribou, alongside broad-scale habitat protection.

Multi-objective optimization can balance trade-offs among boreal caribou, biodiversity, and climate change objectives when conservation hotspots do not overlap

The biodiversity and climate change crises have led countries—including Canada—to commit to protect more land and inland waters and to stabilize greenhouse gas concentrations. Canada is also obligated to recover populations of at-risk species, including boreal caribou. Canada has the opportunity to expand its protected areas network to protect hotspots of high value for biodiversity and climate mitigation. However, co-occurrence of hotspots is rare. Here we ask: is it possible to expand the network to simultaneously protect areas important for boreal caribou, other species at risk, climate refugia, and carbon stores? We used linear programming to prioritize areas for protection based on these conservation objectives, and assessed how prioritization for multiple, competing objectives affected the outcome for each individual objective. Our multi-objective approach produced reasonably strong representation of value across objectives. Although trade-offs were required, the multi-objective outcome was almost always better than when we ignored one objective to maximize value for another, highlighting the risk of assuming that a plan based on one objective will also result in strong outcomes for others. Multi-objective optimization approaches could be used to plan for protected areas networks that address biodiversity and climate change objectives, even when hotspots do not co-occur.

Lowering the rate of timber harvesting to mitigate impacts of climate change on boreal caribou habitat quality in eastern Canada

Many boreal populations of woodland caribou (Rangifer tarandus caribou) have declined in Canada, a trend essentially driven by the increasing footprint of anthropogenic disturbances and the resulting habitat-mediated apparent competition that increases predation pressure. However, the influence of climate change on these ecological processes remains poorly understood. We evaluated how climate change will affect boreal caribou habitat over the 2030–2100 horizon and in a 9.94 Mha study area, using a climate-sensitive simulation ensemble that integrates climate-induced changes in stand dynamics, fire regime, and different levels of commercial timber harvesting. We assessed the relative importance of these three drivers under projections made using different radiative forcing scenarios (RCP 2.6, 4.5, 8.5). Habitat quality was estimated from resource selection functions built with telemetry data collected from 121 caribou between 2004 and 2011 in 7 local populations. At the beginning of our simulations, caribou habitat was already structured along a south-to-north increasing quality gradient. Simulations revealed changes in forest cover that are driven by climate-induced variations in fire regime and scenarios of harvesting levels, resulting in the loss of older coniferous forests and an increase in deciduous stands. These changes induced a generalized decrease in the average habitat quality and in the percentage of high-quality habitat for caribou, and in a northward recession of suitable habitat. Timber harvesting was the most important agent of change for the 2030–2050 horizon, although it was slowly replaced by changes in fire regime until 2100. Our results clearly showed that it is possible to maintain the current average habitat quality for caribou in future scenarios that consider a reduction in harvested volumes, the only lever under our control. This suggests that we still have the capacity to conciliate socioeconomic development and caribou conservation imperatives in the face of climate change, an important issue debated throughout the species distribution range.

Stairway to heaven or highway to hell? How characteristics of forest roads shape their use by large mammals in the boreal forest

Decades of expansion of industrial resource extraction in boreal forests have resulted in the legacy of thousands of kilometers of linear features (seismic lines, forest roads) that have fragmented several wildlife habitats. The decommissioning of anthropogenic linear features and the restoration of suitable habitat are top priorities for the recovery of several species at risk, among which, the threatened populations of boreal caribou (Rangifer tarandus caribou). However, the decommissioning of linear features found in caribou range is expensive, and determining which characteristics make them more beneficial to caribou predators and competitors could assist in prioritizing those that may be most critical for boreal caribou habitat restoration. We thus aimed to determine how fine-scale forest road characteristics influence their use by gray wolf (Canis lupus), black bear (Ursus americanus), moose (Alces americanus) and caribou. We used camera traps and generalized linear mixed models to test the effect of road-scale characteristics on the use of forest roads by wolves, bears and moose while also considering larger-scale covariates. Wolves had a greater probability of using roads that were surrounded by wetlands and had a low lateral cover density. For bears, the intensity of use was lower on 20+ year-old roads when compared to 0–10-year-old roads, and higher on roads surrounded by coniferous stands. Moose intensity of use was higher on 11–20-year-old roads and lower on 30+ year-old roads, and decreased on roads surrounded by clearcuts and with a lower number of deciduous stems growing on them. We could not test for caribou use as we did not capture enough events. Nevertheless, by showing which forest roads are more used by caribou predators (wolves and bears) and its apparent competitor (moose), our study highlights the importance of considering both road-scale characteristics and the landscape context in which roads are built to prioritize the most detrimental roads to caribou conservation and guide efficient restoration efforts of its habitat.

The direct and habitat-mediated influence of climate on the biogeography of boreal caribou in Canada

Effective species conservation efforts require insight into whether a species’ extent of occurrence may shift due to changing climate, habitat loss, or both. The extent of occurrence of the threatened boreal population of woodland caribou (Rangifer tarandus caribou; caribou) has contracted due to environmental and anthropogenic disruption, with further contractions predicted as boreal habitat shifts with the changing climate. However, the direct and indirect climate drivers of caribou extent of occurrence have not been explicitly investigated. We estimated and compared the influence of climate and habitat drivers on the occurrence of caribou ranges across the Canadian boreal forest. We fit path models that estimated the direct effects of climate on caribou range occurrence and its indirect effect through climate's influence on caribou habitat (i.e., forest cover, presence of peatland, human disturbance and wildfire). Our analysis suggests that the distribution of caribou ranges is less sensitive to the direct effects of climate than to those of habitat and human disturbance. However, through its relationship to caribou habitat, climate exerts indirect influence over the distribution of caribou. As the climate changes, future distributions of caribou may be more heavily relegated to refuge habitats, particularly peatlands in the western boreal forest. Our biogeographical approach enables more informed decisions for large-scale caribou conservation efforts (e.g. establishment of protected areas, habitat restoration) that account for potential shifts in the distribution of caribou under changing environmental and climatic conditions.