Steeve Côté | Université Laval (original) (raw)

Papers by Steeve Côté

Annual Review of Ecology, Evolution, and Systematics, 2004

Key Words browsing, Cervidae, forest regeneration, herbivory, plant-herbivore interactions ■ Abst... more Key Words browsing, Cervidae, forest regeneration, herbivory, plant-herbivore interactions ■ Abstract Deer have expanded their range and increased dramatically in abundance worldwide in recent decades. They inflict major economic losses in forestry, agriculture, and transportation and contribute to the transmission of several animal and human diseases. Their impact on natural ecosystems is also dramatic but less quantified. By foraging selectively, deer affect the growth and survival of many herb, shrub, and tree species, modifying patterns of relative abundance and vegetation dynamics. Cascading effects on other species extend to insects, birds, and other mammals. In forests, sustained overbrowsing reduces plant cover and diversity, alters nutrient and carbon cycling, and redirects succession to shift future overstory composition. Many of these simplified alternative states appear to be stable and difficult to reverse. Given the influence of deer on other organisms and natural processes, ecologists should actively participate in efforts to understand, monitor, and reduce the impact of deer on ecosystems.

Canadian Journal of Zoology

Processes of habitat selection occur at multiple spatiotemporal scales, where large-scale selecti... more Processes of habitat selection occur at multiple spatiotemporal scales, where large-scale selection is often determined by predation risk and landscape features, and finer scale selection by resource abundance and quality. To determine whether this hierarchy exists in relatively homogenous systems, we investigated patterns of habitat (landscape topography) and resource (feeding patch and plant group) selection by a medium-sized ungulate, the Tibetan argali (Ovis ammon hodgsoni Blyth, 1840), in the high-altitude rangelands of the Indian Trans-Himalaya. We ran ecological niche factor analyses to explore habitat selection, bias-reduced logistic regression to analyze the selection of feeding patches, fuzzy correspondence analysis for vegetation categories, and microhistological analyses for the selection of plant groups. For springs and summers of 2005–2007, argali preferred an intermediate range of altitude, slope, and forage abundance. Selection of feeding patch was mainly determined by forage quality, not biomass, selecting graminoids and forbs, in particular. The avoidance of habitat with high forage abundance could indicate a trade-off between forage quality and quantity; a pattern consistent at the feeding-patch scale. Our results provide evidence that the hierarchical pattern of habitat selection probably also occurs in relatively homogeneous systems.

Behavioral Ecology, Jan 1, 2010

Sexual segregation, a widely observed phenomenon in vertebrates, is commonly categorized into hab... more Sexual segregation, a widely observed phenomenon in vertebrates, is commonly categorized into habitat and social segregation. A universal explanation for sexual segregation is, however, lacking and debated. Causes of segregation and their division into proximate and ultimate causes is also highly debated, and the relative contributions of habitat and social factors to segregation are also seldom quantified. We studied the Eurasian wild sheep in trans-Himalayan rangelands to identify these causes and estimate the contributions of habitat and social components to sexual segregation. We observed male, lactating, and nonlactating female groups feeding during 3 springs and summers. The 3 groups strongly segregated and differed in their activity budgets, partly because of antipredation risks, with lactating females being the most vigilant (40% of the time). At the feeding habitat scale, males selected the patches of highest quality. We found that the social component contributed the most to segregation (70%) as compared with habitat segregation (30%). This is the first study that quantifies the contribution of habitat and social components to sexual segregation. We emphasize the role of antipredator behavior of lactating females on activity budgets and selection of relatively poor-quality sites as compared with other groups and illustrate that the usual division into proximal and ultimate causes of sexual segregation is not as clear-cut as usually presented.

Global warming threatens to reduce population connectivity for terrestrial wildlife through signi... more Global warming threatens to reduce population connectivity for terrestrial wildlife through significant and rapid changes to sea ice. Using genetic fingerprinting, we contrasted extant connectivity in island-dwelling Peary caribou in northern Canada with continental-migratory caribou. We next examined if sea-ice contractions in the last decades modulated population connectivity and explored the possible impact of future climate change on long-term connectivity among island caribou. We found a strong correlation between genetic and geodesic distances for both continental and Peary car-ibou, even after accounting for the possible effect of sea surface. Sea ice has thus been an effective corridor for Peary caribou, promoting inter-island connectivity and population mixing. Using a time series of remote sensing sea-ice data, we show that landscape resistance in the Canadian Arctic Archipelago has increased by approximately 15% since 1979 and may further increase by 20 –77% by 2086 under a high-emission scenario (RCP8.5). Under the persistent increase in greenhouse gas concentrations, reduced connectivity may isolate island-dwelling caribou with potentially significant consequences for population viability.

Biological Conservation, 2006

Herbivory Vegetation change

Ecological Indicators, 2014

ABSTRACT Indicator species have been used successfully for estimating ecosystem integrity, but co... more ABSTRACT Indicator species have been used successfully for estimating ecosystem integrity, but comparative studies for defining optimal taxonomic group remain scarce. Furthermore, species combinations may constitute more integrative tools than single species indicators, but case studies are needed to test their efficiency. We used Indicator Species Analysis, which statistically determines the association of species to one or several groups of sites, to obtain indicators of ecosystem recovery after various deer density reductions. We used five taxonomic groups: plants, carabid beetles, bees, moths and songbirds. To test whether species combinations could complement single indicator species, we used plants as a model taxon and examined the indicator value of joint occurrence of two or three plant species. Our study relies on experimental controlled browsing enclosures established for six years on Anticosti Island (Quebec). Four levels of deer density (0, 7.5 and 15 deer km−2 and natural densities between 27 and 56 deer km−2) were studied in two vegetation cover types (uncut forests and cut-over areas), in a full factorial design for a total of eight experimental treatments. For all taxa but bees, we tested 54 treatment groups consisting in one specific density or in a sequence of two or more consecutive deer densities in one or both cover types (ten groups for bees, sampled only in cut-over areas). We found 12 plants, 11 moths and one songbird to be single species indicators of ecosystem conditions obtained under 12 different treatment groups. Six treatment groups were indicated by plants and six different ones by moths, of which one group was also identified by a songbird species. Moths were thus worth the extra sampling effort, especially since the groups they indicated were more treatment-specific (mainly one or two deer density treatments). We tested the same 54 treatment groups for plant species combinations represented by two or three co-occurring species. Plant combinations efficiently complemented plant singletons for detecting ecosystem conditions obtained under various deer densities. In fact, although singletons were highly predictive, 17 additional treatment groups were identified exclusively with two- and three-species combinations, some being more treatment-specific. Our findings show that plants and moths provide complementary indicators of ecosystem conditions under various deer densities, and that computing species combinations increases our capacity to monitor ecosystem recovery after reducing herbivore densities.

Canadian Journal of Zoology, 2010

Processes of habitat selection occur at multiple spatiotemporal scales, where large-scale selecti... more Processes of habitat selection occur at multiple spatiotemporal scales, where large-scale selection is often determined by predation risk and landscape features, and finer scale selection by resource abundance and quality. To determine whether this hierarchy exists in relatively homogenous systems, we investigated patterns of habitat (landscape topography) and resource (feeding patch and plant group) selection by a medium-sized ungulate, the Tibetan argali (Ovis ammon hodgsoni Blyth, 1840), in the high-altitude rangelands of the Indian Trans-Himalaya. We ran ecological niche factor analyses to explore habitat selection, bias-reduced logistic regression to analyze the selection of feeding patches, fuzzy correspondence analysis for vegetation categories, and microhistological analyses for the selection of plant groups. For springs and summers of 2005-2007, argali preferred an intermediate range of altitude, slope, and forage abundance. Selection of feeding patch was mainly determined by forage quality, not biomass, selecting graminoids and forbs, in particular. The avoidance of habitat with high forage abundance could indicate a trade-off between forage quality and quantity; a pattern consistent at the feeding-patch scale. Our results provide evidence that the hierarchical pattern of habitat selection probably also occurs in relatively homogeneous systems.

Sport hunting may help in controlling cervid populations over large areas. As with natural predat... more Sport hunting may help in controlling cervid populations over large areas. As with natural predators, several environmental factors can influence sport harvest. A better understanding of the environmental variables that limit the efficiency of sport hunting could provide guidelines for more efficient wildlife management using hunting. We studied white-tailed deer (Odocoileus virginianus) hunting on a high deer density island where hunting was the sole form of predation. Our objective was to study the behavior of sport hunters and determine the habitat characteristics (e.g., abundance of deer forage, visibility of the deer from the hunter's point of view, and accessibility of the territory to hunters) that are associated with a successful harvest. We collected movements and harvest site location data from 477 hunters equipped with handheld Global Positioning System (GPS) units. Harvest sites were visited and characterized, along with a paired random site, to determine the environmental conditions associated with a successful hunt. We also developed a model to predict the daily number of deer seen by hunters considering weather conditions, hunter characteristics (e.g., age, experience), and date of hunting. We used the mean number of deer seen per hunter per day as a relative index of local density in each hunted territory. At both the site and landscape scales, the combination of visibility and access had a positive effect on the distribution of harvested deer. Habitat types with less visual obstruction from vegetation enabled hunters to see more deer in a given day. At the site scale, harvested deer were located in areas with a lower density of access routes compared to areas where hunters travelled throughout the day. Using an innovative approach of studying hunter behavior with GPS technology, digital maps, and questionnaires, we highlighted the factors associated with hunter success. Our study suggests that habitat characteristics could be modified to increase harvest by improving accessibility and visibility near roads. Creating openings in mature and regenerating forest near access roads could make sport hunting a more efficient management tool, but the potential impact of increased forage availability in forest openings should not be overlooked. ß 2012 The Wildlife Society.

Journal of Wildlife Diseases, 2013

Besnoitia tarandi has been documented in free-ranging reindeer and caribou (Rangifer tarandus spp... more Besnoitia tarandi has been documented in free-ranging reindeer and caribou (Rangifer tarandus spp.) since 1922 throughout their arctic and subarctic ranges; however, very little is known about its epidemiology. We evaluated variables associated with B. tarandi prevalence and cyst density with the use of barren-ground caribou (Rangifer tarandus) from two migratory herds in northern Quebec: the Riviè re-aux-Feuilles and the Riviè re-George herds. Diagnosis of infection was made upon the microscopic observation of characteristic cysts in a formalin-fixed section of skin from the anterior aspect of the metatarsus. The density of cysts (number of B. tarandi cysts/mm 2 ) was calculated in a section of the dermis extending from the epidermis of the skin to the base of the hair follicles and adnexal structures. Statistically significant associations between B. tarandi prevalence and cyst density, sex, age, and time of harvest were observed. Male caribou had a slightly higher prevalence compared to females, whereas cyst densities were similar between sexes. We found a nonlinear increase in the odds of infection by B. tarandi by age combined with the opposite trend for intensity of infection. Higher B. tarandi prevalence was observed in caribou sampled in the fall compared to June of the same year, suggesting that transmission is increased during the summer. Higher densities of cysts observed during the fall compared to June of the following year may be the result of the elimination of B. tarandi cysts from the dermis during the winter, or lower winter survival of heavily infected caribou. Comparisons of B. tarandi prevalence and density across herds should take into account these different variables.

Naturaliste canadien, 2007

Résumé Le broutement sélectif par les cervidés contribue à moduler la composition et les processu... more Résumé Le broutement sélectif par les cervidés contribue à moduler la composition et les processus écologiques au sein des écosystèmes forestiers, mais à forte densité il peut sérieusement en compromettre la régénération. L'impact de la population de cerfs de Virginie introduite à ...

Deer have expanded their range and increased dramatically in abundance worldwide in recent decade... more Deer have expanded their range and increased dramatically in abundance worldwide in recent decades. They inflict major economic losses in forestry, agriculture, and transportation and contribute to the transmission of several animal and human diseases. Their impact on natural ecosystems is also dramatic but less quantified. By foraging selectively, deer affect the growth and survival of many herb, shrub, and

and sharing with colleagues.

Canadian Journal of Forest Research, 2015

Overabundant populations of large herbivores have strong persistent effects on forest composition... more Overabundant populations of large herbivores have strong persistent effects on forest composition, structure, and function. However, the mechanism through which plant communities recover their original composition and function after herbivore management remains poorly understood. We assessed the temporal trajectories of the herbaceous communities in Abies balsamea (L.) Mill. and Picea glauca (Moench) Voss stands on Anticosti Island (Quebec, Canada) over 8 years following clear-cutting and deer management. The impact of deer exclusion or reduction to 7.5 and 15 deer·km -2 was compared with benchmark in situ deer densities (27 and 56 deer·km -2 ). Effects of deer management treatments on plant species and functional trait assemblages over time were assessed using principal response curves. Although complete deer exclusion seemed necessary to modify species composition from that occurring under intense browsing, a reduced density of 7.5 deer·km -2 was sufficient to induce significant changes in functional trait assemblages of regenerating stands. For instance, reduced deer densities favored plants with brightly colored flowers and compound inflorescences pollinated by animals and producing large seeds and fleshy fruits dispersed by animals. We conclude that the boreal forest's herbaceous communities are resilient to chronic browsing when deer population reduction and forest clearcutting are applied in synergy.

PLoS ONE, 2012

Heterogeneity in foraging behaviour can profoundly influence ecological processes shaping populat... more Heterogeneity in foraging behaviour can profoundly influence ecological processes shaping populations. To scale-up from individual foraging behaviour to processes occurring at the population scale, one needs to sample foraging behaviour at the individual level, and over large temporal scales or during critical seasons known to influence life-history traits. We developed an innovative technique to monitor foraging behaviour at the individual level in secretive species, a technique that can be ultimately used to investigate the links between foraging behaviour and life-history traits. First, the technique used a novel approach, namely the combination of telemetry tracking and biomarking of faeces with food dyes to locate fresh signs of presence left by individuals equipped with GPS collars. Second, the technique is based on the simultaneous or successive sampling of life-history traits and individual foraging behaviour, using tracks with high probabilities of recovery of dyed faeces. We first describe our methodological approach, using a case study of a large herbivore, and then provide recommendations and guidelines for its use. Sampling single snow tracks of individuals equipped with a GPS collar was a reliable way to assess individual winter foraging behaviour in a white-tailed deer (Odocoileus virginianus Zimmermann) population. During that period, the probability of recovery of dyed faeces within the range of the collar precision was very high for single snow tracks of equipped deer (97%). Our approach is well suited to study individual foraging behaviour, and could ultimately be used to investigate the interplay between intra-population heterogeneity in foraging behaviour, lifehistory traits, and demographic processes.

Annual Review of Ecology, Evolution, and Systematics, 2004

Key Words browsing, Cervidae, forest regeneration, herbivory, plant-herbivore interactions ■ Abst... more Key Words browsing, Cervidae, forest regeneration, herbivory, plant-herbivore interactions ■ Abstract Deer have expanded their range and increased dramatically in abundance worldwide in recent decades. They inflict major economic losses in forestry, agriculture, and transportation and contribute to the transmission of several animal and human diseases. Their impact on natural ecosystems is also dramatic but less quantified. By foraging selectively, deer affect the growth and survival of many herb, shrub, and tree species, modifying patterns of relative abundance and vegetation dynamics. Cascading effects on other species extend to insects, birds, and other mammals. In forests, sustained overbrowsing reduces plant cover and diversity, alters nutrient and carbon cycling, and redirects succession to shift future overstory composition. Many of these simplified alternative states appear to be stable and difficult to reverse. Given the influence of deer on other organisms and natural processes, ecologists should actively participate in efforts to understand, monitor, and reduce the impact of deer on ecosystems.

Canadian Journal of Zoology

Processes of habitat selection occur at multiple spatiotemporal scales, where large-scale selecti... more Processes of habitat selection occur at multiple spatiotemporal scales, where large-scale selection is often determined by predation risk and landscape features, and finer scale selection by resource abundance and quality. To determine whether this hierarchy exists in relatively homogenous systems, we investigated patterns of habitat (landscape topography) and resource (feeding patch and plant group) selection by a medium-sized ungulate, the Tibetan argali (Ovis ammon hodgsoni Blyth, 1840), in the high-altitude rangelands of the Indian Trans-Himalaya. We ran ecological niche factor analyses to explore habitat selection, bias-reduced logistic regression to analyze the selection of feeding patches, fuzzy correspondence analysis for vegetation categories, and microhistological analyses for the selection of plant groups. For springs and summers of 2005–2007, argali preferred an intermediate range of altitude, slope, and forage abundance. Selection of feeding patch was mainly determined by forage quality, not biomass, selecting graminoids and forbs, in particular. The avoidance of habitat with high forage abundance could indicate a trade-off between forage quality and quantity; a pattern consistent at the feeding-patch scale. Our results provide evidence that the hierarchical pattern of habitat selection probably also occurs in relatively homogeneous systems.

Behavioral Ecology, Jan 1, 2010

Sexual segregation, a widely observed phenomenon in vertebrates, is commonly categorized into hab... more Sexual segregation, a widely observed phenomenon in vertebrates, is commonly categorized into habitat and social segregation. A universal explanation for sexual segregation is, however, lacking and debated. Causes of segregation and their division into proximate and ultimate causes is also highly debated, and the relative contributions of habitat and social factors to segregation are also seldom quantified. We studied the Eurasian wild sheep in trans-Himalayan rangelands to identify these causes and estimate the contributions of habitat and social components to sexual segregation. We observed male, lactating, and nonlactating female groups feeding during 3 springs and summers. The 3 groups strongly segregated and differed in their activity budgets, partly because of antipredation risks, with lactating females being the most vigilant (40% of the time). At the feeding habitat scale, males selected the patches of highest quality. We found that the social component contributed the most to segregation (70%) as compared with habitat segregation (30%). This is the first study that quantifies the contribution of habitat and social components to sexual segregation. We emphasize the role of antipredator behavior of lactating females on activity budgets and selection of relatively poor-quality sites as compared with other groups and illustrate that the usual division into proximal and ultimate causes of sexual segregation is not as clear-cut as usually presented.

Global warming threatens to reduce population connectivity for terrestrial wildlife through signi... more Global warming threatens to reduce population connectivity for terrestrial wildlife through significant and rapid changes to sea ice. Using genetic fingerprinting, we contrasted extant connectivity in island-dwelling Peary caribou in northern Canada with continental-migratory caribou. We next examined if sea-ice contractions in the last decades modulated population connectivity and explored the possible impact of future climate change on long-term connectivity among island caribou. We found a strong correlation between genetic and geodesic distances for both continental and Peary car-ibou, even after accounting for the possible effect of sea surface. Sea ice has thus been an effective corridor for Peary caribou, promoting inter-island connectivity and population mixing. Using a time series of remote sensing sea-ice data, we show that landscape resistance in the Canadian Arctic Archipelago has increased by approximately 15% since 1979 and may further increase by 20 –77% by 2086 under a high-emission scenario (RCP8.5). Under the persistent increase in greenhouse gas concentrations, reduced connectivity may isolate island-dwelling caribou with potentially significant consequences for population viability.

Biological Conservation, 2006

Herbivory Vegetation change

Ecological Indicators, 2014

ABSTRACT Indicator species have been used successfully for estimating ecosystem integrity, but co... more ABSTRACT Indicator species have been used successfully for estimating ecosystem integrity, but comparative studies for defining optimal taxonomic group remain scarce. Furthermore, species combinations may constitute more integrative tools than single species indicators, but case studies are needed to test their efficiency. We used Indicator Species Analysis, which statistically determines the association of species to one or several groups of sites, to obtain indicators of ecosystem recovery after various deer density reductions. We used five taxonomic groups: plants, carabid beetles, bees, moths and songbirds. To test whether species combinations could complement single indicator species, we used plants as a model taxon and examined the indicator value of joint occurrence of two or three plant species. Our study relies on experimental controlled browsing enclosures established for six years on Anticosti Island (Quebec). Four levels of deer density (0, 7.5 and 15 deer km−2 and natural densities between 27 and 56 deer km−2) were studied in two vegetation cover types (uncut forests and cut-over areas), in a full factorial design for a total of eight experimental treatments. For all taxa but bees, we tested 54 treatment groups consisting in one specific density or in a sequence of two or more consecutive deer densities in one or both cover types (ten groups for bees, sampled only in cut-over areas). We found 12 plants, 11 moths and one songbird to be single species indicators of ecosystem conditions obtained under 12 different treatment groups. Six treatment groups were indicated by plants and six different ones by moths, of which one group was also identified by a songbird species. Moths were thus worth the extra sampling effort, especially since the groups they indicated were more treatment-specific (mainly one or two deer density treatments). We tested the same 54 treatment groups for plant species combinations represented by two or three co-occurring species. Plant combinations efficiently complemented plant singletons for detecting ecosystem conditions obtained under various deer densities. In fact, although singletons were highly predictive, 17 additional treatment groups were identified exclusively with two- and three-species combinations, some being more treatment-specific. Our findings show that plants and moths provide complementary indicators of ecosystem conditions under various deer densities, and that computing species combinations increases our capacity to monitor ecosystem recovery after reducing herbivore densities.

Canadian Journal of Zoology, 2010

Processes of habitat selection occur at multiple spatiotemporal scales, where large-scale selecti... more Processes of habitat selection occur at multiple spatiotemporal scales, where large-scale selection is often determined by predation risk and landscape features, and finer scale selection by resource abundance and quality. To determine whether this hierarchy exists in relatively homogenous systems, we investigated patterns of habitat (landscape topography) and resource (feeding patch and plant group) selection by a medium-sized ungulate, the Tibetan argali (Ovis ammon hodgsoni Blyth, 1840), in the high-altitude rangelands of the Indian Trans-Himalaya. We ran ecological niche factor analyses to explore habitat selection, bias-reduced logistic regression to analyze the selection of feeding patches, fuzzy correspondence analysis for vegetation categories, and microhistological analyses for the selection of plant groups. For springs and summers of 2005-2007, argali preferred an intermediate range of altitude, slope, and forage abundance. Selection of feeding patch was mainly determined by forage quality, not biomass, selecting graminoids and forbs, in particular. The avoidance of habitat with high forage abundance could indicate a trade-off between forage quality and quantity; a pattern consistent at the feeding-patch scale. Our results provide evidence that the hierarchical pattern of habitat selection probably also occurs in relatively homogeneous systems.

Sport hunting may help in controlling cervid populations over large areas. As with natural predat... more Sport hunting may help in controlling cervid populations over large areas. As with natural predators, several environmental factors can influence sport harvest. A better understanding of the environmental variables that limit the efficiency of sport hunting could provide guidelines for more efficient wildlife management using hunting. We studied white-tailed deer (Odocoileus virginianus) hunting on a high deer density island where hunting was the sole form of predation. Our objective was to study the behavior of sport hunters and determine the habitat characteristics (e.g., abundance of deer forage, visibility of the deer from the hunter's point of view, and accessibility of the territory to hunters) that are associated with a successful harvest. We collected movements and harvest site location data from 477 hunters equipped with handheld Global Positioning System (GPS) units. Harvest sites were visited and characterized, along with a paired random site, to determine the environmental conditions associated with a successful hunt. We also developed a model to predict the daily number of deer seen by hunters considering weather conditions, hunter characteristics (e.g., age, experience), and date of hunting. We used the mean number of deer seen per hunter per day as a relative index of local density in each hunted territory. At both the site and landscape scales, the combination of visibility and access had a positive effect on the distribution of harvested deer. Habitat types with less visual obstruction from vegetation enabled hunters to see more deer in a given day. At the site scale, harvested deer were located in areas with a lower density of access routes compared to areas where hunters travelled throughout the day. Using an innovative approach of studying hunter behavior with GPS technology, digital maps, and questionnaires, we highlighted the factors associated with hunter success. Our study suggests that habitat characteristics could be modified to increase harvest by improving accessibility and visibility near roads. Creating openings in mature and regenerating forest near access roads could make sport hunting a more efficient management tool, but the potential impact of increased forage availability in forest openings should not be overlooked. ß 2012 The Wildlife Society.

Journal of Wildlife Diseases, 2013

Besnoitia tarandi has been documented in free-ranging reindeer and caribou (Rangifer tarandus spp... more Besnoitia tarandi has been documented in free-ranging reindeer and caribou (Rangifer tarandus spp.) since 1922 throughout their arctic and subarctic ranges; however, very little is known about its epidemiology. We evaluated variables associated with B. tarandi prevalence and cyst density with the use of barren-ground caribou (Rangifer tarandus) from two migratory herds in northern Quebec: the Riviè re-aux-Feuilles and the Riviè re-George herds. Diagnosis of infection was made upon the microscopic observation of characteristic cysts in a formalin-fixed section of skin from the anterior aspect of the metatarsus. The density of cysts (number of B. tarandi cysts/mm 2 ) was calculated in a section of the dermis extending from the epidermis of the skin to the base of the hair follicles and adnexal structures. Statistically significant associations between B. tarandi prevalence and cyst density, sex, age, and time of harvest were observed. Male caribou had a slightly higher prevalence compared to females, whereas cyst densities were similar between sexes. We found a nonlinear increase in the odds of infection by B. tarandi by age combined with the opposite trend for intensity of infection. Higher B. tarandi prevalence was observed in caribou sampled in the fall compared to June of the same year, suggesting that transmission is increased during the summer. Higher densities of cysts observed during the fall compared to June of the following year may be the result of the elimination of B. tarandi cysts from the dermis during the winter, or lower winter survival of heavily infected caribou. Comparisons of B. tarandi prevalence and density across herds should take into account these different variables.

Naturaliste canadien, 2007

Résumé Le broutement sélectif par les cervidés contribue à moduler la composition et les processu... more Résumé Le broutement sélectif par les cervidés contribue à moduler la composition et les processus écologiques au sein des écosystèmes forestiers, mais à forte densité il peut sérieusement en compromettre la régénération. L'impact de la population de cerfs de Virginie introduite à ...

Deer have expanded their range and increased dramatically in abundance worldwide in recent decade... more Deer have expanded their range and increased dramatically in abundance worldwide in recent decades. They inflict major economic losses in forestry, agriculture, and transportation and contribute to the transmission of several animal and human diseases. Their impact on natural ecosystems is also dramatic but less quantified. By foraging selectively, deer affect the growth and survival of many herb, shrub, and

and sharing with colleagues.

Canadian Journal of Forest Research, 2015

Overabundant populations of large herbivores have strong persistent effects on forest composition... more Overabundant populations of large herbivores have strong persistent effects on forest composition, structure, and function. However, the mechanism through which plant communities recover their original composition and function after herbivore management remains poorly understood. We assessed the temporal trajectories of the herbaceous communities in Abies balsamea (L.) Mill. and Picea glauca (Moench) Voss stands on Anticosti Island (Quebec, Canada) over 8 years following clear-cutting and deer management. The impact of deer exclusion or reduction to 7.5 and 15 deer·km -2 was compared with benchmark in situ deer densities (27 and 56 deer·km -2 ). Effects of deer management treatments on plant species and functional trait assemblages over time were assessed using principal response curves. Although complete deer exclusion seemed necessary to modify species composition from that occurring under intense browsing, a reduced density of 7.5 deer·km -2 was sufficient to induce significant changes in functional trait assemblages of regenerating stands. For instance, reduced deer densities favored plants with brightly colored flowers and compound inflorescences pollinated by animals and producing large seeds and fleshy fruits dispersed by animals. We conclude that the boreal forest's herbaceous communities are resilient to chronic browsing when deer population reduction and forest clearcutting are applied in synergy.

PLoS ONE, 2012

Heterogeneity in foraging behaviour can profoundly influence ecological processes shaping populat... more Heterogeneity in foraging behaviour can profoundly influence ecological processes shaping populations. To scale-up from individual foraging behaviour to processes occurring at the population scale, one needs to sample foraging behaviour at the individual level, and over large temporal scales or during critical seasons known to influence life-history traits. We developed an innovative technique to monitor foraging behaviour at the individual level in secretive species, a technique that can be ultimately used to investigate the links between foraging behaviour and life-history traits. First, the technique used a novel approach, namely the combination of telemetry tracking and biomarking of faeces with food dyes to locate fresh signs of presence left by individuals equipped with GPS collars. Second, the technique is based on the simultaneous or successive sampling of life-history traits and individual foraging behaviour, using tracks with high probabilities of recovery of dyed faeces. We first describe our methodological approach, using a case study of a large herbivore, and then provide recommendations and guidelines for its use. Sampling single snow tracks of individuals equipped with a GPS collar was a reliable way to assess individual winter foraging behaviour in a white-tailed deer (Odocoileus virginianus Zimmermann) population. During that period, the probability of recovery of dyed faeces within the range of the collar precision was very high for single snow tracks of equipped deer (97%). Our approach is well suited to study individual foraging behaviour, and could ultimately be used to investigate the interplay between intra-population heterogeneity in foraging behaviour, lifehistory traits, and demographic processes.