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Côté, Steeve D.

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Steeve D.

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Université Laval. Département de biologie

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  • PublicationAccès libre
    An experimental study of how variation in deer density affects vegetation and songbird assemblages of recently harvested boreal forests
    (National Research Council, 2012-05-11) Tremblay, Jean-Pierre; Cardinal, Étienne; Côté, Steeve D.; Martin, Jean-Louis
    Intense browsing by abundant large herbivores can threaten the ecological integrity of ecosystems by inducing modifications in the structure and composition of vegetation that trigger trophic cascades affecting plant and animal communities. We investigated the relationships between density of white-tailed deer (Odocoileus virginianus (Zimmermann, 1780)), forest succession after clear-cut, and songbird communities on Anticosti Island, Quebec, Canada. We hypothesized that lower deer densities would alter the trajectory of forest succession after clear-cutting and lead to a rapid recovery of habitat attributes favorable to songbirds associated with a dense complex shrub layer. Six years after establishing a controlled browsing experiment (0, 7.5, 15, and >27 deer·km–2) in recent clearcuts, reducing deer densities ≤7.5 deer·km–2 initiated the restoration of balsam fir (Abies balsamea (L.) Mill.) forests and increased the regeneration of paper birch (Betula papyrifera Marshall). Increasing birch ground cover from 10% to 20% increased songbird total abundance, species richness, and diversity by 17%, 39%, and 31%, respectively. Alder Flycatcher (Empidonax alnorum Brewster, 1895) was only present at ≤7.5 deer·km–2 and strongly associated with birch regeneration. The regeneration of browse-resistant plants such as white spruce (Picea glauca (Moench) Voss) in some areas at high deer density favored the maintenance of many shrub-dependent songbirds but also species usually associated with forest canopy. Active management of deer populations in Canadian harvested boreal forests will mitigate losses in vegetation and songbirds caused by over-browsing.
  • PublicationAccès libre
    Linking alternative food sources to winter habitat selection of herbivores in overbrowsed landscapes
    (Bioone, 2011-12-07) Massé, Ariane; Côté, Steeve D.
    During winter, ungulates in boreal forests must cope with high energetic costs related to locomotion in deep snow and reduced forage abundance and quality. At high density, ungulates face additional constraints, because heavy browsing reduces availability of woody browse, the main source of forage during winter. Under these severe conditions, large herbivores might forage on alternative food sources likely independent of browsing pressure, such as litterfall or windblown trees. We investigated the influence of alternative food sources on winter habitat selection, by studying female white-tailed deer (Odocoileus virginianus) living in 2 landscapes with contrasted browse abundance, recently logged and regenerated landscapes, in a population at high density and on a large island free of predators. We fitted 21 female white-tailed deer with Global Positioning System (GPS) collars and delineated winter home ranges and core areas. We measured snow conditions in different habitat categories and sampled vegetation in the core areas and in the rest of the home ranges to determine how forage abundance, protective cover, and snow conditions influenced habitat selection within the home range. In both landscapes, deer were less likely to use open habitat categories as snow accumulated on the ground. At a finer scale, deer inhabiting the regenerated landscape intensively used areas where balsam fir cover was intermediate with greater balsam fir browse density than in the rest of the home range. In the recently logged landscape, deer were more likely to be found near edges between clear-cuts and balsam fir stands and in areas where windblown balsam fir trees were present; the latter being the most influential variable. Although balsam fir browse was sparse and mainly out of reach in this landscape, deer increased the use of areas where it was present. Our results offer novel insights into the resource selection processes of northern ungulates, as we showed that access to winter forage, such as woody browse and alternative food sources, depends on climatic conditions and stochastic events, such as abundant compacted snow or windthrows. To compensate for these scarce and unpredictable food supplies, deer selected habitat categories, but mostly areas within those habitat categories, where the likelihood of finding browse, litterfall, and windblown trees was greatest.
  • PublicationRestreint
    Conservative maternal care in an iteroparous mammal : a resource allocation experiment
    (Heidelberg, 2007-08-08) Therrien, Jean-François; Festa-Bianchet, Marco; Côté, Steeve D.; Ouellet, Jean-Pierre
    When resources are limited, life history theory predicts a trade-off between growth, reproduction and survival. In summer, lactating females of temperate large herbivores such as the white-tailed deer (Odocoileus virginianus) normally have access to abundant forage but also face the high energetic needs of lactation and recovery from winter mass loss. At high population density, however, females may face a trade-off between allocating resources for maintenance and for reproduction. To simulate the effects of increased intra-specific competition at high density, we measured for 2 years how an experimental food restriction of approximately 20% affected current reproduction and body mass changes of adult females and their fawns during the fawning and lactation periods. Fawn survival decreased 35%, and fawn growth decreased 26% in the food-restricted treatment. There was no effect of food restriction on female mass. Irrespective of treatment, however, lactating females gained 30 g/day less than non-lactating females, and females that had weaned a fawn the previous year gained 20 g/day less than females that had not. We conclude that when resources were scarce, females adopted a conservative strategy favouring their own survival, mass recovery and future reproductive potential over their current reproduction, probably to maximise their lifetime reproductive success.
  • PublicationRestreint
    Influence of forage biomass and cover on deer space use at a fine scale : a controlled-density experiment
    (Taylor & Francis Group, 2015-12-03) Coulombe, Marie-Lou; Massé, Ariane; Côté, Steeve D.; Huot, Jean
    In many areas of North America and Europe, population densities of large herbivores are increasing and strongly affecting species composition and structure of plant communities. Although reduced resources associated with increasing density affect life history traits of large herbivores, their effects on foraging behaviour have received little attention. We experimentally controlled population density in large enclosures to assess how increasing density affected white-tailed deer (Odocoileus virginianus) space use in relation to forage biomass and cover at a fine scale. We quantified space use in 3 blocks, each with 2 enclosures, one containing deer at a density of 7.5 deer-km−2 (low density) and the other containing deer at a density of 15 deer-km−2 (high density). We interpolated forage biomass, lateral cover, and canopy cover in space by kriging and divided deer observations (radiolocations) into 3 diel-periods: dawn/dusk, day, and night. Deer space use was positively related to forage biomass and negatively related to lateral cover at both densities, but it was not affected by the diel-period. Deer increased the use of areas with dense canopy cover at low density, but not at high density. Population density thus modified deer resource use by constraining deer at high density to forage where canopy cover is lower but forage biomass higher. Our results provide evidence of density dependence in foraging decisions, as deer space use patterns appeared to be based more strongly on forage biomass than on cover, particularly when population density was high.
  • PublicationRestreint
    Linking habitat heterogeneity to space use by large herbivores at multiple scales: from habitat mosaics to forest canopy openings
    (Elsevier, 2012-09-12) Massé, Ariane; Côté, Steeve D.
    Although habitat selection and home range size of herbivores in forested landscapes are generally related to the composition and spatial arrangement of open and forested habitat categories, it is unclear how herbivores respond to finer habitat mosaics such as more productive canopy openings within forest stands. We aimed to determine the relationships between habitat selection and home range size of 32 whitetailed deer (Odocoileus virginianus) females and spatial heterogeneity in forage and cover at multiple scales. We used GPS telemetry to delineate summer and winter home ranges and to evaluate habitat selection. We used landscape metrics to measure spatial heterogeneity of open and closed habitat categories within each home range and in three circles of radii of 1000, 2000 and 3000 m centered on each home range, and field surveys to quantify spatial patterns in canopy openings within forest stands. Deer responded to forage abundance at multiple scales during summer, as they selected peatlands within the landscape, canopy openings within forest stands, and reduced the size of their home range with increasing forbs and deciduous shrubs cover. Deer also responded to forage abundance during winter as they selected areas with high proportions of food-rich balsam fir stands to establish their home range and had a smaller home range size when the density of food sources increased. However, in areas where the proportion of food-rich balsam fir stands was less available, deer selected heterogeneous habitat mosaics to settle their winter home range. Moreover, deer responded positively to edge density of cutblocks only during winter and they did not select canopy openings during that season. Winter forage such as windblown fir trees were highly associated to edges between clear-cuts and balsam fir stands making these large openings an important element of deer winter habitat in ecosystem modified by long-term browsing. Our results emphasize the significance of considering multiple and nested mosaics of openings and continuous cover when assessing habitat selection patterns and home range size of herbivores living in forested landscapes, as the influence of spatial heterogeneity in resources varied with the constraints of seasonal environments.
  • PublicationAccès libre
    Influence of density and climate on the population dynamics of a large herbivore under harsh environmental conditions
    (Bioone, 2010-11-01) Côté, Steeve D.; Coulson, Tim; Simard, Marie-Anouk; Gingras, André
    Dynamics of herbivore populations can be influenced both by density-dependent processes and climate. We used age-at-harvest data for adult female white-tailed deer (Odocoileus virginianus) collected over 23 years to estimate survival and reproduction by age class and to identify effects of environmental factors. The study population was located on Anticosti Island (QC, Canada), at the northern limit of the species' range; the population was at high density, and the landscape had scarce forage and abundant snow during winter. Despite severe environmental conditions, population growth apparently increased during the study; adult survival was similar to other populations, although reproduction appeared lower. Winter severity was not related to survival, but density affected adult female survival. Density at estrus was the main factor influencing reproduction of 2- and 3–4-year-olds and also affected reproduction of prime-aged females (5–9-yr-olds), but not of older females. Reproductive rate of younger females was influenced by environmental conditions in autumn, such as high density or snow conditions that limited forage availability. Reproductive success of 5–9- and ≥10-year-old females appeared dependent on spring conditions favoring high-quality forage, probably through effects on neonatal survival. Relative to other studies on northern ungulates, demographic processes in our study appeared to be more affected by autumn and spring climate, in addition to population density, than by winter climate. We thus propose that population density, as well as autumn and spring climate, should be considered in management strategies. Harvest data offered a unique opportunity to study forest ungulates, for which individual monitoring is rarely possible.
  • PublicationRestreint
    The effects of decreasing winter diet quality on foraging behavior and life-history traits of white-tailed deer fawns
    (Wildlife Society, 2010-12-13) Sauvé, Daniel; Côté, Steeve D.; Taillon, Joëlle
    Many high-density populations of wild ungulates have exerted strong negative impacts on their habitat. A decrease in forage quantity and quality may affect individual growth, fecundity, and survival, especially under harsh winter conditions. On Anticosti Island, Que´bec, Canada, browsing by introduced white-tailed deer (Odocoileus virginianus) negatively affected boreal forest composition. Since the preferred contemporary winter forage of deer, balsam fir (Abies balsamea), has been almost completely extirpated from the island at browse height, deer are forced to increase the proportion of normally avoided forage, such as white spruce (Picea glauca), in their winter diet. We predicted that an increase in the proportion of white spruce in the diet would have detrimental effects on deer body condition and would affect their behavior and life history traits. We experimentally simulated a deterioration of winter forage quality in semi-natural enclosures by increasing the proportion of white spruce in the diet and examined the effects of winter diet quality on 1) forage intake, 2) body condition loss, 3) activity budget, and 4) survival of whitetailed deer fawns. Fawns fed the poor-quality diet maintained a higher forage intake rate throughout the winter than fawns fed the control diet, suggesting a compensatory response to the decrease of forage quality by consuming more forage during winter. Body mass decreased over the winter, but we did not observe any significant effects of diet quality on body mass loss. Diet quality did not influence the activity budget of fawns, but deer decreased activity in cold weather. The main determinant of overwinter survival was individual body mass in early winter. Our study suggests that deer have adapted to the extreme conditions encountered on Anticosti (i.e., harsh and long winters, low-quality browse, and a high-density population). Even though white spruce stands are gradually replacing balsam fir stands, our results suggest that deer on Anticosti could maintain a high-density population by increasing the amount of white spruce in their diet. However, future studies are necessary to address the long-term effects of a diet dominated by white spruce on deer body condition, survival, and reproduction under natural conditions.
  • PublicationRestreint
    Neighbouring plants and perception of predation risk modulate winter browsing by white-tailed deer (Odocoileus virginianus)
    (NRC Research Pres, 2017-09-13) Tremblay, Jean-Pierre; Perroud, Lucie; Côté, Steeve D.; Champagne, Émilie; Dumont, André
    The presence of neighbouring plants and predation risk can affect trophic interactions between plants and herbivores. We hypothesized that the relative preference for neighbouring species would determine winter herbivory and that predation risk would modulate browsing pressure. We tested these hypotheses using feeding trials in two regions with high white-tailed deer (Odocoileus virginianus (Zimmermann, 1780)) densities: Outaouais and Anticosti Island (Quebec, Canada). In each, we selected a species of interest and compared browsing rates and time spent foraging with neighbours relatively preferred or avoided. In a subexperiment, we included coyote (Canis latrans Say, 1823) urine to test for threat-sensitive foraging and interactions with neighbour effects. In Outaouais, time spent foraging on the focal species was reduced by the presence of potentially avoided neighbours and deer reduced browsing with increased perceived predation risk. On Anticosti, browsing rates on the focal species increased with avoided neighbours, with no effect of the predator urine. Anticosti deer have been in a predator-free environment for more than 120 years, likely reducing antipredator behaviours. This study demonstrates both neighbour effects and threat-sensitive foraging, phenomena that could interact and thus would benefit from being studied together to better represent trophic interactions in natural environments.
  • PublicationRestreint
    Long term effects of deer browsing and trampling on the vegetation of peatlands
    (ScienceDirect, 2005-11-15) Pellerin, Stéphanie; Côté, Steeve D.; Huot, Jean
    Overabundance of wild ungulates, especially exotic species, is a major threat to several ecosystems worldwide. While the response of forest vegetation to high density of herbivores has been well studied, far less is known about peatland vegetation. In this paper, we assessed the long term impact of white-tailed deer (Odocoileus virginianus) on plant communities of ombrotrophic (bog) and minerotrophic (fen) peatlands in eastern North America. Vegetation of five peatlands that have experienced high deer densities for at least 75 years was compared with that of five peatlands situated at proximity but on deer-free islands. We investigated deer impacts on plant species composition and cover, shrub height and cloudberry (Rubus chamaemorus) fruit/flower production and morphology. In bogs, white-tailed deer had no long-term impact on plant species assemblages, but reduced lichen cover and increased sedges and grasses cover as well as the surface area of bare peat. On the other hand, the floristic composition of fens differed significantly between sites where deer were present or absent. Plant diversity was greater in undisturbed fens than in disturbed fens, especially for shrubs, sedges and liverworts. No detrimental effects of browsing on shrub height were observed. Conversely, deer browsing seemed to have deleterious impacts on cloudberry fruit/flower production as well as on the number of leaves per individual. Overall, our results suggest that white-tailed deer had some important impacts on the vegetation of peatlands that could be harmful for the long-term conservation of peatland plant diversity.
  • PublicationRestreint
    Maternal care in white-tailed deer : trade-off between maintenance and reproduction under food restriction
    (Elsevier, 2007-12-03) Therrien, Jean-François; Festa-Bianchet, Marco; Côté, Steeve D.; Ouellet, Jean-Pierre
    Lactation is the most energetically costly component of maternal investment in mammals. For large temperate herbivores, summer is characterized by relatively abundant forage but also high energetic needs for lactation and recovery from winter mass loss. We experimentally restricted food supply by about 20%, and compared the nursing and foraging behaviours of control and food-restricted adult female white-tailed deer, Odocoileus virginianus, and their fawns during lactation. We considered two fawn ages: 0–30 days (after which time spent suckling dropped markedly) and 30–80 days (the end of the nursing period). From 0 to 30 days of age, food-restricted fawns performed 17 more suckling bouts/day and spent twice as much time suckling than control fawns. Compared with controls, food-restricted fawns gained 26% less mass from birth to 80 days. Body growth was inversely related to time spent suckling and to the frequency of nursing bouts, but positively related to survival. Food-restricted fawns had twice as many suckling solicitations and rejected suckling attempts as control fawns. Solicitations for allosuckling and successful allosuckling bouts were also more than twice as high in the food-restricted group as in the control group. Mothers and fawns from the food-restricted group spent more time foraging than control individuals. We conclude that a reduction in food availability during summer, which may occur under high intraspecific competition, should lead to drastic changes in foraging and nursing behaviours as well as reduced growth rate of juveniles of large northern herbivores.