We investigated whether paved roads adjacent to 16 ponds acted as barriers to movements of juveni... more We investigated whether paved roads adjacent to 16 ponds acted as barriers to movements of juvenile wood frogs (Lithobates sylvaticus), green frogs (Lithobates clamitans), mole salamanders (Ambystoma laterale, A. maculatum), and American toads (Anaxyrus americanus) in eastern New Brunswick, Canada. Using pitfall traps and drift fences, we recorded captures of juveniles dispersing away from their natal ponds into forest habitat (pondside fences) or across the road (roadside fences) over two field seasons. To explain variations in abundance of dispersers among sites, we measured several road-associated variables including traffic intensity and roadside habitat structure, pond quality, and weather variables. We estimated the activity patterns (across 4-day periods) and seasonal abundance of juveniles in transit between ponds and terrestrial habitat using generalized linear mixed models. For all groups, activity across 4-day periods increased with either total precipitation or minimum air temperature. However, road-associated variables were also important for some species. Mole salamander activity was lowest next to roads. Wood frog activity increased with minimum air temperature, but the effect was weakest at roadside fences (minimum air temperature × fence position interaction). Seasonal abundance of most groups varied with habitat structure or pond hydroperiod. Green frog abundance decreased with increasing traffic intensity, but abundance was higher at roadside fences than pondside fences. In contrast, wood frog seasonal abundance tended to be lowest at roadside fences. We conclude that road-associated disturbances are detectable at fine temporal scales and that amphibian responses to such variables can be influenced by weather variables.
Le Québec offre un potentiel considérable pour le développement de l'industrie éolienne. Cette in... more Le Québec offre un potentiel considérable pour le développement de l'industrie éolienne. Cette industrie peut être à l'origine de mortalités chez les rapaces et pourrait affecter certaines espèces vulnérables comme le faucon pèlerin. De 2008 à 2010, nous avons comparé l'utilisation de 5 types de milieux par 10 femelles nicheuses de faucon pèlerin dans le Québec méridional, afin de déterminer ceux à favoriser pour l'implantation de parcs éoliens. Les milieux les moins utilisés par les femelles étaient ceux considérés comme diminuant les risques de collision avec les éoliennes. Après l'envol des fauconneaux, les femelles parcouraient de plus grandes distances que lorsque les fauconneaux étaient confinés au nid. À cette période, 90 % des localisations télémétriques dans les cultures de maïs et de soya ont été enregistrées à l'intérieur d'un rayon de 8,3 km d'un nid, comparativement à un rayon de 15,9 km dans les autres cultures. Aussi, les femelles avaient moins de chances d'utiliser les cultures de maïs et de soya que les autres cultures et les milieux non propices pour la chasse. Nos résultats permettent de faire des recommandations quant à la localisation de projets éoliens, en termes de milieux à favoriser et de distances à respecter, afin de minimiser les risques de collision du faucon pèlerin.
... Can. J. Zool. 70(11): 2178-2183 Abstract, ISI. Ferron J, Potvin F, Dussault C. 1998. Short-te... more ... Can. J. Zool. 70(11): 2178-2183 Abstract, ISI. Ferron J, Potvin F, Dussault C. 1998. Short-term effects of logging on snowshoe hares in the boreal forest. Can. J. For. Res. ... Can. J. Zool. 79(1): 1-4 Abstract, ISI. Lehmkuhl JF, Hansen CA, Sloan K. 1994. ...
Tree cavities are used as shelter and breeding nests by numerous avian and mammalian species. In ... more Tree cavities are used as shelter and breeding nests by numerous avian and mammalian species. In cold environments, tree cavities are often proposed as the best winter nest choice because of the superior protection they offer from precipitation, wind, cold temperatures, and predators. As such, they represent a critical resource, which has the potential to limit population size of non-excavating species. We assessed factors affecting site occupancy in the boreal forest by northern flying squirrels, a secondary user of tree cavities, and to identify which nest type is preferred during the colder days of the autumn-winter period. We trapped flying squirrels twice in 59 aspen-dominated stands in the autumn period using low-(1.5 m above ground-level) and high-mounted (4 m) traps to determine site occupancy. A total of 85 individuals were captured on 2,880 trap-nights. During the winter period, we radio-tracked 26 individuals to 87 diurnal nests in 220 locations. None of the habitat variables considered (cavity availability, woody debris, and lateral cover) explained site occupancy. Detectability decreased with precipitation, and was lower using high traps than low traps. Both females and males used tree cavities (26%), external nests (39%), and ground nests (35%). In cold weather, females preferred ground nests, whereas males preferred external nests. Our results do not support the hypothesis that tree cavities represent a limiting factor to northern flying squirrels in cold environments. Instead, this species seems to be a generalist and is opportunistic, using a variety of nest types. Nevertheless, practices ensuring the persistence of large diameter live cavity trees, providing better insulative properties, are likely to increase the relative use of tree cavities as nest sites by northern flying squirrels. ß 2011 The Wildlife Society.
Jack pine specimens were examined for longitudinal and radial variations in selected wood quality... more Jack pine specimens were examined for longitudinal and radial variations in selected wood quality parameters. Wood density and ring width of cross-sections were measured systematically from pith to bark along the merchantable stem using X-ray densitometry. Effects of cambial age and stem height were analyzed using a linear mixed model with two levels of nesting. A strong interaction between the two factors was found in corewood. Tree individual variation increased with cambial age for all studied wood properties and was larger in earlywood than in latewood. Radial patterns in the studied parameters closely approximated published ones in the lower stem but lessened considerably with increasing stem height. By contrast, longitudinal patterns reversed with cambial age in earlywood. High coordination was found between longitudinal patterns in corewood and radial patterns in the stem base, indicating a similar maturation pattern in the apical meristem and cambia. However, with increasing cambial age, this high coordination disappeared rapidly.
Orientation is a key component to successful movements between habitats. We hypothesized that bar... more Orientation is a key component to successful movements between habitats. We hypothesized that barren agricultural landscapes hinder the ability of frogs to orient and move between habitats. Specifically, we predicted that when presented with a choice between a short route through a hostile environment and a longer but safer route, individuals would select the one that entails the least risk. During a field experiment, we translocated 104 Edible Frogs (Rana klepton esculenta) into a recently harrowed field according to two treatments: the distance to their pond of origin (5-70 m) and the distance to a wooded hedgerow (10-60 m). The frogs' ability to orient toward the pond decreased with pond distance and increased with distance to the hedgerow, but we did not detect interactive effects. In addition, frogs were more successful in orienting toward the pond under high wind conditions. We have shown that both the configuration of the landscape and weather variables influence the movement behavior of amphibians in agricultural settings, and these may have important implications for population persistence.
Nocturnal car traffic often results in amphibian casualties, especially during rainy nights. The ... more Nocturnal car traffic often results in amphibian casualties, especially during rainy nights. The behavior of amphibians presumably influences their vulnerability to mortality on the road, but this hypothesis remains untested. We investigated the behavioral response of individuals of six species of amphibians on roads when confronted by an approaching vehicle. We first conducted a field study consisting of 50 night-driving surveys over 4 yr during which we recorded the behavior (i.e., moving or immobile) of frogs, toads, tree frogs, and salamanders encountered on a 20-km stretch of road. In an effort to tease apart the effects of headlights and the sound of motors on amphibian behavior, we carried out a field experiment on a test road where we exposed individuals to different car-associated stimuli. Here, we tested the hypothesis that simultaneous exposure to headlights and the sound of a car motor would elicit a stronger response than exposure to a single stimulus or a control. Based on the observations of the 2767 individuals in the field survey, immobility was the most common response to the approach of a car (mean probability of 0.82 of remaining immobile); the response differed across species but depended on the season of the survey (May-June vs. July-September). Similarly, the 91 individuals included in the field experiment were more likely to move during the control treatment than during any of the car-associated treatments. The combined stimuli elicited the strongest response, followed by the headlights-only and the motor-only treatments. Spring peepers (Pseudacris crucifer) tended to move more often than the other species we tested in the field experiment, which suggests they spend less time on the road and are less vulnerable to traffic mortality than other species. Both the field survey and field experiment consistently indicated that amphibians tend to remain immobile at the approach of a vehicle. This behavior highlights the vulnerability of amphibians to road traffic and should be considered in measures to mitigate road impacts.
Groupe de recherche en écologie des tourbières, Université Laval, QC, Canada SUMMARY 1. van Duine... more Groupe de recherche en écologie des tourbières, Université Laval, QC, Canada SUMMARY 1. van Duinen et al. (Freshwater Biol., 2006) raise an interesting point regarding Mazerolle et al.'s (Freshwater Biol., 2006, 51, p. 333) conclusion on the ability of invertebrates, especially sedentary species, to colonise newly created bogs pools. We wish to clarify that targeted large arthropods and the absence of smaller sedentary species was purely a result of sampling design. 2. van postulate that colonisation rates by bog specialists should be higher in Canada than in the Netherlands, given the extensive amount of intact peatlands in Canada. Here, we emphasise the importance of taking the regional context into account when assessing restoration success as our study site occurs in a landscape where most bog pools have been drained.
Many investigators have hypothesized that landscape attributes such as the amount and proximity o... more Many investigators have hypothesized that landscape attributes such as the amount and proximity of habitat are important for amphibian spatial patterns. This has produced a number of studies focusing on the effects of landscape characteristics on amphibian patterns of occurrence in patches or ponds, most of which conclude that the landscape is important. We identified two concerns associated with these studies: one deals with their applicability to other landscape types, as most have been conducted in agricultural landscapes; the other highlights the need to account for the probability of detection. We tested the hypothesis that landscape characteristics influence spatial patterns of amphibian occurrence at ponds after accounting for the probability of detection in little-studied peatland landscapes undergoing peat mining. We also illustrated the costs of not accounting for the probability of detection by comparing our results to conventional logistic regression analyses. Results indicate that frog occurrence increased with the percent cover of ponds within 100, 250, and 1000 m, as well as the amount of forest cover within 1000 m. However, forest cover at 250 m had a negative influence on frog presence at ponds. Not accounting for the probability of detection resulted in underestimating the influence of most variables on frog occurrence, whereas a few were overestimated. Regardless, we show that conventional logistic regression can lead to different conclusions than analyses accounting for detectability. Our study is consistent with the hypothesis that landscape characteristics are important in determining the spatial patterns of frog occurrence at ponds. We strongly recommend estimating the probability of detection in field surveys, as this will increase the quality and conservation potential of models derived from such data.
Jack pine specimens were examined for longitudinal and radial variations in selected wood quality... more Jack pine specimens were examined for longitudinal and radial variations in selected wood quality parameters. Wood density and ring width of cross-sections were measured systematically from pith to bark along the merchantable stem using X-ray densitometry. Effects of cambial age and stem height were analyzed using a linear mixed model with two levels of nesting. A strong interaction between the two factors was found in corewood. Tree individual variation increased with cambial age for all studied wood properties and was larger in earlywood than in latewood. Radial patterns in the studied parameters closely approximated published ones in the lower stem but lessened considerably with increasing stem height. By contrast, longitudinal patterns reversed with cambial age in earlywood. High coordination was found between longitudinal patterns in corewood and radial patterns in the stem base, indicating a similar maturation pattern in the apical meristem and cambia. However, with increasing cambial age, this high coordination disappeared rapidly.
An animal's capacity to recolonize a patch depends on at least two components: its ability to det... more An animal's capacity to recolonize a patch depends on at least two components: its ability to detect the patch and its ability to reach it. However, the disruption of such processes by anthropic disturbances could explain low animal abundance patterns observed by many investigators in certain landscapes. Through field experiments, we compared the orientation and homing success of northern green frogs (Rana clamitans melanota Rafinesque, 1820) and northern leopard frogs (Rana pipiens Schreber, 1782) translocated across disturbed or undisturbed surfaces. We also monitored the path selected by individuals when presented with a choice between a short distance over a disturbed surface and a longer, undisturbed route. Finally, we measured the water loss and behaviour of frogs on substrates resulting from anthropogenic disturbances and a control. When presented with a choice, 72% of the frogs avoided disturbed surfaces. Although able to orient towards the pond of capture when translocated on disturbed surfaces, frogs had a lower probability of homing successfully to the pond than when translocated at a similar distance on an undisturbed surface. Frogs lost the most water on substrates associated with disturbance and in the absence of cover. Our data illustrate that anthropically disturbed areas devoid of cover, such as mined peatlands and agricultural fields, disrupt the ability of frogs to reach habitat patches and are likely explanations to their reduced abundance patterns in such environments.
Bogs, or ombrotrophic peatlands, are well represented in parts of southeastern Canada but are sub... more Bogs, or ombrotrophic peatlands, are well represented in parts of southeastern Canada but are subjected to increasing pressure from the peat industry. We assessed the impact of peat mining on small mammals inhabiting unexploited bog fragments on the periphery of mined bogs. We conducted two separate studies in bogs mined to different levels (0-83%) in southeastern Québec and New Brunswick. The first study used a low sampling effort over 1 month in 26 bogs, while the second used a high sampling effort of 6 months spread across 2 years in 12 bogs. Of the 15 small-mammal species encountered, only 2 were bog specialists. Abundance and species richness of small mammals in bog fragments increased significantly with percentage of area mined and, in some cases, increased with bog area. Both studies suggest that disturbances resulting from peat mining facilitate the invasion of more generalized small-mammal species. Furthermore, small mammals were more abundant near forest or mined edges than at bog centers, and some species responded strongly to vegetation cover. The response of small mammals to peat mining contrasts with the one documented for birds, amphibians, and plants.
We investigated whether paved roads adjacent to 16 ponds acted as barriers to movements of juveni... more We investigated whether paved roads adjacent to 16 ponds acted as barriers to movements of juvenile wood frogs (Lithobates sylvaticus), green frogs (Lithobates clamitans), mole salamanders (Ambystoma laterale, A. maculatum), and American toads (Anaxyrus americanus) in eastern New Brunswick, Canada. Using pitfall traps and drift fences, we recorded captures of juveniles dispersing away from their natal ponds into forest habitat (pondside fences) or across the road (roadside fences) over two field seasons. To explain variations in abundance of dispersers among sites, we measured several road-associated variables including traffic intensity and roadside habitat structure, pond quality, and weather variables. We estimated the activity patterns (across 4-day periods) and seasonal abundance of juveniles in transit between ponds and terrestrial habitat using generalized linear mixed models. For all groups, activity across 4-day periods increased with either total precipitation or minimum air temperature. However, road-associated variables were also important for some species. Mole salamander activity was lowest next to roads. Wood frog activity increased with minimum air temperature, but the effect was weakest at roadside fences (minimum air temperature × fence position interaction). Seasonal abundance of most groups varied with habitat structure or pond hydroperiod. Green frog abundance decreased with increasing traffic intensity, but abundance was higher at roadside fences than pondside fences. In contrast, wood frog seasonal abundance tended to be lowest at roadside fences. We conclude that road-associated disturbances are detectable at fine temporal scales and that amphibian responses to such variables can be influenced by weather variables.
Le Québec offre un potentiel considérable pour le développement de l'industrie éolienne. Cette in... more Le Québec offre un potentiel considérable pour le développement de l'industrie éolienne. Cette industrie peut être à l'origine de mortalités chez les rapaces et pourrait affecter certaines espèces vulnérables comme le faucon pèlerin. De 2008 à 2010, nous avons comparé l'utilisation de 5 types de milieux par 10 femelles nicheuses de faucon pèlerin dans le Québec méridional, afin de déterminer ceux à favoriser pour l'implantation de parcs éoliens. Les milieux les moins utilisés par les femelles étaient ceux considérés comme diminuant les risques de collision avec les éoliennes. Après l'envol des fauconneaux, les femelles parcouraient de plus grandes distances que lorsque les fauconneaux étaient confinés au nid. À cette période, 90 % des localisations télémétriques dans les cultures de maïs et de soya ont été enregistrées à l'intérieur d'un rayon de 8,3 km d'un nid, comparativement à un rayon de 15,9 km dans les autres cultures. Aussi, les femelles avaient moins de chances d'utiliser les cultures de maïs et de soya que les autres cultures et les milieux non propices pour la chasse. Nos résultats permettent de faire des recommandations quant à la localisation de projets éoliens, en termes de milieux à favoriser et de distances à respecter, afin de minimiser les risques de collision du faucon pèlerin.
... Can. J. Zool. 70(11): 2178-2183 Abstract, ISI. Ferron J, Potvin F, Dussault C. 1998. Short-te... more ... Can. J. Zool. 70(11): 2178-2183 Abstract, ISI. Ferron J, Potvin F, Dussault C. 1998. Short-term effects of logging on snowshoe hares in the boreal forest. Can. J. For. Res. ... Can. J. Zool. 79(1): 1-4 Abstract, ISI. Lehmkuhl JF, Hansen CA, Sloan K. 1994. ...
Tree cavities are used as shelter and breeding nests by numerous avian and mammalian species. In ... more Tree cavities are used as shelter and breeding nests by numerous avian and mammalian species. In cold environments, tree cavities are often proposed as the best winter nest choice because of the superior protection they offer from precipitation, wind, cold temperatures, and predators. As such, they represent a critical resource, which has the potential to limit population size of non-excavating species. We assessed factors affecting site occupancy in the boreal forest by northern flying squirrels, a secondary user of tree cavities, and to identify which nest type is preferred during the colder days of the autumn-winter period. We trapped flying squirrels twice in 59 aspen-dominated stands in the autumn period using low-(1.5 m above ground-level) and high-mounted (4 m) traps to determine site occupancy. A total of 85 individuals were captured on 2,880 trap-nights. During the winter period, we radio-tracked 26 individuals to 87 diurnal nests in 220 locations. None of the habitat variables considered (cavity availability, woody debris, and lateral cover) explained site occupancy. Detectability decreased with precipitation, and was lower using high traps than low traps. Both females and males used tree cavities (26%), external nests (39%), and ground nests (35%). In cold weather, females preferred ground nests, whereas males preferred external nests. Our results do not support the hypothesis that tree cavities represent a limiting factor to northern flying squirrels in cold environments. Instead, this species seems to be a generalist and is opportunistic, using a variety of nest types. Nevertheless, practices ensuring the persistence of large diameter live cavity trees, providing better insulative properties, are likely to increase the relative use of tree cavities as nest sites by northern flying squirrels. ß 2011 The Wildlife Society.
Jack pine specimens were examined for longitudinal and radial variations in selected wood quality... more Jack pine specimens were examined for longitudinal and radial variations in selected wood quality parameters. Wood density and ring width of cross-sections were measured systematically from pith to bark along the merchantable stem using X-ray densitometry. Effects of cambial age and stem height were analyzed using a linear mixed model with two levels of nesting. A strong interaction between the two factors was found in corewood. Tree individual variation increased with cambial age for all studied wood properties and was larger in earlywood than in latewood. Radial patterns in the studied parameters closely approximated published ones in the lower stem but lessened considerably with increasing stem height. By contrast, longitudinal patterns reversed with cambial age in earlywood. High coordination was found between longitudinal patterns in corewood and radial patterns in the stem base, indicating a similar maturation pattern in the apical meristem and cambia. However, with increasing cambial age, this high coordination disappeared rapidly.
Orientation is a key component to successful movements between habitats. We hypothesized that bar... more Orientation is a key component to successful movements between habitats. We hypothesized that barren agricultural landscapes hinder the ability of frogs to orient and move between habitats. Specifically, we predicted that when presented with a choice between a short route through a hostile environment and a longer but safer route, individuals would select the one that entails the least risk. During a field experiment, we translocated 104 Edible Frogs (Rana klepton esculenta) into a recently harrowed field according to two treatments: the distance to their pond of origin (5-70 m) and the distance to a wooded hedgerow (10-60 m). The frogs' ability to orient toward the pond decreased with pond distance and increased with distance to the hedgerow, but we did not detect interactive effects. In addition, frogs were more successful in orienting toward the pond under high wind conditions. We have shown that both the configuration of the landscape and weather variables influence the movement behavior of amphibians in agricultural settings, and these may have important implications for population persistence.
Nocturnal car traffic often results in amphibian casualties, especially during rainy nights. The ... more Nocturnal car traffic often results in amphibian casualties, especially during rainy nights. The behavior of amphibians presumably influences their vulnerability to mortality on the road, but this hypothesis remains untested. We investigated the behavioral response of individuals of six species of amphibians on roads when confronted by an approaching vehicle. We first conducted a field study consisting of 50 night-driving surveys over 4 yr during which we recorded the behavior (i.e., moving or immobile) of frogs, toads, tree frogs, and salamanders encountered on a 20-km stretch of road. In an effort to tease apart the effects of headlights and the sound of motors on amphibian behavior, we carried out a field experiment on a test road where we exposed individuals to different car-associated stimuli. Here, we tested the hypothesis that simultaneous exposure to headlights and the sound of a car motor would elicit a stronger response than exposure to a single stimulus or a control. Based on the observations of the 2767 individuals in the field survey, immobility was the most common response to the approach of a car (mean probability of 0.82 of remaining immobile); the response differed across species but depended on the season of the survey (May-June vs. July-September). Similarly, the 91 individuals included in the field experiment were more likely to move during the control treatment than during any of the car-associated treatments. The combined stimuli elicited the strongest response, followed by the headlights-only and the motor-only treatments. Spring peepers (Pseudacris crucifer) tended to move more often than the other species we tested in the field experiment, which suggests they spend less time on the road and are less vulnerable to traffic mortality than other species. Both the field survey and field experiment consistently indicated that amphibians tend to remain immobile at the approach of a vehicle. This behavior highlights the vulnerability of amphibians to road traffic and should be considered in measures to mitigate road impacts.
Groupe de recherche en écologie des tourbières, Université Laval, QC, Canada SUMMARY 1. van Duine... more Groupe de recherche en écologie des tourbières, Université Laval, QC, Canada SUMMARY 1. van Duinen et al. (Freshwater Biol., 2006) raise an interesting point regarding Mazerolle et al.'s (Freshwater Biol., 2006, 51, p. 333) conclusion on the ability of invertebrates, especially sedentary species, to colonise newly created bogs pools. We wish to clarify that targeted large arthropods and the absence of smaller sedentary species was purely a result of sampling design. 2. van postulate that colonisation rates by bog specialists should be higher in Canada than in the Netherlands, given the extensive amount of intact peatlands in Canada. Here, we emphasise the importance of taking the regional context into account when assessing restoration success as our study site occurs in a landscape where most bog pools have been drained.
Many investigators have hypothesized that landscape attributes such as the amount and proximity o... more Many investigators have hypothesized that landscape attributes such as the amount and proximity of habitat are important for amphibian spatial patterns. This has produced a number of studies focusing on the effects of landscape characteristics on amphibian patterns of occurrence in patches or ponds, most of which conclude that the landscape is important. We identified two concerns associated with these studies: one deals with their applicability to other landscape types, as most have been conducted in agricultural landscapes; the other highlights the need to account for the probability of detection. We tested the hypothesis that landscape characteristics influence spatial patterns of amphibian occurrence at ponds after accounting for the probability of detection in little-studied peatland landscapes undergoing peat mining. We also illustrated the costs of not accounting for the probability of detection by comparing our results to conventional logistic regression analyses. Results indicate that frog occurrence increased with the percent cover of ponds within 100, 250, and 1000 m, as well as the amount of forest cover within 1000 m. However, forest cover at 250 m had a negative influence on frog presence at ponds. Not accounting for the probability of detection resulted in underestimating the influence of most variables on frog occurrence, whereas a few were overestimated. Regardless, we show that conventional logistic regression can lead to different conclusions than analyses accounting for detectability. Our study is consistent with the hypothesis that landscape characteristics are important in determining the spatial patterns of frog occurrence at ponds. We strongly recommend estimating the probability of detection in field surveys, as this will increase the quality and conservation potential of models derived from such data.
Jack pine specimens were examined for longitudinal and radial variations in selected wood quality... more Jack pine specimens were examined for longitudinal and radial variations in selected wood quality parameters. Wood density and ring width of cross-sections were measured systematically from pith to bark along the merchantable stem using X-ray densitometry. Effects of cambial age and stem height were analyzed using a linear mixed model with two levels of nesting. A strong interaction between the two factors was found in corewood. Tree individual variation increased with cambial age for all studied wood properties and was larger in earlywood than in latewood. Radial patterns in the studied parameters closely approximated published ones in the lower stem but lessened considerably with increasing stem height. By contrast, longitudinal patterns reversed with cambial age in earlywood. High coordination was found between longitudinal patterns in corewood and radial patterns in the stem base, indicating a similar maturation pattern in the apical meristem and cambia. However, with increasing cambial age, this high coordination disappeared rapidly.
An animal's capacity to recolonize a patch depends on at least two components: its ability to det... more An animal's capacity to recolonize a patch depends on at least two components: its ability to detect the patch and its ability to reach it. However, the disruption of such processes by anthropic disturbances could explain low animal abundance patterns observed by many investigators in certain landscapes. Through field experiments, we compared the orientation and homing success of northern green frogs (Rana clamitans melanota Rafinesque, 1820) and northern leopard frogs (Rana pipiens Schreber, 1782) translocated across disturbed or undisturbed surfaces. We also monitored the path selected by individuals when presented with a choice between a short distance over a disturbed surface and a longer, undisturbed route. Finally, we measured the water loss and behaviour of frogs on substrates resulting from anthropogenic disturbances and a control. When presented with a choice, 72% of the frogs avoided disturbed surfaces. Although able to orient towards the pond of capture when translocated on disturbed surfaces, frogs had a lower probability of homing successfully to the pond than when translocated at a similar distance on an undisturbed surface. Frogs lost the most water on substrates associated with disturbance and in the absence of cover. Our data illustrate that anthropically disturbed areas devoid of cover, such as mined peatlands and agricultural fields, disrupt the ability of frogs to reach habitat patches and are likely explanations to their reduced abundance patterns in such environments.
Bogs, or ombrotrophic peatlands, are well represented in parts of southeastern Canada but are sub... more Bogs, or ombrotrophic peatlands, are well represented in parts of southeastern Canada but are subjected to increasing pressure from the peat industry. We assessed the impact of peat mining on small mammals inhabiting unexploited bog fragments on the periphery of mined bogs. We conducted two separate studies in bogs mined to different levels (0-83%) in southeastern Québec and New Brunswick. The first study used a low sampling effort over 1 month in 26 bogs, while the second used a high sampling effort of 6 months spread across 2 years in 12 bogs. Of the 15 small-mammal species encountered, only 2 were bog specialists. Abundance and species richness of small mammals in bog fragments increased significantly with percentage of area mined and, in some cases, increased with bog area. Both studies suggest that disturbances resulting from peat mining facilitate the invasion of more generalized small-mammal species. Furthermore, small mammals were more abundant near forest or mined edges than at bog centers, and some species responded strongly to vegetation cover. The response of small mammals to peat mining contrasts with the one documented for birds, amphibians, and plants.
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Papers by Marc Mazerolle