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Joel Bety - One of the best experts on this subject based on the ideXlab platform.
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variability in stable isotopes of Snowy Owl feathers and contribution of marine resources to their winter diet
Journal of Avian Biology, 2017Co-Authors: Audrey Robillard, Jean-françois Therrien, Gilles Gauthier, Guy Fitzgerald, Jennifer F Provencher, Joel BetyAbstract:The Snowy Owl is an elusive arctic predator known for its nomadic behaviour. Satellite tracking has revealed that some adult Snowy Owls could make an extensive use of the marine environment during the non-breeding season. However, the relative contribution of marine resources to their diet is unknown. Stable isotope analyses can be useful to document the diet of mobile animals during periods of the year when individuals are less accessible. This study aimed to assess variation in isotopic values (δ13C and δ15N) of various feather types, and the usefulness of feathers to determine the contribution of the marine environment to the winter diet of Snowy Owls captured in summer. We sampled feathers coming from 6 body regions of 18 breeding females at two sites in the eastern Canadian Arctic in 2013 and 2014. Prior to analyses, diet-tissue discrimination factors of Snowy Owl feathers were established in captivity. Variability in isotopic values among feather types was relatively low and pairwise correlations in isotopic values between feathers on the same individual were variable and often low, which suggests differences in the diet at the time when various feathers were synthesized. Diet reconstruction models detected a contribution of marine sources to Snowy Owl feathers ranging from 4% to 19% among feather types. However, the marine contribution was highly variable when single feathers were examined within individuals, ranging from 3% to 71%. This indicated that no single feather type could be used alone to reliably infer the contribution of marine resources to the winter diet of Owls, possibly due to a high variability in the timing and sequence of molt. For asynchronous molters like Snowy Owls, we recommend sampling multiple feathers from various body regions, excluding wing feathers, to investigate winter diet or habitat use. This article is protected by copyright. All rights reserved.
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Is pre-breeding prospecting behaviour affected by snow cover in the irruptive Snowy Owl? A test using state-space modelling and environmental data annotated via Movebank
Movement Ecology, 2015Co-Authors: Jean-françois Therrien, Gilles Gauthier, David Pinaud, Nicolas Lecomte, Keith L Bildstein, Joel BetyAbstract:Background Tracking individual animals using satellite telemetry has improved our understanding of animal movements considerably. Nonetheless, thorough statistical treatment of Argos datasets is often jeopardized by their coarse temporal resolution. State-space modelling can circumvent some of the inherent limitations of Argos datasets, such as the limited temporal resolution of locations and the lack of information pertaining to the behavioural state of the tracked individuals at each location. We coupled state-space modelling with environmental characterisation of modelled locations on a 3-year Argos dataset of 9 breeding Snowy Owls to assess whether searching behaviour for breeding sites was affected by snow cover and depth in an arctic predator that shows a lack of breeding site fidelity. Results The state-space modelling approach allowed the discrimination of two behavioural states (searching and moving) during pre-breeding movements. Tracked Snowy Owls constantly switched from moving to searching behaviour during pre-breeding movements from mid-March to early June. Searching events were more likely where snow cover and depth was low. This suggests that Snowy Owls adapt their searching effort to environmental conditions encountered along their path. Conclusions This modelling technique increases our understanding of movement ecology and behavioural decisions of individual animals both locally and globally according to environmental variables.
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is pre breeding prospecting behaviour affected by snow cover in the irruptive Snowy Owl a test using state space modelling and environmental data annotated via movebank
Movement ecology, 2015Co-Authors: Jean-françois Therrien, Gilles Gauthier, David Pinaud, Nicolas Lecomte, Keith L Bildstein, Joel BetyAbstract:Background: Tracking individual animals using satellite telemetry has improved our understanding of animal movements considerably. Nonetheless, thorough statistical treatment of Argos datasets is often jeopardized by their coarse temporal resolution. State-space modelling can circumvent some of the inherent limitations of Argos datasets, such as the limited temporal resolution of locations and the lack of information pertaining to the behavioural state of the tracked individuals at each location. We coupled state-space modelling with environmental characterisation of modelled locations on a 3-year Argos dataset of 9 breeding Snowy Owls to assess whether searching behaviour for breeding sites was affected by snow cover and depth in an arctic predator that shows a lack of breeding site fidelity. Results: The state-space modelling approach allowed the discrimination of two behavioural states (searching and moving) during pre-breeding movements. Tracked Snowy Owls constantly switched from moving to searching behaviour during pre-breeding movements from mid-March to early June. Searching events were more likely where snow cover and depth was low. This suggests that Snowy Owls adapt their searching effort to environmental conditions encountered along their path.
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Irruptive movements and breeding dispersal of Snowy Owls: a specialized predator exploiting a pulsed resource
Journal of Avian Biology, 2014Co-Authors: Jean-françois Therrien, Gilles Gauthier, David Pinaud, Joel BetyAbstract:Mobility and irruptive movements have been proposed as mechanisms that could allow some diet specialists to inhabit and breed in environments with highly unpredictable resources, like the arctic tundra. Th e Snowy Owl, one of the main avian predators of the tundra, is known to specialize on lemmings during the breeding season. Th ese small mammals are also well known for their tremendous spatial and temporal variations in abundance. We examined the spring (pre-breeding, from March to June) movements of Snowy Owls by tracking 9 breeding females in the Canadian Arctic for up to 3 yr with satellite transmitters. We used state-space modeling to assess searching behavior and measure breeding dispersal distances. We also ascertain lemming abundance at some of the sites used by the marked Owls. Tracked Owls displayed searching movements for extended periods (up to 108 d) and traveled over large distances (up to 4093 km) each spring. Th e distance between furthest apart searching areas in a given year averaged 828 km (range 220 to 2433 km). Settlement date, distance between searching areas, traveled distance and the duration of prospecting movements were longer in the year where density of lemmings recorded in the eastern High-Arctic (Bylot Island) was lowest. Nonetheless, Snowy Owls settled in areas where local lemming abundance was relatively high. Individual breeding dispersal distance between consecutive years averaged 725 km (range 18 to 2224). Overall, the high mobility of female Snowy Owls allowed these diet specialists to behave as irruptive migrants and to sustain their reproductive activities during consecutive years even under highly fl uctuating resources.
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An avian terrestrial predator of the Arctic relies on the marine ecosystem during winter
Journal of Avian Biology, 2011Co-Authors: Jean-françois Therrien, Gilles Gauthier, Joel BetyAbstract:Top predators of the arctic tundra are facing a long period of very low prey availability during winter and subsidies from other ecosystems such as the marine environment may help to support their populations. Satellite tracking of Snowy Owls, a top predator of the tundra, revealed that most adult females breeding in the Canadian Arctic overwinter at high latitudes in the eastern Arctic and spend several weeks (up to 101 d) on the sea-ice between December and April. Analysis of high-resolution satellite images of sea-ice indicated that Owls were primarily gathering around open water patches in the ice, which are commonly used by wintering seabirds, a potential prey. Such extensive use of sea-ice by a tundra predator considered a small mammal specialist was unexpected, and suggests that marine resources subsidize Snowy Owl populations in winter. As sea-ice regimes in winter are expected to change over the next decades due to climate warming, this may affect the wintering strategy of this top predator and ultimately the functioning of the tundra ecosystem.
Jean-françois Therrien - One of the best experts on this subject based on the ideXlab platform.
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Seasonal Movements of Female Snowy Owls Breeding in the Western North American Arctic
Journal of Raptor Research, 2017Co-Authors: Frank I Doyle, Jean-françois Therrien, Gilles Gauthier, Donald G Reid, Charles J. KrebsAbstract:Abstract The Snowy Owl (Bubo scandiacus) is a circumpolar raptor that nests in Arctic tundra. Satellite tracking of nesting Snowy Owls in Alaska and eastern Canada has allowed researchers to document the widely nomadic movements of these Owls between summer and winter ranges. This study expands that knOwledge for Snowy Owls in the western Canadian Arctic. Based on previous studies, we predicted that Owls: (1) would not have strong fidelity to specific winter or summer ranges; (2) would travel widely in search of breeding and nonbreeding areas at which they would settle for considerable time (months); (3) would choose areas to settle based on prey concentration; and (4) would use a mix of overwintering strategies, with some staying in Arctic and boreal regions, and some migrating south. Movement patterns of four female Owls captured at nesting sites on Herschel Island, Yukon Territory, Canada, supported the first two predictions. The third prediction was partly supported: some sites of summer settlement we...
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variability in stable isotopes of Snowy Owl feathers and contribution of marine resources to their winter diet
Journal of Avian Biology, 2017Co-Authors: Audrey Robillard, Jean-françois Therrien, Gilles Gauthier, Guy Fitzgerald, Jennifer F Provencher, Joel BetyAbstract:The Snowy Owl is an elusive arctic predator known for its nomadic behaviour. Satellite tracking has revealed that some adult Snowy Owls could make an extensive use of the marine environment during the non-breeding season. However, the relative contribution of marine resources to their diet is unknown. Stable isotope analyses can be useful to document the diet of mobile animals during periods of the year when individuals are less accessible. This study aimed to assess variation in isotopic values (δ13C and δ15N) of various feather types, and the usefulness of feathers to determine the contribution of the marine environment to the winter diet of Snowy Owls captured in summer. We sampled feathers coming from 6 body regions of 18 breeding females at two sites in the eastern Canadian Arctic in 2013 and 2014. Prior to analyses, diet-tissue discrimination factors of Snowy Owl feathers were established in captivity. Variability in isotopic values among feather types was relatively low and pairwise correlations in isotopic values between feathers on the same individual were variable and often low, which suggests differences in the diet at the time when various feathers were synthesized. Diet reconstruction models detected a contribution of marine sources to Snowy Owl feathers ranging from 4% to 19% among feather types. However, the marine contribution was highly variable when single feathers were examined within individuals, ranging from 3% to 71%. This indicated that no single feather type could be used alone to reliably infer the contribution of marine resources to the winter diet of Owls, possibly due to a high variability in the timing and sequence of molt. For asynchronous molters like Snowy Owls, we recommend sampling multiple feathers from various body regions, excluding wing feathers, to investigate winter diet or habitat use. This article is protected by copyright. All rights reserved.
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Winter Use of a Highly Diverse Suite of Habitats by Irruptive Snowy Owls
Northeastern Naturalist, 2017Co-Authors: Jean-françois Therrien, Scott Weidensaul, David F. Brinker, Trish Miller, Eugene Jacobs, Drew Weber, Thomas J. Mcdonald, Mike Lanzone, Norman SmithAbstract:Abstract Bubo scandiacus (Snowy Owl) is an irregular winter visitor in the northeastern US and southeastern Canada, where winter irruptions occur roughly every 4 years with varying intensity. The consecutive winters of 2013–2014 and 2014–2015 saw unusually large irruptions of Snowy Owls across eastern North American states and provinces and the Great Lakes region. We tracked 34 individuals equipped with high spatial- and temporalresolution GPS–GSM transmitters and obtained data that documented in detail the diverse suite of habitats used by irruptive Snowy Owls overwintering and migrating through the region, from heavily urbanized city centers to open agricultural areas, as well as ice floes drifting on the Great Lakes or concentrating along the shores of the Atlantic Ocean.
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Is pre-breeding prospecting behaviour affected by snow cover in the irruptive Snowy Owl? A test using state-space modelling and environmental data annotated via Movebank
Movement Ecology, 2015Co-Authors: Jean-françois Therrien, Gilles Gauthier, David Pinaud, Nicolas Lecomte, Keith L Bildstein, Joel BetyAbstract:Background Tracking individual animals using satellite telemetry has improved our understanding of animal movements considerably. Nonetheless, thorough statistical treatment of Argos datasets is often jeopardized by their coarse temporal resolution. State-space modelling can circumvent some of the inherent limitations of Argos datasets, such as the limited temporal resolution of locations and the lack of information pertaining to the behavioural state of the tracked individuals at each location. We coupled state-space modelling with environmental characterisation of modelled locations on a 3-year Argos dataset of 9 breeding Snowy Owls to assess whether searching behaviour for breeding sites was affected by snow cover and depth in an arctic predator that shows a lack of breeding site fidelity. Results The state-space modelling approach allowed the discrimination of two behavioural states (searching and moving) during pre-breeding movements. Tracked Snowy Owls constantly switched from moving to searching behaviour during pre-breeding movements from mid-March to early June. Searching events were more likely where snow cover and depth was low. This suggests that Snowy Owls adapt their searching effort to environmental conditions encountered along their path. Conclusions This modelling technique increases our understanding of movement ecology and behavioural decisions of individual animals both locally and globally according to environmental variables.
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is pre breeding prospecting behaviour affected by snow cover in the irruptive Snowy Owl a test using state space modelling and environmental data annotated via movebank
Movement ecology, 2015Co-Authors: Jean-françois Therrien, Gilles Gauthier, David Pinaud, Nicolas Lecomte, Keith L Bildstein, Joel BetyAbstract:Background: Tracking individual animals using satellite telemetry has improved our understanding of animal movements considerably. Nonetheless, thorough statistical treatment of Argos datasets is often jeopardized by their coarse temporal resolution. State-space modelling can circumvent some of the inherent limitations of Argos datasets, such as the limited temporal resolution of locations and the lack of information pertaining to the behavioural state of the tracked individuals at each location. We coupled state-space modelling with environmental characterisation of modelled locations on a 3-year Argos dataset of 9 breeding Snowy Owls to assess whether searching behaviour for breeding sites was affected by snow cover and depth in an arctic predator that shows a lack of breeding site fidelity. Results: The state-space modelling approach allowed the discrimination of two behavioural states (searching and moving) during pre-breeding movements. Tracked Snowy Owls constantly switched from moving to searching behaviour during pre-breeding movements from mid-March to early June. Searching events were more likely where snow cover and depth was low. This suggests that Snowy Owls adapt their searching effort to environmental conditions encountered along their path.
Agnieszka Nowak - One of the best experts on this subject based on the ideXlab platform.
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Dark‐bellied brent geese Branta b. bernicla breeding near Snowy Owl Nyctea scandiaca nests lay more and larger eggs
Journal of Avian Biology, 2020Co-Authors: Henricus H Van Kleef, Frank Willems, Andrei E Volkov, Joseph J H R Smeets, Damian Nowak, Agnieszka NowakAbstract:Several studies have demonstrated that Snowy Owls Nyctea scandiaca defend an area around their nests against predators, hereby inadvertently creating safe havens for breeding dark-bellied brent geese Branta b. bernicla. However, studies investigating brent goose breeding ecology within the predator-exclusion zones of the Snowy Owls are absent. In 1999 and 2005, years of high lemming abundance Lemmus sibiricus and Dicrostonyx torquatus, brent geese were primarily breeding in association with Snowy Owls in the Medusa river catchment on western Taimyr, Russia. Goose nest failure, either as a result of nest abandonment by the adult birds or of nest depredation, increased with increasing distance from the Owl nests. Within the brent goose colonies, clutch size as well as egg size increased with decreasing distance from the Snowy Owl nest, indicating an increasing adult quality closer to Owl nests. However, as a result of the abandonment of eggs and goslings, the increasing clutch size did not result in a higher nest success during this study. Apparently brent geese compete for breeding sites close to Owl nests, but details of this process remain unknown.
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dark bellied brent geese branta b bernicla breeding near Snowy Owl nyctea scandiaca nests lay more and larger eggs
Journal of Avian Biology, 2007Co-Authors: Henricus H Van Kleef, Frank Willems, Andrei E Volkov, Joseph J H R Smeets, Damian Nowak, Agnieszka NowakAbstract:Several studies have demonstrated that Snowy Owls Nyctea scandiaca defend an area around their nests against predators, hereby inadvertently creating safe havens for breeding dark-bellied brent geese Branta b. bernicla. However, studies investigating brent goose breeding ecology within the predator-exclusion zones of the Snowy Owls are absent. In 1999 and 2005, years of high lemming abundance Lemmus sibiricus and Dicrostonyx torquatus, brent geese were primarily breeding in association with Snowy Owls in the Medusa river catchment on western Taimyr, Russia. Goose nest failure, either as a result of nest abandonment by the adult birds or of nest depredation, increased with increasing distance from the Owl nests. Within the brent goose colonies, clutch size as well as egg size increased with decreasing distance from the Snowy Owl nest, indicating an increasing adult quality closer to Owl nests. However, as a result of the abandonment of eggs and goslings, the increasing clutch size did not result in a higher nest success during this study. Apparently brent geese compete for breeding sites close to Owl nests, but details of this process remain unknown.
Gilles Gauthier - One of the best experts on this subject based on the ideXlab platform.
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Seasonal Movements of Female Snowy Owls Breeding in the Western North American Arctic
Journal of Raptor Research, 2017Co-Authors: Frank I Doyle, Jean-françois Therrien, Gilles Gauthier, Donald G Reid, Charles J. KrebsAbstract:Abstract The Snowy Owl (Bubo scandiacus) is a circumpolar raptor that nests in Arctic tundra. Satellite tracking of nesting Snowy Owls in Alaska and eastern Canada has allowed researchers to document the widely nomadic movements of these Owls between summer and winter ranges. This study expands that knOwledge for Snowy Owls in the western Canadian Arctic. Based on previous studies, we predicted that Owls: (1) would not have strong fidelity to specific winter or summer ranges; (2) would travel widely in search of breeding and nonbreeding areas at which they would settle for considerable time (months); (3) would choose areas to settle based on prey concentration; and (4) would use a mix of overwintering strategies, with some staying in Arctic and boreal regions, and some migrating south. Movement patterns of four female Owls captured at nesting sites on Herschel Island, Yukon Territory, Canada, supported the first two predictions. The third prediction was partly supported: some sites of summer settlement we...
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variability in stable isotopes of Snowy Owl feathers and contribution of marine resources to their winter diet
Journal of Avian Biology, 2017Co-Authors: Audrey Robillard, Jean-françois Therrien, Gilles Gauthier, Guy Fitzgerald, Jennifer F Provencher, Joel BetyAbstract:The Snowy Owl is an elusive arctic predator known for its nomadic behaviour. Satellite tracking has revealed that some adult Snowy Owls could make an extensive use of the marine environment during the non-breeding season. However, the relative contribution of marine resources to their diet is unknown. Stable isotope analyses can be useful to document the diet of mobile animals during periods of the year when individuals are less accessible. This study aimed to assess variation in isotopic values (δ13C and δ15N) of various feather types, and the usefulness of feathers to determine the contribution of the marine environment to the winter diet of Snowy Owls captured in summer. We sampled feathers coming from 6 body regions of 18 breeding females at two sites in the eastern Canadian Arctic in 2013 and 2014. Prior to analyses, diet-tissue discrimination factors of Snowy Owl feathers were established in captivity. Variability in isotopic values among feather types was relatively low and pairwise correlations in isotopic values between feathers on the same individual were variable and often low, which suggests differences in the diet at the time when various feathers were synthesized. Diet reconstruction models detected a contribution of marine sources to Snowy Owl feathers ranging from 4% to 19% among feather types. However, the marine contribution was highly variable when single feathers were examined within individuals, ranging from 3% to 71%. This indicated that no single feather type could be used alone to reliably infer the contribution of marine resources to the winter diet of Owls, possibly due to a high variability in the timing and sequence of molt. For asynchronous molters like Snowy Owls, we recommend sampling multiple feathers from various body regions, excluding wing feathers, to investigate winter diet or habitat use. This article is protected by copyright. All rights reserved.
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Is pre-breeding prospecting behaviour affected by snow cover in the irruptive Snowy Owl? A test using state-space modelling and environmental data annotated via Movebank
Movement Ecology, 2015Co-Authors: Jean-françois Therrien, Gilles Gauthier, David Pinaud, Nicolas Lecomte, Keith L Bildstein, Joel BetyAbstract:Background Tracking individual animals using satellite telemetry has improved our understanding of animal movements considerably. Nonetheless, thorough statistical treatment of Argos datasets is often jeopardized by their coarse temporal resolution. State-space modelling can circumvent some of the inherent limitations of Argos datasets, such as the limited temporal resolution of locations and the lack of information pertaining to the behavioural state of the tracked individuals at each location. We coupled state-space modelling with environmental characterisation of modelled locations on a 3-year Argos dataset of 9 breeding Snowy Owls to assess whether searching behaviour for breeding sites was affected by snow cover and depth in an arctic predator that shows a lack of breeding site fidelity. Results The state-space modelling approach allowed the discrimination of two behavioural states (searching and moving) during pre-breeding movements. Tracked Snowy Owls constantly switched from moving to searching behaviour during pre-breeding movements from mid-March to early June. Searching events were more likely where snow cover and depth was low. This suggests that Snowy Owls adapt their searching effort to environmental conditions encountered along their path. Conclusions This modelling technique increases our understanding of movement ecology and behavioural decisions of individual animals both locally and globally according to environmental variables.
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is pre breeding prospecting behaviour affected by snow cover in the irruptive Snowy Owl a test using state space modelling and environmental data annotated via movebank
Movement ecology, 2015Co-Authors: Jean-françois Therrien, Gilles Gauthier, David Pinaud, Nicolas Lecomte, Keith L Bildstein, Joel BetyAbstract:Background: Tracking individual animals using satellite telemetry has improved our understanding of animal movements considerably. Nonetheless, thorough statistical treatment of Argos datasets is often jeopardized by their coarse temporal resolution. State-space modelling can circumvent some of the inherent limitations of Argos datasets, such as the limited temporal resolution of locations and the lack of information pertaining to the behavioural state of the tracked individuals at each location. We coupled state-space modelling with environmental characterisation of modelled locations on a 3-year Argos dataset of 9 breeding Snowy Owls to assess whether searching behaviour for breeding sites was affected by snow cover and depth in an arctic predator that shows a lack of breeding site fidelity. Results: The state-space modelling approach allowed the discrimination of two behavioural states (searching and moving) during pre-breeding movements. Tracked Snowy Owls constantly switched from moving to searching behaviour during pre-breeding movements from mid-March to early June. Searching events were more likely where snow cover and depth was low. This suggests that Snowy Owls adapt their searching effort to environmental conditions encountered along their path.
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Irruptive movements and breeding dispersal of Snowy Owls: a specialized predator exploiting a pulsed resource
Journal of Avian Biology, 2014Co-Authors: Jean-françois Therrien, Gilles Gauthier, David Pinaud, Joel BetyAbstract:Mobility and irruptive movements have been proposed as mechanisms that could allow some diet specialists to inhabit and breed in environments with highly unpredictable resources, like the arctic tundra. Th e Snowy Owl, one of the main avian predators of the tundra, is known to specialize on lemmings during the breeding season. Th ese small mammals are also well known for their tremendous spatial and temporal variations in abundance. We examined the spring (pre-breeding, from March to June) movements of Snowy Owls by tracking 9 breeding females in the Canadian Arctic for up to 3 yr with satellite transmitters. We used state-space modeling to assess searching behavior and measure breeding dispersal distances. We also ascertain lemming abundance at some of the sites used by the marked Owls. Tracked Owls displayed searching movements for extended periods (up to 108 d) and traveled over large distances (up to 4093 km) each spring. Th e distance between furthest apart searching areas in a given year averaged 828 km (range 220 to 2433 km). Settlement date, distance between searching areas, traveled distance and the duration of prospecting movements were longer in the year where density of lemmings recorded in the eastern High-Arctic (Bylot Island) was lowest. Nonetheless, Snowy Owls settled in areas where local lemming abundance was relatively high. Individual breeding dispersal distance between consecutive years averaged 725 km (range 18 to 2224). Overall, the high mobility of female Snowy Owls allowed these diet specialists to behave as irruptive migrants and to sustain their reproductive activities during consecutive years even under highly fl uctuating resources.
V Karpov - One of the best experts on this subject based on the ideXlab platform.
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the breeding biology of dark bellied brent geese branta b bernicla and king eiders somateria spectabilis on the northeastern taimyr peninsula especially in relation to Snowy Owl nyctea scandiaca nests
Wildfowl, 1994Co-Authors: Ron W Summers, Les G Underhill, E E Syroechkovski, H G Lappo, R P Prŷsjones, V KarpovAbstract:It was established that Brent geese nesting in the northeastern Taimyr Peninsula belong to the nominate race Branta bernicla bernicla. Brent Geese and King Eiders were found nesting close to Snowy Owl nests during the lemming peak of 1991. All nested successfully. It is believed that the waterfOwl benefited from the aggressive nature of the Snowy Owls which exclude predators such as Arctic Foxes from hunting close to their nests. This situation was first described for B. b. nigricans which breeds exclusively near Snowy Owl nests on Wrangel Island. As Snowy Owls breed primarily when lemmings are abundant, the Brent Geese on Wrangel Island and the mainland of the northeastern Taimyr Peninsula are indirectly dependent on the lemmings.