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Z. A. Zorina - One of the best experts on this subject based on the ideXlab platform.
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Do Great Grey Owls Comprehend Means-end Relationships?
International Journal of Comparative Psychology, 2013Co-Authors: T. A. Obozova, Z. A. ZorinaAbstract:Cognitive abilities of the Great Grey Owl (Strix nebulosa) were tested with a means–end problem. Owls were presented the single baited string task and the string discrimination task. Our results suggest that Owls failed to comprehend the physics underlying the object relationships involved in the tasks presented A� common� way� to� assess� animal’s� comprehension� of� means –end paradigm is to offer them tasks which could be solved promptly and without previous learning. In order to assess this capacity the so-called string-pulling paradigm is widely used, in which an animal has to get the remote bait to which a string is attached.
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Do Great Grey Owls Comprehend Means–end Relationships? - eScholarship
International Journal of Comparative Psychology, 2013Co-Authors: T. A. Obozova, Z. A. ZorinaAbstract:Cognitive abilities of the Great Grey Owl (Strix nebulosa) were tested with a means–end problem. Owls were presented the single baited string task and the string discrimination task. Our results suggest that Owls failed to comprehend the physics underlying the object relationships involved in the tasks presented
T. A. Obozova - One of the best experts on this subject based on the ideXlab platform.
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Do Great Grey Owls Comprehend Means-end Relationships?
International Journal of Comparative Psychology, 2013Co-Authors: T. A. Obozova, Z. A. ZorinaAbstract:Cognitive abilities of the Great Grey Owl (Strix nebulosa) were tested with a means–end problem. Owls were presented the single baited string task and the string discrimination task. Our results suggest that Owls failed to comprehend the physics underlying the object relationships involved in the tasks presented A� common� way� to� assess� animal’s� comprehension� of� means –end paradigm is to offer them tasks which could be solved promptly and without previous learning. In order to assess this capacity the so-called string-pulling paradigm is widely used, in which an animal has to get the remote bait to which a string is attached.
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Do Great Grey Owls Comprehend Means–end Relationships? - eScholarship
International Journal of Comparative Psychology, 2013Co-Authors: T. A. Obozova, Z. A. ZorinaAbstract:Cognitive abilities of the Great Grey Owl (Strix nebulosa) were tested with a means–end problem. Owls were presented the single baited string task and the string discrimination task. Our results suggest that Owls failed to comprehend the physics underlying the object relationships involved in the tasks presented
Solheim Roar - One of the best experts on this subject based on the ideXlab platform.
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Molt stage, wing bar patterns and digital photography as tools for assessing age distribution and recognizing individuals of Great Grey and Snowy Owls
2020Co-Authors: Solheim RoarAbstract:The world is heating up. The climate is changing, with increasing temperature changes towards the Arctic. Northern ecosystems of tundra and taiga are subject to changes, even in the most remote areas void of human presence. One of the most profound characteristics of these northern ecosystems are the cyclic changes in population size of mammals, birds and insects, small microtine rodents being the central species in the dynamics. Several studies have demonstrated that the cyclicity of lemmings and voles have changed during the recent decades, with consequences for many other species of the food webs. Changes in the cyclicity of lemmings and voles are especially expected to influence their predators. All arctic and boreal Owl species hunt microtine rodents, and species like the Snowy Owl and the Great Grey Owl are totally dependent on such prey animals to breed. The Snowy Owl is listed as a vulnerable species worldwide, while the Great Grey Owl is considered to have a stable world population. The population of Snowy Owls breeding in Fennoscandia has declined while the Great Grey Owl recently has expanded its breeding distribution. Small mammal hunters like the Snowy Owl and the Great Grey Owl are directly influenced by changes in the cyclicity of microtines. The difference in population development of these two vole hunters in Fennoscandia enhance the importance of monitoring both species under a regime of expected future changes of ecosystem cyclisity. KnOwledge of population size, reproduction and survival, and the age structure of populations are paramount information in such monitoring because reproduction and mortality varies with age. Moult patterns are essential for aging many birds. In species where juvenile and adult feathers look different, such differences can be used for aging a bird when it is captured for banding. In this thesis I present a method for aging Great Grey Owls and Snowy Owls based on the moult patterns in their wings. I have demonstrated the difference between the first juvenile wing feathers and later adult wing feathers, and that it takes three to four years for an Owl to replace all juvenile wing feathers. As long as at least one juvenile wing feather is left in the wing, the number of moults and the age of the Owl can usually be determined. I have further developed a method for individual identification of Great Grey Owls and Snowy Owls based on bar patterns of their wing feathers. I have shown that it is possible to use photographs of free flying Owls for aging and identification of individuals. Identification based on visible characters is a long established and used technique in studies on mammals, but has hitherto not been used on free flying birds. Using photographs in such studies is a non-invasive technique which may enhance the amount of data available in population studies of birds. I have used these techniques in three studies on Snowy Owls and Great Grey Owls. Snowy Owls were photographed along transect routes during a summer invasion on Beliy Island north of the Yamal Peninsula in Russia in July 2015. A minimum of 25 Owls were identified, sexed and aged by studying the moult and bar patterns of their wings from photos of Owls in flight. The moult patterns showed that 80% of the Owls were hatched in 2012-14. Results from Norwegian satellite studies of Snowy Owls showed that 12 adult Owls which bred in Norway in 2011 spent the summers 2012-14 along the Russian Arctic. This implies that Snowy Owls must have bred successfully in these parts of the Russian Arctic in 2012-14. An expanding population of Great Grey Owls was studied in Hedmark county, south-eastern Norway in 2009-2018, when the number of recorded nestings rose from 1 to 119. Adult breeding Owls were captured for banding or control, and their wings were photographed for moult analyses and aging. Birds which could not be captured were photographed in flight. The photographic method increased the amount of birds which could be aged, and especially the amount of males which may be more reluctant to approach intruders at the nest site, and thus avoid capture. In 2011 no less than 77% of the recorded breeding Great Grey Owls were young birds hatched the previous year. Control of two nesting Great Grey Owls banded as nestlings in Sweden in 2010 indicated that good reproduction in mid-central Sweden in 2010 followed by natal dispersal of young birds was the foundation of the breeding population in Hedmark. I have demonstrated that data gathered through public sciences can be used to age Great Grey Owls when they hunt in open landscapes outside the breeding range during a vole depression year. More than 4000 reports of Great Grey Owls were received through the national species archives in Norway and Sweden in 2012, the majority of data derived from Sweden. Slightly more than 800 of these reports were accompanied by photo(s) of the Owl, and of these 323 could be used to age the bird. The number of individuals was reduced to 144 by the ID number of localities, because one Owl may be reported by different observers. Wing and tail feathers showed that at least 76% of all the Great Grey Owls reported in 2012 were juvenile birds hatched in 2011. This demonstrated that also 2011 was a good reproduction year of Great Grey Owls in south Scandinavia.Det blir varmere. Klimaet er i endring, og endringene gir størst utslag på nordlige breddegrader. Økosystemene i tundra og taiga-sonene er dermed også gjenstand for endringer, selv i fjerntliggende områder hvor mennesker sjeldent ferdes. Ett av særtrekkene ved disse nordlige økosystemene er regelmessige svigninger i bestandene av både pattedyr, fugler og insekter, med smågnagere som sentrale nøkkelarter i dynamikken. Flere studier har vist endringer i syklisiteten til smågnagere de siste tiårene, med konsekvenser for mange arter i næringsnettet. I første rekke forventes endringer i smågnagernes syklisitet å påvirke smågnagerjegere. Alle arktiske og boreale uglearter jakter smågnagere, og arter som snøugle og lappugle er helt avhengige av disse byttedyrene for å kunne hekke. Snøugla er listet som sårbar på verdensbasis, mens verdensbestanden av lappugle er klassifisert som stabil. I Fennoscandia har hekkeutbredelse og bestandsstørrelse for snøugle avtatt, mens lappugla nylig har ekspandert som hekkefugl. Som smågnagerjegere er snøugle og lappugle direkte påvirket av smågnagersvigningene. Forskjellen i bestandsutvikling for disse to smågnagerspesialistene i Fennoscandia gjør det spesielt interessant å overvåke deres bestandsutvikling i lys av eventuelle endringer i smågnagernes syklisitet. Slik overvåking krever kunnskap om artenes bestandstørrelse, reproduksjon og overlevelse, og kjennskap til aldersstruktur i en bestand er fundamental informasjon, siden reproduksjon og dødelighet varierer med individenes alder. Mytemønstre er essensiell kunnskap for å kunne aldersbestemme mange fugler. Hos arter hvor juvenile og adulte fjær er forskjellige kan dette brukes for å aldersbestemme fugler fanget for ringmerking. I denne avhandlingen presenterer jeg en metode for å kunne aldersbestemme lappugler og snøugler basert på mytemønster i fuglenes vinger. Jeg har vist hvordan forskjeller på fuglenes første sett av juvenile vingefjær skiller seg fra neste sett av adulte vingefjær, og at det tar tre til fire år før alle juvenile vingefjær er skiftet ut. Så lenge noen juvenile fjær fremdeles er tilbake i vingene, er det som regel mulig å se hvor mange fjærskifter fuglene har gjennomgått siden de ble klekket, og dermed også bestemme fuglens alder. Jeg har også vist hvordan flekkmønster i fuglenes vingefjær kan brukes til å gjenkjenne individer og å skille mellom forskjellige fugler. Ved hjelp av fotografier av lappugler og snøugler i flukt er det også mulig å foreta aldersbestemmelse og identifikasjon av frittflyvende ugler uten å fange dem inn. Slik individgjenkjenning uten innfanging og merking har lenge vært benyttet på pattedyr, men har tidligere ikke blitt brukt på frittflyvende fugler. Bruk av fotografering for å gjenkjenne eller skille mellom individer representerer en ikke-invasiv teknikk som også kan øke mengden av data i bestandsstudier av fugler. Metodene for aldersbestemmelse og individgjenkjenning har blitt anvendt i tre ulike studier av snøugle og lappugle. Under en sommerinvasjon av snøugler på Beliy øya nord for Yamalhalvøya i Russland i juli 2015, ble så mange snøugler som mulig fotografert langs fire takseringsruter på tundraen. Ved å sammenligne flekkmønster i uglenes vinger ble et minimum på 25 ugler identifisert for kjønns- og aldersbestemmelse. Mytemønster i vingene viste at 80% av fuglene var klekket i årene 2012-14. Sammenholdt med bevegelsene hos 12 voksne snøugler som ble satellittmerket på hekkeplass i Norge i 2011 viste materialet at det må ha funnet sted vellykket hekking flere steder langs arktisk tundra i Russland i flere av årene 2012-14. Bestanden av hekkende lappugler ble fulgt i Hedmark fra 2009-2018, da antallet hekkefugler økte fra ett par til 119 par i 2017. Voksne hekkefugler ble fanget inn for ringmerking eller kontroll, og deres vinger ble fotografert for aldersbestemmelse ved hjelp av mytemønster i vingene. Fugler som ikke lot seg fange ble forsøkt fotografert i flukt. Dette økte mengden tilgjengelig materiale, spesielt for hanner som er vanskeligere å fange på reirplass enn hunner. Året 2011 med 22 hekkefunn skilte seg ut, da hele 77% av hekkefuglene var ungfugler klekket i 2010. Aldersbestemmelse og gjenfunn av fugler ringmerket som reirunger i midt-Sverige viste at lappuglenes etablering av en hekkefuglbestand i Hedmark skyldes spredning av ungfugler etter et godt hekkeår i Sverige i 2010. I det siste studiet har jeg vist hvordan opplysninger samlet inn av publikum (public sciences) kan anvendes for å aldersbestemme lappugler når de jakter i åpent landskap under et smågnagerbunnår. I løpet av 2012 ble mer enn 4000 enkeltrapporter om snøugler lagt inn i artsdatabanken, hovedsakelig i Sverige. Litt over 800 av rapportene var ledsaget av bilder av den observerte lappugla, hvorav 323 kunne brukes til å aldersbestemme fuglen. Ved hjelp av lokalitetenes ID-numre ble antallet lappugleindivider redusert til 144 fugler. Aldersbestemmelse ved hjelp av fjær viste at minst 76% av fuglene var ungfugler klekket i 2011, noe som viste at også dette året var et godt reproduksjonsår for lappugler i Sør-Skandinavia
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Molt stage, wing bar patterns and digital photography as tools for assessing age distribution and recognizing individuals of Great Grey and Snowy Owls
2020Co-Authors: Solheim RoarAbstract:The world is heating up. The climate is changing, with increasing temperature changes towards the Arctic. Northern ecosystems of tundra and taiga are subject to changes, even in the most remote areas void of human presence. One of the most profound characteristics of these northern ecosystems are the cyclic changes in population size of mammals, birds and insects, small microtine rodents being the central species in the dynamics. Several studies have demonstrated that the cyclicity of lemmings and voles have changed during the recent decades, with consequences for many other species of the food webs. Changes in the cyclicity of lemmings and voles are especially expected to influence their predators. All arctic and boreal Owl species hunt microtine rodents, and species like the Snowy Owl and the Great Grey Owl are totally dependent on such prey animals to breed. The Snowy Owl is listed as a vulnerable species worldwide, while the Great Grey Owl is considered to have a stable world population. The population of Snowy Owls breeding in Fennoscandia has declined while the Great Grey Owl recently has expanded its breeding distribution. Small mammal hunters like the Snowy Owl and the Great Grey Owl are directly influenced by changes in the cyclicity of microtines. The difference in population development of these two vole hunters in Fennoscandia enhance the importance of monitoring both species under a regime of expected future changes of ecosystem cyclisity. KnOwledge of population size, reproduction and survival, and the age structure of populations are paramount information in such monitoring because reproduction and mortality varies with age. Moult patterns are essential for aging many birds. In species where juvenile and adult feathers look different, such differences can be used for aging a bird when it is captured for banding. In this thesis I present a method for aging Great Grey Owls and Snowy Owls based on the moult patterns in their wings. I have demonstrated the difference between the first juvenile wing feathers and later adult wing feathers, and that it takes three to four years for an Owl to replace all juvenile wing feathers. As long as at least one juvenile wing feather is left in the wing, the number of moults and the age of the Owl can usually be determined. I have further developed a method for individual identification of Great Grey Owls and Snowy Owls based on bar patterns of their wing feathers. I have shown that it is possible to use photographs of free flying Owls for aging and identification of individuals. Identification based on visible characters is a long established and used technique in studies on mammals, but has hitherto not been used on free flying birds. Using photographs in such studies is a non-invasive technique which may enhance the amount of data available in population studies of birds. I have used these techniques in three studies on Snowy Owls and Great Grey Owls. Snowy Owls were photographed along transect routes during a summer invasion on Beliy Island north of the Yamal Peninsula in Russia in July 2015. A minimum of 25 Owls were identified, sexed and aged by studying the moult and bar patterns of their wings from photos of Owls in flight. The moult patterns showed that 80% of the Owls were hatched in 2012-14. Results from Norwegian satellite studies of Snowy Owls showed that 12 adult Owls which bred in Norway in 2011 spent the summers 2012-14 along the Russian Arctic. This implies that Snowy Owls must have bred successfully in these parts of the Russian Arctic in 2012-14. An expanding population of Great Grey Owls was studied in Hedmark county, south-eastern Norway in 2009-2018, when the number of recorded nestings rose from 1 to 119. Adult breeding Owls were captured for banding or control, and their wings were photographed for moult analyses and aging. Birds which could not be captured were photographed in flight. The photographic method increased the amount of birds which could be aged, and especially the amount of males which may be more reluctant to approach intruders at the nest site, and thus avoid capture. In 2011 no less than 77% of the recorded breeding Great Grey Owls were young birds hatched the previous year. Control of two nesting Great Grey Owls banded as nestlings in Sweden in 2010 indicated that good reproduction in mid-central Sweden in 2010 followed by natal dispersal of young birds was the foundation of the breeding population in Hedmark. I have demonstrated that data gathered through public sciences can be used to age Great Grey Owls when they hunt in open landscapes outside the breeding range during a vole depression year. More than 4000 reports of Great Grey Owls were received through the national species archives in Norway and Sweden in 2012, the majority of data derived from Sweden. Slightly more than 800 of these reports were accompanied by photo(s) of the Owl, and of these 323 could be used to age the bird. The number of individuals was reduced to 144 by the ID number of localities, because one Owl may be reported by different observers. Wing and tail feathers showed that at least 76% of all the Great Grey Owls reported in 2012 were juvenile birds hatched in 2011. This demonstrated that also 2011 was a good reproduction year of Great Grey Owls in south Scandinavia
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Age of Great Grey Owls Strix nebulosa observed in Scandinavia in 2012 as revealed by digital photos in the national species report archives.
Sveriges ornitologiska förening, 2014Co-Authors: Solheim RoarAbstract:Record breaking numbers of breeding Great Grey Owls Strix nebulosa were reported in Sweden and Norway in 2010 and 2011, followed by 4105 observations in 2012 as revealed by the national Species archives. Based on locality id numbers, at least 144 individuals were reported with photos which could be used to age the individuals. The majority (76%) of these birds were young birds hatched in 2011 (83% including birds aged probably 2CY). Among dead Owls brought to the Natural History Museum in Stockholm, the percentages of Owls hatched in 2011 were similar (78% and 88%). The high percentage of young Owls could be caused by young birds hunting closer to human settlement than older birds, but more likely it was caused by a higher total production of young in south-central Scandinavia in 2011 than in 2010. This study shows that photos in the national species archives reveal the age structure of the Great Grey Owl population, fundamental data to understand the current distributional expansion of this species. This method may also be applied to other species.publishedVersionnivå
Trond Berg - One of the best experts on this subject based on the ideXlab platform.
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Age structure in a newly established and increasing population: initially high proportion of young birds among nesting Great Grey Owls.
Journal of Ornithology, 2020Co-Authors: Geir A. Sonerud, Roar Solheim, Trond BergAbstract:The mechanisms behind expansions of the distribution of a bird species and the ensuing establishment of new populations are poorly known. The distribution of Great Grey Owl (Strix nebulosa) in the western Palearctic has generally expanded towards southwest during the past fifty years, and particularly so in Fennoscandia. In the past decade, the recorded breeding population in Norway, confined to Hedmark county bordering Sweden, increased from 1 pair in 2009 to > 100 pairs in 2017–2018, extending the southwestern border of the distribution > 100 km. We studied the age structure of this expanding population based on the molting pattern of the wing feathers of birds captured at the nest site for banding and of non-captured birds photographed in flight. In Fennoscandia the Great Grey Owl relies on shrews and microtine rodents, which usually fluctuate in 3–4 years cycles. The proportion of 1-year old birds among the nesting Great Grey Owls was higher in peak year two of each small mammal population cycle (2011, 2014 and 2018) than in peak year one (2010, 2013 and 2017), and was particularly high (77%) in 2011 when the Owl population was far lower (22 nestings recorded) than in later corresponding years (64 nestings in 2014 and 103 in 2018). Thus, this population seems to have been founded to a large extent by birds nesting as 1 year olds, and most likely having dispersed from Sweden. The ability to determine the age of Great Grey Owls without having to capture them extended our data set, in particular for males, which are more reluctant to attack intruders at the nest site and, therefore, less likely to be captured for banding. Being able to age a bird without having to capture it is important, because trapping does not sample a bird population randomly.
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Age structure in a newly established and increasing population: initially high proportion of young birds among nesting Great Grey Owls
Journal of Ornithology, 2020Co-Authors: Geir A. Sonerud, Roar Solheim, Trond BergAbstract:Altersstruktur in einer neu entstandenen und wachsenden Population: anfänglich hoher Anteil an Jungvögeln bei brütenden Bartkäuzen Die Mechanismen hinter der zunehmenden Verbreitung einer Vogelart und der damit einhergehenden Etablierung neuer Populationen sind kaum bekannt. Die Verbreitung des Bartkauzes (Strix nebulosa) in der Westpaläarktis hat sich in den letzten fünfzig Jahren allgemein nach Südwesten ausgedehnt, vor allem in Fennoskandien. In den letzten zehn Jahren nahm die erfasste Brutpopulation in Norwegen, die auf den an Schweden angrenzenden Bezirk Hedmark beschränkt war, von einem Paar in 2009 auf >100 Paare in 2017-2018 zu, was zu einer zunehmenden Verbreitung der südwestlichen Grenze um >100 km führte. Wir untersuchten die Altersstruktur dieser zunehmenden Population basierend auf dem Mausermuster der Flügelfedern der Vögel, die am Nistplatz zur Beringung gefangen wurden, und nicht gefangenen Individuen, die im Flug fotografiert wurden. In Fennoskandien ist der Bartkauz auf Spitz- und Wühlmäuse angewiesen, dessen Bestände gewöhnlich in Zyklen von 3-4 Jahren schwanken. Der Anteil der einjährigen Bartkäuze innerhalb der brütenden Population war im zweiten Spitzenjahr der Zyklen jeder Kleinsäugerpopulation (2011, 2014 und 2018) höher als im ersten Spitzenjahr (2010, 2013 und 2017). Im Jahr 2011 war der Anteil an Einjährigen besonders hoch (77%), obwohl die Bartkauzpopulation viel kleiner war (22 Nester erfasst) als in den späteren entsprechenden Jahren (64 Nester in 2014 und 103 in 2018). Somit scheint diese Population vor allem von Vögeln gegründet worden zu sein, die als einjährige Vögel brüteten und sich höchstwahrscheinlich von Schweden aus ausgebreitet haben. Die Möglichkeit, das Alter von Bartkäuzen zu bestimmen, ohne diese fangen zu müssen, hat unseren Datensatz insbesondere bei den Männchen erweitert, die eher Eindringlinge am Nistplatz durch Angriffe zurückhalten und daher mit geringerer Wahrscheinlichkeit bei der Beringung gefangen werden. Die Altersbestimmung eines Vogels, ohne diesen fangen zu müssen, ist bedeutend, da ein Fang zu keiner zufälligen Stichprobe der Vogelpopulation führt. The mechanisms behind expansions of the distribution of a bird species and the ensuing establishment of new populations are poorly known. The distribution of Great Grey Owl ( Strix nebulosa ) in the western Palearctic has generally expanded towards southwest during the past fifty years, and particularly so in Fennoscandia. In the past decade, the recorded breeding population in Norway, confined to Hedmark county bordering Sweden, increased from 1 pair in 2009 to > 100 pairs in 2017–2018, extending the southwestern border of the distribution > 100 km. We studied the age structure of this expanding population based on the molting pattern of the wing feathers of birds captured at the nest site for banding and of non-captured birds photographed in flight. In Fennoscandia the Great Grey Owl relies on shrews and microtine rodents, which usually fluctuate in 3–4 years cycles. The proportion of 1-year old birds among the nesting Great Grey Owls was higher in peak year two of each small mammal population cycle (2011, 2014 and 2018) than in peak year one (2010, 2013 and 2017), and was particularly high (77%) in 2011 when the Owl population was far lower (22 nestings recorded) than in later corresponding years (64 nestings in 2014 and 103 in 2018). Thus, this population seems to have been founded to a large extent by birds nesting as 1 year olds, and most likely having dispersed from Sweden. The ability to determine the age of Great Grey Owls without having to capture them extended our data set, in particular for males, which are more reluctant to attack intruders at the nest site and, therefore, less likely to be captured for banding. Being able to age a bird without having to capture it is important, because trapping does not sample a bird population randomly.
Ivar Mysterud - One of the best experts on this subject based on the ideXlab platform.
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range extensions of some boreal Owl species comments on snow cover ice crusts and climate change
Arctic Antarctic and Alpine Research, 2016Co-Authors: Ivar MysterudAbstract:Recent observations have documented that some boreal Owl species in Europe have made unexpected eruptive movements and some have extended their distribution, among them the Great Grey Owl (Strix nebulosa). Based on published data, it can be assumed that both the numbers and distribution have varied considerably in the past 120 years. In the Finnish population, for example, there has been a clear southward shift in range— from Lapland toward the central and eastern regions (Sulkava and Huhtala, 1997). In Sweden, the Great Grey Owl is distributed throughout the boreal zone but is most frequently found in the northeasternmost parts of the country (Hipkiss et al., 2008). In 2010–2012, the species was found nesting in unprecedented numbers in southeastern Norway (Solheim, 2009, 2014a). Record-breaking numbers of breeding individuals were reported in Sweden and Norway in 2010 and 2011, followed by 4105 observations in 2012 as revealed by the National Species Archives in Sweden (Solheim, 2014b). In the first half of the last century, the species was known as a rare breeder only in northernmost Norway (i.e., in Pasvik, Finnmark) (Hagen, 1989; Sulkava and Huhtala, 1997). Today it is a regular breeder over a considerable part of the southeast forested area in the country (Solheim, 2014b). Other extensions have been noted as well. In 2007–2009, the species was found in Belarus near the Polish border, southwest of its regular breeding grounds, and the species recently has been visiting many other areas (Ławicki et al., 2013). Rapid range extensions and population movements are so marked that they indicate a large-scale ecological change. Is it caused by climate change and global warming?
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Range Extensions of Some Boreal Owl Species: Comments on Snow Cover, Ice Crusts, and Climate Change
Arctic Antarctic and Alpine Research, 2016Co-Authors: Ivar MysterudAbstract:Recent observations have documented that some boreal Owl species in Europe have made unexpected eruptive movements and some have extended their distribution, among them the Great Grey Owl (Strix ne...
