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Kurt K. Burnham - One of the best experts on this subject based on the ideXlab platform.
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Timing of breeding and offspring number covary with plumage colour among Gyrfalcons Falco rusticolus
Ibis, 2013Co-Authors: Jeff A Johnson, Kurt K. BurnhamAbstract:Plumage colour variation exists among Gyrfalcons throughout their Arctic and sub-Arctic circumpolar distribution, ranging from white through silver and grey to almost black. Although different colour variants coexist within many populations, a few geographical regions, such as northern Greenland, possess a single variant, suggesting that local environments may influence plumage colour variation. In central-west Greenland (66.5–67.5°N), where multiple colour variants exist, white male Gyrfalcons fathered sig- nificantly earlier clutches than grey males. No significant association was observed between female colour and lay date. However, significantly more offspring were pro- duced by both male and female white Gyrfalcons than by grey variants when controlling for lay date, and silver Gyrfalcons produced an intermediate number of offspring for both sexes. This pattern was further supported by breeding plumage colour pairings. Grey females paired with grey males nested significantly later in the season and produced fewer offspring than those paired with white males, whereas no difference in lay date or offspring number was found between white males paired with white or with grey females. The difference in the number of offspring produced at each nest-site was also inversely correlated with the distance to the nearest neighbouring nest, and grey males nested in closer proximity to other nests compared with white and silver colour variants. These results suggest that factors associated with territory occupancy and timing of breeding may regulate reproductive success differently between colour variants, with directional selection favouring light-coloured Gyrfalcons and resulting in earlier lay date and a high frequency of white plumage colour variants in this population. Although gene flow exists between our study population and those further north (>75°N), white Gyrfal- cons prevail where the breeding season duration is even shorter, suggesting that nesting chronology in combination with genetic drift may play an important role in influencing plumage colour polymorphism among Gyrfalcon populations.
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Genetics of plumage color in the Gyrfalcon (falco rusticolus): Analysis of the melanocortin-1 receptor gene
Journal of Heredity, 2012Co-Authors: Jeff A Johnson, Angie D. Ambers, Kurt K. BurnhamAbstract:Genetic variation at the melanocortin-1 receptor (MC1R) gene is correlated with melanin color variation in a few reported vertebrates. In Gyrfalcon (Falco rusticolus), plumage color variation exists throughout their arctic and subarctic circumpolar distribution, from white to gray and almost black. Multiple color variants do exist within the majority of populations; however, a few areas (e.g., northern Greenland and Iceland) possess a single color variant. Here, we show that the white/melanic color pattern observed in Gyrfalcons is explained by allelic variation at MC1R. Six nucleotide substitutions in MC1R resulted in 9 alleles that differed in geographic frequency with at least 2 MC1R alleles observed in almost all sampled populations in Greenland, Iceland, Canada, and Alaska. In north Greenland, where white Gyrfalcons predominate, a single MC1R allele was observed at high frequency (>98%), whereas in Iceland, where only gray Gyrfalcons are known to breed, 7 alleles were observed. Of the 6 nucleotide substitutions, 3 resulted in amino acid substitutions, one of which (Val128Ile) was perfectly associated with the white/melanic polymorphism. Furthermore, the degree of melanism was correlated with number of MC1R variant alleles, with silver Gyrfalcons all heterozygous and the majority of dark gray individuals homozygous (Ile128). These results provide strong support that MC1R is associated with plumage color in this species.
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Seasonal movements of Gyrfalcons Falco rusticolus include extensive periods at sea
Ibis, 2011Co-Authors: Kurt K. Burnham, Ian NewtonAbstract:Little information exists on the movements of Gyrfalcons Falco rusticolus outside the breeding season, particularly amongst High Arctic populations, with almost all current knowledge based on Low Arctic populations. This study is the first to provide data on summer and winter ranges and migration distances. We highlight a behaviour previously unknown in Gyrfalcons, in which birds winter on sea ice far from land. During 2000– 2004, data were collected from 48 Gyrfalcons tagged with satellite transmitters in three parts of Greenland: Thule (northwest), Kangerlussuaq (central-west) and Scoresbysund (central-east). Breeding home-range size for seven adult females varied from 140 to 1197 km2 and was 489 and 503 km2 for two adult males. Complete outward migrations from breeding to wintering areas were recorded for three individuals: an adult male which travelled 3137 km over a 38-day period (83 km⁄ day) from northern Ellesmere Island to southern Greenland, an adult female which travelled 4234 km from Thule to southern Greenland (via eastern Canada) over an 83-day period (51 km⁄ day), and an adult female which travelled 391 km from Kangerlussuaq to southern Greenland over a 13-day period (30 km⁄ day). Significant differences were found in winter home-range size between Falcons tagged on the west coast (383–6657 km2) and east coast (26 810– 63 647 km2). Several Falcons had no obvious winter home-ranges and travelled continu- ally during the non-breeding period, at times spending up to 40 consecutive days at sea, presumably resting on icebergs and feeding on seabirds. During the winter, one juvenile female travelled over 4548 km over an approximately 200-day period, spending over half that time over the ocean between Greenland and Iceland. These are some of the largest winter home-ranges ever documented in raptors and provide the first documentation of the long-term use of pelagic habitats by any falcon. In general, return migrations were faster than outward ones. This study highlights the importance of sea ice and fjord regions in southwest Greenland as winter habitat for Gyrfalcons, and provides the first detailed insights into the complex and highly variable movement patterns of the species. Keywords: breeding home-range, Greenland, outward migration, return migration, sea ice, winter home-range. The Gyrfalcon Falco rusticolus is the largest falcon and breeds in the circumpolar High Arctic to Sub- arctic zones, some individuals migrating south as far as northern temperate zones during the late *Corresponding author. Email: kburnham@higharctic.org ª 2011 The Authors Ibis ª 2011 British Ornithologists’ Union autumn and winter (Cade 1982, Cade et al.
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Gyrfalcon Falco rusticolus post‐glacial colonization and extreme long‐term use of nest‐sites in Greenland
Ibis, 2009Co-Authors: Kurt K. Burnham, William A. Burnham, Ian NewtonAbstract:Gyrfalcons Falco rusticolus use the same nest-sites over long periods of time, and in the cold dry climate of Greenland, guano and other nest debris decay slowly. Nineteen guano samples and three feathers were collected from 13 Gyrfalcon nests with stratified faecal accumulation in central-west and northwest Greenland. Samples were 14 C dated, with the oldest guano sample dating to c. 2740‐2360 calendar years (cal yr) before present (BP) and three others were probably > 1000 cal yr BP. Feather samples ranged from 670 to 60 cal yr BP. Although the estimated age of material was correlated with sample depth, both sample depth and guano thickness gave a much less reliable prediction of sample age than use of radiocarbon dating on which the margin of error was less. Older samples were obtained from sites farther from the current Greenland Ice Sheet and at higher elevations, while younger samples were closer to the current ice sheet and at lower elevations. Values for d 13 C showed that Gyrfalcons nesting farther from the Greenland Ice Sheet had a more marine diet, whereas those nesting closer to the ice sheet (= further inland) fed on a more terrestrial diet. The duration of nest-site use by Gyrfalcons is a probable indicator of both the time at which colonization occurred and the palaeoenvironmental conditions and patterns of glacial retreat. Nowhere before has such extreme long-term to present use of raptor nest-sites been documented.
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Gyrfalcon falco rusticolus post-glacial colonization and extreme long-term use of nest-sites in Greenland
Ibis, 2009Co-Authors: Kurt K. Burnham, William A. Burnham, Ian NewtonAbstract:Gyrfalcons Falco rusticolus use the same nest-sites over long periods of time, and in the cold dry climate of Greenland, guano and other nest debris decay slowly. Nineteen guano samples and three feathers were collected from 13 Gyrfalcon nests with stratified faecal accumulation in central-west and northwest Greenland. Samples were 14C dated, with the oldest guano sample dating to c. 2740–2360 calendar years (cal yr) before present (BP) and three others were probably > 1000 cal yr BP. Feather samples ranged from 670 to 60 cal yr BP. Although the estimated age of material was correlated with sample depth, both sample depth and guano thickness gave a much less reliable prediction of sample age than use of radiocarbon dating on which the margin of error was less. Older samples were obtained from sites farther from the current Greenland Ice Sheet and at higher elevations, while younger samples were closer to the current ice sheet and at lower elevations. Values for d13C showed that Gyrfalcons nesting farther from the Greenland Ice Sheet had a more marine diet, whereas those nesting closer to the ice sheet (= further inland) fed on a more terrestrial diet. The duration of nest-site use by Gyrfalcons is a probable indicator of both the time at which colonization occurred and the palaeoenvironmental conditions and patterns of glacial retreat. Nowhere before has such extreme long-term to present use of raptor nest-sites been documented.
Travis L. Booms - One of the best experts on this subject based on the ideXlab platform.
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dietary plasticity in a specialist predator the Gyrfalcon falco rusticolus new insights into diet during brood rearing
Journal of Raptor Research, 2019Co-Authors: Bryce W Robinson, Travis L. Booms, Marc J Bechard, David L AndersonAbstract:Climate and landscape change are expected to affect species' distributions and interactions, with potentially harmful consequences for specialist predators. Availability of optimal prey can affect reproductive success in raptors, especially in the Arctic, where dramatic differences in prey availability occur both within and between years. However, behavioral responses of dietary specialist, resident predators such as Gyrfalcons (Falco rusticolus) to changes in prey availability remain poorly understood. To improve understanding of how climate-driven changes in prey availability may affect diet of avian predators in the Arctic, we characterized Gyrfalcon diet on the Seward Peninsula, Alaska, in 2014 and 2015 from images representing 2008 prey items obtained by motion-activated cameras at 20 nests. We documented two important dietary shifts: the proportion of ptarmigan (Willow Ptarmigan [Lagopus lagopus] and Rock Ptarmigan [L. muta]) in the diet declined throughout the brood-rearing period in both years, and also differed between years. In both cases, ptarmigan were replaced by Arctic ground squirrels (Urocitellus parryii) in the diet. Despite shifts in prey composition, dietary breadth did not change, which revealed a facultative shift in prey use in which Gyrfalcons relied on prey of large size rather than prey of a particular taxon. We describe previously undocumented prey-use patterns during Gyrfalcon breeding, specifically an interchange between two prey species that are keystones in tundra ecology. These results are important for informing predictive models of climate change and adaptive species management plans. Further study of the interchange between prey types described in this study can strengthen insight into key ecosystem processes, and the cause and effect of potential decoupling of predator-prey interactions.
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Linking Alaska'S Predicted Climate, Gyrfalcon, and Ptarmigan Distributions in Space and Time: a Unique 200-Year Perspective
Gyrfalcons and ptarmigan in a changing world: proceedings of a conference held February 2011 Boise Idaho. Volume I., 2012Co-Authors: Travis L. Booms, Mari Lindgren, F. HuettmannAbstract:Gyrfalcons (Falco rusticolus), Rock Ptarmigan (Lagopus muta), and Willow Ptarmi- gan (L. lagopus) are quintessential Arctic species that are closely linked within the Arctic ecosys- tem. They likely face similar challenges in the face of rapid changes to their Arctic climate. Gyrfalcons in particular may be most challenged by rapid climate change because of their rela- tively specialized ecological niche, small population size, and K-selected life history strategy. Given this situation, we were interested in predicting how the distribution of these species may change under current climate predictions. Therefore, we modeled the fundamental niche of each species in relation to temperature and precipitation in space and time across 200 years in Alaska (1900-2100). Though the realized niche will ultimately determine where species are distributed in the future, we interpreted our predictions as representing the areas in which environmental con- ditions will allow the species to occur. We were interested in the large-scale, climate-induced trends in expansion, contraction, and overlap of these areas over time. We used the Scenarios Network for Alaska Planning (SNAPs) regionalized/downscaled decadal mean June and December temperature and precipitation predictions from the A1B scenario, and as proposed by the United Nations Intergovernmental Panel on Climate Change (IPCC), to for- ward-model distributions from 2009-2099 in 30-year intervals. We used historical temperature and precipitation measurements from 1900-2006 to backwards-model the distribution of the species' fundamental niche to qualitatively assess forward-modeling predictive accuracy. Forward-models predicted that the fundamental niches of Gyrfalcons and ptarmigan will contract spatially, and backwards-models suggested that they have contracted in the past as Alaska's cli- mate has warmed. Over the 200-year period, the total geographic area over which the species' fundamental niches were predicted to occur decreased overall by 20% (Willow Ptarmigan), 40% (Rock Ptarmigan) and 60% (Gyrfalcon). The distribution of the predicted fundamental niche of each species also became more fragmented, and the percent of spatial overlap between predicted presence of Gyrfalcons and ptarmigan declined over time. These alterations may affect the species' long-term viability and co-evolution and will likely influence important biological processes such as dispersal, genetic diversity, predator-prey dynamics, and basic behavior. Pre- dicted shifts in the geographic distribution of their fundamental niches may have cascading effects on other species, communities, and systems. For science-based, pro-active, adaptive management, we propose to implement findings from this model by testing them further and making spatial models and their predictions an inherent part of the management and legal procedures used to address conservation in the world of rapid Arctic climate change.
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linking alaska s predicted climate Gyrfalcon and ptarmigan distributions in space and time a unique 200 year perspective
Gyrfalcons and Ptarmigan in a Changing World, 2011Co-Authors: Travis L. BoomsAbstract:—Gyrfalcons (Falco rusticolus), rock Ptarmigan (Lagopus muta), and Willow Ptarmigan (L. lagopus) are quintessential Arctic species that are closely linked within the Arctic ecosystem. they likely face similar challenges in the face of rapid changes to their Arctic climate. Gyrfalcons in particular may be most challenged by rapid climate change because of their relatively specialized ecological niche, small population size, and K-selected life history strategy. Given this situation, we were interested in predicting how the distribution of these species may change under current climate predictions. therefore, we modeled the fundamental niche of each species in relation to temperature and precipitation in space and time across 200 years in Alaska (1900-2100). though the realized niche will ultimately determine where species are distributed in the future, we interpreted our predictions as representing the areas in which environmental conditions will allow the species to occur. We were interested in the large-scale, climate-induced trends in expansion, contraction, and overlap of these areas over time. We used the scenarios Network for Alaska Planning (sNAPs) regionalized/downscaled decadal mean June and December temperature and precipitation predictions from the A1b scenario, and as proposed by the United Nations Intergovernmental Panel on climate change (IPcc), to forward-model distributions from 2009-2099 in 30-year intervals. We used historical temperature and precipitation measurements from 1900-2006 to backwards-model the distribution of the species’ fundamental niche to qualitatively assess forward-modeling predictive accuracy. Forward-models predicted that the fundamental niches of Gyrfalcons and ptarmigan will contract spatially, and backwards-models suggested that they have contracted in the past as Alaska’s climate has warmed. Over the 200-year period, the total geographic area over which the species’ fundamental niches were predicted to occur decreased overall by 20% (Willow Ptarmigan), 40% (rock Ptarmigan) and 60% (Gyrfalcon). the distribution of the predicted fundamental niche of each species also became more fragmented, and the percent of spatial overlap between predicted presence of Gyrfalcons and ptarmigan declined over time. these alterations may affect the species’ long-term viability and co-evolution and will likely influence important biological processes such as dispersal, genetic diversity, predator-prey dynamics, and basic behavior. Predicted shifts in the geographic distribution of their fundamental niches may have cascading effects on other species, communities, and systems. For science-based, pro-active, adaptive management, ALAsKA’s NAtUrAL HIstOry was widely driven by the glacial retreat about 11,000 years ago. From then on, beringia spread and retreated to include what is today’s Alaska. Indigenous people affected the landscape (Glavin 2000), but a larger influence was post-contact with outside groups such as the russian colonization, the purchase of the Alaska territory by the United states in 1867, Alaska entering statehood in 1959, and industrial changes during the last 50 years. cumulative landscape modifications that have occurred since statehood are difficult to quantify or measure, but have had a significant effect in some respects, e.g. fragmentation, invasive species, and habitat loss (murphy et al. 2010). Despite Alaska’s reputation for being wild, the last frontier, and carrying endless and well-managed landscapes, it is clear that: a) truly pristine and untouched environments do not exist in times of man-made climate change (turner et al. 2002; chapin et al. 2009), b) Alaska is already dealing with major conservation challenges, including land cover and land use changes, development of natural resources, invasive species, and man-made climate change (symon et al. 2005, Hinzmann et al. 2005), c) climate change will affect Alaska to a greater extent than places of lower latitudes (martin et al. 2009), d) the Intergovernmental Panel on climate change (IPcc) scenarios of future climates have been demonstrated to underestimate rates of change in some systems (stroeve 2007), and e) the global population and Alaska’s urbanization is continuing to rise. the effects of these issues are found across the state and are affecting Gyrfalcons (Falco rusticolus), their prey, and their habitats. Biology of Gyrfalcons.—Gyrfalcons are apex predators that sit at the top of a food chain. therefore, changes in the food chain and habitats upon which this species depends are likely to be evident in these birds. this is especially so because the species breeds only in Arctic and sub-Arctic landscapes and relies heavily on a few prey species. Across Alaska and its circumpolar distribution, the Gyrfalcon is a ptarmigan specialist. Although it can take a diversity of prey species in several combinations and fractions, in nearly all instances ptarmigan makeup the majority of the diet, especially during pair bonding and egg production (booms et al. 2008). Hence, understanding and predicting how ptarmigan have and will adjust to landscape changes is integral to understanding, managing and predicting the response of Gyrfalcons. However, the Gyrfalcon’s reliance on ptarmigan does not necessitate that their spatial distributions and abundances are linear or automatic. buffer mechanisms and delays might exist that may blur the link and render it indirect, as documented in other systems (Watson 2010, Krebs et al. 2001). Biology of Ptarmigan.—Little is known about ptarmigan in Alaska’s landscape because the species has received little research or surveying effort in the state. the distribution and ecological niche of ptarmigan in Alaska and
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developing Gyrfalcon surveys and monitoring for alaska
Gyrfalcons and Ptarmigan in a Changing World, 2011Co-Authors: Mark R Fuller, Philip F. Schempf, Travis L. BoomsAbstract:A BSTRACT .—We developed methods to monitor the status of Gyrfalcons in Alaska. Results of sur veys and monitoring will be informative for resource managers and will be useful for studying potential changes in ecological communities of the high latitudes. We estimated that the proba bility of detecting a Gyrfalcon at an occupied nest site was between 64% and 87% depending on observer experience and aircraft type (fixed wing or helicopter). The probability of detection is an important factor for estimating occupancy of nesting areas, and occupancy can be used as a metric for monitoring species’ status. We conclude that surveys of nesting habitat to monitor occu pancy during the breeding season are practical because of the high probability of seeing a Gyr falcon from aircraft. Aerial surveys are effective for searching sample plots or index areas in the expanse of the Alaskan terrain. Furthermore, several species of cliff-nesting birds can be surveyed concurrently from aircraft. Occupancy estimation also can be applied using data from other field search methods (e.g., from boats) that have proven useful in Alaska. We believe a coordinated broad-scale, inter-agency, collaborative approach is necessary in Alaska. Monitoring can be facil itated by collating and archiving each set of results in a secure universal repository to allow for statewide meta-analysis. Received 16 September 2011, accepted 10 November 2011. F
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Nest-Site Fidelity and Dispersal of Gyrfalcons Estimated by Noninvasive Genetic Sampling
The Condor, 2011Co-Authors: Travis L. Booms, George K Sage, Brian J. Mccaffery, Sandra L. Talbot, K. G. Mccracken, Philip F. SchempfAbstract:We used feathers from adult Gyrfalcons (Falco rusticolus) molted in breeding territories and blood samples from nestlings to document nest-site fidelity and dispersal of breeding adults and juveniles at three areas 100 350 km apart in Yukon Delta National Wildlife Refuge, Alaska, 20032007. We used genotypes from seven polymor- phic microsatellite loci that provided a mean probability of identity of 0.91 105. Breeding Gyrfalcons were highly faith- ful to study area and territory; we documented no dispersals of breeding birds among study areas and only one dispersal between territories. But their fidelity to nest sites was low; 22% of birds returned to the same nest site the following year. Distance among alternate nests within a territory averaged 750 m and was similar for both sexes. Mean tenure in a terri- tory was 2.8 years, similar for both sexes, and distributed bimodally with peaks at 1 and 4 years. Mean annual turnover rate at the Ingakslugwat Hills (Volcanoes) study area was 20%. We detected three young that established breeding ter- ritories at distances ranging from 0 to 254 km from their natal territory, representing 2.5% apparent recruitment. Gyr- falcons in the Askinuk Mountains study area were slightly but statistically significantly differentiated genetically from those in the Volcanoes and Kilbuck Mountain study areas. These data are the first published on the nest-site fidelity, breeding dispersal, and natal dispersal of the Gyrfalcon in North America and demonstrate the utility of noninvasive genetic sampling to greatly improve our understanding of avian dispersal and its underlying mechanisms.
Jeff A Johnson - One of the best experts on this subject based on the ideXlab platform.
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Timing of breeding and offspring number covary with plumage colour among Gyrfalcons Falco rusticolus
Ibis, 2013Co-Authors: Jeff A Johnson, Kurt K. BurnhamAbstract:Plumage colour variation exists among Gyrfalcons throughout their Arctic and sub-Arctic circumpolar distribution, ranging from white through silver and grey to almost black. Although different colour variants coexist within many populations, a few geographical regions, such as northern Greenland, possess a single variant, suggesting that local environments may influence plumage colour variation. In central-west Greenland (66.5–67.5°N), where multiple colour variants exist, white male Gyrfalcons fathered sig- nificantly earlier clutches than grey males. No significant association was observed between female colour and lay date. However, significantly more offspring were pro- duced by both male and female white Gyrfalcons than by grey variants when controlling for lay date, and silver Gyrfalcons produced an intermediate number of offspring for both sexes. This pattern was further supported by breeding plumage colour pairings. Grey females paired with grey males nested significantly later in the season and produced fewer offspring than those paired with white males, whereas no difference in lay date or offspring number was found between white males paired with white or with grey females. The difference in the number of offspring produced at each nest-site was also inversely correlated with the distance to the nearest neighbouring nest, and grey males nested in closer proximity to other nests compared with white and silver colour variants. These results suggest that factors associated with territory occupancy and timing of breeding may regulate reproductive success differently between colour variants, with directional selection favouring light-coloured Gyrfalcons and resulting in earlier lay date and a high frequency of white plumage colour variants in this population. Although gene flow exists between our study population and those further north (>75°N), white Gyrfal- cons prevail where the breeding season duration is even shorter, suggesting that nesting chronology in combination with genetic drift may play an important role in influencing plumage colour polymorphism among Gyrfalcon populations.
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Genetics of plumage color in the Gyrfalcon (falco rusticolus): Analysis of the melanocortin-1 receptor gene
Journal of Heredity, 2012Co-Authors: Jeff A Johnson, Angie D. Ambers, Kurt K. BurnhamAbstract:Genetic variation at the melanocortin-1 receptor (MC1R) gene is correlated with melanin color variation in a few reported vertebrates. In Gyrfalcon (Falco rusticolus), plumage color variation exists throughout their arctic and subarctic circumpolar distribution, from white to gray and almost black. Multiple color variants do exist within the majority of populations; however, a few areas (e.g., northern Greenland and Iceland) possess a single color variant. Here, we show that the white/melanic color pattern observed in Gyrfalcons is explained by allelic variation at MC1R. Six nucleotide substitutions in MC1R resulted in 9 alleles that differed in geographic frequency with at least 2 MC1R alleles observed in almost all sampled populations in Greenland, Iceland, Canada, and Alaska. In north Greenland, where white Gyrfalcons predominate, a single MC1R allele was observed at high frequency (>98%), whereas in Iceland, where only gray Gyrfalcons are known to breed, 7 alleles were observed. Of the 6 nucleotide substitutions, 3 resulted in amino acid substitutions, one of which (Val128Ile) was perfectly associated with the white/melanic polymorphism. Furthermore, the degree of melanism was correlated with number of MC1R variant alleles, with silver Gyrfalcons all heterozygous and the majority of dark gray individuals homozygous (Ile128). These results provide strong support that MC1R is associated with plumage color in this species.
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Population Differentiation and Adaptive Selection on Plumage Color Distributions in Gyrfalcons.
Gyrfalcons and Ptarmigan in a Changing World, 2011Co-Authors: Jeff A JohnsonAbstract:—Extensive plumage color variation exists among Gyrfalcons (Falco rusticolus) throughout their circumpolar distribution, from white to silver, grey to brown and almost black. Multiple color variants do exist within some populations at differing frequencies; however, a few geographic locations possess a single predominate color variant. In northern Greenland and the high Arctic Canadian islands (>75°N), white Gyrfalcons prevail with the majority of adults possessing little if no barring on the retrices. Further south in western Greenland (66.5–67.5°N), silver and grey Gyrfalcons are also observed, whereas, in Iceland and some Eurasian populations, grey and dark grey to brown Gyrfalcons dominate, respectively. The above color pattern distributions are largely supported by population genetic differentiation measures based on neutral markers (i.e., microsatellite loci) identifying significant subdivision between Greenland and Iceland relative to other surveyed populations in north central Canada, Alaska, and Norway. In fact, within Greenland, asymmetric north to south dispersal patterns have been identified with genetic data. These distributional color patterns are also explained by allelic frequency distributions of the melanocortin-1 receptor (MC1R) gene, which has been identified as an important gene associated with hair and plumage color in some vertebrates. In Gyrfalcons, the white/melanic polymorphism in MC1R is perfectly associated with a fixed nonsynonymous point substitution. A single MC1R allele was observed in northern Greenland among white individuals, whereas further south an additional four alleles were observed among non-white individuals. Multiple MC1R alleles, including the “white” allele, were also observed in Canada, Alaska, and Iceland. However, no homozygous individuals for the “white” allele were observed in Iceland. Clearly, a significant geographic pattern exists relative to plumage color, and its distribution is supported by genetics. Multiple hypotheses are proposed to explain these patterns, such as directional selection based on crypsis and thermoregulation; however, ultimate mechanisms remain equivocal and require further study. These findings have important implications regarding a population’s response to its environment and climate may be an important factor regulating Greenland Gyrfalcon plumage color distributions. To what extent similar patterns exist elsewhere in the species’ distribution with regard to plumage color and reproduction is not known. Received 1 March 2011, accepted 25 July
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Genetic structure among continental and island populations of Gyrfalcons\rdoi:10.1111/j.1365-294X.2007.03373.x
Molecular Ecology, 2007Co-Authors: Jeff A Johnson, Kurt K. Burnham, William A. Burnham, David P MindellAbstract:Abstract Little is known about the possible influence that past glacial events have had on the phylogeography and population structure of avian predators in the Arctic and sub-Arctic. In this study, we use microsatellite and mitochondrial control region DNA variation to investigate the population genetic structure of Gyrfalcons (Falco rusticolus) throughout a large portion of their circumpolar distribution. In most locations sampled, the mtDNA data revealed little geographic structure; however, five out of eight mtDNA haplotypes were unique to a particular geographic area (Greenland, Iceland, or Alaska) and the Iceland population differed from others based on haplotype frequency differences (FST). With the microsatellite results, significant population structure (FST, principal components analysis, and cluster analysis) was observed identifying Greenland and Iceland as separate populations, while Norway, Alaska and Canada were identified as a single population consistent with contemporary gene flow across Russia. Within Greenland, differing levels of gene flow between western and eastern sampling locations was indicated with apparent asymmetric dispersal in western Greenland from north to south. This dispersal bias is in agreement with the distribution of plumage colour variants with white Gyrfalcons in much higher proportion in northern Greenland. Lastly, because the mtDNA control region sequence differed by only one to four nucleotides from a common haplotype among all Gyrfalcons, we infer that the observed microsatellite population genetic structure has developed since the last glacial maximum. This conclusion is further supported by our finding that a closely related species, the saker falcon (Falco cherrug), has greater genetic heterogeneity, including mtDNA haplotypes differing by 1-16 nucleotide substitutions from a common Gyrfalcon haplotype. This is consistent with Gyrfalcons having expanded rapidly from a single glacial-age refugium to their current circumpolar distribution. Additional sampling of Gyrfalcons from Fennoscandia and Russia throughout Siberia is necessary to test putative gene flow between Norway and Alaska and Canada as suggested by this study.
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Genetic structure among continental and island populations of Gyrfalcons
Molecular Ecology, 2007Co-Authors: Jeff A Johnson, Kurt K. Burnham, William A. Burnham, David P MindellAbstract:Little is known about the possible influence that past glacial events have had on the phylogeography and population structure of avian predators in the Arctic and sub-Arctic. In this study, we use microsatellite and mitochondrial control region DNA variation to investigate the population genetic structure of Gyrfalcons (Falco rusticolus) throughout a large portion of their circumpolar distribution. In most locations sampled, the mtDNA data revealed little geographic structure; however, five out of eight mtDNA haplotypes were unique to a particular geographic area (Greenland, Iceland, or Alaska) and the Iceland population differed from others based on haplotype frequency differences (F(ST)). With the microsatellite results, significant population structure (F(ST), principal components analysis, and cluster analysis) was observed identifying Greenland and Iceland as separate populations, while Norway, Alaska and Canada were identified as a single population consistent with contemporary gene flow across Russia. Within Greenland, differing levels of gene flow between western and eastern sampling locations was indicated with apparent asymmetric dispersal in western Greenland from north to south. This dispersal bias is in agreement with the distribution of plumage colour variants with white Gyrfalcons in much higher proportion in northern Greenland. Lastly, because the mtDNA control region sequence differed by only one to four nucleotides from a common haplotype among all Gyrfalcons, we infer that the observed microsatellite population genetic structure has developed since the last glacial maximum. This conclusion is further supported by our finding that a closely related species, the saker falcon (Falco cherrug), has greater genetic heterogeneity, including mtDNA haplotypes differing by 1-16 nucleotide substitutions from a common Gyrfalcon haplotype. This is consistent with Gyrfalcons having expanded rapidly from a single glacial-age refugium to their current circumpolar distribution. Additional sampling of Gyrfalcons from Fennoscandia and Russia throughout Siberia is necessary to test putative gene flow between Norway and Alaska and Canada as suggested by this study.
Ian Newton - One of the best experts on this subject based on the ideXlab platform.
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Seasonal movements of Gyrfalcons Falco rusticolus include extensive periods at sea
Ibis, 2011Co-Authors: Kurt K. Burnham, Ian NewtonAbstract:Little information exists on the movements of Gyrfalcons Falco rusticolus outside the breeding season, particularly amongst High Arctic populations, with almost all current knowledge based on Low Arctic populations. This study is the first to provide data on summer and winter ranges and migration distances. We highlight a behaviour previously unknown in Gyrfalcons, in which birds winter on sea ice far from land. During 2000– 2004, data were collected from 48 Gyrfalcons tagged with satellite transmitters in three parts of Greenland: Thule (northwest), Kangerlussuaq (central-west) and Scoresbysund (central-east). Breeding home-range size for seven adult females varied from 140 to 1197 km2 and was 489 and 503 km2 for two adult males. Complete outward migrations from breeding to wintering areas were recorded for three individuals: an adult male which travelled 3137 km over a 38-day period (83 km⁄ day) from northern Ellesmere Island to southern Greenland, an adult female which travelled 4234 km from Thule to southern Greenland (via eastern Canada) over an 83-day period (51 km⁄ day), and an adult female which travelled 391 km from Kangerlussuaq to southern Greenland over a 13-day period (30 km⁄ day). Significant differences were found in winter home-range size between Falcons tagged on the west coast (383–6657 km2) and east coast (26 810– 63 647 km2). Several Falcons had no obvious winter home-ranges and travelled continu- ally during the non-breeding period, at times spending up to 40 consecutive days at sea, presumably resting on icebergs and feeding on seabirds. During the winter, one juvenile female travelled over 4548 km over an approximately 200-day period, spending over half that time over the ocean between Greenland and Iceland. These are some of the largest winter home-ranges ever documented in raptors and provide the first documentation of the long-term use of pelagic habitats by any falcon. In general, return migrations were faster than outward ones. This study highlights the importance of sea ice and fjord regions in southwest Greenland as winter habitat for Gyrfalcons, and provides the first detailed insights into the complex and highly variable movement patterns of the species. Keywords: breeding home-range, Greenland, outward migration, return migration, sea ice, winter home-range. The Gyrfalcon Falco rusticolus is the largest falcon and breeds in the circumpolar High Arctic to Sub- arctic zones, some individuals migrating south as far as northern temperate zones during the late *Corresponding author. Email: kburnham@higharctic.org ª 2011 The Authors Ibis ª 2011 British Ornithologists’ Union autumn and winter (Cade 1982, Cade et al.
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Gyrfalcon Falco rusticolus post‐glacial colonization and extreme long‐term use of nest‐sites in Greenland
Ibis, 2009Co-Authors: Kurt K. Burnham, William A. Burnham, Ian NewtonAbstract:Gyrfalcons Falco rusticolus use the same nest-sites over long periods of time, and in the cold dry climate of Greenland, guano and other nest debris decay slowly. Nineteen guano samples and three feathers were collected from 13 Gyrfalcon nests with stratified faecal accumulation in central-west and northwest Greenland. Samples were 14 C dated, with the oldest guano sample dating to c. 2740‐2360 calendar years (cal yr) before present (BP) and three others were probably > 1000 cal yr BP. Feather samples ranged from 670 to 60 cal yr BP. Although the estimated age of material was correlated with sample depth, both sample depth and guano thickness gave a much less reliable prediction of sample age than use of radiocarbon dating on which the margin of error was less. Older samples were obtained from sites farther from the current Greenland Ice Sheet and at higher elevations, while younger samples were closer to the current ice sheet and at lower elevations. Values for d 13 C showed that Gyrfalcons nesting farther from the Greenland Ice Sheet had a more marine diet, whereas those nesting closer to the ice sheet (= further inland) fed on a more terrestrial diet. The duration of nest-site use by Gyrfalcons is a probable indicator of both the time at which colonization occurred and the palaeoenvironmental conditions and patterns of glacial retreat. Nowhere before has such extreme long-term to present use of raptor nest-sites been documented.
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Gyrfalcon falco rusticolus post-glacial colonization and extreme long-term use of nest-sites in Greenland
Ibis, 2009Co-Authors: Kurt K. Burnham, William A. Burnham, Ian NewtonAbstract:Gyrfalcons Falco rusticolus use the same nest-sites over long periods of time, and in the cold dry climate of Greenland, guano and other nest debris decay slowly. Nineteen guano samples and three feathers were collected from 13 Gyrfalcon nests with stratified faecal accumulation in central-west and northwest Greenland. Samples were 14C dated, with the oldest guano sample dating to c. 2740–2360 calendar years (cal yr) before present (BP) and three others were probably > 1000 cal yr BP. Feather samples ranged from 670 to 60 cal yr BP. Although the estimated age of material was correlated with sample depth, both sample depth and guano thickness gave a much less reliable prediction of sample age than use of radiocarbon dating on which the margin of error was less. Older samples were obtained from sites farther from the current Greenland Ice Sheet and at higher elevations, while younger samples were closer to the current ice sheet and at lower elevations. Values for d13C showed that Gyrfalcons nesting farther from the Greenland Ice Sheet had a more marine diet, whereas those nesting closer to the ice sheet (= further inland) fed on a more terrestrial diet. The duration of nest-site use by Gyrfalcons is a probable indicator of both the time at which colonization occurred and the palaeoenvironmental conditions and patterns of glacial retreat. Nowhere before has such extreme long-term to present use of raptor nest-sites been documented.
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Occurrence of Mesocestoides canislagopodis (Rudolphi, 1810) (Krabbe, 1865) in mammals and birds in Iceland and its molecular discrimination within the Mesocestoides species complex
Parasitology Research, 2016Co-Authors: Karl Skirnisson, Damien Jouet, Hubert Ferté, O K NielsenAbstract:The life cycle of Mesocestoides tapeworms (Cestoda: Cyclophyllidea: Mesocestoididae) requires three hosts. The first intermediate host is unknown but believed to be an arthropod. The second intermediate host is a vertebrate. The primary definitive host is a carnivore mammal, or a bird of prey, that eats the tetrathyridium-infected second intermediate host. One representative of the genus, Mesocestoides canislagopodis, has been reported from Iceland. It is common in the arctic fox (Vulpes lagopus) and has also been detected in domestic dogs (Canis familiaris) and cats (Felis domestica). Recently, scolices of a non-maturing Mesocestoides sp. have also been detected in Gyrfalcon (Falco rusticolus) intestines, and tetrathyridia in the body cavity of rock ptarmigan (Lagopus muta). We examined the taxonomic relationship of Mesocestoides from arctic fox, Gyrfalcon, and rock ptarmigan using molecular methods, both at the generic level (D1 domain LSU ribosomal DNA) and at the specific level (cytochrome c oxidase subunit I (COI) and 12S mitochondrial DNA). All stages belonged to Mesocestoides canislagopodis. Phylogenetic analysis of the combined 12S-COI at the specific level confirmed that M. canislagopodis forms a distinct clade, well separated from three other recognized representatives of the genus, M. litteratus, M. lineatus, and M. corti/vogae. This is the first molecular description of this species. The rock ptarmigan is a new second intermediate host record, and the Gyrfalcon a new primary definitive host record. However, the adult stage seemed not to be able to mature in the Gyrfalcon, and successful development is probably restricted to mammalian hosts.
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Population cycles in rock ptarmigan Lagopus muta: modelling and parameter estimation
Natural History, 2004Co-Authors: Kjartan G Magnússon, Jenný Brynjarsdóttir, O K NielsenAbstract:We have modelled population change of rock ptarmigan using data from spring censuses and age ratios (spring and late summer) from a study area in north-east Iceland 1981 - 2004. Modelling of mortality rates has shown a significant time trend (increasing) for mortality of adult birds (Z2 ), but not for excess fall and winter mortality of juvenile birds (ZX,W ). The juvenile mortality rate ZX,W has though changed in a cyclic way peaking 2 - 4 years after the peak in ptarmigan numbers. The model fits the abundance data well and projections give rise to cyclic behaviour with an 11 -12 year period provided the adult mortality rate is not too high. Higher adults mortality values result in damped oscillations. Sensitivity test, excluding two outliers, improved the model fit. Two delayed density dependent factors emerge from the model to explain the cyclic behaviour in the ptarmigan population: (a) Excess juvenile fall and winter mortality rates, lagging ptarmigan population by 2 - 4 years. (b) Negative impact of population size on chick production, lag 2 years. Gyrfalcon, being a resident specialized predator, fits predictions for the ptarmigan cycle to be generated by predation as the falcons show a phase shift longer than one-quarter of the ptarmigan cycle, also there is significant relation between excess juvenile fall and winter mortality rates and falcon numbers. Our thesis is that the primary mechanism for the ptarmigan cycle is winter predation by Gyrfalcons on first-year birds giving rise to the delayed density response (a). In addition the second delayed density response (b), the late summer Gyrfalcon predation on hens and subsequent total loss of their broods, is implicitly accounted for by the model.
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Gyrfalcon predation on ptarmigan: Numerical and functional responses
Journal of Animal Ecology, 1999Co-Authors: O K NielsenAbstract:1. Gyrfalcon predation on ptarmigan during the breeding season was studied in north-east Iceland 1981±97. The ptarmigan population went through a complete 10-year cycle of numbers with a 4´3-fold dierence in density between high and low years. The yearly number of occupied Gyrfalcon territories was correlated with ptarmigan density with a 3-year time-lag. Total falcon numbers in late summer (territorial adults + ¯edglings) showed a 2-year lag with ptarmigan numbers. Variability in falcon density was signi®cantly less than that of ptarmigan. It is sug-gested that the factors contributing to the time-lag between the two populations are the year-round residency of falcons on nesting territories, and late maturity (2-to 4-year-old). Mean brood size and the proportion of the territorial falcon popula-tion breeding successfully showed no relation to ptarmigan numbers. 2. Ptarmigan density in spring was an important factor determining composition and variability in the diet of Gyrfalcons during the breeding season. Alternative prey for falcons included waterfowl, alcids and waders. Adult ptarmigan featured highly in Gyrfalcon diet in all years. The functional response curve to changes in ptarmigan density was slightly convex or close to linear and showed relatively little change in the average number of ptarmigan killed per individual predator over the range of ptarmigan densities observed. 3. The impact of Gyrfalcon predation on the ptarmigan population and ptarmigan density was in opposite phases, and the predation rate peaked during the decline and the low phase of the ptarmigan cycle. This suggests that Gyrfalcons accelerate decline, accentuate the amplitude and aect the length of the low phase of the ptar-migan cycle. The following factors seem to promote the destabilizing eects of pre-dation by Gyrfalcons: they are resident specialist predators, they show a delayed numerical response to changes in ptarmigan density and a high utilization of this prey at all phases of the ptarmigan cycle.
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Falco rusticolus Gyrfalcon
BWP Update, 1998Co-Authors: Tom J. Cade, Pasi Koskimies, O K NielsenAbstract:The information in this update draws heavily on Icelandic Scandinavian, Finnish, and Russian sources (>100 citations), as well as on recent American and Canadian publications. Since 1980 research on the Gyrfalcon in the western Palearctic has increased greatly, especially in Iceland (O K Nielsen), Norway (P J Tommeraas and associates), Sweden (U Falkdalen and associates in Projekt Jaktfalk), and Finland (P Koskimies). Much new work has also been accomplished in the Nearctic, but unfortunately fresh data from Greenland and Russia lag far behind. The main recent findings and interpretations follow: field characters have been clarified to emphasize differences in appearance and flight behaviour between Gyrfalcons and other similar species. In most parts of the range, habitat associations are closely tied to the occurrence of Willow Grouse Lagopus lagopus and Ptarmigan L. mutus, the chief prey species of this predominantly resident arctic raptor. Its overall distribution has not changed significantly in the 20th century. Much new information on Gyrfalcon populations, especially in Iceland and Fennoscandia, indicates that although, in many parts of the range, breeding pairs fluctuate markedly in number in 4- or 10-year cycles-or sometimes irregularly-there has been little long-term change in overall population size in the last >50 years; however, there is evidence from Lapland that breeding density was much reduced around the turn of the last century, probably owing mainly to habitat changes and consequent reduction in Lagopus populations, secondarily to human persecution. Conservation should emphasize habitat restoration for grouse and other prey species, preservation of traditional eyries, and protection from human disturbance and persecution. Most Gyrfalcons specialize on Lagopus spp. for food summer and winter (60-90% of diet), but some, especially in the high Arctic, specialize on other prey such as Little Auks Alle alle, lemmings Lemmus and Dicrostonyx, and Arctic Hare Lepus arcticus. Gyrfalcons show both functional and numerical responses to changes in grouse density. Gyrfalcons more often use the stick nest of Ravens Corvus corax on cliffs or trees than any other nesting sites; tree-nesting Gyrfalcons in the Russian Arctic have been reported to refurbish old stick nests of other species for their own use. Breeding success depends more on spring weather than on food supply. Survival statistics are still meagre, and much research is needed. Body mass (weight) normally varies in individuals by as much as 250-500 g depending on sex and state of nutrition; males usually fall between 1000 and 1400 g, females between 1250 and 2000 g. The term 'morph' has been incorrectly applied to the Gyrfalcon's continuous variation in plumage from the whitest to darkest individuals. DNA and cross-breeding experiments show that the Gyrfalcon is most closely related to the Saker Falco cherrug and likely conspecific with it.
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Population fluctuations of Gyrfalcon and rock ptarmigan: analysis of export figures from Iceland
Wildlife Biology, 1995Co-Authors: O K Nielsen, Gunlagur PetrussonAbstract:We analysed harvest data for Gyrfalcon Falco rusticolus and rock ptarmigan Lagopus mutus from Iceland with respect to regularity in fluctuations of numbers. The Gyrfalcon data concerned live trapped birds exported to Denmark between 1731 and 1793, and totalled 4,848 falcons, including 4,318 grey, 156 half-white and 374 white colour morphs. According to contemporary sources grey birds were part of the local breeding population (islandus-type birds) but the other morphs represented mainly visitors from Greenland. This is also the current situation but some of the lightest Icelandic breeders could be classified as half-white. The rock ptarmigan harvest data concerned birds exported to Europe in the period 1864-1919, in total ca 3.3 million birds. The data series for white and half-white Gyrfalcons were significantly correlated (r = 0.501, p < 0.001). The data series for grey and white morphs (r = -0.099, P = 0.445) and grey and the half-white morphs (r = -0.1183, P = 0.360), showed no correlation. Time series analysis showed that the white (candicans-type) morph fluctuated irregularly. The half-white morph behaved similarly but also showed some affinity with the grey morph, and could have represented a mixture of local breeders and Greenlandic winter visitors. Grey morph Gyrfalcons and rock ptarmigan showed regular fluctuations in numbers with a 10-year periodicity. The reliance of Icelandic Gyrfalcons on rock ptarmigan during the early part of the breeding season and in all phases of the ptarmigan cycle is well established and may offer a case for causal connections between the two cyclic populations.