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Gauthier, G., Doyle, F. I., Gilg, O., Menyushina, I. E., Morrison, R. I. G., Ovsyanikov, N., Pokrovsky, I., Reid, D. G., Sokolov, A. and Therrien, J.-F. (2011). Birds of prey. Bachelor's thesis, , .
Abstract: Arctic predatory birds are a diverse group that includes raptors (falcons, hawks, eagles and owls) and tundra seabirds (jaegers and gulls). Many species show irruptive behaviour, which makes it difficult to assess population trends and possible range expansion or contraction. A few species such as the peregrine falcon in North America and Russia, the short-eared owl in Nunavut, the great skua in Greenland and the parasitic jaeger in Greenland and the Russian Far East have nonetheless shown recent range expansion and/or population increase. In contrast, there is evidence that populations of the gyrfalcon in the Yukon North Slope and some parts of Russia, the snowy owl in Europe and the Russian Far East and the pomarine jaeger in the Russian Far East may have recently declined. Population cycles of lemmings and voles have a strong impact on the local abundance and reproduction of most avian predators. However, this varies according to the degree of specialisation of predatory birds on small mammals and among sites. Snowy owls showed the strongest response to fluctuations in small mammal abundance. Rough-legged hawks and long-tailed jaegers also showed a strong response at some sites but not at others such as in northern Yukon and in some parts of Siberia. Intensive studies on Bylot Island showed that avian predators consume a very high proportion of the annual lemming production and could regulate the abundance of collared lemmings during the snow-free period. Satellite-tracking of snowy owls in North America allowed us to measure the scale of their annual movements. Female owls moved over long distances between consecutive breeding seasons (from 18 to 2224 km) and always settled and bred in areas where lemmings were abundant. Most owls attempted to breed every year in far apart areas, which confirms that when small mammals crash in an area, owls will not forego breeding but will rather move over long distances to find suitable breeding conditions (i.e. high small mammal populations). During winter, most female owls remained in the Arctic (north of 55° of latitude) but, surprisingly, they extensively used the sea ice for up to 101 days in the Eastern Canadian Arctic. Birds of prey are top predators and could act as indicator species for the tundra ecosystem. Climate induced changes such as increase in shrub abundance, shift in the distribution of small mammal species or collapse of lemming population cycles in some areas could negatively impact the populations of several birds of prey. An additional source of concern in some areas is illegal killing or trapping for trade. The new links revealed by our study between the terrestrial and marine ecosystems also suggest that some populations of predators such as the snowy owl may be supported by the marine ecosystem in winter. Therefore, a broader, cross-ecosystem perspective may be required when assessing the status or threats faced by these predators. Monitoring of avian predators should not only provide information on the status of their populations but also on the health of the whole Arctic ecosystem
– In: Gauthier, G. and Berteaux, D. (eds.),
Final synthesis report. Centre d’études nordiques, Université Laval, pp. 62-75.
Programme: 1036
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Richard, Y. (2012). Détermination du statut parasitaire de trois populations de lemming à collier en relation avec leurs densités.
Abstract: Les fluctuations cycliques d’abondance, que présentent certaines populations, sont des phénomènes d’un grand intérêt en biologie. Etudiés chez différentes espèces, au niveau théorique principalement, ces cycles peuvent être induits par différents facteurs. Le parasitisme est l’un d’eux. Mais a l’inverse de certains, tel que la prédation, ce facteurs est relativement peu étudié, surtout en population naturel. Le lemming à collier, Dicrostonyx groenlandicus, suivi depuis de nombreuses années par Gilg et al., est connu pour présenter de telles fluctuations cycliques sur une période de quatre à cinq ans et est ainsi un modèle d’étude d’intérêt. Ainsi en utilisant une méthode par flottaison, pour la première fois appliquée à des fèces de lemmings produit en hiver, nous allons déterminer le statut parasitaire de trois populations groenlandaises de ce rongeur et essayer de relier celui-ci à ses variations de densité. Il s’avère que ces lemmings sont infectés par des Cestodes et des Eimeria. De plus, les variations observées au niveau du nombre moyen de parasites par hôte et de leur prévalence sont principalement dues à des différences entre population, plus qu’à un effet de la densité d’hôte. La poursuite de cette étude à plus long terme, ainsi que des analyses complémentaires par des méthodes de biologie moléculaire sont nécessaires pour une identification précise des différents parasites et l’établissement certain des résultats que nous avons obtenus.
Programme: 1036
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Aurélien Royer, Sophie Montuire, Olivier Gilg, Véronique Laroulandie. (2019). A taphonomic investigation of small vertebrate accumulations produced by the snowy owl (Bubo scandiacus) and its implications for fossil studies (Vol. 514).
Abstract: The action of predators, such as diurnal raptors, owls, mammals or humans, influence the nature of small vertebrate fossil assemblages but currently their taphonomic features are still poorly understood. In this study, we investigate the taphonomic signature of the snowy owl (Bubo scandiacus) based on an analysis of pellets collected at breeding sites located in Greenland and the Canadian Arctic. This taxon is widely distributed through the North Hemisphere and was an important predator in Pleistocene times. Taphonomic parameters suggest that, contrary to previous assumptions, B. scandiacus produces, on average, moderate digestion of incisors, molars and post-cranial elements, and should be classed as a Category 3 or Category 3/4 predator according to the terminology established by Andrews. Significant inter-site variability was observed for some of the damage considered (in particular, digestion on incisors), and a key finding is that variability and the associated statistical confidence intervals are crucial notions that should be taken into account when assessing taphonomical features, in order to reliably identify the potential predator(s) responsible for small vertebrate fossil accumulations.
Keywords: Birds Digestion Lemming Modern owl pellets Paleoenvironmental reconstruction Predation Taphonomy
Programme: 1036
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Gilg, O. (2015). The Impact of Climate change on the Arctic fauna and flora.
Abstract: Ocean & Science Days, Road to COP21 Paris Climate 2015, Paris, France, 30 November 2015.
Programme: 1036
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Perroud, L. (2014). Étude des stratégies de soins parentaux des limicoles en région arctique : le cas du bécasseau sanderling (Calidris alba)..
Abstract: Presents the methods and provides the scripts to be used for the standardized analyses of the TinyTag measurments (to assess the fate and breeding stategies of wader nests)
Programme: 1036
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Wynn, R. B., D. Brown, G. Thomas, C. A. Holt, S. A. Hanssen, B. Moe, and O. Gilg. (2014). Spring migration routes of Long-tailed Skuas around and across the UK – results of observational and tracking data. Br. Birds, 107, 220–228.
Abstract: In 2013 a record spring passage of Long-tailed Skuas Stercorarius
longicaudus was observed in Scotland, including an unprecedented overland
movement. Tracking data for the species has also hinted at overland migration in
Scotland. Here, the tracking data are reviewed and the spring passage status of
Long-tailed Skuas in the UK assessed, with a particular focus on observed overland
movements, and first-hand accounts of major movements in spring 2013
Programme: 1036
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Schmidt, N. M., O. Gilg, J. Aars, and R. A. Ims. (2014). Fat, furry and flexible – characteristics of mammals living in the Arctic (in “Arctic Ecology” edited by David N. Thomas, Wiley-Blackwell Ed.).
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Barraquand Frédéric, Høye Toke T, Henden John-André, Yoccoz Nigel G, Gilg Olivier, Schmidt Niels M, Sittler Benoît, Ims Rolf A, . (2014). Demographic responses of a site-faithful and territorial predator to its fluctuating prey: long-tailed skuas and arctic lemmings
. Journal of Animal Ecology, 83(2), 375–387.
Abstract: 1. Environmental variability, through interannual variation in food availability or climatic variables, is usually detrimental to population growth. It can even select for constancy in key life-history traits, though some exceptions are known. Changes in the level of environmental variability are therefore important to predict population growth or life-history evolution. Recently, several cyclic vole and lemming populations have shown large dynamical changes that might affect the demography or life-histories of rodent predators.
2. Skuas constitute an important case study among rodent predators, because of their strongly saturating breeding productivity (they lay only two eggs) and high degree of site fidelity, in which they differ from nomadic predators raising large broods in good rodent years. This suggests that they cannot capitalize on lemming peaks to the same extent as nomadic predators and might be more vulnerable to collapses of rodent cycles.
3. We develop a model for the population dynamics of long-tailed skuas feeding on lemmings to assess the demographic consequences of such variable and non-stationary prey dynamics, based on data collected in NE Greenland. The model shows that populations of long-tailed skua sustain well changes in lemming dynamics, including temporary collapses (e.g. 10 years). A high floater-to-breeder ratio emerges from rigid territorial behaviour and a long-life expectancy, which buffers the impact of adult abundance’s decrease on the population reproductive output.
4. The size of the floater compartment is affected by changes in both mean and coefficient of variation of lemming densities (but not cycle amplitude and periodicity per se). In Greenland, the average lemming density is below the threshold density required for successful breeding (including during normally cyclic periods). Due to Jensen’s inequality, skuas therefore benefit from lemming variability; a positive effect of environmental variation.
5. Long-tailed skua populations are strongly adapted to fluctuating lemming populations, an instance of demographic lability in the reproduction rate. They are also little affected by poor lemming periods, if there are enough floaters, or juveniles disperse to neighbouring populations. The status of Greenland skua populations therefore strongly depends upon floater numbers and juvenile movements, which are not known. This reveals a need to intensify colour-ringing efforts on the long-tailed skua at a circumpolar scale.
Keywords: demographic buffering, environmental variance, floaters, population cycles, territoriality,
Programme: 1036
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Gilg, O. (2014). Oiseaux (in “Groenland à découvert”, CNRS éd.).
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Rob S. A. van Bemmelen, Yann Kolbeinsson, Raül Ramos, Olivier Gilg, José A. Alves, Malcolm Smith, Hans Schekkerman, Aleksi Lehikoinen, Ib Krag Petersen, Böðvar Þórisson, Aleksandr A. Sokolov, Kaisa Välimäki, Tim van der Meer, J. David Okill, Mark Bolton, Børge Moe, Sveinn Are Hanssen, Loïc Bollache, Aevar Petersen, Sverrir Thorstensen, Jacob González-Solís, Raymond H. G. Klaassen, Ingrid Tulp. (2019). A Migratory Divide Among Red-Necked Phalaropes in the Western Palearctic Reveals Contrasting Migration and Wintering Movement Strategies (Vol. 7).
Abstract: Non-breeding movement strategies of migratory birds may be expected to be flexibly adjusted to the distribution and quality of habitat, but only few studies compare movement strategies between populations using distinct migration routes and wintering areas. In thisour study, individual movement strategies of Rred-necked pPhalaropes Phalaropus lobatus, a long-distance migratory wader using saline waters in the non-breeding period, were studied using light-level geolocators. Results revealed the existence of two populations with distinct migration routes and wintering areas: one breeding in the north-eastern North Atlantic and migrating ca. 10,000 km oversea to the tropical eastern Pacific Ocean and the other breeding in Fennoscandia and Russia migrating ca. 6,000 km – largely over land – to the Arabian Sea (Indian Ocean). In line with our expectations, the transoceanic migration between the North Atlantic and the Pacific was associated with proportionately longer wings, a more even spread of stopovers in autumn and a higher migration speed in spring compared to the migration between Fennoscandian-Russian breeding grounds and the Arabian Sea. In the wintering period, birds wintering in the Pacific were stationaryresided in roughly a singlethe same area, whereas individuals wintering in the Arabian Sea showed individually consistent movementsd extensively between different areas, reflecting differences in spatio-temporal variation in primary productivity between the two wintering areas. Our study is unique in showing how habitat distribution shapes movement strategies over the entire non-breeding period within a species.
Keywords: Flexibility Itineracy Migration strategy Phalaropus lobatus plasticity Red-necked Phalarope
Programme: 1036
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