120 results on '"Singh, Navinder J."'
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102. Toward a mechanistic understanding of animal migration: incorporating physiological measurements in the study of animal movement
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Jachowski, David S., primary and Singh, Navinder J., additional
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- 2015
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103. Animal-habitat relationships in high altitude rangelands
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Singh, Navinder J., Yoccoz, Nigel G., and Fox, Joseph L.
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VDP::Matematikk og naturvitenskap: 400::Zoologiske og botaniske fag: 480 ,VDP::Mathematics and natural science: 400::Zoology and botany: 480 - Abstract
The papers of the thesis are not available in Munin: 1. Navinder J Singh, Nigel G Yoccoz, Nicolas Lecomte, Steeve D Côté and Joseph L Fox: «Scale and selection of habitat and resources: Tibetan argali in high altitude rangelands» (manuscript). Published version, Can. J. Zool. 88: 436-447 (2010), available at http://dx.doi.org/10.1139/Z10-015 2. Navinder J Singh, Christophe Bonenfant, Nigel G Yoccoz and Steeve D Côté: «Proximate and ultimate causes of sexual segregation in eurasian wildsheep, the Tibetan argali (Ovis ammon hodgsoni)» (manuscript). Later published (with altered title) in Behavioral Ecology, 2010, 21(2):410-418, available at http://dx.doi.org/10.1093/beheco/arp205 3. Navinder J Singh, Nigel G Yoccoz, Yash Veer Bhatnagar and Joseph L Fox: «Using resource selection functions to sample rare species in high-altitude ecosystems: a case study with Tibetan argali» (manuscript). Later published (with altered title) in Biodiversity and Conservation, Volume 18, Number 11, October 2009, available at http://dx.doi.org/10.1007/s10531-009-9615-5 4. Navinder J Singh, Joseph L Fox, Yash Veer Bhatnagar, Nicolas Lecomte and Nigel G Yoccoz: «Changing nomadic pastorialism in transhimalyan rangelands of India - causes and consequences» (manuscript). 5. Singh, N.J., Bhatnagar, Y.V., Yoccoz, N.G. and Fox, J L: «Assessing wildlife-livestock interaction in Indian transhimalya: Tibetan argali as a case study» (manuscript) 6. Navinder J. Singh, Joseph L. Fox and Yash Veer Bhatnagar: «Tibetan argali in India, Nepal and the western Tibet autonomous region, China», chapter in Richard P Reading (Ed): «Argali biology and conservation», Denver Zoological Foundation (In press). This study conducted in the high altitude rangelands of Indian Transhimalaya, deals with basic questions regarding the ecology of an endangered species, the wildsheep Tibetan argali (Ovis ammon hodgsoni) and applied issues related to its conservation and potential conflict with the local nomadic pastoralists. The basic questions on ecology are aimed at delineating the habitat and resource selection processes, identifying factors causing sexual segregation and efficient surveying and sampling. The applied aspect focuses on the changing face of pastoralism and the potential impacts of modernising livestock husbandry on argali. Overall, the study provides a general framework towards the understanding of argali-habitat relationships at different spatio-temporal scales. The spatial determinant associated with altitude in the area, predicts argali habitat and resource selection in this relatively homogenous landscape. These determine the range of other topographic variables and forage characteristics selected by argali. The selection of feeding patches in the selected range of altitude and topography is mainly characterised by their greenness and the quality of plant groups. Adjusting to changing forage quality, argali display an opportunistic feeding strategy, selecting grasses in early spring and switching to forbs later in summer. Nevertheless, the habitat selection process did not appear to differ among the sexes to drive sexual segregation. There was, however, strong segregation among the sexes as well as between lactating and non lactating females. The reasons for segregation appeared to be predominantly social, but driven ultimately by predation and concomitantly by resources. The habitat selection information was used to design a stratified random sampling strategy that led to i) a significant reduction in survey effort in sampling these sparsely distributed species and ii) reduction in sampling bias. The applied aspect of the study outlines and evaluates the dramatic changes in the nomadic pastoralism that have occurred in the past five decades in the study area. These have led to a loss of pastures (-25 to -33%) of the nomads, consequent readjustment in traditional patterns of pasture use, intensified grazing pressures (25 to 70%) and rangeland degradation in the area. Such changes may have serious consequences on the survival of local wildlife, as tested with a study of the effects on argali of livestock presence and resource exploitation. Hence, a successful conservation and recovery strategy should focus on: minimising the impacts of livestock on argali, identifying the factors affecting the persistence of the current populations, increasing local sub populations of this species to prevent extinction due to stochastic events, prevent loss of genetic diversity and excessive fragmentation and thus ensuring gene flow. Ecological Niche Factor Analyses (ENFA), bias-reduced logistic regression and Fuzzy correspondence analyses (FCA) were used to answer habitat and resource selection questions. A sexual segregation and aggregation statistic (SSAS) was used to estimate the components of sexual segregation and test segregation. SSAS combined with canonical correspondence analyses (CCA) allowed the estimation of segregation based on habitat variables. Logistic regression models were formulated to estimate models on which the stratified random sampling strategy was based. The Animal - Habitat relationships in high altitude rangelands overall study also included surveys, interviews and literature reviews to understand the nomads’ movement and pasture use patterns of their livestock. Kernel density estimations (KDE) were used to estimate extent of range overlaps between livestock and argali.
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- 2008
104. Habitat-performance relationships of a large mammal on a predator-free island dominated by humans.
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Allen, Andrew M., Dorey, Augusta, Malmsten, Jonas, Edenius, Lars, Ericsson, Göran, and Singh, Navinder J.
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HABITAT selection ,PARTURITION ,POPULATION dynamics ,MAMMAL reproduction - Abstract
The demographic consequences of changes in habitat use driven by human modification of landscape, and/or changes in climate, are important for any species. We investigated habitat-performance relationships in a declining island population of a large mammal, the moose ( Alces alces), in an environment that is predator-free but dominated by humans. We used a combination of demographic data, knowledge of habitat selection, and multiannual movement data of female moose ( n = 17) to understand how space use patterns affect fecundity and calf survival. The calving rate was 0.64 and was similar to calving rates reported in other populations. Calf survival was 0.22 (annually) and 0.32 (postsummer), which are particularly low compared to other populations where postsummer survival is typically above 0.7. Home ranges were mainly composed of arable land (>40%), and selection for arable land was higher in winter than in summer, which contrasts with previous studies. Females that spent more time in broadleaf forest in the summer prior to the rut had higher fecundity rates, while more time spent in arable land resulted in lower fecundity rates. Females that spent more time in thicket/scrubland habitats during winter had lower calf survival, while females that had higher use of mixed forests tended to have higher calf survival. The dominance, and subsequent use, of suboptimal foraging habitats may lead to poor body condition of females at parturition, which may lower calf body weights and affect the mother's ability to lactate. In addition, our results indicated that the growing season has advanced significantly in recent decades, which may be causing a mismatch between parturition and optimal resource availability. These effects may exacerbate the female's ability to meet the energetic demands of lactation. Therefore, the observed low calf survival appears to be caused by a combination of factors related to current land use and may also be due to changing vegetation phenology. These results have important implications for the management of species in human-dominated landscapes in the face of climate change, and for an increased understanding of how species may adapt to future land use and climate change. [ABSTRACT FROM AUTHOR]
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- 2017
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105. Changing motivations during migration: linking movement speed to reproductive status in a migratory large mammal
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Singh, Navinder J., primary and Ericsson, Göran, additional
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- 2014
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106. Partial Migration and Transient Coexistence of Migrants and Residents in Animal Populations
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Singh, Navinder J., primary and Leonardsson, Kjell, additional
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- 2014
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107. Biodiversity offsets in theory and practice
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Bull, Joseph W., primary, Suttle, K. Blake, additional, Gordon, Ascelin, additional, Singh, Navinder J., additional, and Milner-Gulland, E. J., additional
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- 2013
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108. Habitat selection by adult Golden Eagles Aquila chrysaetos during the breeding season and implications for wind farm establishment.
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Singh, Navinder J., Moss, Edward, Hipkiss, Tim, Ecke, Frauke, Dettki, Holger, Sandström, Per, Bloom, Peter, Kidd, Jeff, Thomas, Scott, and Hörnfeldt, Birger
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Capsule:Global Positioning System (GPS)-tagged adult Golden EaglesAquila chrysaetosbreeding in forests in northern Sweden selected clear-cuts, coniferous forests with lichens and steep slopes during the breeding season but avoided wetlands and mixed forest. Aims:To investigate the habitat selection patterns of tree-nesting Golden Eagles, and identify how potential conflicts with wind farm development could be minimized. Methods:The study is based on GPS tracking data from 22 adult eagles. We estimated home range sizes using a biased random bridge approach and habitat selection patterns using resource selection functions following a use-availability design. Results:Core home range size among adults was variable during the breeding season (5–30 km2). Individual movement extents were variable, but sexes did not significantly differ in their scale of movement. At the landscape scale, individuals selected for clear-cuts and coniferous forest with ground lichens, whereas wetland, water bodies and mixed forest were avoided. Steeper and south facing slopes were selected for, whereas, north facing slopes were avoided. Conclusions:Potential conflicts between eagles and wind energy establishment can be reduced if wind farms are placed away from steep slopes, minimizing areas that are clear-cut during construction, and locating turbines within dense, young and other less favoured forest habitats. [ABSTRACT FROM AUTHOR]
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- 2016
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109. Toward a mechanistic understanding of animal migration: incorporating physiological measurements in the study of animal movement.
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Jachowski, David S. and Singh, Navinder J.
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- 2016
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110. Conserving a moving target: planning protection for a migratory species as its distribution changes
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Singh, Navinder J., primary and Milner-Gulland, Eleanor J., additional
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- 2010
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111. Wildlife hunting by indigenous tribes: a case study from Arunachal Pradesh, north-east India
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Aiyadurai, Ambika, primary, Singh, Navinder J., additional, and Milner-Gulland, E. J., additional
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- 2010
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112. Monitoring ungulates in Central Asia: current constraints and future potential.
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Singh, Navinder J. and Milner-Gulland, E.J.
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WILDLIFE monitoring , *ENVIRONMENTAL protection , *HABITAT modification , *WILDLIFE conservation , *HABITAT conservation , *PROTECTED areas , *CONFIDENCE intervals - Abstract
Asia’s rangelands and mountains are strongholds for several endemic ungulate species. Little is known about the ecology of these species because of the region’s remoteness and the lack of robust scientific studies. Hunting, habitat modification, increased livestock grazing, disease and development are the major threats to the species. There is an urgent need for better monitoring to identify the size, distribution and dynamics of the populations of these species, and the threats to them, for effective conservation. The feasibility of standard scientific monitoring is greatly influenced by the remoteness of the region, the pre-existing scientific ideology, lack of expertise in the latest monitoring methods and awareness of biases and errors, and low capacity and logistical and financial constraints. We review the existing methods used for monitoring ungulates, identify the practical and institutional challenges to effective monitoring in Central Asia and categorize the methods based on various criteria so that researchers can plan better monitoring studies suited to particular species. We illustrate these issues using examples from several contrasting ungulate species. We recommend that scientific surveys should be complemented by increases in participatory monitoring, involving local people. The future of ungulate monitoring in Central Asia lies in a better recognition of the existing errors and biases in monitoring programmes and methods, allocation of more monitoring effort in terms of manpower, finances and logistics, understanding of robust scientific methods and sampling theory, and changing the scientific culture, as well as a commitment to ensuring that we monitor the things that matter. [ABSTRACT FROM AUTHOR]
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- 2011
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113. Offset between GPS collar-recorded temperature in moose and ambient weather station data
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Ericsson, Göran, Dettki, Holger, Neumann, Wiebke, Arnemo, Jon M., and Singh, Navinder J.
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Ecology ,Animal Science and Zoology ,Management, Monitoring, Policy and Law ,Ecology, Evolution, Behavior and Systematics ,Nature and Landscape Conservation - Full Text
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114. Airborne eDNA captures the diversity and dynamics of a subarctic ecosystem across three decades
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Karlsson, Edvin, Sullivan, Alexis R., Svensson, Daniel, Bellieny-Rabelo, Daniel, Siddique, Abu Bakar, Villegas, José Antonio, Johansson, Anna-Mia, Grahn, Håkan, Sundell, David, Brindefalk, Björn, Norman, Anita, Sjödin, Andreas, Singh, Navinder J., Brodin, Tomas, Forsman, Mats, Stenberg, Per, Karlsson, Edvin, Sullivan, Alexis R., Svensson, Daniel, Bellieny-Rabelo, Daniel, Siddique, Abu Bakar, Villegas, José Antonio, Johansson, Anna-Mia, Grahn, Håkan, Sundell, David, Brindefalk, Björn, Norman, Anita, Sjödin, Andreas, Singh, Navinder J., Brodin, Tomas, Forsman, Mats, and Stenberg, Per
115. Increased summer temperature is associated with reduced calf mass of a circumpolar large mammal through direct thermoregulatory and indirect, food quality, pathways.
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Holmes, Sheila M., Dressel, Sabrina, Morel, Julien, Spitzer, Robert, Ball, John P., Ericsson, Göran, Singh, Navinder J., Widemo, Fredrik, Cromsigt, Joris P. G. M., and Danell, Kjell
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FOOD quality , *FEED analysis , *CALVES , *MOOSE , *MAMMALS , *TEMPERATURE - Abstract
Climate change represents a growing ecological challenge. The (sub) arctic and boreal regions of the world experience the most rapid warming, presenting an excellent model system for studying how climate change affects mammals. Moose (Alces alces) are a particularly relevant model species with their circumpolar range. Population declines across the southern edge of this range are linked to rising temperatures. Using a long-term dataset (1988–1997, 2017–2019), we examine the relative strength of direct (thermoregulatory costs) and indirect (food quality) pathways linking temperature, precipitation, and the quality of two important food items (birch and fireweed) to variation in moose calf mass in northern Sweden. The direct effects of temperature consistently showed stronger relationships to moose calf mass than did the indirect effects. The proportion of growing season days where the temperature exceeded a 20 °C threshold showed stronger direct negative relationships to moose calf mass than did mean temperature values. Finally, while annual forb (fireweed) quality was more strongly influenced by temperature and precipitation than were perennial (birch) leaves, this did not translate into a stronger relationship to moose calf weight. The only indirect path with supporting evidence suggested that mean growing season temperatures were positively associated with neutral detergent fiber, which was, in turn, negatively associated with calf mass. While indirect impacts of climate change deserve further investigation, it is important to recognize the large direct impacts of temperature on cold-adapted species. [ABSTRACT FROM AUTHOR]
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- 2023
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116. Evolution of chain migration in an aerial insectivorous bird, the common swift Apus apus.
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Åkesson, Susanne, Atkinson, Phil W., Bermejo, Ana, Puente, Javier, Ferri, Mauro, Hewson, Chris M., Holmgren, Jan, Kaiser, Erich, Kearsley, Lyndon, Klaassen, Raymond H. G., Kolunen, Heikki, Matsson, Gittan, Minelli, Fausto, Norevik, Gabriel, Pietiäinen, Hannu, Singh, Navinder J., Spina, Fernando, Viktora, Lukas, and Hedenström, Anders
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BIRD migration , *NORMALIZED difference vegetation index , *ELEVATING platforms - Abstract
Spectacular long‐distance migration has evolved repeatedly in animals enabling exploration of resources separated in time and space. In birds, these patterns are largely driven by seasonality, cost of migration, and asymmetries in competition leading most often to leapfrog migration, where northern breeding populations winter furthest to the south. Here, we show that the highly aerial common swift Apus apus, spending the nonbreeding period on the wing, instead exhibits a rarely found chain migration pattern, where the most southern breeding populations in Europe migrate to wintering areas furthest to the south in Africa, whereas the northern populations winter to the north. The swifts concentrated in three major areas in sub‐Saharan Africa during the nonbreeding period, with substantial overlap of nearby breeding populations. We found that the southern breeding swifts were larger, raised more young, and arrived to the wintering areas with higher seasonal variation in greenness (Normalized Difference Vegetation Index) earlier than the northern breeding swifts. This unusual chain migration pattern in common swifts is largely driven by differential annual timing and we suggest it evolves by prior occupancy and dominance by size in the breeding quarters and by prior occupancy combined with diffuse competition in the winter. [ABSTRACT FROM AUTHOR]
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- 2020
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117. Animal migration in the Anthropocene: threats and mitigation options.
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Cooke SJ, Piczak ML, Singh NJ, Åkesson S, Ford AT, Chowdhury S, Mitchell GW, Norris DR, Hardesty-Moore M, McCauley D, Hammerschlag N, Tucker MA, Horns JJ, Reisinger RR, Kubelka V, and Lennox RJ
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- Animals, Humans, Human Activities, Climate Change, Ecosystem, Biodiversity, Animal Migration, Conservation of Natural Resources
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Animal migration has fascinated scientists and the public alike for centuries, yet migratory animals are facing diverse threats that could lead to their demise. The Anthropocene is characterised by the reality that humans are the dominant force on Earth, having manifold negative effects on biodiversity and ecosystem function. Considerable research focus has been given to assessing anthropogenic impacts on the numerical abundance of species/populations, whereas relatively less attention has been devoted to animal migration. However, there are clear linkages, for example, where human-driven impacts on migration behaviour can lead to population/species declines or even extinction. Here, we explore anthropogenic threats to migratory animals (in all domains - aquatic, terrestrial, and aerial) using International Union for the Conservation of Nature (IUCN) Threat Taxonomy classifications. We reveal the diverse threats (e.g. human development, disease, invasive species, climate change, exploitation, pollution) that impact migratory wildlife in varied ways spanning taxa, life stages and type of impact (e.g. from direct mortality to changes in behaviour, health, and physiology). Notably, these threats often interact in complex and unpredictable ways to the detriment of wildlife, further complicating management. Fortunately, we are beginning to identify strategies for conserving and managing migratory animals in the Anthropocene. We provide a set of strategies that, if embraced, have the potential to ensure that migratory animals, and the important ecological functions sustained by migration, persist., (© 2024 The Authors. Biological Reviews published by John Wiley & Sons Ltd on behalf of Cambridge Philosophical Society.)
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- 2024
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118. Body mass is associated with hibernation length, body temperature, and heart rate in free-ranging brown bears.
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Evans AL, Fuchs B, Singh NJ, Thiel A, Giroud S, Blanc S, Laske TG, Frobert O, Friebe A, Swenson JE, and Arnemo JM
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Background: Despite centuries of research, debate remains on the scaling of metabolic rate to mass especially for intraspecific cases. The high variation of body mass within brown bears presents a unique opportunity to study the intraspecific effects of body mass on physiological variables. The amplitude of metabolic rate reduction in hibernators is dependent on body mass of the species. Small hibernators have high metabolic rates when euthermic but experience a drastic decrease in body temperature during torpor, which is necessary to reach a very low metabolic rate. Conversely, large hibernators, such as the brown bear (Ursus arctos), show a moderate decrease in temperature during hibernation, thought to be related to the bear's large size. We studied body mass, abdominal body temperature, heart rate, and accelerometer-derived activity from 63 free-ranging brown bears (1-15 years old, 15-233 kg). We tested for relationships between body mass and body temperature, heart rate, and hibernation duration., Results: The smallest individuals maintained lower body temperatures during hibernation, hibernated longer, and ended hibernation later than large bears. Unlike body temperature, winter heart rates were not associated with body mass. In summer, the opposite pattern was found, with smaller individuals having higher body temperature and daytime heart rates. Body mass was associated with body temperature in the winter hypometabolic state, even in a large hibernating mammal. Smaller bears, which are known to have higher thermal conductance, reached lower body temperatures during hibernation. During summer, smaller bears had higher body temperatures and daytime heart rates, a phenomenon not previously documented within a single mammalian species., Conclusion: We conclude that the smallest bears hibernated more deeply and longer than large bears, likely from a combined effect of basic thermodynamics, the higher need for energy savings, and a lower cost of warming up a smaller body., (© 2023. BioMed Central Ltd., part of Springer Nature.)
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- 2023
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119. Population fluctuations and synanthropy explain transmission risk in rodent-borne zoonoses.
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Ecke F, Han BA, Hörnfeldt B, Khalil H, Magnusson M, Singh NJ, and Ostfeld RS
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- Humans, Animals, Rodentia
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Population fluctuations are widespread across the animal kingdom, especially in the order Rodentia, which includes many globally important reservoir species for zoonotic pathogens. The implications of these fluctuations for zoonotic spillover remain poorly understood. Here, we report a global empirical analysis of data describing the linkages between habitat use, population fluctuations and zoonotic reservoir status in rodents. Our quantitative synthesis is based on data collated from papers and databases. We show that the magnitude of population fluctuations combined with species' synanthropy and degree of human exploitation together distinguish most rodent reservoirs at a global scale, a result that was consistent across all pathogen types and pathogen transmission modes. Our spatial analyses identified hotspots of high transmission risk, including regions where reservoir species dominate the rodent community. Beyond rodents, these generalities inform our understanding of how natural and anthropogenic factors interact to increase the risk of zoonotic spillover in a rapidly changing world., (© 2022. The Author(s).)
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- 2022
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120. Large mammal telomere length variation across ecoregions.
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Fohringer C, Hoelzl F, Allen AM, Cayol C, Ericsson G, Spong G, Smith S, and Singh NJ
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- Animals, Animals, Wild genetics, Female, Humans, Male, Seasons, Telomere genetics, Deer genetics, Ecosystem
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Background: Telomere length provides a physiological proxy for accumulated stress in animals. While there is a growing consensus over how telomere dynamics and their patterns are linked to life history variation and individual experience, knowledge on the impact of exposure to different stressors at a large spatial scale on telomere length is still lacking. How exposure to different stressors at a regional scale interacts with individual differences in life history is also poorly understood. To better understand large-scale regional influences, we investigated telomere length variation in moose (Alces alces) distributed across three ecoregions. We analyzed 153 samples of 106 moose representing moose of both sexes and range of ages to measure relative telomere lengths (RTL) in white blood cells., Results: We found that average RTL was significantly shorter in a northern (montane) and southern (sarmatic) ecoregion where moose experience chronic stress related to severe summer and winter temperatures as well as high anthropogenic land-use compared to the boreal region. Our study suggests that animals in the northern boreal forests, with relatively homogenous land use, are less disturbed by environmental and anthropogenic stressors. In contrast, animals in areas experiencing a higher rate of anthropogenic and environmental change experience increased stress., Conclusion: Although animals can often adapt to predictable stressors, our data suggest that some environmental conditions, even though predictable and ubiquitous, can generate population level differences of long-term stress. By measuring RTL in moose for the first time, we provide valuable insights towards our current understanding of telomere biology in free-ranging wildlife in human-modified ecosystems., (© 2022. The Author(s).)
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- 2022
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