Publications by authors named "John Odden"

19 Publications

  • Page 1 of 1

Harvest models of small populations of a large carnivore using Bayesian forecasting.

Ecol Appl 2020 04 28;30(3):e02063. Epub 2020 Jan 28.

Norwegian Institute for Nature Research, P.O. Box 5685, Torgard, NO-7485, Trondheim, Norway.

Harvesting large carnivores can be a management tool for meeting politically set goals for their desired abundance. However, harvesting carnivores creates its own set of conflicts in both society and among conservation professionals, where one consequence is a need to demonstrate that management is sustainable, evidence-based, and guided by science. Furthermore, because large carnivores often also have high degrees of legal protection, harvest quotas have to be carefully justified and constantly adjusted to avoid damaging their conservation status. We developed a Bayesian state-space model to support adaptive management of Eurasian lynx harvesting in Scandinavia. The model uses data from the annual monitoring of lynx abundance and results from long-term field research on lynx biology, which has provided detailed estimates of key demographic parameters. We used the model to predict the probability that the forecasted population size will be below or above the management objectives when subjected to different harvest quotas. The model presented here informs decision makers about the policy risks of alternative harvest levels. Earlier versions of the model have been available for wildlife managers in both Sweden and Norway to guide lynx harvest quotas and the model predictions showed good agreement with observations. We combined monitoring data with data on vital rates and were able to estimate unobserved additional mortality rates, which are most probably due to poaching. In both countries, the past quota setting strategy suggests that there has been a de facto threshold strategy with increasing proportion, which means that there is no harvest below a certain population size, but above this threshold there is an increasing proportion of the population harvested as the population size increases. The annual assessment of the monitoring results, the use of forecasting models, and a threshold harvest approach to quota setting will all reduce the risk of lynx population sizes moving outside the desired goals. The approach we illustrate could be adapted to other populations of mammals worldwide.
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http://dx.doi.org/10.1002/eap.2063DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7187313PMC
April 2020

Eurasian lynx fitness shows little variation across Scandinavian human-dominated landscapes.

Sci Rep 2019 06 20;9(1):8903. Epub 2019 Jun 20.

Grimsö Wildlife Research Station, Department of Ecology, Swedish University of Agricultural Sciences, SE-73091, Riddarhyttan, Sweden.

Despite extensive research on the ecology and behavioural adaptations of large carnivores in human-dominated landscapes, information about the fitness consequences of sharing landscapes is still limited. We assessed the variation in three consecutive components of female fitness: the probability of reproduction, litter size and juvenile survival in relation to environmental and human factors in a solitary carnivore, the Eurasian lynx (Lynx lynx), occurring in human-dominated landscapes in Scandinavia. We used demographic data from 57 radio-collared adult females between 1995-2011 (126 radio-years). Overall, the yearly probability of female reproduction was 0.80, mean litter size was 2.34 (range 1-4) and the probability to find a female that reproduced in the spring being accompanied by at least one offspring during the subsequent winter was 0.70. We did not find evidence that food availability was a key factor influencing female fitness. Female lynx may adapt to food availability when establishing their home ranges by adopting an obstinate strategy, ensuring a minimum amount of prey necessary for survival and reproduction even during periods of prey scarcity. In human-dominated landscapes, where sufficient prey are available for lynx, mortality risk may have a larger influence on lynx population dynamics compared to food availability. Our results suggest that lynx population dynamics in human-dominated landscapes may be mainly driven by human impacts on survival.
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http://dx.doi.org/10.1038/s41598-019-45569-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6586631PMC
June 2019

Framing pictures: A conceptual framework to identify and correct for biases in detection probability of camera traps enabling multi-species comparison.

Ecol Evol 2019 Feb 23;9(4):2320-2336. Epub 2019 Jan 23.

Norwegian Institute for Nature Research Trondheim Norway.

Obtaining reliable species observations is of great importance in animal ecology and wildlife conservation. An increasing number of studies use camera traps (CTs) to study wildlife communities, and an increasing effort is made to make better use and reuse of the large amounts of data that are produced. It is in these circumstances that it becomes paramount to correct for the species- and study-specific variation in imperfect detection within CTs. We reviewed the literature and used our own experience to compile a list of factors that affect CT detection of animals. We did this within a conceptual framework of six distinct scales separating out the influences of (a) animal characteristics, (b) CT specifications, (c) CT set-up protocols, and (d) environmental variables. We identified 40 factors that can potentially influence the detection of animals by CTs at these six scales. Many of these factors were related to only a few overarching parameters. Most of the animal characteristics scale with body mass and diet type, and most environmental characteristics differ with season or latitude such that remote sensing products like NDVI could be used as a proxy index to capture this variation. Factors that influence detection at the microsite and camera scales are probably the most important in determining CT detection of animals. The type of study and specific research question will determine which factors should be corrected. Corrections can be done by directly adjusting the CT metric of interest or by using covariates in a statistical framework. Our conceptual framework can be used to design better CT studies and help when analyzing CT data. Furthermore, it provides an overview of which factors should be reported in CT studies to make them repeatable, comparable, and their data reusable. This should greatly improve the possibilities for global scale analyses of (reused) CT data.
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http://dx.doi.org/10.1002/ece3.4878DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6392353PMC
February 2019

Moving in the Anthropocene: Global reductions in terrestrial mammalian movements.

Authors:
Marlee A Tucker Katrin Böhning-Gaese William F Fagan John M Fryxell Bram Van Moorter Susan C Alberts Abdullahi H Ali Andrew M Allen Nina Attias Tal Avgar Hattie Bartlam-Brooks Buuveibaatar Bayarbaatar Jerrold L Belant Alessandra Bertassoni Dean Beyer Laura Bidner Floris M van Beest Stephen Blake Niels Blaum Chloe Bracis Danielle Brown P J Nico de Bruyn Francesca Cagnacci Justin M Calabrese Constança Camilo-Alves Simon Chamaillé-Jammes Andre Chiaradia Sarah C Davidson Todd Dennis Stephen DeStefano Duane Diefenbach Iain Douglas-Hamilton Julian Fennessy Claudia Fichtel Wolfgang Fiedler Christina Fischer Ilya Fischhoff Christen H Fleming Adam T Ford Susanne A Fritz Benedikt Gehr Jacob R Goheen Eliezer Gurarie Mark Hebblewhite Marco Heurich A J Mark Hewison Christian Hof Edward Hurme Lynne A Isbell René Janssen Florian Jeltsch Petra Kaczensky Adam Kane Peter M Kappeler Matthew Kauffman Roland Kays Duncan Kimuyu Flavia Koch Bart Kranstauber Scott LaPoint Peter Leimgruber John D C Linnell Pascual López-López A Catherine Markham Jenny Mattisson Emilia Patricia Medici Ugo Mellone Evelyn Merrill Guilherme de Miranda Mourão Ronaldo G Morato Nicolas Morellet Thomas A Morrison Samuel L Díaz-Muñoz Atle Mysterud Dejid Nandintsetseg Ran Nathan Aidin Niamir John Odden Robert B O'Hara Luiz Gustavo R Oliveira-Santos Kirk A Olson Bruce D Patterson Rogerio Cunha de Paula Luca Pedrotti Björn Reineking Martin Rimmler Tracey L Rogers Christer Moe Rolandsen Christopher S Rosenberry Daniel I Rubenstein Kamran Safi Sonia Saïd Nir Sapir Hall Sawyer Niels Martin Schmidt Nuria Selva Agnieszka Sergiel Enkhtuvshin Shiilegdamba João Paulo Silva Navinder Singh Erling J Solberg Orr Spiegel Olav Strand Siva Sundaresan Wiebke Ullmann Ulrich Voigt Jake Wall David Wattles Martin Wikelski Christopher C Wilmers John W Wilson George Wittemyer Filip Zięba Tomasz Zwijacz-Kozica Thomas Mueller

Science 2018 Jan;359(6374):466-469

Senckenberg Biodiversity and Climate Research Centre, Senckenberg Gesellschaft für Naturforschung, 60325 Frankfurt (Main), Germany.

Animal movement is fundamental for ecosystem functioning and species survival, yet the effects of the anthropogenic footprint on animal movements have not been estimated across species. Using a unique GPS-tracking database of 803 individuals across 57 species, we found that movements of mammals in areas with a comparatively high human footprint were on average one-half to one-third the extent of their movements in areas with a low human footprint. We attribute this reduction to behavioral changes of individual animals and to the exclusion of species with long-range movements from areas with higher human impact. Global loss of vagility alters a key ecological trait of animals that affects not only population persistence but also ecosystem processes such as predator-prey interactions, nutrient cycling, and disease transmission.
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http://dx.doi.org/10.1126/science.aam9712DOI Listing
January 2018

The range of the mange: Spatiotemporal patterns of sarcoptic mange in red foxes (Vulpes vulpes) as revealed by camera trapping.

PLoS One 2017 19;12(4):e0176200. Epub 2017 Apr 19.

Norwegian Institute for Nature Research, Trondheim, Norway.

Sarcoptic mange is a widely distributed disease that affects numerous mammalian species. We used camera traps to investigate the apparent prevalence and spatiotemporal dynamics of sarcoptic mange in a red fox population in southeastern Norway. We monitored red foxes for five years using 305 camera traps distributed across an 18000 km2 area. A total of 6581 fox events were examined to visually identify mange compatible lesions. We investigated factors associated with the occurrence of mange by using logistic models within a Bayesian framework, whereas the spatiotemporal dynamics of the disease were analysed with space-time scan statistics. The apparent prevalence of the disease fluctuated over the study period with a mean of 3.15% and credible interval [1.25, 6.37], and our best logistic model explaining the presence of red foxes with mange-compatible lesions included time since the beginning of the study and the interaction between distance to settlement and season as explanatory variables. The scan analyses detected several potential clusters of the disease that varied in persistence and size, and the locations in the cluster with the highest probability were closer to human settlements than the other survey locations. Our results indicate that red foxes in an advanced stage of the disease are most likely found closer to human settlements during periods of low wild prey availability (winter). We discuss different potential causes. Furthermore, the disease appears to follow a pattern of small localized outbreaks rather than sporadic isolated events.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0176200PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5397041PMC
April 2017

Intensity of space use reveals conditional sex-specific effects of prey and conspecific density on home range size.

Ecol Evol 2016 May 28;6(9):2957-67. Epub 2016 Mar 28.

Department of Ecology Swedish University of Agricultural Sciences Grimsö Wildlife Research Station SE-73091 Riddarhyttan Sweden.

Home range (HR) size variation is often linked to resource abundance, with sex differences expected to relate to sex-specific fitness consequences. However, studies generally fail to disentangle the effects of the two main drivers of HR size variation, food and conspecific density, and rarely consider how their relative influence change over spatiotemporal scales. We used location data from 77 Eurasian lynx (Lynx lynx) from a 16-year Scandinavian study to examine HR sizes variation relative to prey and conspecific density at different spatiotemporal scales. By varying the isopleth parameter (intensity of use) defining the HR, we show that sex-specific effects were conditional on the spatial scale considered. Males had larger HRs than females in all seasons. Females' total HR size declined as prey and conspecific density increased, whereas males' total HR was only affected by conspecific density. However, as the intensity of use within the HR increased (from 90% to 50% isopleth), the relationship between prey density and area showed opposing patterns for females and males; for females, the prey density effect was reduced, while for males, prey became increasingly important. Thus, prey influenced the size of key regions within male HRs, despite total HR size being independent of prey density. Males reduced their HR size during the mating season, likely to remain close to individual females in estrous. Females reduced their HR size postreproduction probably because of movement constrains imposed by dependent young. Our findings highlight the importance of simultaneously considering resources and intraspecific interactions as HR size determinants. We show that sex-specific demands influence the importance of prey and conspecific density on space use at different spatiotemporal scales. Thus, unless a gradient of space use intensity is examined, factors not related to total HR size might be disregarded despite their importance in determining size of key regions within the HR.
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http://dx.doi.org/10.1002/ece3.2032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4863019PMC
May 2016

Recovery of large carnivores in Europe's modern human-dominated landscapes.

Science 2014 Dec;346(6216):1517-9

Department of Biology and Biotechnologies, University of Rome "La Sapienza," Viale dell'Università 32, 00185 Roma, Italy.

The conservation of large carnivores is a formidable challenge for biodiversity conservation. Using a data set on the past and current status of brown bears (Ursus arctos), Eurasian lynx (Lynx lynx), gray wolves (Canis lupus), and wolverines (Gulo gulo) in European countries, we show that roughly one-third of mainland Europe hosts at least one large carnivore species, with stable or increasing abundance in most cases in 21st-century records. The reasons for this overall conservation success include protective legislation, supportive public opinion, and a variety of practices making coexistence between large carnivores and people possible. The European situation reveals that large carnivores and people can share the same landscape.
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http://dx.doi.org/10.1126/science.1257553DOI Listing
December 2014

Activity patterns of Eurasian lynx are modulated by light regime and individual traits over a wide latitudinal range.

PLoS One 2014 17;9(12):e114143. Epub 2014 Dec 17.

Norwegian Institute for Nature Research, Trondheim, Norway.

The activity patterns of most terrestrial animals are regarded as being primarily influenced by light, although other factors, such as sexual cycle and climatic conditions, can modify the underlying patterns. However, most activity studies have been limited to a single study area, which in turn limit the variability of light conditions and other factors. Here we considered a range of variables that might potentially influence the activity of a large carnivore, the Eurasian lynx, in a network of studies conducted with identical methodology in different areas spanning latitudes from 49°7'N in central Europe to 70°00'N in northern Scandinavia. The variables considered both light conditions, ranging from a day with a complete day-night cycle to polar night and polar day, as well as individual traits of the animals. We analysed activity data of 38 individual free-ranging lynx equipped with GPS-collars with acceleration sensors, covering more than 11,000 lynx days. Mixed linear additive models revealed that the lynx activity level was not influenced by the daily daylight duration and the activity pattern was bimodal, even during polar night and polar day. The duration of the active phase of the activity cycle varied with the widening and narrowing of the photoperiod. Activity varied significantly with moonlight. Among adults, males were more active than females, and subadult lynx were more active than adults. In polar regions, the amplitude of the lynx daily activity pattern was low, likely as a result of the polycyclic activity pattern of their main prey, reindeer. At lower latitudes, the basic lynx activity pattern peaked during twilight, corresponding to the crepuscular activity pattern of the main prey, roe deer. Our results indicated that the basic activity of lynx is independent of light conditions, but is modified by both individual traits and the activity pattern of the locally most important prey.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0114143PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4269461PMC
September 2015

Physiologically persistent Corpora lutea in Eurasian lynx (Lynx lynx) - longitudinal ultrasound and endocrine examinations intra-vitam.

PLoS One 2014 5;9(3):e90469. Epub 2014 Mar 5.

Department Reproduction Management and Reproduction Biology, Leibniz Institute for Zoo and Wildlife Research, Forschungsverbund Berlin e.V., Berlin, Germany.

Felids generally follow a poly-estrous reproductive strategy. Eurasian lynx (Lynx lynx) display a different pattern of reproductive cyclicity where physiologically persistent corpora lutea (CLs) induce a mono-estrous condition which results in highly seasonal reproduction. The present study was based around a sono-morphological and endocrine study of captive Eurasian lynx, and a control-study on free-ranging lynx. We verified that CLs persist after pregnancy and pseudo-pregnancy for at least a two-year period. We could show that lynx are able to enter estrus in the following year, while CLs from the previous years persisted in structure and only temporarily reduced their function for the period of estrus onset or birth, which is unique among felids. The almost constant luteal progesterone secretion (average of 5 ng/ml serum) seems to prevent folliculogenesis outside the breeding season and has converted a poly-estrous general felid cycle into a mono-estrous cycle specific for lynx. The hormonal regulation mechanism which causes lynx to have the longest CL lifespan amongst mammals remains unclear. The described non-felid like ovarian physiology appears to be a remarkably non-plastic system. The lynx's reproductive ability to adapt to environmental and anthropogenic changes needs further investigation.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0090469PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3943960PMC
January 2015

Density of wild prey modulates lynx kill rates on free-ranging domestic sheep.

PLoS One 2013 20;8(11):e79261. Epub 2013 Nov 20.

Norwegian Institute for Nature Research, Trondheim, Norway.

Understanding the factors shaping the dynamics of carnivore-livestock conflicts is vital to facilitate large carnivore conservation in multi-use landscapes. We investigated how the density of their main wild prey, roe deer Capreolus capreolus, modulates individual Eurasian lynx Lynx lynx kill rates on free-ranging domestic sheep Ovis aries across a range of sheep and roe deer densities. Lynx kill rates on free-ranging domestic sheep were collected in south-eastern Norway from 1995 to 2011 along a gradient of different livestock and wild prey densities using VHF and GPS telemetry. We used zero-inflated negative binomial (ZINB) models including lynx sex, sheep density and an index of roe deer density as explanatory variables to model observed kill rates on sheep, and ranked the models based on their AICc values. The model including the effects of lynx sex and sheep density in the zero-inflation model and the effect of lynx sex and roe deer density in the negative binomial part received most support. Irrespective of sheep density and sex, we found the lowest sheep kill rates in areas with high densities of roe deer. As roe deer density decreased, males killed sheep at higher rates, and this pattern held for both high and low sheep densities. Similarly, females killed sheep at higher rates in areas with high densities of sheep and low densities of roe deer. However, when sheep densities were low females rarely killed sheep irrespective of roe deer density. Our quantification of depredation rates can be the first step towards establishing fairer compensation systems based on more accurate and area specific estimation of losses. This study demonstrates how we can use ecological theory to predict where losses of sheep will be greatest, and can be used to identify areas where mitigation measures are most likely to be needed.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0079261PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3835786PMC
September 2014

Selecting habitat to survive: the impact of road density on survival in a large carnivore.

PLoS One 2013 10;8(7):e65493. Epub 2013 Jul 10.

Fort Lauderdale Research and Education Center, University of Florida, Fort Lauderdale, Florida, United States of America.

Habitat selection studies generally assume that animals select habitat and food resources at multiple scales to maximise their fitness. However, animals sometimes prefer habitats of apparently low quality, especially when considering the costs associated with spatially heterogeneous human disturbance. We used spatial variation in human disturbance, and its consequences on lynx survival, a direct fitness component, to test the Hierarchical Habitat Selection hypothesis from a population of Eurasian lynx Lynx lynx in southern Norway. Data from 46 lynx monitored with telemetry indicated that a high proportion of forest strongly reduced the risk of mortality from legal hunting at the home range scale, while increasing road density strongly increased such risk at the finer scale within the home range. We found hierarchical effects of the impact of human disturbance, with a higher road density at a large scale reinforcing its negative impact at a fine scale. Conversely, we demonstrated that lynx shifted their habitat selection to avoid areas with the highest road densities within their home ranges, thus supporting a compensatory mechanism at fine scale enabling lynx to mitigate the impact of large-scale disturbance. Human impact, positively associated with high road accessibility, was thus a stronger driver of lynx space use at a finer scale, with home range characteristics nevertheless constraining habitat selection. Our study demonstrates the truly hierarchical nature of habitat selection, which aims at maximising fitness by selecting against limiting factors at multiple spatial scales, and indicates that scale-specific heterogeneity of the environment is driving individual spatial behaviour, by means of trade-offs across spatial scales.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0065493PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3707854PMC
March 2014

One size fits all: Eurasian lynx females share a common optimal litter size.

J Anim Ecol 2014 Jan 16;83(1):107-15. Epub 2013 Jul 16.

Unité Mixte de Recherche 5558 "Biométrie et Biologie Evolutive", Bât. G. Mendel, Université de Lyon, Université Lyon1, 43 bd du 11 novembre 1918, 69622, Villeurbanne Cedex, France.

Lack proposed that the average clutch size of altricial species should be determined by the average maximum number of young the parents can raise such that all females in a given population should share a common optimal clutch size. Support for this model remains equivocal and recent studies have suggested that intra-population variation in clutch size is adaptive because each female has its own optimal clutch size associated with its intrinsic ability to raise offspring. Although Lack litter size and condition-dependent litter size are presented as two competing models, both are based on the concept of individual optimization. We propose a unified optimal litter size model (called 'adaptive litter size') and identify a set of conditions under which a common vs. a state-dependent optimal litter size should be observed. We test whether females of Eurasian lynx (Lynx lynx) have a common optimal litter size, or whether they adjust their litter size according to their state. We used a detailed individual-based data set collected from contrasting populations of Eurasian lynx in Scandinavia. Observed reproductive patterns in female lynx provide strong support for the existence of a common optimal litter size. Litter size did not vary according to female body mass or reproductive category, or among contrasted populations and years. A litter size of 2 was associated with a higher fitness than both smaller and larger litters, and thus corresponded to the 'adaptive litter size' for female lynx. We suggest that the reproductive pattern of female lynx might correspond to a risk avoidance tactic common to all individuals, which has evolved in response to strong environmental constraints generated by a highly unpredictable food supply during lactation.
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http://dx.doi.org/10.1111/1365-2656.12110DOI Listing
January 2014

Patterns of variation in reproductive parameters in Eurasian lynx (Lynx lynx).

Acta Theriol (Warsz) 2012 Jul 27;57(3):217-223. Epub 2011 Nov 27.

Detailed knowledge of the variation in demographic rates is central for our ability to understand the evolution of life history strategies and population dynamics, and to plan for the conservation of endangered species. We studied variation in reproductive output of 61 radio-collared Eurasian lynx females in four Scandinavian study sites spanning a total of 223 lynx-years. Specifically, we examined how the breeding proportion and litter size varied among study areas and age classes (2-year-old vs. >2-year-old females). In general, the breeding proportion varied between age classes and study sites, whereas we did not detect such variation in litter size. The lack of differences in litter sizes among age classes is at odds with most findings in large mammals, and we argue that this is because the level of prenatal investment is relatively low in felids compared to their substantial levels of postnatal care.
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http://dx.doi.org/10.1007/s13364-011-0066-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3374089PMC
July 2012

Predicting the potential demographic impact of predators on their prey: a comparative analysis of two carnivore-ungulate systems in Scandinavia.

J Anim Ecol 2012 Mar 11;81(2):443-54. Epub 2011 Nov 11.

Norwegian Institute for Nature Research, PO Box 5685, Sluppen, NO-7485 Trondheim, Norway.

1. Understanding the role of predation in shaping the dynamics of animal communities is a fundamental issue in ecological research. Nevertheless, the complex nature of predator-prey interactions often prevents researchers from modelling them explicitly. 2. By using periodic Leslie-Usher matrices and a simulation approach together with parameters obtained from long-term field projects, we reconstructed the underlying mechanisms of predator-prey demographic interactions and compared the dynamics of the roe deer-red fox-Eurasian lynx-human harvest system with those of the moose-brown bear-gray wolf-human harvest system in the boreal forest ecosystem of the southern Scandinavian Peninsula. 3. The functional relationship of both roe deer and moose λ to changes in predation rates from the four predators was remarkably different. Lynx had the strongest impact among the four predators, whereas predation rates by wolves, red foxes, or brown bears generated minor variations in prey population λ. Elasticity values of lynx, wolf, fox and bear predation rates were -0·157, -0·056, -0·031 and -0·006, respectively, but varied with both predator and prey densities. 4. Differences in predation impact were only partially related to differences in kill or predation rates, but were rather a result of different distribution of predation events among prey age classes. Therefore, the age composition of killed individuals emerged as the main underlying factor determining the overall per capita impact of predation. 5. Our results confirm the complex nature of predator-prey interactions in large terrestrial mammals, by showing that different carnivores preying on the same prey species can exert a dramatically different demographic impact, even in the same ecological context, as a direct consequence of their predation patterns. Similar applications of this analytical framework in other geographical and ecological contexts are needed, but a more general evaluation of the subject is also required, aimed to assess, on a broader systematic and ecological range, what specific traits of a carnivore are most related to its potential impact on prey species.
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http://dx.doi.org/10.1111/j.1365-2656.2011.01928.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3440569PMC
March 2012

The cost of maturing early in a solitary carnivore.

Oecologia 2010 Dec 6;164(4):943-8. Epub 2010 Jul 6.

Norwegian Institute for Nature Research, Trondheim, Norway.

Central to the theory of life history evolution is the existence of trade-offs between different traits, such as the trade-off between early maturity and an extended period of body growth. Based on analysis of the reproductive tracts of harvested Eurasian lynx (Lynx lynx) females in Norway, we find that females that mature early are generally heavier than those that postpone maturation. A higher proportion of 1.5-year-old females showed signs of ovulation in areas with high prey density, where they were also heavier. Further, we show that female Eurasian lynx that mature early have the same number of placental scars (an index of breeding investment and litter size) as older females, suggesting that they have a relatively high investment in their first litter. This induces a cost in terms of body weight development, as those females that had matured at the age of 1.5 years were substantially lighter by the age of 2.5 years than those that postponed breeding. This effect tended to be more pronounced in areas with low prey density. We discuss to what extent this might affect their future fitness prospects, and suggest that such costs of maturing early in terms of body weight development might be high in terrestrial large carnivores due to a prolonged period of postnatal care.
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http://dx.doi.org/10.1007/s00442-010-1713-2DOI Listing
December 2010

Sustainably harvesting a large carnivore? Development of Eurasian lynx populations in Norway during 160 years of shifting policy.

Environ Manage 2010 May 6;45(5):1142-54. Epub 2010 Mar 6.

Terrestrial Ecology, Norwegian Institute for Nature Research, Tungasletta 2, Trondheim, Norway.

The management of large carnivores in multi-use landscapes is always controversial, and managers need to balance a wide range of competing interests. Hunter harvest is often used to limit population size and distribution but is proving to be both controversial and technically challenging. Eurasian lynx (Lynx lynx) are currently managed as a game species in Norway. We describe an adaptive management approach where quota setting is based on an annual census and chart the population development through the period 1996-2008, as management has become significantly more sophisticated and better informed by the increased availability of scientific data. During this period the population has been through a period of high quotas and population decline caused by fragmented management authority and over optimistic estimates of lynx reproduction, followed by a period of recovery due to quota reductions. The modern management regime is placed in the context of shifting policy during the last 160 years, during which management goals have moved from extermination stimulated by bounties, through a short phase of protection, and now to quota-regulated harvest. Much management authority has also been delegated from central to local levels. We conclude that adaptive management has the potential to keep the population within some bounded limits, although there will inevitably be fluctuation.
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http://dx.doi.org/10.1007/s00267-010-9455-9DOI Listing
May 2010

Climate, season, and social status modulate the functional response of an efficient stalking predator: the Eurasian lynx.

J Anim Ecol 2009 Jul 31;78(4):741-51. Epub 2009 Mar 31.

Faculty of Forestry and Wildlife Management, Hedmark University College, Evenstad, NO-2480 Koppang, Norway.

1. Predation plays a major role in shaping the structure and dynamics of ecological communities, and the functional response of a predator is of crucial importance to the dynamics of any predator-prey system by linking the trophic levels. For large mammals, there is a dearth of field studies documenting functional responses, and observations at low prey density are particularly scarce. Furthermore, there is a lack of understanding about how variables such as season, social status and climate modulate the functional response curves. 2. We analysed kill rate data collected over a 10-year period based on radio-marked lynx (Lynx lynx) mainly preying on roe deer (Capreolus capreolus) along a steep prey density gradient in south-eastern Norway. 3. The asymptotic kill rate was reached at a very low prey density for both solitary individuals and family groups (i.e. females with their dependent kittens), indicative of an efficient predator. This highlights the importance of understanding the interplay between predator and prey at low prey densities. 4. A purely prey-dependent functional response was a poor descriptor of the data, as the curve was strongly modulated by season and differences between lynx of different social status. In addition, there was a clear effect of abiotic climatic factors (indexed by the North Atlantic Oscillation) on observed kill rates in the more snow-rich portion of our study area. 5. Our analysis suggests that simple functional response curves might be poor descriptors of predator consumption rates in complex natural system, and that auxiliary factors are likely to induce complexity into any predator-prey systems that would not be captured by simple deterministic approaches.
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http://dx.doi.org/10.1111/j.1365-2656.2009.01547.xDOI Listing
July 2009

A slow life in hell or a fast life in heaven: demographic analyses of contrasting roe deer populations.

J Anim Ecol 2009 May;78(3):585-94

Hedmark University College, Evenstad, Koppang 2480, Norway.

1. Environmental conditions shape population growth through their impact on demographic parameters. While knowledge has accumulated concerning the effects of population density and climatic conditions, a topical question now concerns how predation and harvest influence demographic parameters and population growth (lambda). 2. We performed a comparative demographic analysis based on projection matrix models for female roe deer. Population-specific matrices were parameterized based on longitudinal data from five intensively monitored populations in Norway and France, spanning a large variability in environmental characteristics such as densities of large predators, hunter harvest and seasonality. 3. As expected for a large iteroparous vertebrate, temporal variation was invariably higher in recruitment than in adult survival, and the elasticity of adult survival was consistently higher than that of recruitment. However, the relative difference in elasticity of lambda to recruitment and adult survival varied strongly across populations, and was closely correlated with adult survival. 4. Different traits accounted for most of the variance in lambda in different ecological settings. Adult survival generally contributed more in populations with low mean adult survival and low mean growth rate during the study period. Hunters and predators (Eurasian lynx and red foxes) occurred in two of our study populations and contributed substantially to the variance in lambda, accounting for a total of 35% and 70% in the two populations respectively. 5. Across populations, we did not find any evidence that roe deer increased their reproductive output when faced with harsh conditions, resulting in some populations having negative growth rates. 6. Generation time, a measure of the speed of the life-history cycle, increased from less than 4 years in the most productive population ('roe deer heaven') to more than 6 years in declining populations facing predation from lynx, red fox and hunters ('roe deer hell'), and was tightly and inversely correlated with lambda. Such a deceleration of the life cycle in declining populations might be a general feature in large herbivores. 7. Our results shows that the plethora of environmental conditions faced by populations of large herbivores also induce high intraspecific variation in their ranking along the 'fast-slow' continuum of life-history tactics.
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http://dx.doi.org/10.1111/j.1365-2656.2009.01523.xDOI Listing
May 2009

Habitat differentiation within the large-carnivore community of Norway's multiple-use landscapes.

J Appl Ecol 2008 Oct;45(5):1382-1391

The re-establishment of large carnivores in Norway has led to increased conflicts and the adoption of regional zoning for these predators. When planning the future distribution of large carnivores, it is important to consider details of their potential habitat tolerances and strength of inter-specific differentiation. We studied differentiation in habitat and kill sites within the large-carnivore community of south-eastern Norway.We compared habitat selection of the brown bear Ursus arctos L., Eurasian lynx Lynx lynx L., wolf Canis lupus L. and wolverine Gulo gulo L., based on radio-tracking data. Differences in kill site locations were explored using locations of documented predator-killed sheep Ovis aries L. We modelled each species' selection for, and differentiation in, habitat and kill sites on a landscape scale using resource selection functions and multinomial logistic regression. Based on projected probability of occurrence maps, we estimated continuous patches of habitat within the study area.Although bears, lynx, wolves and wolverines had overlapping distributions, we found a clear differentiation for all four species in both habitat and kill sites. The presence of bears, wolves and lynx was generally associated with rugged, forested areas at lower elevations, whereas wolverines selected rugged terrain at higher elevations. Some degree of sympatry was possible in over 40% of the study area, although only 1.5% could hold all four large carnivores together.Synthesis and applications. A geographically differentiated management policy has been adopted in Norway, aimed at conserving viable populations of large carnivores while minimizing the potential for conflicts. Sympatry of all four carnivores will be most successful if regional zones are established of adequate size spanning an elevational gradient. High prey densities, low carnivore densities, low dietary overlap and scavenging opportunities have most probably led to reduced competitive exclusion. Although regional sympatry enhances the conservation of an intact guild of large carnivores, it may well increase conflict levels and resistance to carnivore conservation locally.
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http://dx.doi.org/10.1111/j.1365-2664.2008.01527.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2658717PMC
October 2008