Centre for Advanced Study

at the Norwegian Academy of Science and Letters

Climate effects on harvested large mammal populations


The principle objective is to contribute towards a fundamental understanding of how climate affects large mammal populations directly and indirectly through food distribution and the harvesting process. The main novelty of our proposal is to address indirect effects of climate change operating through food distribution and the harvesting process on large mammal populations. A limitation of current knowledge is that most such data derive from large herbivores. We propose to addressing this question by comparing large herbivores being affected indirectly by plant distribution with a large omnivore potentially being affected by both plant and prey distribution. We generally aim to use a comparative approach to understand how three different processes feedback on each other; life histories (especially related to timing of events; WP1), behaviour (especially space use; WP2), and the harvesting process (WP3). Finally, we aim to review these linkages in WP4. As this topic has not been addressed at such a broad scale previously, we expect that the collective efforts of these top researchers working with the excellent databases that we have amassed will result in a quantum leap in our understanding of the effects of climate change on large mammals. The objective of this proposal is to bring together internationally leading experts on the importance of climate variation on the life history and behavior of large mammals. These large-mammal experts have made major advances in this area through their work on several species of large herbivores. We propose to expand this perspective by bringing this group together with members of the Scandinavian Brown Bear Research Project. We envision a fruitful and long-term cooperation that will result in an in-depth understanding of the effects of climate variation on life history and behavior that will allow us to predict population responses of large mammals generally to ongoing climate change and human harvesting. We predict that the combination of these strong researchers and their extensive datasets at CAS will result in a more comprehensive and integrated cooperation than would be possible through usual interproject cooperation. This cooperation strengthens the scientific environments of the participating Norwegian institutions.

End Report

The CAS year has been extremely productive and motivating. We have finalized 18 papers that are already printed (or in press), and we have 16 papers either submitted or resubmitted after revision. Nevertheless, it is among the 13 titles that is still “in preparation” that we find some of our main achievements and something that would not be possible without the conditions provided by CAS.

Although our aim was to assess the total impact of climate in interaction with harvesting on bears, it was not until our start-up meeting in early September we realized that the analytical framework termed Integral Projection Models (IPMs) provided the methodological platform we needed to achieve our ambitious aims. This was thus partly an unexpected outcome of our first initial meeting.

CAS fellows Richard Bischof and Christophe Bonenfant have taken the lead on the model linking survival and reproduction to body size. Knowledge of demographic rates is crucial for our understanding of population dynamics and thus wildlife management and conservation. For long-lived species, longitudinal individual based monitoring studies represent potential goldmines for the extraction of demographic parameters, including survival and reproduction. However, monitoring studies lasting for decades tend to evolve in terms of approaches and technology, as well as change in intensity and focus, ultimately resulting in a patchwork of information posing a considerable analytical challenge to combine efficiently. In addition, although demographic parameters are constituents of the same population-level processes (e.g. population growth), most studies estimate vital rates through a series of separate analyses, thereby potentially missing interactions and tradeoffs between them.

A core part of our work has thus been to develop a Bayesian multi-state capture recapture model to analyze female brown bear monitoring data from our 30-year monitoring project in Sweden, combining information from physical captures, telemetry, re-sightings, and dead recoveries. We then used this model to jointly estimate cause-specific mortality and reproductive parameters, as well as the effects of various individual, temporal (such as climate), and spatial attributes on these quantities, including the effects of different harvesting regimes. The comprehensive estimation approach revealed pronounced influences of individual attributes and environmental characteristics on both survival and reproduction.

Our efforts revealed that long-term monitoring and joint inclusion of key vital rates into hierarchical estimation models can yield valuable quantitative and structural information about the processes driving the population dynamics of elusive species in a rapidly changing world.

The functions needed for the full IPM is in place. The last function linking body mass through the ontogeny was already available before project stated by CAS fellow Andreas Zedrosser. Therefore, all of the functions that we use in this simulation model to assess how climate and harvesting might impact the bear population, given different climate change scenarios and different management regimes, are now with Tim Coulson. This is a very general framework for testing both ecological and evolutionary responses to different stressors (in addition to climate and harvesting).

The IPM is a model linking individual processes at the level of life history to population level patterns in demographic rates determining dynamics. However, the IPM alone does not go into the mechanisms of how or why climate affect a specific vital rate or life history trait in the bears. Therefore, we have also worked on a series of papers going more in detail on mechanisms. In our effort to further our understanding of the impact of climate on the life history of hunted bears, it was indeed necessary to document food habits and determine if hunting affected the bear’s foraging efficiency, especially on berries in the period of hyperphagia, because predicted climate change is expected to affect berry production negatively. Our earlier work had shown that bears become more nocturnal after meeting a person and after the hunting season started.

The more detailed work on foraging processes and physiological and behavioural responses has allowed us to successfully connect climate to berry production, to connect bear movements, foraging, and life history parameters to berry occurrence, and connect the risk of hunting morality to the bears’ foraging behavior, movements, and habitat use. This gives us an important empirical background on which to interpret results we will obtain from the IPM.

The IPM approach has resulted in an unexpected dividend to the project, by compiling all of the data described above into a single format for this model work. We will continue to update this database, which will certainly be used by PhDs, post docs, and researchers in the bear project in years to come and for a multitude of scientific questions. Such an effort would have been extremely difficult without the CAS year.


  • Bischof, Richard
    Research Fellow Norwegian University of Life Sciences (NMBU) 2015/2016
  • Bonenfant, Christophe Etienne Robert
    Research Fellow Lyon University 2015/2016
  • Cohas, Aurelie
    Research Fellow Lyon University 2015/2016
  • Coulson, Tim Neal
    Professor University of Oxford 2015/2016
  • Loe, Leif Egil
    Professor Norwegian University of Life Sciences (NMBU) 2015/2016
  • Rivrud, Inger Maren
    Postdoctoral Fellow University of Oslo (UiO) 2015/2016
  • Zedrosser, Andreas
    Associate Professor Telemark University College 2015/2016

Previous events


Group leader

  • Atle Mysterud

    Title Professor Institution University of Oslo (UiO) Year at CAS 2015/2016
  • Jon E. Swenson

    Title Professor Institution Norwegian University of Life Sciences (NMBU) Year at CAS 2015/2016