Disturbance, recovery and tundra vegetation change : Final report project 17/92 - to Svalbard Environmental Protection Fund

Preprin

Social constraints in cross-boundary collaborative deer management

This study was funded by the Norwegian Research Council as part of the DeerUnit project (Grant number 230275). We are very grateful to all landowners who took part in the survey. We would also like to acknowledge comments from Vebjørn Veiberg on a previous draft.Peer reviewedPublisher PD

Gut microbiome biogeography in reindeer supersedes millennia of ecological and evolutionary separation

publishedVersionpublishedVersio

A Migratory Northern Ungulate in the Pursuit of Spring: Jumping or Surfing the Green Wave?

The forage-maturation hypothesis (FMH) states that herbivores migrate along a phenological gradient of plant development in order to maximize energy intake. Despite strong support for the FMH, the actual relationship between plant phenology and ungulate movement has remained enigmatic. We linked plant phenology (MODIS–normalized difference vegetation index [NDVI] data) and space use of 167 migratory and 78 resident red deer (Cervus elaphus), using a space-time-time matrix of “springness,” defined as the instantaneous rate of green-up. Consistent with the FMH, migrants experienced substantially greater access to early plant phenology than did residents. Deer were also more likely to migrate in areas where migration led to greater gains in springness. Rather than “surfing the green wave” during migration, migratory red deer moved rapidly from the winter to the summer range, thereby “jumping the green wave.” However, migrants and, to a lesser degree, residents did track phenological green-up through parts of the growing season by making smaller-scale adjustments in habitat use. Despite pronounced differences in their life histories, we found only marginal differences between male and female red deer in this study. Those differences that we did detect pointed toward additional constraints on female space-use tactics, such as those posed by calving and caring for dependent offspring.We conclude that whereas in some systems migration itself is a way to surf the green wave, in others it may simply be a means to reconnect with phenological spring at the summer range. In the light of ubiquitous anthropogenic environmental change, understanding the relationship between the green wave and ungulate space use has important consequences for the management and conservation of migratory ungulates and the phenomenon of migration itself

Context-dependent fitness costs of reproduction despite stable body mass costs in an Arctic herbivore

1.The cost of reproduction on demographic rates is often assumed to operate through changing body condition. Several studies have found that reproduction depresses body mass more if the current conditions are severe, such as high population densities or adverse weather, than under benign environmental conditions. However, few studies have investigated the association between the fitness components and body mass costs of reproduction. 2.Using 25 years of individual-based capture–recapture data from Svalbard reindeer Rangifer tarandus platyrhynchus, we built a novel Bayesian state-space model that jointly estimated interannual change in mass, annual reproductive success and survival, while accounting for incomplete observations. The model allowed us to partition the differential effects of intrinsic and extrinsic factors on both non-reproductive mass change and the body mass cost of reproduction, and to quantify their consequences on demographic rates.3. Contrary to our expectation, the body mass cost of reproduction (mean = –5.8 kg) varied little between years (CV = 0.08), whereas the between-year variation in body mass changes, that were independent of the previous year's reproductive state, varied substantially (CV = 0.4) in relation to autumn temperature and the amount of rain-on-snow in winter. This body mass loss led to a cost of reproduction on the next reproduction, which was amplified by the same environmental covariates, from a 10% reduction in reproductive success in benign years, to a 50% reduction in harsh years. The reproductive mass loss also resulted in a small reduction in survival.4. Our results show how demographic costs of reproduction, driven by interannual fluctuations in individual body condition, result from the balance between body mass costs of reproduction and body mass changes that are independent of previous reproductive state. We illustrate how a strong context-dependent fitness cost of reproduction can occur, despite a relatively fixed body mass cost of reproduction. This suggests that female reindeer display a very conservative energy allocation strategy, either aborting their reproductive attempt at an early stage or weaning at a relatively constant cost. Such a strategy might be common in species living in a highly stochastic and food limited environment

A summer heatwave reduced activity, heart rate and autumn body mass in a cold-adapted ungulate

Acknowledgements. We are grateful for the feedback from Robyn Hetem and two anonymous reviewers for their constructive inputs. We thank Clare Stawski and Murray M. Humphries for commenting on an earlier version of this work. Field work would not be possible without the collaboration with the Reindeer Herders’ Association and local support from Mika Tervonen, Unto Paadar and Jukka Siitari, and field assistants Elise Tjørnsletten, Kine Øren and Erlend Søby. Veterinarians Marja Nourgam and Amanda Høyer Boesen contributed to the anaesthesia and surgery of the reindeer. We thank Asgeir Bjarnason at Star-Oddi LTD for help and guidance with biologger programming and data processing, and Larissa Beumer for advice on the HMM approach. Cassandra Ugland validated the HR measurements. The work was supported by the Norwegian Research Council grant number 267613 and 315454.Peer reviewedPostprin

Congruent responses to weather variability in high arctic herbivores

Assessing the role of weather in the dynamics of wildlife populations is a pressing task in the face of rapid environmental change. Rodents and ruminants are abundant herbivore species in most Arctic ecosystems, many of which are experiencing particularly rapid climate change. Their different life-history characteristics, with the exception of their trophic position, suggest that they should show different responses to environmental variation. Here we show that the only mammalian herbivores on the Arctic islands of Svalbard, reindeer (Rangifer tarandus) and sibling voles (Microtus levis), exhibit strong synchrony in population parameters. This synchrony is due to rain-on-snow events that cause ground ice and demonstrates that climate impacts can be similarly integrated and expressed in species with highly contrasting life histories. The finding suggests that responses of wildlife populations to climate variability and change might be more consistent in Polar regions than elsewhere owing to the strength of the climate impact and the simplicity of the ecosystem

Stress responses to repeated captures in a wild ungulate

While capture-mark-recapture studies provide essential individual-level data in ecology, repeated captures and handling may impact animal welfare and cause scientific bias. Evaluating the consequences of invasive methodologies should be an integral part of any study involving capture of live animals. We investigated short- and long-term stress responses to repeated captures within a winter on the physiology, behaviour, and reproductive success of female Svalbard reindeer (Rangifer tarandus platyrhynchus). Short-term responses were evaluated using serum concentrations of glucocorticoids and catecholamines during handling, and post-release recovery times in heart rate and activity levels. Repeated captures were associated with an increase in measured catecholamines and glucocorticoids, except cortisone, and delayed recovery in heart rate but not activity. Four months later, in summer, individuals captured repeatedly in winter exhibited a small increase in behavioural response to human disturbance and had a lower probability of being observed with a calf, compared to animals not captured, or captured only once. Our findings imply that single annual capture events have no significant negative consequences for Svalbard reindeer, but repeated captures within a season may impact offspring survival in the same year. Such unanticipated side effects highlight the importance of addressing multiple indicators of animal responses to repeated captures

Determinants of heart rate in Svalbard reindeer reveal mechanisms of seasonal energy management

Funding. This study was supported by Norges Miljø- og Biovitenskape- lige Universitet (PhD Grant to L.M.T.) and Norges Forskningsråd (KLIMAFORSK project no. 267613). Acknowledgements. We thank two anonymous reviewers for constructive, detailed and insightful feedback that helped to strengthen our manuscript. We thank Mads Forchhammer and the logistics department at the University Centre in Svalbard for supporting the field campaigns. We also thank DVM Amanda Høyer Boesen for assistance with surgeries in 2018. Åshild Ø. Pedersen and Stein Tore Pedersen contributed to successful field campaigns. We are grateful for the technical support received from Ásgeir Bjarnason at StarOddi Ltd during logger programming and validations of recordings. Finally, we thank Lucy Hawkes, Andreas Fahlman and Katsufumi Sato for inviting us to contribute to the theme issue ‘Measuring physiology in free-living animals’.Peer reviewedPublisher PD