An International Polar Year initiative to use predators as indicators of arctic changes

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What is the IPY-Arctic Predators project?

1 main objective and 5 particular objectives

Abstract and key-words of the project

An ecosystem-based approach: linking ecosystem functioning to predator populations

Development of indicator parameters to detect trophic change

A network of field sites

An international team



Main objective

To establish robust monitoring and assessment methods for terrestrial arctic predators to be employed as predictors of tundra ecosystem functionning in a changing climate

5 particular objectives

1 - To elucidate the relation between predator guild structure and food web structure under varying climates and trophic interaction cycles


2 - To establish the arctic fox as a key indicator of tundra food web structure and functioning by developing protocols for determining fox trophic position in time and space


3 - To engage Russian scientists and PhD students as to improve on ecosystem monitoring and research in the vast Russian sector of the circumpolar tundra biome


4 - To provide a legacy from IPY in terms of robust methods for large-scale and long-term monitoring of tundra ecosystems


5 - To initiate what is intended to be a lasting Norwegian-Russian cooperation concerning research and management of tundra ecosystems




Abstract of the project

Strongly cyclic interaction between plants, herbivores and predators typically drives the food web dynamics over large tracts of the arctic tundra biome. These interaction cycles, however, now appear to be fading out at the southern edge of tundra, possibly due to climate warming. The Arctic Climate Impact Assessment (ACIA) highlights this change, if it was to spread further north into the tundra biome, to be one of the key processes by which terrestrial arctic biodiversity and ecosystem functioning could be lost. However, ACIA also acknowledged that there is currently very little research and monitoring that could detect dampened food web cyclicity and predict its consequences. The present IPY project is devoted to improve on this state of affair. Specifically, we will conduct research so as to establish arctic predators as predictors (indicators) of change in food web dynamics, based on the principle that species at the top of food webs often are most vulnerable and/or sensitive to changes. Our main research effort will be to calibrate a number of indicator parameters against data on food web structure from a number of sites distributed circumpolar within the international ArcticWOLVES initiative. The aim is then to establish a robust set of indicators to be used in large-scale/long-term research and monitoring of tundra ecosystem state. We intend to cover a large part of the Russian sector of the tundra biome and to involve (and fund) a large team of Russian ecosystem ecologists and students. The project should represent a boost for Norwegian-Russian cooperation on research and monitoring of tundra ecosystems.



System ecology, food webs, indicators of change, monitoring, trophic interaction cycles, top-down cascades, rain-on-snow events, validation, robustness



trophic structure
Simplified overview of the tri-trophic tundra food web showing a central role of lemming populations

While scientists still debate which trophic interaction drives the lemming cycle, one thing is clear:

The cyclic food web dynamics are essential for the integrity of many tundra ecosystems, both in terms of structure (i.e. maintenance of biodiversity) and functioning (e.g. energy conversion and nutrient recycling) (Ims & Fuglei 2005; Chernov & Matveyeva 1997)

On the background of the importance of the trophic interaction cycles for tundra ecosystem integrity, recent concerns are due to indications that the cycles may be becoming weaker. Indigenous tundra people report "missed lemming peak years" (Callaghan et al. 2004), although such reports cannot be backed up quantitatively due to lack of long-term monitoring in the arctic.

A key question motivating the present proposal is therefore the following: Will the observed dampening of trophic cycles at the south-western fringes of the Euro-Asian arctic spread further north-east into the arctic tundra region? The executive summary of the ACIA processes (ACIA 2004) has highlighted this question as a key issue concerning the fate of arctic terrestrial biodiversity and future tundra ecosystem functioning. Another important conclusion from the ACIA-process is that research and monitoring is too scanty, little focused and uncoordinated to be able to address this issue. Hence, the overarching aim of the ArcticWOLVES  and Arctic Predators initiative within an IPY is to remedy this unfavourable state of affairs by preparing the ground for adequate monitoring and research.

From an international point of view the project will provide tools and insights necessary for elucidating theoretical conjectures regarding tundra ecosystem functioning. The project aims to fill some key gaps in current knowledge, research and monitoring identified by the ACIA (2004). It will address processes and species, highly relevant for conservation of arctic biodiversity as well as provide guidelines for managements of wildlife of aesthetic and economic value to people of the arctic.  The major objective underlying the present proposal is to conduct research aimed at establishing predators as robust indicators of tundra ecosystem state.





We will establish the arctic fox as a key indicator because it is the only mammalian predator exclusive to the tundra biome, where it is omnipresent and a key predator in several respects. Due to the high degree of opportunism (Elmhagen et al. 2000), fox diets and trophic position can possibly be treated as a “blue print” of food web structure. Finally, the retreat of the arctic fox from the southern margin of the tundra biome was one of the first biotic indications of continent wide climate change (Hersteinsson and Macdonald 1992).

snow goose and fox

We estimate population density and reproduction by monitoring arctic fox dens. At several of our project sites, time series of arctic fox breeding and den use are available. We will use harvesting statistics to obtain supplementary information about population dynamics and to build predictive models based on climatic scenarios for forecasting arctic fox population trends and providing advice for harvesting management.

For each site, we will establish the time-specific trophic position of arctic fox through diet analysis (analysis of faeces and stomach contents of harvested foxes) and stable carbon (d13C) and nitrogen (d15N) isotope signatures in different tissues (Kelly 2000; Post 2002).


Tundra ecosystems harbour two main trophic guilds of predators with one specialised on small rodent prey (lemmings and voles) and consists mainly of bird species (raptors) such as the snowy owl, rough-legged buzzard, and three species of skuas (Wiklund et al. 1999). Mammals belonging to this guild are mainly the two small mustelids; i.e. weasel and stoat. It is this guild of “lemming predators” that is most likely to be sensitive to the dampening of the lemming cycle. The other trophic guild consists of generalist predators such as corvids, eagles, wolverine and wolves that frequently scavenge on carcasses of large herbivores (e.g. reindeers) or use subsidies from the marine food webs (i.e. sea birds). Being truly opportunistic predators, foxes (red and arctic foxes) may belong to the lemming predators guild in inland tundra, while in more maritime areas, foxes will be generalists depending more on marine subsidies (Roth 2003). Thus a combination of indicators based on composition and guild position of the entire predator assemblage is likely to reflect the site and time-specific structure of the food web.

We developed a standard protocol to mesure the density of raptor pairs and their breeding propension and success. Densities of small mustelids are assessed by the use of tracking tunnels. Automatic digital cameras will record relative densities of scavengers at 10 established “carcass stations” per field site (see the ecosystem-finnmark website). Predator abundance estimates will provide the primary data for establishing site and time specific predator community structure.

wolverineWolverine at "carcass station" in the varanger pensula


For assessing the predictive power of the different indicator parameters, we will outline food web structure and climate at each field site. We will focus on the two upper trophic levels in the food web (herbivores and predators). We expect to depict food webs at least qualitatively for each site because all sites has a history of ecological research. Moreover, we will estimate the main food web compartments in quantitative terms. For some of the sites (such as Svalbard, Wrangel Island and Varanger peninsula) quantitative biomass and production estimates are already available for some temporally stable food web compartment. To highlight what is crucial missing information, a “gap analysis” has been conducted in a workshop at UiT with all project members being present. Identified gaps will then be filled by supplementary field work.

For all sites temporally varying compartments of the food web need to be quantified each year:
 Small rodents: standardized index trapping and lemming winter nest counts
 Ptarmigan, geese and waders: Colony censuses, line transect counts.
 Large herbivore: Population size and carcass counts

Site-specific past signatures climate and primary productivity will be established by dendrochronological analyses of Cassiope tetragona and use of remote sensing data such as NDVI (Callaghan et al. 1989; Aanes et al. 2002; Pettorelli et al. 2005).

Fox functional responses to prey availability will be estimated in order to adjust for non-linearities between diet and food web structure. Prey biomass will be obtained based on year-specific quantitative information about food web structure at each field site and diets will be obtained from faeces-stomach and stable isotopes analysis.

Stable isotope signatures are used increasingly in ecosystem studies because this method has advantages over conventional diet analysis. It avoids biases resulting from differential digestion of soft versus hard-bodied prey items and integrates information over relatively long window of time rather than just a time snapshot as is the case for stomach or faeces contents. In order to validate the relationship between diets and isotope signatures at different time scales, we will conduct an experiment in which farmed arctic foxes are subjected to experimental diets simulating different food web structures. These validation experiments will be conducted at facilities certified to conduct such experiments at the Norwegian University of Life Sciences (UMB) in cooperation with Dr. Ø. Ahlstrøm.

Each of the indicators will be validated with respect to:
 Reliability: Predictability with respect to food web structure in time and space
 Cost efficiency: Information per effort sampling/analysis
 Complementarity/Redundancy: Degree of exclusive information contents
Based on principles of parsimony and robustness we will jointly assess these indicator criteria to identify adequate set of indicators for future monitoring and research purposes (Yoccoz et al. 2001). This assessment will be based on data from all project field sites obtained from two years (2007 and 2008) of sampling from the 7 primary field sites in this proposal as well as relevant data from sites of the Canadian ArcticWOLVES.





ACIA. 2004. Cambridge University Press

Aanes, R., B. E. Sæther, F. M. Smith, et al. 2002. Ecology Letters 5:445-453

Callaghan, T. V., L. O. Bjorn, Y. Chernov, T. Chapin, T. R. Christensen, B. Huntley, R. A. Ims, M. Johansson, D. Jolly, S. Jonasson, N. Matveyeva, N. Panikov, W. Oechel, and G. Shaver. 2004. Ambio 33:448-458

Chernov, Y. I., and N. V. Matveyeva. 1997 in Wielgolaski, ed. Ecosystems of the World. Elsevier Amsterdam

Elmhagen, B., M. Tannerfeldt, P. Verucci, and A. Angerbjörn. 2000. Journal of Zoology, London 251:139-149

Hersteinsson, P., and D. W. Macdonald. 1992. Oikos 64:505-515

Ims, R. A., and E. Fuglei. 2005. Bioscience 55:311-322

Kelly, J. F. 2000. Canadian Journal of Zoology 78:1-27

Pettorelli, N., J. O. Vik, A. Mysterud, et al. 2005. Trends Ecology and Evolution 20:503-510

Post, D. M. 2002. Ecology 83:703-718

Roth, J. D. 2003. Journal of Animal Ecology 72:668-676

Wiklund, C. G., A. Angerbjörn, E. Isakson, N. Kjellen, and M. Tannerfeldt. 1999. Ambio 28:281-286

Yoccoz, N. G., J. D. Nichols, and T. Boulinier. 2001a. Trends in Ecology and Evolution 16:446-453


university of Moscow




institute of ecology


Norwegian polar institute

nenetski nature reserve



 IPY-Arctic Predators project

Department of Biology, University of Tromsø and Norwegian Polar Institute N-9037 Tromsø, Norway

Phone: +47 77 64 62 72
- Website design by Nicolas Lecomte