Nature of the beast? Resolving drivers of prey choice, competition and resilience in wolves

Wolves were well-established members of the Pleistocene (Ice Age) carnivore community in Europe but today, many surviving populations of these charismatic animals are endangered because of human persecution and environmental change. As keystone predators, wolves play a vital role in maintaining biodiversity, particularly in keeping mammalian herbivore and medium-sized carnivore numbers in check, thereby limiting over-browsing on vegetation and over-predation on small vertebrates respectively. In this regard, they are the most influential large predator in the northern Palaearctic. The ripples from their activity can therefore be felt in diverse positive ways throughout the ecosystem but serious concerns exist as to the viability of European wolf populations under different scenarios of environmental and climate change. A key goal is therefore to understand how wolves have adapted to changing circumstances so that current and future conservation policy can be appropriately tailored.

One of the best ways to approach this issue is through the study of diet, since this is closely linked to climate and environment (determining which prey species are available) and to competition for resources from other carnivores. Our previous research into the British fossil wolf record revealed marked changes in the size and shape of the jaws and teeth over the last half a million years, which together with evidence from tooth breakage and wear, indicate that wolves modified their diet (consuming more/less meat versus non-meat foods) in response to changing environmental parameters.

Such morphological change cannot readily be measured in the short time scales (years to decades) of modern ecological studies but the rich Pleistocene fossil record offers a chronologically well-resolved series of wolf specimens spanning tens to hundreds of thousands of years, allowing patterns of change to be fully tested against diverse variables such as changing climates, environments, carnivore competition and prey availability. We successfully tested these palaeodietary assumptions in two NERC-funded studies on fossil wolf remains from three different climatic episodes (glacial and interglacial), using direct measurements of bone chemistry through carbon and nitrogen stable isotope analysis in order to verify changing prey choice through time. We now propose to expand this study in what will be the most comprehensive and state-of-the-art examination of diet in modern and recent fossil (<250,000 years) European wolves by using a series of independent proxies operating on different temporal scales.

Working with conservation biologists, a key aim is the integration of morphological and dietary evidence from modern wolves from Sweden, Poland and Croatia, using a combination of GPS data on radio-collared wolves to identify kill sites, analysis of the contents of wolf scats, and stable isotope evidence from recently culled or dead specimens. As well as revealing seasonal and geographical variation in wolf diet, our research will allow for the first time: (1) direct comparison of modern, Holocene and Pleistocene wolf diet; (2) investigation of the degree to which direct (stable isotope, dental microwear) and indirect (morphometric) measurements of diet are in step with real-time dietary evidence from scat analyses and kill sites; (3) evaluation of the influence of diet on the morphology of modern wolves and (4) the opportunity to "ground truth" the evidence generated by current palaeodietary approaches, by assessing whether it replicates that obtained from analyses of modern wolf diet. By understanding the ecological trajectory of past and current wolf populations, we will generate a new, evidence-based view of the impacts on European large carnivores of climate, prey choice and environment.

As well as academic beneficiaries, we will reach new audiences through public outreach at the Wildwood Trust and art commissions for gallery and online display.