Cross-continental differences in patterns of predation: will naive moose in Scandinavia ever learn?

Abstract

Predation has been recognized as a major selective force in the evolution of behavioural characteristics of mammals. As a consequence of local predator extinction, prey may lose knowledge about natural predators but usually express behavioural adjustments after return of predators. Human harvest may replace natural predation but prey selection may differ from that of natural predators leading to a change in the behavioural response of prey. We show that hunting success (HS) of re-colonizing wolves (Canis lupus) on moose (Alces alces) in Scandinavia was higher than reported in North America, where moose have been continuously exposed to wolves and grizzly bears. We found no evidence that moose expressed behavioural adjustments that lowered the HS of wolves in territories that had been occupied by wolves for up to 21 years. Moose behaviour towards wolves and humans typically differs in Scandinavia compared to North America. We explain the differences found to be caused by variation in predation pressure by large carnivores and the rate, and mode, of human harvest during the twentieth century.

Decomposing risk: Landscape structure and wolf behavior generate different predation patterns in two sympatric ungulates

“…Although our study does not allow us to fully reveal the underlying mechanism generating such a constant trend in predation efficiency, it still supports previous findings (Sand et al 2006) about the naı¨ve nature of Scandinavian moose and about the lack of a behavioral adjustment by moose in response to wolf predation, and the more general finding that large-bodied ungulates have a reduced behavioral response when exposed to predation from cursorial predators (Thacker et al 2011). Other potential explanations are available, but less likely to be the main drivers of the whole process.…”

“…Other potential explanations are available, but less likely to be the main drivers of the whole process. Prey animals under nutritional limitation, especially when living in herds, have been shown to strongly reduce their response to predators , Winnie and Creel 2007, Vijayan et al 2012, but moose in our study area are not likely to experience significant nutritional constraints (Sand et al 2012) or density dependence (Sand et al 2006, Grøtan et al 2009). …”

“…In the majority of the territories, moose was the dominant prey species (60-100%), with the exception of two territories (Hasselfors and Riala), in which roe deer constituted 70% and 95% of all ungulates killed. Procedures for capturing and handling wolves, and for cluster identification, are described in Sand et al (2005Sand et al ( , 2006Sand et al ( , 2008 and Zimmermann et al (2007). Details about the wolf territories included in the study are provided in Appendix A.…”

“…Although this process is generally supported as an effective way to promote biodiversity and to restore the complexity of trophic interactions inside ecosystems (Treves and Karanth 2003), it also poses a series of potential threats to the status of the preexisting ungulate populations, which often have lived in the absence of natural predation for several generations, and are therefore often claimed to have become more vulnerable (Berger et al 2001, Sand et al 2006. Moreover, global change and the impact of human activities on natural ecosystems are rapidly changing the characteristics of the environments in which such recolonization processes are occurring (Karl and Trenberth 2003).…”

The good bad wolf—wolf evaluation reveals the roots of the Finnish wolf conflict

“…Because large carnivores were few, hunting played a key role in controlling ungulate populations. As a consequence of the wolf_s long absence, the moose is poorly adapted to predation by wolves and is relatively easy prey for them (Sand et al 2006b). …”