"The diet of a facultative scavenger, the wolverine (Gulo gulo), after recolonization of wolf (Canis lupus) in southern Norway"

• Main Author: Gustavsen, Line
• Other Authors: Atle Mysterud (UIO), Arild Landa (NINA)
• Format: Master Thesis
• Language: English
• Published: 2006
• Subjects: økologi jerv rekolonisering ulv diett-analyse Sør-Norge; VDP::488; Norway; Alces alces; Canis lupus; Gulo gulo; Rangifer tarandus; ulv
• Online Access: http://hdl.handle.net/10852/11728; http://urn.nb.no/URN:NBN:no-14010

Abstract In the recent decades large carnivores have started to recolonize former occupied areas in North America and in Europe. Increases in predator population sizes can affect the whole ecosystem functioning, but little work has been done on this area in Europe, especially when it comes to how scavengers are affected. The wolverine (Gulo gulo) is both a predator and a scavenger, and switches between this two roles. In this study, the wolverines’ diet was investigated in southern Norway based on scats found during winters in 2002 to 2004. My aim was to find out if recolonizing wolves (Canis lupus) might have changed the wolverines’ diet. I also investigated if there were sexual differences in diet in the wolverine population, and if diet varied annually and according to habitat. Moose (Alces alces) stood for 42.3% of the diet, reindeer (Rangifer tarandus) for 29.1% and small game (mainly rodents) for 29.7%. There was a broad structure in the data, and two axes were identified by Principal Component Analysis. The first axis (explaining 49.7% of the variation) was positively correlated with frequency of small game. The second axis (cumulative variance explained 91.7%) was strongly correlated with frequency of occurrence of small game that had been eaten and negatively correlated with the occurrence of both reindeer and (partly) moose that had been eaten. Before the re-colonization of wolves and recent increases in moose density, reindeer was the most important prey for the wolverine, but during the period of this study moose was the most important food source for the overall population. As predicted, the wolverines ate more moose inside than outside of wolf territories, indicating that wolves have increased the availability of moose carrions for wolverines. Females ate more small game than males, and males ate more big game than females. There were also annual variations in the diet but there were no marked variations between the different habitats apart from altitude. This study highlights how recolonization of carnivores can affect the diet of a scavenger by increasing the amount of carrions that are available, and thus change ecosystem functioning in northern habitats.