Estimating carrion biomass originating from Red deer Cervus elaphus and its ecological effect on vertebrate scavengers in Vestland county, Norway.

Abstract

Ungulates make up the majority of carrion in numerous terrestrial ecosystems. Humans have removed large carnivores from many ecosystems, and carcass waste from human hunting has taken over as the most important source of carrion. Understanding the availability of carrion is therefore crucial for comprehending its ecological impact, and my goal was to assess carrion availability in Vestland county in western Norway. I used literature to calculate the amount of red deer carrion biomass from several different causes, harvest, traffic accidents and other causes of death. I conducted a questionnaire to investigate how hunters use offal and how they treat waste from the harvest. Additionally, I investigated which scavengers that utilized carrion from red deer in an area of Vestland county that had low numbers of apex predators using eleven camera traps. I found that across Norway, a significant amount of biomass from red deer is left available for the scavengers from both the annual hunting season and from other causes of death. I found that the hunters often leave waste from harvest available for the scavengers. Based on camera traps, I found that the three corvid species; crow, raven and magpie are the most abundant scavengers with 95% of all visits. This study showed that hunters in Norway and particularly Vestland county contributed with large amount of carrion through harvest of red deer, in addition to traffic accidents and death by other causes. Carrion is often left available for scavengers and that the most observed scavengers in the study site were corvids. Based on the findings, I expect increased survival of corvids due to large amount of carrion available.