Effects of canine breakage on tiger survival, reproduction and human-tiger conflict

Human-tiger conflict (HTC) fuels tiger population declines through retaliation killing by local people and government-sanctioned removal of problem individuals. This may have significant impacts on population persistence. In tigers and other large felids, broken canines are often assumed to be an infirmity that leads to HTC, but peer-reviewed literature does not support this. Thus, removal of animals with broken canines from the wild may result in unnecessary mortality. We examined data from wild Amur tigers to establish a baseline for degree of canine breakage in wild tigers not involved in conflict (referred to as 'research tigers'), to test for sex and age-related patterns in canine breakage and to estimate the impacts on survival and reproduction. We further compared canine breakage in research tigers to that in tigers captured or killed in HTC situations (HTC; 'conflict tigers'). We detected no difference (P = 0.76) in the percentage of tigers with broken canines between the two groups (24% in research tigers vs. 27% in conflict tigers) and no difference between sexes (P = 0.84), but the proportion of animals with broken canines increased with age class (P < 0.001). We detected no impact of canine breakage on survival or reproduction of research tigers and four research tigresses produced one to three litters each, despite one to three broken canines. Broken canines were considered a significant health issue in 2 of 17 cases, resulting in depredation in one case. Our data support the premise that broken canines do not usually represent a serious health issue and are usually not related to HTC. The assumption that broken canines lead to HTC appears invalid and may result in tigers being unnecessarily removed from the wild by managers. Similar results have been found for lions and the trend may be true for other large cats and carnivores as well.