People feeding wildlife may interfere with male intrasexual competition: the case study of peri-urban fallow deer

Wildlife populations are continuously altered by humans, whether this be through known drivers like disturbance, habitat modification and loss, recreation and hunting, or via the relatively new phenomenon of artificial feeding. Through the provisioning of anthropogenic food, we are shaping wildlife in ways that we are only beginning to unravel via artificial selection. Artificial feeding may be having particularly profound effects on ruminant species because of their sensitivity to changes in their diet. Wild ruminants such as cervids, are typically highly dimorphic, polygynous species, meaning that during the pre-rut males fight to establish dominance hierarchies that dictate access to females during the core rut when mating occurs. Achieving a high rank during the pre-rut period is heavily dependent on male body size, antler size, and condition. In turn, these factors are influenced by nutrition and energy intake. Therefore, using a population of fallow deer residing in an urban park on the edge of a capital city that are regularly fed by the public, we examined whether artificial feeding is influencing male dominance hierarchies during the pre-rut. Human-wildlife feeding interactions were collected across two summers (2019-2020) and males were ranked via behavioural observations based on their tendency to beg for food from people. In the same years, antler sizes were acquired through non-invasive photogrammetry, and male-male interactions during the entire rut were collected. We analysed all pre-rut interactions and ranked males into a dominance hierarchy. Through path analysis we disentangled the relationships between age, begging rank, antler size, and hierarchy. After accounting for male age and antler size, we found that males with a higher tendency to beg for food occupied a lower position in the male hierarchy – this, however, was recorded in the year when human-deer interactions were higher, suggesting a direct link between artificial feeding and male ability to climb the male hierarchy. This indicates that begging for food is detrimental to male rut performance, and subsequent mating success. We propose that this may be linked to low food quality, gastrointestinal tract abnormalities, and feeding intensity. Our results add to the growing literature on the effects of artificial feeding on wildlife biology and ecology, whilst also highlighting the need for further research in order to fully understand the mechanisms that drive these effects. We also emphasise the need for more regulation into these human-wildlife interactions to mitigate disease risk and injury to both humans and wildlife alike.