Does artificial feeding impact neonate growth rates in a large free-ranging mammal?

Abstract

Variation and disparity in resource access between individuals in an animal population within human-dominated landscapes require attention as artificial selection processes may be at work. Independent, recreational human–wildlife feeding interactions constitute an increasingly prevalent, yet understudied, food resource for birds and mammals living in our cities. However, only a limited number of risk-taking individuals may access it. Using urban fallow deer as our model species, we hypothesized that if these interactions result in positive effects for the engaging individual, e.g. increased milk quality and yield, then this would result in the increased growth rates of their offspring. Alternatively, if these individuals were prioritizing investing time in engagement with humans, resulting in decreased maternal care, then this would result in slower growth rates in their offspring. We found that the offspring of those females that regularly interacted with humans displayed significantly faster growth rates than their risk-adverse counterparts. This advantage for fearless mothers in terms of boosted neonatal growth rates could be mirrored in birds accessing garden feeders, seagulls or pigeons utilizing urban resources, or seals approaching city harbours. Here, we add a new piece to the complex puzzle of how humans are impacting wildlife living within human-dominated landscapes.

Do human–wildlife interactions predict offspring hiding strategies in peri-urban fallow deer?

“…Previous studies have shown that extractive activities like hunting and fishing are pushing selection towards less desirable traits in wild animals [64]. Based on our bedsite selection findings coupled with previous findings of increased fawn birth weights and growth rates [7,32,48], consistent beggar mothers seem to have higher reproductive success than their conspecifics that beg less. It could be argued that feeding activities promote the artificial selection of bolder begging behaviours [7,12].…”

“…Previous research has also shown that prolonged nursing occurs in heavier offspring in other ungulates [62]. Combining these early-life characteristics of higher birth weight and faster growth rates [7,32,48] with our findings about bedsite characteristics (low visibility) and location (more distant from humans and their dogs compared with the other females in this population) [34], the offspring of bolder mothers are consistently awarded multiple survival advantages (to be further explored by future research) from in utero to young adult life stages. This provides evidence that begging mothers are better adapted to this environment than shyer females.…”

“…Social grooming can occur either from mother to fawn or fawn to mother. We confirmed a mother-fawn pair after three independent sightings (not occurring in the same observation period) involving one or a combination of these interactions [32]. We only included fawns that had a confirmed mother-fawn pairing as our aim was to investigate whether a mother's begging rank affected her fawn's bedsite location.…”

Fawn bedsite selection by a large ungulate living in a peri-urban area

“…an objective proxy for age sensu Amin et al (2021), determined by placing the fawn into a 100-litre bag, which was weighed using a digital scale – resolution: 0.01 kg, Dario Markenartikelvertrieb); GPS coordinates of the bedsite (using a Garmin etrex 30 hand-held unit); and bedsite visibility (see below for full description). Fawns were routinely recaptured to monitor body growth (Griffin et al, 2023), allowing us to collect bedsite characteristics in older fawns. Our final database consisted of fawn capture data collected in 2018 (n = 102 individual fawns), 2019 (n = 81), and 2020 (n = 100).…”

Should we feed wildlife? A call for further research into this recreational activity

“…If engagement with feeding interactions is not random, and instead is driven by behavioral type, then they may also only be occurring in a subset of the population. Recent studies have indicated that independent feeding of wildlife can impact the weight and growth rates of offspring (Griffin, Haigh, et al, 2023; Griffin, Haigh, Amin, et al, 2022) (Figure 2) and that the resultingly larger neonates have increased survival rates (Amin et al, 2022). This highlights the potential that artificial selection may be at work and we may involuntarily be manipulating wild populations.…”