Diet selection and asocial learning: Natal habitat influence on lifelong foraging strategies in solitary large mammals

Abstract

Exploring the process of diet selection will contribute to improvement in our understanding of animal foraging strategies. The overwhelming majority of ecological research on animal learning and foraging concentrates on how social learning influences the feeding styles of animals living in groups. In solitary animals that live long after independence from their mothers, foraging experience after independence is expected to have a significant influence on diet selection, but few studies have addressed this point. We used brown bears (Ursus arctos), which spend 1–2 years with their mothers before foraging alone, as a model species and investigated how their diet changed later in life. We estimated the diets of bears at the individual level by using stable isotope analysis of guard hairs and examined the factors that drove dietary variation. We also quantified the extent to which the diets of bears shifted by comparing the diets of bears at the time of capture with the average diet in their natal habitat. Our results indicated that females retained the average diet of their natal habitat, whereas the diets of males significantly changed more than 6 years after becoming independent from their mothers, when they reached physical maturity. Males were dependent on energy‐rich marine animals at older ages regardless of their natal habitats, which we attribute to several factors, including habitat exploration, acquisition of foraging experience, and social dominance. Our results provide the first evidence, suggesting that foraging experience after independence influences diet selection later in life in solitary large mammals.

Ontogeny shapes individual specialization

“…Foraging behavior that causes conflict with humans has also been shown to change in ursids over their lifetimes, remarking the crucial role of individuality and plasticity in behavior 53 . Social learning from the mother of behavior 54 , including individual specialization and foraging on anthropogenic food resources, has been previously observed in ursids 55, 56, 57, 58 . However, none of these studies tracked offspring diet over their lifetimes or were able to simultaneously account for the mother’s diet, genetics, the environment, and other maternal effects that could explain similar patterns of individual specialization.…”

“…Maternal learning of behavior [46], including dietary specialization and foraging on anthropogenic food resources is commonly observed in ursids [47][48][49][50]. However, none of these studies tracked offspring diet over their lifetimes or were able to simultaneously account for the mother's diet, genetics, the environment, and other maternal effects, that could explain similar patterns of dietary specialization.…”

Age estimation based on blood DNA methylation levels in brown bears

“…Additionally, foraging strategies differ among individuals even within a population (Jimbo et al, 2022;Servheen & Gunther, 2022). Factors linked to lifestyle, including obesity, weight reduction, and overfeeding, have been suggested to affect DNA methylation (Samblas et al, 2019;Yamazaki et al, 2021) Wilkinson & South, 2002).…”

“…One possible reason for this difference is that captive bears are fed the same type and quantity of food throughout the year in a stable environment, whereas wild bears consume a variety of foods in differing quantities depending on the season (Naves et al, 2006; Shirane et al, 2021). Additionally, foraging strategies differ among individuals even within a population (Jimbo et al, 2022; Servheen & Gunther, 2022). Factors linked to lifestyle, including obesity, weight reduction, and overfeeding, have been suggested to affect DNA methylation (Samblas et al, 2019; Yamazaki et al, 2021).…”

Ontogeny shapes individual specialization

“…Foraging behavior that causes con ict has also been shown to change in ursids across life time, remarking the crucial role of individuality and plasticity in behavior 46 . Maternal learning of behavior 47 , including dietary specialization and foraging on anthropogenic food resources is commonly observed in ursids 48,49,50,51 . However, none of these studies tracked offspring diet over their lifetimes or were able to simultaneously account for the mother's diet, genetics, the environment, and other maternal effects, that could explain similar patterns of dietary specialization.…”