Assessing the nutritional consequences of switching foraging behavior in wood bison

Abstract

Diet is one of the most common traits used to organize species of animals into niches.For ruminant herbivores, the breadth and uniqueness of their dietary niche are placed on a spectrum from browsers that consume woody (i.e., browse) and herbaceous (i.e., forbs) plants, to grazers with graminoid-rich diets. However, seasonal changes in plant availability and quality can lead to switching of their dietary niche, even within species. In this study, we examined whether a population of wood bison (Bison bison athabascae) in northeast Alberta, Canada, seasonally switched their foraging behavior, and if so, whether this was associated with changes in nutrient acquisition. We hypothesized that bison should switch foraging behaviors from grazing in the winter when standing, dead graminoids are the only foliar plants readily available to browsing during spring and summer as nutritious and digestible foliar parts of browse and forbs become available. If bison are switching foraging strategy to maximize protein consumption, then there should be a corresponding shift in the nutritional niche.Alternatively, if bison are eating different plants, but consuming similar amounts of nutrients, then bison are switching their dietary niche to maintain a particular nutrient composition. We found wood bison were grazers in the winter and spring, but switch to a browsing during summer. However, only winter nutrient consumption of consumed plants differed significantly among seasons. Between spring and summer, bison maintained a specific nutritional composition in their diet despite compositional differences in the consumed plants. Our evidence suggests that bison are selecting plants to maintain a target macronutrient composition. We posit that herbivore's can and will switch their dietary niche to maintain a target nutrient composition.

CNS Ageing in Health and Neurodegenerative Disorders

“…An association has also been established between several factors, such as reduced physical activity, adolescent obesity and vitamin D deficiency, with telomere shrinkage, as well as a higher risk of MS. This indication is in agreement with the fact that the mechanisms underlying the disease are linked to cellular ageing and senescence which, in general, are further fueled by exacerbated inflammation and oxidative stress [ 102 ]. Over time, inflammation and oxidative stress lead to senescent cell accumulation, subsequently resulting in neurodegeneration and secondary progression of MS [ 103 , 104 ].…”

Is the diet cyclic phase‐dependent in boreal vole populations?

“…The DNA metabarcoding in the present study suggests only modest differences among summer and winter diets. This may suggest that multiple diets exist within a similar nutritional niche (Hecker et al., 2021 ). Other methods in combination are thus needed to assess whether food quality or quantity in winter causes population crashes in voles.…”

“…The DNA metabarcoding in the present study suggests only modest differences among summer and winter diets. This may suggest that multiple diets exist within a similar nutritional niche (Hecker et al, 2021).…”

Small rodent population cycles and plants – after 70 years, where do we go?

“…If rodents can compensate for reduced quality of their main food items by dietary switching to other available foods, they are likely to do so, given that they are known to be flexible in selecting foods (Underwood, 1999; Huitu et al ., 2014). Whether a taxonomic switch of diet is equivalent to a qualitative switch is, however, not clear, as herbivores may select their diet based on phytochemical quality rather than taxonomic composition (Felton et al ., 2021; Hecker, Edwards & Nielsen, 2021). Furthermore, we note that even for specialised herbivores that feed on a narrow range of food items, such as forest lepidopterans, a link between herbivore‐induced plant quality changes and population cycles may not be present (Myers & Cory, 2013).…”

“…However, as the evidence base related to these was very sparse, we cannot confidently conclude that ingestion of phenolic compounds is related to population cycles. While switching to poorer quality food plants in times of scarcity has been observed in other herbivores (Vogel et al, 2020;Hecker et al, 2021), the links between individual-level foraging behaviour and population dynamics are, in general, poorly understood for herbivores [but see DeGabriel et al (2009) for an example of spatial configuration of food quality]. To assess this hypothesis empirically, we propose that future studies focus on rodent feeding ecology during the winter.…”