Through the taste buds of a large herbivore: foodscape modeling contributes to an understanding of forage selection processes

How large herbivores track resource quantity and quality through time has
formed the core of an abundance of literature on migratory populations in
recent decades. Yet, relating foraging processes and habitat selection
patterns in resident populations, where spatial heterogeneity of food
resources is fine‐grained and/or where the portion of edible plants (i.e.
the foodscape) is low, is challenging. We addressed this issue in a
mountain population of chamois Rupicapra rupicapra, an intermediate
feeder, whose individuals do not migrate. We relied on a rare combination
of data on habitat use of 50 GPS‐collared females and data on the quantity
(biomass) and quality (phenology) of edible resources in their landscape,
derived from field sampling of vegetation, remote sensing, and diet (DNA
barcoding). The foodscape of the chamois was composed of a low proportion
of the available biomass (<17%), including relatively high‐quality
plants, with low spatial covariation between plant phenology and biomass.
Chamois avoided areas with a low edible biomass (where the intake rate may
be too low) and focused on areas with plants at approximately the
flowering stage, whatever the average plant phenological stage available.
Due to this constant preference for flowering plants, home range selection
ratios therefore shifted during the summer from a selection of more
advanced plants in June to their avoidance in August. When the phenology
scores of all plants available, rather than edible plants only, were
considered, areas with relatively more advanced plants were selected all
summer long. This exemplifies that, when traits from edible plants are
different from those of all plants available, it is crucial to consider
the actual foodscape to decipher forage and habitat selection processes.
By integrating species‐specific dimensions of resources in habitat
selection studies, we believe understanding of the foraging processes will
be improved.