Another hypothesis developed within the framework
of optimal foraging theory and termed the
‘energy-saving’ hypothesis, predicts that male ungulates
with time consuming mating tactics should
allocate most of their non-rutting time to lying
instead of foraging, as the efficiency to assimilate
energy (e.g. from poor-quality plants at this period
of the year) may fall below the level necessary to
reach basal energetic requirements (Willisch & Ingold
2007). More specifically, because male ungulates
are likely constrained to maintain a cyclic
pattern of forage intake and rumination to assimilate
energy (Robbins 1993) and rutting activities possibly
disrupt that cycle, males should minimise their
energy expenditures by lying more than foraging, as
the costs of foraging are potentially greater than the
energy gains. This strategy was suggested to explain
the greater proportion of non-rutting time spent
lying instead of foraging by male Alpine chamois
(Rupicapra rupicapra, Willisch & Ingold 2007).