Although bighorn sheep rams and male mountain
goats decreased both the time spent foraging and
lying from the pre-rut to the rut, they nonetheless
attempted to spend time in these maintenance
behaviours when less time was required for matingrelated
activities (e.g. Fig. 3), revealing a trade-off
between energy intake and reproduction. It is important
to note, however, that foraging time can only
provide at best a rough approximation of forage
intake and thus energy gain. We chose to use lying
time as a surrogate of ruminating time, although
males do not necessarily spend all their lying time
ruminating. We did this because precise estimates of
ruminating time are difficult to obtain in the field,
especially for long periods, because it requires the
observer to keep permanent eye contact with the
mouth of the animal. However, ruminating time is
typically correlated with lying time, while the
amount of time ruminating when standing is generally
negligible. For instance, in bighorn sheep, males
spend on average 58% of their lying time ruminating
based on 399 focal observations of males aged
1 yr and older observed outside the breeding season
(K. Ruckstuhl, unpubl. data).