The effects of temporal (time of day and season) factors and size, sex, female reproductive state
and group size on the diel time-use of free-ranging red kangaroos (Macropus rufus) was examined.
Particular emphasis was given to the effects on their foraging behaviour, with foraging divided into
cropping, chewing and searching components. The study was conducted in semi-arid western New South
Wales from July 1991 to March 1992, a time of deepening drought conditions in New South Wales.
Group size had very little influence on the time-use of M. rufus. It was negatively but only weakly
correlated with the proportion of foraging time spent chewing (chewing intensity). No significant
differences in time-use were found between size classes of adult males (large and medium-sized males),
females with or without pouch young, or females with different-sized pouch young (no visible young,
small pouch young or large pouch young). Differences occurred between adult males, adult females
and subadult kangaroos. These differences were mainly associated with their chewing and searching
behaviour and were related to body size; as body size increased the proportion of time spent chewing
and the intensity of chewing increased while the proportion of time searching and the proportion of
foraging time spent searching (searching intensity) decreased. Neither the proportion of time spent
cropping or foraging nor the proportion of foraging time spent cropping (cropping intensity) or the
proportion of active time spent foraging (foraging intensity) differed between any size/sex/reproductive
class. Temporal effects had a considerable influence on time-use. M. rufus were most active at night
and in the few hours after sunrise and sunset. Seasonal changes in time-use were largely a result of
changes in daytime behaviour. M. rufus foraged less and rested more during the day in winter than in
spring or summer. There was no increase in the intensity or proportion of time spent foraging or
cropping at night to compensate for the reduction in diurnal foraging. It is hypothesised that temporal
variations in time-use were related to variations in weather and vegetation conditions.
The effects of gregarine parasites, body size, and time of day on spermatophore production and sexual selection in field crickets