We test predictions about differences in the foraging behaviors of mal
e and female giraffes (Giraffa camelopardalis tippelskirchi Matchie) t
hat derive from a hypothesis linking sexual size dimorphism to foragin
g behavior. This body-size hypothesis predicts that males will exhibit
specific behaviors that increase their dry-matter intake rate relativ
e to females. Foraging behavior was examined at two hierarchical level
s corresponding to two spatial and temporal scales, within patches and
within habitats. Patches are defined as individual trees or shrubs an
d habitats are defined as collections of patches within plant communit
ies. Males were predicted to increase dry-matter intake rate within pa
tches by taking larger bites, cropping bites more quickly, chewing les
s, and chewing faster. Within habitats, males were expected to increas
e intake rate by increasing the proportion of foraging time devoted to
food ingestion as opposed to inter-patch travel time and vigilance. T
he predictions were tested in a free-ranging population of giraffes in
Mikumi National Park, Tanzania. Males spent less total time foraging
than females but allocated a greater proportion of their foraging time
to forage ingestion as opposed to travel between patches. There was n
o sex difference in rumination time but males spent more time in activ
ities other than foraging and rumination, such as walking. Within patc
hes, males took larger bites than females, but females cropped bites m
ore quickly and chewed faster. Males had longer per-bite handling time
s than females but had shorter handling times per gram of intake. With
in habitats, males had longer average patch residence times but there
was There was no overall difference between sexes in vigilance while f
oraging, although there were significant sex by habitat and sex by sea
son interactions. Although not all the predictions were confirmed, ove
rall the results agree qualitatively with the body-size hypothesis. Se
x-related differences in foraging behavior led to greater estimated in
take rates for males at the within-patch and within-habitat scales.