| dc.description.abstract | The research described in this thesis
was carried out between June 1968 and May ,
1969 in an area of approximately 10.14
square kilometres in the plains of'Nairobi
'National Park. Of this area abo~~ 4074
square kilometres are covered by vegetation
suitable for giraffe browsing. From vegetation
and giraffe distribution maps that were
prepared it is evident that Acacia drepanolobium
savanna and woodland/thicket are the
main feeding zones for giraffe. The density
of giraffe in the area was approximately one
per square kilometre.
When browsing? giraffe either break off
twigs with their tongues or bite off separate
leaves with their teeth. All types of trees
bushes and f,orbs are eaten? but long strands
of vegetation are not able to be ingested
It was found that giraffe spend 50 - 100
secollds browsing each bush of A .•drepanolobiumo
The exact time spent browsing on this speciesp
and others, is dependant upon the number of
young shoots availble per tree The shape
of the different small trees and bushes also
affects the browsing time. Generally less
browse is available on ,an individual flat topped
apecfea such as !.drepanolobium than on
II
other more rounded bushes; -therefore a longer
period of time is spent browsing each bush of
the latter type. An average of 557 shoots per
hour of A.drepanolobium are eaten during continuous
feeding. The browse also provides most
of the water a giraffe requires, and drinking
was rarely seen.
Rumination periods last from a few minutes
to over an hour. The longest period of rumination seen was for 75 minutes. Chewing is at
the rate of about one chew per second
The daily activity from month to month
was very variable9 but a basic feeding pattern
was recognized. At daybreak there was little
feeding activity but by 07000 hours feeding
reached a peak for the daY9 7701% of all activity
at this time was feeding This level decreases
through the morning to a minimum of feeding just after noon. During the afternoon and
evening feeding steadily increases again Giraffe
spent on average 63.9~ of the day feeding
The amount of ruminating is inversely related to browsing, and the peak rumination
period is between 12.00 and 13000 hours During
the study, as a whole9 13.2% of the day was spent
ruminating. The remaining 2289% of the d~y was
filled by "other activities" such as walkingp
which activities occur~ed at a constant level
throughout the day. During the hours of darkIII
'ness browsing appeared to be much r-e duc ed ,
The commonest plant in the area was
A.drepanolobium which was also the key
browse species and 60.7% of all browsing
was on this species. Contrary to popular
belief the long neck of the giraffe is
not necessarily used for browsing tall
trees and if more succulent browse is
available at a level below head height
this will be chosen. The commonest
height at which feeding was seen was between
0.5 - 2.0 metres, and this category
included the majority of A0drepanolobium
bushes.
Changes in the weather during the wet
season can cause a shift in the diet from
A.drepanolobium to other larger bushes
and the height at which feeding occurs
as correspondingly r-af aed , As the young
browse is removed from the tops of the
bushes the height of feeding become. lowero
During the dry season when there was little
succulent browse available Aedrepanolobium
was again the main browse species. ·There
was maximum browsing on !.drepanolobium
when precipitation was such that new growth
was stimulated but the firm condition of
the clay soil did not deteriorate and hinder
v
ceased in both these species
From experimental ex closures it was
snown tha'~ browse production of ~oglabra a~
4-,,0 metr..,s was greater than that at .200 metres
on the same busho
It was estimated that-female giraffe
consume about 607 kilograms of green browse
per day~ It seems that provided that the
habitat is maintained in its present state 1
and provided that the movement of giraffe
is not restricted there will be no danger
from over browsing. | en |
