14 
EANHS Bulletin 30(1) 
living hyraxes of various species 
While periodicity and seasonality of 
the Greai Calls, very loud sounds that 
earn to a considerable distance and 
arc heard mostly at night, have been 
commented on. little is mentioned in 
the literature about any of the other 
vc cassations presented in this paper 
MATERIALS AND METHODS 
A small captive population of southern 
tree hyraxes was studied between 
December 1978 and December 1988 
All sounds except the Great Calls were 
recorded only from this group; some 
Great Calls were also been recorded 
Irom free living animals 
The group consisted of an adult 
male and female and their offspring 
of both sexes from six litters 
Vocalisations were recorded on 
check-sheets a well as on tape- 
recorders Some of the latter were 
subsequently analysed with 
sonograms. 
The tree hyraxes spent most of the 
time in a wire mesh enclosure 8 m x 
3.5 m x 2 4 m high, which was 
separated Irom the observation room 
by a door and louvre windows. During 
observations the door and louvres w ere 
usually opened allowing the animals 
to explore the observation room. 
Night observations were also 
conducted, especially when new-born 
were present. At other times the Great 
Calls were heard in the nearby house 
at night and recorded, although without 
knowing who the caller was. 
Some Great Calls Irom Irec living 
hyraxes around .i house in the Nairobi 
suburb of Langaia were recorded 
during mans nights by one of us (P.F ). 
RESULTS AND DISCUSSION 
Altogether twenty-eight different 
sounds were noted, of which five were 
non-vocally produced. The one most 
often mentioned m the literature is the 
Great Call It is evident when 
comparing tape recordings ot Great 
Calls of the western tree hyrax w ith 
those of the eastern tree hyrax of this 
study, that these calls differ between 
species 
Most other sounds reported here 
can only be heard Irom close-up and 
thus were not recorded by previous 
observers ol wild populations. 
The Great Call 
The Great Call of the southern tree 
hyrax consists of two distinctly 
different sounds Initially there is a 
croak (winding up) averaging 4 
(maximum 16) repetitions, followed by 
a very loud penetrating scream 
averaging 7 8 (maximum 15) repeats. 
II an individual engaged in several 
bouts of screaming, the first call was 
always preceded by a higher number 
of croaks than the subsequent calls. 
Examining the average and 
maximum number of both kinds of 
sounds, individual differences can be 
observed which, together with other 
characteristics ot the sound make it 
probable that the animals recognise the 
individuals calling 
This study has definitely 
