June. 2000 
15 
established that both sexes produce the 
Great Call and also the circumstances 
under which they arc made 
The adult female had been caught 
a year before the male and during this 
period when no male was present she 
had called at intervals of 20-30 days 
for periods of 2-3 days. This is similar 
to the periodicity of observed bouts ot 
copulation at 2-3 week intervals. She 
was last heard to call on 16 December. 
1979; the adult male joined her on 
19 December For the next ten years 
she was never known to call again 
Captive female jaguars and leopards 
have also been known to call only when 
no male is present (G. Peters, pers. comm ) 
While, lor the female, the call has 
to be seen in a sexual context, for the 
male it seems to have mostly territorial 
significance as also observed by 
Richard (1964) The male first called 
8 months after arrival and then in 
response to the taped cal) of the female. 
For the first several months he seemed 
under severe stress. Subsequently he 
reacted to taped calls of any hyrax by 
showing great excitement and himself 
calling. 
When examining the periodicity of 
the male’s call it became evident that 
it was also connected with breeding 
activity Sixty percent of copulation 
periods coincided wiih his most active 
calling periods. This may be because 
of heightened territoriality during 
breeding activity. 
Young males first called at sexual 
maturity aged 20-30 months. 
Although the female called almost 
exclusively by day (50 out of 53 calls) 
all other animals called almost only at 
night. 
In the wild this call is mostly heard 
by night, although there arc reports 
from many areas ot daytime calls In 
one instance free living hyraxes always 
called in response to passing trains 
whistling at midday in the Muguga 
area (John Gulhrie, pers com ). 
The calls are not evenly distributed 
during the night and certain peak times 
are evident. In the present study, in 
the captive animals, two peaks 
occurred during the night, first 
between 2! 00-23:00 hrs and again 
between 2:00-5:00 hrs (Figure 2) 
Similar peaks were found in the free 
living hyrax in Langata. 
Various authors report similar 
periods of calling in the wild, i.e. 
20:00-23:00 hrs (Rohm. 1957). 20 00- 
23:00 hrs and 3:00-5:00 hrs (Kingdom 
1974). 21:00-22 30 hrs and 2:00-3.00 
hrs (Fey. I960). 
Except in the case of the adult 
female, members of the captive colony 
called more when the light was on in 
the hyrax cage and during moonlight 
(n=2!4, 68% light. 32% dark) than 
when it was dark From the free living 
population in Langata. many more 
calls were heard during dark than 
during moonlit nights (30 as opposed 
to 130) This discrepancy between the 
free living and captive populations is 
unclear 
This study cannot answer the 
question of seasonal distribution of 
calls. However. Milner & Harris 
(1999) report that the western tree 
hyrax called more during the dry than 
the wet season, while a report from 
Nanyuki in Kenya indicated more calls 
