Elephants Elephants - Wildpro - Twycross Zoo

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vocalisation when in oestrus (Poole 1999) ‘the oestrus call’. Thus females can
communicate their reproductive state by olfactory, visual and auditory means.
Both Asian and African male elephants exhibit a condition known as musth.
When in musth males have elevated levels of testosterone (Cooper et al 1990),
aggression and reproductive activity (Poole and Moss 1981) (Poole et al 1984)
(Dickerman and Zachariah 1997) (Niemuller 1991). The discharge of fluid
from the temporal gland increases and is continuous; the penis develops a
greenish colouration and dribbles a mucous discharge; they also vocalize
frequently. It has been shown that males emit volatile compounds from the
temporal gland which may inform other bulls and cows of their condition
(Rasmussen et al 1990) (Rasmussen 1997). There are many questions as to the
function of musth (Wingate and Lasley 2001) and a suggestion that it may be a
relatively recent phenomenon in the African species (Rasmussen et al 1990). In
Amboseli no male under 24 years of age has been seen in musth and bouts of
musth among individuals of the 25-35 age group are short and sporadic, while
older males have longer bouts lasting several months (Poole 1989a). This
work has also shown that the number of males in musth correlates closely
with the number of oestrus females and is highest during the rainy season,
when females are more likely to ovulate. Information from Sri Lanka (Kurt,
pers com) and India (Desai and Johnsingh 1995) show that bulls over 20 years
of age have longer musth periods and that bulls have individual periods of
musth. Both Asian and African bulls settle into a regular cycle of musth with
increasing age.
It has recently been demonstrated that the chemical composition of musth
males changes with age in Asian elephants (Rasmussen et al 2002); youngest
males (8-13 yrs) exhibited a honey like odour which changes to a more foulsmelling
compound as animals mature (25-35 age group). Elephants can
therefore distinguish between older and younger musth males.
It has been shown that females can distinguish, by olfaction, between musth
and non-musth males and also that they are more responsive during the
follicular stage of the oestrus cycle (Ganswindt et al 2005) (Schulte and
Rasmussen 1999). Oestrus females enter into consortship with a musth male
who guards her from copulatory attempts from lower ranking males. Females
also prefer older musth males and males in musth rank above non-musth
males in agonistic interactions (Poole 1989a). Thus in the Amboseli
population, males did not complete successfully for females until they were 25
or older and large musth males of over 35 were more frequently seen
guarding females mid-oestrus. Males may check the reproductive state of
females by putting the trunk tip to the vulval opening and then inserting it in
the mouth, the elephant equivalent of flehmen.
Copulation is rapid, the male mounts the female from the rear and mounting
and copulation take on average 45 seconds (Estes 1991). Females may give a
low frequency post-copulatory call (Poole 1989b).